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Server-less Python Web Services for AWS Lambda and API Gateway

Project description

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Zappa - Serverless Python

|Build Status| |Coverage| |PyPI| |Slack| || |Patreon|

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- `About <#about>`__
- `Installation and Configuration <#installation-and-configuration>`__

- `Running the Initial Setup /
Settings <#running-the-initial-setup--settings>`__

- `Basic Usage <#basic-usage>`__

- `Initial Deployments <#initial-deployments>`__
- `Updates <#updates>`__
- `Rollback <#rollback>`__
- `Scheduling <#scheduling>`__
- `Undeploy <#undeploy>`__
- `Package <#package>`__
- `Template <#template>`__
- `Status <#status>`__
- `Tailing Logs <#tailing-logs>`__
- `Remote Function Invocation <#remote-function-invocation>`__
- `Django Management Commands <#django-management-commands>`__
- `SSL Certification <#ssl-certification>`__

- `Executing in Response to AWS
Events <#executing-in-response-to-aws-events>`__
- `Asynchronous Task Execution <#asynchronous-task-execution>`__
- `Task Sources <#task-sources>`__
- `Direct Invocation <#direct-invocation>`__
- `Restrictions <#restrictions>`__
- `Advanced Settings <#advanced-settings>`__

- `YAML Settings <#yaml-settings>`__

- `Advanced Usage <#advanced-usage>`__

- `Keeping The Server Warm <#keeping-the-server-warm>`__
- `Serving Static Files / Binary
Uploads <#serving-static-files--binary-uploads>`__
- `Enabling CORS <#enabling-cors>`__
- `Large Projects <#large-projects>`__
- `Enabling Bash Completion <#enabling-bash-completion>`__
- `Enabling Secure Endpoints on API
Gateway <#enabling-secure-endpoints-on-api-gateway>`__
- `API Key <#api-key>`__
- `IAM Policy <#iam-policy>`__
- `API Gateway Authorizers <#api-gateway-authorizers>`__
- `Cognito User Pool Authorizer <#cognito-user-pool-authorizer>`__
- `Deploying to a Custom Domain Name with SSL
Certificates <#deploying-to-a-custom-domain-name-with-ssl-certificates>`__
- `Deploying to a Domain With a Let's Encrypt Certificate (DNS
Auth) <#deploying-to-a-domain-with-a-lets-encrypt-certificate-dns-auth>`__
- `Deploying to a Domain With a Let's Encrypt Certificate (HTTP
Auth) <#deploying-to-a-domain-with-a-lets-encrypt-certificate-http-auth>`__
- `Deploying to a Domain With Your Own SSL
Certs <#deploying-to-a-domain-with-your-own-ssl-certs>`__
- `Deploying to a Domain With AWS Certificate
Manager <#deploying-to-a-domain-with-aws-certificate-manager>`__
- `Setting Environment Variables <#setting-environment-variables>`__
- `Local Environment Variables <#local-environment-variables>`__
- `Remote Environment Variables <#remote-environment-variables>`__
- `API Gateway Context Variables <#api-gateway-context-variables>`__
- `Catching Unhandled Exceptions <#catching-unhandled-exceptions>`__
- `Using Custom AWS IAM Roles and
Policies <#using-custom-aws-iam-roles-and-policies>`__
- `Globally Available Server-less
Architectures <#globally-available-server-less-architectures>`__
- `Raising AWS Service Limits <#raising-aws-service-limits>`__
- `Using Zappa With Docker <#using-zappa-with-docker>`__
- `Dead Letter Queues <#dead-letter-queues>`__

- `Zappa Guides <#zappa-guides>`__
- `Zappa in the Press <#zappa-in-the-press>`__
- `Sites Using Zappa <#sites-using-zappa>`__
- `Related Projects <#related-projects>`__
- `Hacks <#hacks>`__
- `Contributing <#contributing>`__

- `Using a Local Repo <#using-a-local-repo>`__

- `Patrons <#patrons>`__
- `Support / Development / Training /
Consulting <#support--development--training--consulting>`__

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In a hurry? Click to see (now slightly out-dated) slides from Serverless

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**Zappa** makes it super easy to build and deploy all Python WSGI
applications on AWS Lambda + API Gateway. Think of it as "serverless"
web hosting for your Python apps. That means **infinite scaling**,
**zero downtime**, **zero maintenance** - and at a fraction of the cost
of your current deployments!

If you've got a Python web app (including Django and Flask apps), it's
as easy as:


$ pip install zappa
$ zappa init
$ zappa deploy

and now you're server-less! *Wow!*

What do you mean "serverless"?

Okay, so there still is a server - but it only has a *40 millisecond*
life cycle! Serverless in this case means **"without any permanent

With a traditional HTTP server, the server is online 24/7, processing
requests one by one as they come in. If the queue of incoming requests
grows too large, some requests will time out. With Zappa, **each request
is given its own virtual HTTP "server"** by Amazon API Gateway. AWS
handles the horizontal scaling automatically, so no requests ever time
out. Each request then calls your application from a memory cache in AWS
Lambda and returns the response via Python's WSGI interface. After your
app returns, the "server" dies.

Better still, with Zappa you only pay for the milliseconds of server
time that you use, so it's many **orders of magnitude cheaper** than
VPS/PaaS hosts like Linode or Heroku - and in most cases, it's
completely free. Plus, there's no need to worry about load balancing or
keeping servers online ever again.

It's great for deploying serverless microservices with frameworks like
Flask and Bottle, and for hosting larger web apps and CMSes with Django.
Or, you can use any WSGI-compatible app you like! You **probably don't
need to change your existing applications** to use it, and you're not
locked into using it.

Zappa also lets you build hybrid event-driven applications that can
scale to **trillions of events** a year with **no additional effort** on
your part! You also get **free SSL certificates**, **global app
deployment**, **API access management**, **automatic security policy
generation**, **precompiled C-extensions**, **auto keep-warms**,
**oversized Lambda packages**, and **many other exclusive features**!

And finally, Zappa is **super easy to use**. You can deploy your
application with a single command out of the box!


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Installation and Configuration

*Before you begin, make sure you are running Python 2.7 or Python 3.6
and you have a valid AWS account and your `AWS credentials
file <>`__
is properly installed.*

**Zappa** can easily be installed through pip, like so:


$ pip install zappa

Please note that Zappa ***must*** be installed into your project's
environment <>`__.

*(If you use `pyenv <>`__ and love to
manage virtualenvs with **pyenv-virtualenv**, you just have to call
``pyenv local [your_venv_name]`` and it's ready.
`Conda <>`__ users should comment
`here <>`__.)*

Next, you'll need to define your local and server-side settings.

Running the Initial Setup / Settings

**Zappa** can automatically set up your deployment settings for you with
the ``init`` command:


$ zappa init

This will automatically detect your application type (Flask/Django -
Pyramid users `see
here <>`__)
and help you define your deployment configuration settings. Once you
finish initialization, you'll have a file named *zappa\_settings.json*
in your project directory defining your basic deployment settings. It
will probably look something like this for most WSGI apps:

.. code:: javascript

// The name of your stage
"dev": {
// The name of your S3 bucket
"s3_bucket": "lmbda",

// The modular python path to your WSGI application function.
// In Flask and Bottle, this is your 'app' object.
// Flask (
// app = Flask()
// Bottle (
// app = bottle.default_app()
"app_function": ""

or for Django:

.. code:: javascript

"dev": { // The name of your stage
"s3_bucket": "lmbda", // The name of your S3 bucket
"django_settings": "your_project.settings" // The python path to your Django settings.

*Psst: If you're deploying a Django application with Zappa for the first
time, you might want to read Edgar Roman's `Django Zapp
Guide <>`__.*

You can define as many stages as your like - we recommend having *dev*,
*staging*, and *production*.

Now, you're ready to deploy!

Basic Usage

Initial Deployments

Once your settings are configured, you can package and deploy your
application to a stage called "production" with a single command:


$ zappa deploy production
Your application is now live at:

And now your app is **live!** How cool is that?!

To explain what's going on, when you call ``deploy``, Zappa will
automatically package up your application and local virtual environment
into a Lambda-compatible archive, replace any dependencies with versions
`precompiled for
Lambda <>`__, set up the
function handler and necessary WSGI Middleware, upload the archive to
S3, create and manage the necessary Amazon IAM policies and roles,
register it as a new Lambda function, create a new API Gateway resource,
create WSGI-compatible routes for it, link it to the new Lambda
function, and finally delete the archive from your S3 bucket. Handy!


If your application has already been deployed and you only need to
upload new Python code, but not touch the underlying routes, you can


$ zappa update production
Your application is now live at:

This creates a new archive, uploads it to S3 and updates the Lambda
function to use the new code, but doesn't touch the API Gateway routes.


You can also ``rollback`` the deployed code to a previous version by
supplying the number of revisions to return to. For instance, to
rollback to the version deployed 3 versions ago:


$ zappa rollback production -n 3


Zappa can be used to easily schedule functions to occur on regular
intervals. This provides a much nicer, maintenance-free alternative to
Celery! These functions will be packaged and deployed along with your
``app_function`` and called from the handler automatically. Just list
your functions and the expression to schedule them using `cron or rate
syntax <>`__
in your *zappa\_settings.json* file:

.. code:: javascript

"production": {
"events": [{
"function": "your_module.your_function", // The function to execute
"expression": "rate(1 minute)" // When to execute it (in cron or rate format)

And then:


$ zappa schedule production

And now your function will execute every minute!

If you want to cancel these, you can simply use the ``unschedule``


$ zappa unschedule production

And now your scheduled event rules are deleted.

See the `example <example/>`__ for more details.

Advanced Scheduling

Sometimes a function needs multiple expressions to describe its
schedule. To set multiple expressions, simply list your functions, and
the list of expressions to schedule them using `cron or rate
syntax <>`__
in your *zappa\_settings.json* file:

.. code:: javascript

"production": {
"events": [{
"function": "your_module.your_function", // The function to execute
"expressions": ["cron(0 20-23 ? * SUN-THU *)", "cron(0 0-8 ? * MON-FRI *)"] // When to execute it (in cron or rate format)

This can be used to deal with issues arising from the UTC timezone
crossing midnight during business hours in your local timezone.

It should be noted that overlapping expressions will not throw a
warning, and should be checked for, to prevent duplicate triggering of


If you need to remove the API Gateway and Lambda function that you have
previously published, you can simply:


$ zappa undeploy production

You will be asked for confirmation before it executes.

If you enabled CloudWatch Logs for your API Gateway service and you
don't want to keep those logs, you can specify the ``--remove-logs``
argument to purge the logs for your API Gateway and your Lambda


$ zappa undeploy production --remove-logs


If you want to build your application package without actually uploading
and registering it as a Lambda function, you can use the ``package``


$ zappa package production

If you have a ``zip`` callback in your ``callbacks`` setting, this will
also be invoked.

.. code:: javascript

"production": { // The name of your stage
"callbacks": {
"zip": "my_app.zip_callback"// After creating the package

You can also specify the output filename of the package with ``-o``:


$ zappa package production -o


Similarly, if you only want the API Gateway CloudFormation template, for
use the ``template`` command:


$ zappa template production --l your-lambda-arn -r your-role-arn

Note that you must supply your own Lambda ARN and Role ARNs in this
case, as they may not have been created for you.

You can use get the JSON output directly with ``--json``, and specify
the output file with ``--output``.


If you need to see the status of your deployment and event schedules,
simply use the ``status`` command.


$ zappa status production

Tailing Logs

You can watch the logs of a deployment by calling the ``tail``
management command.


$ zappa tail production

By default, this will show all log items. In addition to HTTP and other
events, anything ``print``\ ed to ``stdout`` or ``stderr`` will be shown
in the logs.

You can use the argument ``--http`` to filter for HTTP requests, which
will be in the Apache Common Log Format.


$ zappa tail production --http

Similarly, you can do the inverse and only show non-HTTP events and log


$ zappa tail production --non-http

If you don't like the default log colors, you can turn them off with

You can also limit the length of the tail with ``--since``, which
accepts a simple duration string:


$ zappa tail production --since 4h # 4 hours
$ zappa tail production --since 1m # 1 minute
$ zappa tail production --since 1mm # 1 month

You can filter out the contents of the logs with ``--filter``, like so:


$ zappa tail production --http --filter "POST" # Only show POST HTTP requests

Note that this uses the `CloudWatch Logs filter
syntax <>`__.

Remote Function Invocation

You can execute any function in your application directly at any time by
using the ``invoke`` command.

For instance, suppose you have a basic application in a file called
"my\", and you want to invoke a function in it called
"my\_function". Once your application is deployed, you can invoke that
function at any time by calling:


$ zappa invoke production 'my_app.my_function'

Any remote print statements made and the value the function returned
will then be printed to your local console. **Nifty!**

You can also invoke interpretable Python 2.7 or Python 3.6 strings
directly by using ``--raw``, like so:


$ zappa invoke production "print 1 + 2 + 3" --raw

Django Management Commands

As a convenience, Zappa can also invoke remote Django ''
commands with the ``manage`` command. For instance, to perform the basic
Django status check:


$ zappa manage production showmigrations admin

Obviously, this only works for Django projects which have their settings
properly defined.

For commands which have their own arguments, you can also pass the
command in as a string, like so:


$ zappa manage production "shell --version"

Commands which require direct user input, such as ``createsuperuser``,
should be `replaced by commands <>`__
which use ``zappa <env> invoke --raw``.

*(Please note that commands which take over 30 seconds to execute may
time-out. See `this related
issue <>`__
for a work-around.)*

SSL Certification

If you want to use Zappa applications on a custom domain or subdomain,
you'll need to supply a valid SSL certificate.

Zappa gives you three options here: Custom SSL certificates, AWS
Certificate Manager-generated certificates, and Let's Encrypt

If your domain is located within an AWS Route 53 Hosted Zone and you've
defined settings for ``domain`` and either ``certificate``,
``certificate_arn`` or ``lets_encrypt_key`` (ex:
``openssl genrsa 2048 > account.key``), all you need to do is:


$ zappa certify production

And your domain will be verified, certified and registered!

More detailed instructions are available `in this handy
guide <>`__
and lower down in this README file.

Executing in Response to AWS Events

Similarly, you can have your functions execute in response to events
that happen in the AWS ecosystem, such as S3 uploads, DynamoDB entries,
Kinesis streams, and SNS messages.

In your *zappa\_settings.json* file, define your `event
sources <>`__
and the function you wish to execute. For instance, this will execute
``your_module.process_upload_function`` in response to new objects in
your ``my-bucket`` S3 bucket. Note that ``process_upload_function`` must
accept ``event`` and ``context`` parameters.

.. code:: javascript

"production": {
"events": [{
"function": "your_module.process_upload_function",
"event_source": {
"arn": "arn:aws:s3:::my-bucket",
"events": [
"s3:ObjectCreated:*" // Supported event types:

And then:


$ zappa schedule production

And now your function will execute every time a new upload appears in
your bucket!

To access the key's information in your application context, you'll want
``process_upload_function`` to look something like this:

.. code:: python

import boto3
s3_client = boto3.client('s3')

def process_upload_function(event, context):
Process a file upload.

# Get the uploaded file's information
bucket = event['Records'][0]['s3']['bucket']['name'] # Will be `my-bucket`
key = event['Records'][0]['s3']['object']['key'] # Will be the file path of whatever file was uploaded.

# Get the bytes from S3
s3_client.download_file(bucket, key, '/tmp/' + key) # Download this file to writable tmp space.
file_bytes = open('/tmp/' + key).read()

Similarly, for a `Simple Notification
Service <>`__ event:

.. code:: javascript

"events": [
"function": "your_module.your_function",
"event_source": {
"arn": "arn:aws:sns:::your-event-topic-arn",
"events": [

`DynamoDB <>`__
`Kinesis <>`__
are slightly different as it is not event based but pulling from a

.. code:: javascript

"events": [
"function": "replication.replicate_records",
"event_source": {
"arn": "arn:aws:dynamodb:us-east-1:1234554:table/YourTable/stream/2016-05-11T00:00:00.000",
"starting_position": "TRIM_HORIZON", // Supported values: TRIM_HORIZON, LATEST
"batch_size": 50, // Max: 1000
"enabled": true // Default is false

You can find more `example event sources
here <>`__.

Asynchronous Task Execution

Zappa also now offers the ability to seamlessly execute functions
asynchronously in a completely separate AWS Lambda instance!

For example, if you have a Flask API for ordering a pie, you can call
your ``bake`` function seamlessly in a completely seperate Lambda
instance by using the ``zappa.async.task`` decorator like so:

.. code:: python

from flask import Flask
from zappa.async import task
app = Flask(__name__)

def make_pie():
""" This takes a long time! """
ingredients = get_ingredients()
pie = bake(ingredients)

def order_pie():
""" This returns immediately! """
return "Your pie is being made!"

And that's it! Your API response will return immediately, while the
``make_pie`` function executes in a completely different Lambda

Task Sources

By default, this feature uses direct AWS Lambda invocation. You can
instead use AWS Simple Notification Service as the task event source by
using the ``task_sns`` decorator, like so:

.. code:: python

from zappa.async import task_sns

Using SNS also requires setting the following settings in your

.. code:: javascript

"dev": {
"async_source": "sns", // Source of async tasks. Defaults to "lambda"
"async_resources": true, // Create the SNS topic to use. Defaults to true.

This will automatically create and subscribe to the SNS topic the code
will use when you call the ``zappa schedule`` command.

Using SNS will also return a message ID in case you need to track your

Direct Invocation

You can also use this functionality without a decorator by passing your
function to ````, like so:

.. code:: python

from zappa.async import run

run(your_function, args, kwargs) # Using Lambda
run(your_function, args, kwargs, service='sns') # Using SNS

Remote Invocations

By default, Zappa will use lambda's current function name and current
AWS region. If you wish to invoke a lambda with a different function
name/region or invoke your lambda from outside of lambda, you must
specify the ``remote_aws_lambda_function_name`` and
``remote_aws_region`` arguments so that the application knows which
function and region to use. For example, if some part of our pizza
making application had to live on an EC2 instance, but we wished to call
the make\_pie() function on its own Lambda instance, we would do it as

\`\`\`python @task(remote\_aws\_lambda\_function\_name='pizza-pie-prod',
remote\_aws\_region='us-east-1') def make\_pie(): """ This takes a long
time! """ ingredients = get\_ingredients() pie = bake(ingredients)

\`\`\ ``If those task() parameters were not used, then EC2 would execute the function locally. These same``\ remote\_aws\_lambda\_function\_name\ ``and``\ remote\_aws\_region\`
arguments can be used on the function as well.


The following restrictions to this feature apply:

- Functions must have a clean import path -- i.e. no closures, lambdas,
or methods.
- ``args`` and ``kwargs`` must be JSON-serializable.
- The JSON-serialized arguments must be within the size limits for
Lambda (128K) or SNS (256K) events.

All of this code is still backwards-compatible with non-Lambda
environments - it simply executes in a blocking fashion and returns the

Advanced Settings

There are other settings that you can define in your local settings to
change Zappa's behavior. Use these at your own risk!

.. code:: javascript

"dev": {
"api_key_required": false, // enable securing API Gateway endpoints with x-api-key header (default False)
"api_key": "your_api_key_id", // optional, use an existing API key. The option "api_key_required" must be true to apply
"apigateway_enabled": true, // Set to false if you don't want to create an API Gateway resource. Default true.
"apigateway_description": "My funky application!", // Define a custom description for the API Gateway console. Default None.
"assume_policy": "my_assume_policy.json", // optional, IAM assume policy JSON file
"attach_policy": "my_attach_policy.json", // optional, IAM attach policy JSON file
"async_source": "sns", // Source of async tasks. Defaults to "lambda"
"async_resources": true, // Create the SNS topic to use. Defaults to true.
"aws_environment_variables" : {"your_key": "your_value"}, // A dictionary of environment variables that will be available to your deployed app via AWS Lambdas native environment variables. See also "environment_variables" and "remote_env" . Default {}.
"aws_kms_key_arn": "your_aws_kms_key_arn", // Your AWS KMS Key ARN
"aws_region": "aws-region-name", // optional, uses region set in profile or environment variables if not set here,
"binary_support": true, // Enable automatic MIME-type based response encoding through API Gateway. Default true.
"callbacks": { // Call custom functions during the local Zappa deployment/update process
"settings": "my_app.settings_callback", // After loading the settings
"zip": "my_app.zip_callback", // After creating the package
"post": "my_app.post_callback", // After command has executed
"cache_cluster_enabled": false, // Use APIGW cache cluster (default False)
"cache_cluster_size": 0.5, // APIGW Cache Cluster size (default 0.5)
"cache_cluster_ttl": 300, // APIGW Cache Cluster time-to-live (default 300)
"cache_cluster_encrypted": false, // Whether or now APIGW Cache Cluster encrypts data (default False)
"certificate": "my_cert.crt", // SSL certificate file location. Used to manually certify a custom domain
"certificate_key": "my_key.key", // SSL key file location. Used to manually certify a custom domain
"certificate_chain": "my_cert_chain.pem", // SSL certificate chain file location. Used to manually certify a custom domain
"certificate_arn": "arn:aws:acm:us-east-1:1234512345:certificate/aaaa-bbb-cccc-dddd", // ACM certificate ARN.
"cloudwatch_log_level": "OFF", // Enables/configures a level of logging for the given staging. Available options: "OFF", "INFO", "ERROR", default "OFF". C
"cloudwatch_data_trace": false, // Logs all data about received events. Default false.
"cloudwatch_metrics_enabled": false, // Additional metrics for the API Gateway. Default false.
"context_header_mappings": { "HTTP_header_name": "API_Gateway_context_variable" }, // A dictionary mapping HTTP header names to API Gateway context variables
"cors": true, // Enable Cross-Origin Resource Sharing. Default false. If true, simulates the "Enable CORS" button on the API Gateway console. Can also be a dictionary specifying lists of "allowed_headers", "allowed_methods", and string of "allowed_origin"
"dead_letter_arn": "arn:aws:<sns/sqs>:::my-topic/queue", // Optional Dead Letter configuration for when Lambda async invoke fails thrice
"debug": true, // Print Zappa configuration errors tracebacks in the 500. Default true.
"delete_local_zip": true, // Delete the local zip archive after code updates. Default true.
"delete_s3_zip": true, // Delete the s3 zip archive. Default true.
"django_settings": "your_project.production_settings", // The modular path to your Django project's settings. For Django projects only.
"domain": "", // Required if you're using a domain
"environment_variables": {"your_key": "your_value"}, // A dictionary of environment variables that will be available to your deployed app. See also "remote_env" and "aws_environment_variables". Default {}.
"events": [
{ // Recurring events
"function": "your_module.your_recurring_function", // The function to execute
"expression": "rate(1 minute)" // When to execute it (in cron or rate format)
{ // AWS Reactive events
"function": "your_module.your_reactive_function", // The function to execute
"event_source": {
"arn": "arn:aws:s3:::my-bucket", // The ARN of this event source
"events": [
"s3:ObjectCreated:*" // The specific event to execute in response to.
"exception_handler": "your_module.report_exception", // function that will be invoked in case Zappa sees an unhandled exception raised from your code
"exclude": ["*.gz", "*.rar"], // A list of regex patterns to exclude from the archive. To exclude boto3 and botocore (available in an older version on Lambda), add "boto3*" and "botocore*".
"extends": "stage_name", // Duplicate and extend another stage's settings. For example, `dev-asia` could extend from `dev-common` with a different `s3_bucket` value.
"extra_permissions": [{ // Attach any extra permissions to this policy. Default None
"Effect": "Allow",
"Action": ["rekognition:*"], // AWS Service ARN
"Resource": "*"
"iam_authorization": true, // optional, use IAM to require request signing. Default false. Note that enabling this will override the authorizer configuration.
"include": ["your_special_library_to_load_at_handler_init"], // load special libraries into PYTHONPATH at handler init that certain modules cannot find on path
"authorizer": {
"function": "your_module.your_auth_function", // Local function to run for token validation. For more information about the function see below.
"arn": "arn:aws:lambda:<region>:<account_id>:function:<function_name>", // Existing Lambda function to run for token validation.
"result_ttl": 300, // Optional. Default 300. The time-to-live (TTL) period, in seconds, that specifies how long API Gateway caches authorizer results. Currently, the maximum TTL value is 3600 seconds.
"token_source": "Authorization", // Optional. Default 'Authorization'. The name of a custom authorization header containing the token that clients submit as part of their requests.
"validation_expression": "^Bearer \\w+$", // Optional. A validation expression for the incoming token, specify a regular expression.
"keep_warm": true, // Create CloudWatch events to keep the server warm. Default true.
"keep_warm_expression": "rate(4 minutes)", // How often to execute the keep-warm, in cron and rate format. Default 4 minutes.
"lambda_description": "Your Description", // However you want to describe your project for the AWS console. Default "Zappa Deployment".
"lambda_handler": "your_custom_handler", // The name of Lambda handler. Default: handler.lambda_handler
"lets_encrypt_key": "s3://your-bucket/account.key", // Let's Encrypt account key path. Can either be an S3 path or a local file path.
"log_level": "DEBUG", // Set the Zappa log level. Can be one of CRITICAL, ERROR, WARNING, INFO and DEBUG. Default: DEBUG
"manage_roles": true, // Have Zappa automatically create and define IAM execution roles and policies. Default true. If false, you must define your own IAM Role and role_name setting.
"memory_size": 512, // Lambda function memory in MB. Default 512.
"prebuild_script": "your_module.your_function", // Function to execute before uploading code
"profile_name": "your-profile-name", // AWS profile credentials to use. Default 'default'.
"project_name": "MyProject", // The name of the project as it appears on AWS. Defaults to a slugified `pwd`.
"remote_env": "s3://my-project-config-files/filename.json", // optional file in s3 bucket containing a flat json object which will be used to set custom environment variables.
"role_name": "MyLambdaRole", // Name of Zappa execution role. Default <project_name>-<env>-ZappaExecutionRole. To use a different, pre-existing policy, you must also set manage_roles to false.
"route53_enabled": true, // Have Zappa update your Route53 Hosted Zones when certifying with a custom domain. Default true.
"runtime": "python2.7", // Python runtime to use on Lambda. Can be one of "python2.7" or "python3.6". Defaults to whatever the current Python being used is.
"s3_bucket": "dev-bucket", // Zappa zip bucket,
"slim_handler": false, // Useful if project >50M. Set true to just upload a small handler to Lambda and load actual project from S3 at runtime. Default false.
"settings_file": "~/Projects/MyApp/settings/", // Server side settings file location,
"timeout_seconds": 30, // Maximum lifespan for the Lambda function (default 30, max 300.)
"touch": false, // GET the production URL upon initial deployment (default True)
"use_precompiled_packages": true, // If possible, use C-extension packages which have been pre-compiled for AWS Lambda. Default true.
"vpc_config": { // Optional VPC configuration for Lambda function
"SubnetIds": [ "subnet-12345678" ], // Note: not all availability zones support Lambda!
"SecurityGroupIds": [ "sg-12345678" ]

YAML Settings

If you prefer YAML over JSON, you can also use a ``zappa_settings.yml``,
like so:

.. code:: yaml

app_function: your_module.your_app
s3_bucket: your-code-bucket
- function: your_module.your_function
arn: arn:aws:s3:::your-event-bucket
- s3:ObjectCreated:*

You can also supply a custom settings file at any time with the ``-s``
argument, ex:


$ zappa deploy dev -s my-custom-settings.yml

Similarly, you can supply a ``zappa_settings.toml`` file:

.. code:: toml

app_function = "your_module.your_app"
s3_bucket = "your-code-bucket"

Advanced Usage

Keeping The Server Warm

Zappa will automatically set up a regularly occurring execution of your
application in order to keep the Lambda function warm. This can be
disabled via the ``keep_warm`` setting.

Serving Static Files / Binary Uploads

Zappa is now able to serve and receive binary files, as detected by
their MIME-type.

However, generally Zappa is designed for running your application code,
not for serving static web assets. If you plan on serving custom static
assets in your web application (CSS/JavaScript/images/etc.,), you'll
likely want to use a combination of AWS S3 and AWS CloudFront.

Your web application framework will likely be able to handle this for
you automatically. For Flask, there is
`Flask-S3 <>`__, and for Django, there
`Django-Storages <>`__.

Similarly, you may want to design your application so that static binary
uploads go `directly to
S3 <>`__,
which then triggers an event response defined in your ``events``
setting! That's thinking serverlessly!

Enabling CORS

The simplest way to enable CORS (Cross-Origin Resource Sharing) for in
your Zappa application is to set ``cors`` to ``true`` in your Zappa
settings file and updating, which is the equivalent of pushing the
"Enable CORS" button in the AWS API Gateway console. This is disabled by
default, but you may wish to enable it for APIs which are accessed from
other domains, etc. It may also conflict with ``binary_support``, so you
should set that to ``false`` in your settings.

You can also simply handle CORS directly in your application. Your web
framework will probably have an extention to do this, such as
`django-cors-headers <>`__
or `Flask-CORS <>`__. Using
these will make your code more portable.

Large Projects

AWS currently limits Lambda zip sizes to 50 megabytes. If your project
is larger than that, set ``slim_handler: true`` in your
``zappa_settings.json``. In this case, your fat application package will
be replaced with a small handler-only package. The handler file then
pulls the rest of the large project down from S3 at run time! The
initial load of the large project may add to startup overhead, but the
difference should be minimal on a warm lambda function. Note that this
will also eat into the *memory* space of your application function.

Enabling Bash Completion

Bash completion can be enabled by adding the following to your .bashrc:

.. code:: bash

eval "$(register-python-argcomplete zappa)"

``register-python-argcomplete`` is provided by the argcomplete Python
package. If this package was installed in a virtualenv then the command
must be run there. Alternatively you can execute:

activate-global-python-argcomplete --dest=- > file

The file's contents should then be sourced in e.g. ~/.bashrc.

Enabling Secure Endpoints on API Gateway


You can use the ``api_key_required`` setting to generate and assign an
API key to all the routes of your API Gateway. After redeployment, you
can then pass the provided key as a header called ``x-api-key`` to
access the restricted endpoints. Without the ``x-api-key`` header, you
will receive a 403. You'll also need to manually associate this API key
with your usage plan in the AWS console. `More information on API keys
in the API
Gateway <>`__.

IAM Policy

You can enable IAM-based (v4 signing) authorization on an API by setting
the ``iam_authorization`` setting to ``true``. Your API will then
require signed requests and access can be controlled via `IAM
policy <>`__.
Unsigned requests will receive a 403 response, as will requesters who
are not authorized to access the API. Enabling this will override the
Authorizer configuration (see below).

API Gateway Authorizers

If you deploy an API endpoint with Zappa, you can take advantage of `API
Authorizers <>`__
to implement a token-based authentication - all you need to do is to
provide a function to create the required output, Zappa takes care of
the rest. A good start for the function is the `AWS Labs blueprint
example <>`__.

If you are wondering for what you would use an Authorizer, here are some
potential use cases:

1. Call out to OAuth provider
2. Decode a JWT token inline
3. Lookup in a self-managed DB (for example DynamoDB)

Zappa can be configured to call a function inside your code to do the
authorization, or to call some other existing lambda function (which
lets you share the authorizer between multiple lambdas). You control the
behavior by specifying either the ``arn`` or ``function_name`` values in
the ``authorizer`` settings block.

Cognito User Pool Authorizer

You can also use AWS Cognito User Pool Authorizer by adding:

.. code:: javascript

"authorizer": {
"provider_arns": [

Deploying to a Custom Domain Name with SSL Certificates

Deploying to a Domain With a Let's Encrypt Certificate (DNS Auth)

If you want to use Zappa on a domain with a free Let's Encrypt
certificate using automatic Route 53 based DNS Authentication, you can
follow `this handy
guide <>`__.

Deploying to a Domain With a Let's Encrypt Certificate (HTTP Auth)

If you want to use Zappa on a domain with a free Let's Encrypt
certificate using HTTP Authentication, you can follow `this
guide <>`__.

However, it's now far easier to use Route 53-based DNS authentication,
which will allow you to use a Let's Encrypt certificate with a single
``$ zappa certify`` command.

Deploying to a Domain With Your Own SSL Certs

1. The first step is to create a custom domain and obtain your SSL cert
/ key / bundle.
2. Ensure you have set the ``domain`` setting within your Zappa settings
JSON - this will avoid problems with the Base Path mapping between
the Custom Domain and the API invoke URL, which gets the Stage Name
appended in the URI
3. Add the paths to your SSL cert / key / bundle to the ``certificate``,
``certificate_key``, and ``certificate_chain`` settings,
respectively, in your Zappa settings JSON
4. Set ``route53_enabled`` to ``false`` if you plan on using your own
DNS provider, and not an AWS Route53 Hosted zone.
5. Deploy or update your app using Zappa
6. Run ``$ zappa certify`` to upload your certificates and register the
custom domain name with your API gateway.

Deploying to a Domain With AWS Certificate Manager

1. Verify your domain in the AWS Ceriticate Manager console.
2. In the console, request a certificate for your domain or subdomain
(``sub.yourdomain.tld``), or request a wildcard domain
3. Copy the entire ARN of that certificate and place it in the Zappa
setting ``certificate_arn``.
4. Set your desired domain in the ``domain`` setting.
5. Call ``$ zappa certify`` to create and associate the API Gateway
distribution using that ceritficate.

Setting Environment Variables

Local Environment Variables

If you want to set local environment variables for a deployment stage,
you can simply set them in your ``zappa_settings.json``:

.. code:: javascript

"dev": {
"environment_variables": {
"your_key": "your_value"

You can then access these inside your application with:

.. code:: python

import os
your_value = os.environ.get('your_key')

If your project needs to be aware of the type of environment you're
deployed to, you'll also be able to get ``SERVERTYPE`` (AWS Lambda),
``FRAMEWORK`` (Zappa), ``PROJECT`` (your project name) and ``STAGE``
(*dev*, *production*, etc.) variables at any time.

Remote AWS Environment Variables

If you want to use native AWS Lambda environment variables you can use
the ``aws_environment_variables`` configuration setting. These are
useful as you can easily change them via the AWS Lambda console or cli
at runtime. They are also useful for storing sensitive credentials and
to take advantage of KMS encryption of environment variables.

During development, you can add your Zappa defined variables to your
locally running app by, for example, using the below (for Django, to

.. code:: python

if 'SERVERTYPE' in os.environ and os.environ['SERVERTYPE'] == 'AWS Lambda':
import json
import os
json_data = open('zappa_settings.json')
env_vars = json.load(json_data)['dev']['environment_variables']
for key, val in env_vars.items():
os.environ[key] = val

Remote Environment Variables

Any environment variables that you have set outside of Zappa (via AWS
Lambda console or cli) will remain as they are when running ``update``,
unless they are also in ``aws_environment_variables``, in which case the
remote value will be overwritten by the one in the settings file. If you
are using KMS-encrypted AWS environment variables, you can set your KMS
Key ARN in the ``aws_kms_key_arn`` setting. Make sure that the values
you set are encrypted in such case.

*Note: if you rely on these as well as ``environment_variables``, and
you have the same key names, then those in ``environment_variables``
will take precedence as they are injected in the lambda handler.*

Remote Environment Variables (via an S3 file)

*S3 remote environment variables were added to Zappa before AWS
introduced native environment variables for Lambda (via the console and
cli). Before going down this route check if above make more sense for
your usecase.*

If you want to use remote environment variables to configure your
application (which is especially useful for things like sensitive
credentials), you can create a file and place it in an S3 bucket to
which your Zappa application has access to. To do this, add the
``remote_env`` key to zappa\_settings pointing to a file containing a
flat JSON object, so that each key-value pair on the object will be set
as an environment variable and value whenever a new lambda instance
spins up.

For example, to ensure your application has access to the database
credentials without storing them in your version control, you can add a
file to S3 with the connection string and load it into the lambda
environment using the ``remote_env`` configuration setting.

super-secret-config.json (uploaded to my-config-bucket):

.. code:: javascript

"DB_CONNECTION_STRING": "super-secret:database"


.. code:: javascript

"dev": {
"remote_env": "s3://my-config-bucket/super-secret-config.json",

Now in your application you can use:

.. code:: python

import os
db_string = os.environ.get('DB_CONNECTION_STRING')

API Gateway Context Variables

If you want to map an API Gateway context variable
to an HTTP header you can set up the mapping in ``zappa_settings.json``:

.. code:: javascript

"dev": {
"context_header_mappings": {
"HTTP_header_name": "API_Gateway_context_variable"

For example, if you want to expose the
$context.identity.cognitoIdentityId variable as the HTTP header
CognitoIdentityId, and $context.stage as APIStage, you would have:

.. code:: javascript

"dev": {
"context_header_mappings": {
"CognitoIdentityId": "identity.cognitoIdentityId",
"APIStage": "stage"

Catching Unhandled Exceptions

By default, if an *unhandled* exception happens in your code, Zappa will
just print the stacktrace into a CloudWatch log. If you wish to use an
external reporting tool to take note of those exceptions, you can use
the ``exception_handler`` configuration option.


.. code:: javascript

"dev": {
"exception_handler": "your_module.unhandled_exceptions",

The function has to accept three arguments: exception, event, and


.. code:: python

def unhandled_exception(e, event, context):
send_to_raygun(e, event) # gather data you need and send
return True # Prevent invocation retry

You may still need a similar exception handler inside your application,
this is just a way to catch exception which happen at the Zappa/WSGI
layer (typically event-based invocations, misconfigured settings, bad
Lambda packages, and permissions issues).

By default, AWS Lambda will attempt to retry an event based (non-API
Gateway, e.g. CloudWatch) invocation if an exception has been thrown.
However, you can prevent this by returning True, as in example above, so
Zappa that will not re-raise the uncaught exception, thus preventing AWS
Lambda from retrying the current invocation.

Using Custom AWS IAM Roles and Policies

By default, the Zappa client will create and manage the necessary IAM
policies and roles to execute Zappa applications. However, if you're
using Zappa in a corporate environment or as part of a continuous
integration, you may instead want to manually manage your remote
execution policies instead. (You can specify which *local* profile to
use for deploying your Zappa application by defining the
``profile_name`` setting, which will correspond to a profile in your AWS
credentials file.)

To manually define the permissions policy of your Zappa execution role,
you must define the following in your *zappa\_settings.json*:

.. code:: javascript

"dev": {
"manage_roles": false, // Disable Zappa client managing roles.
"role_name": "MyLambdaRole", // Name of your Zappa execution role. Default <project_name>-<env>-ZappaExecutionRole.

Ongoing discussion about the minimum policy requirements necessary for a
Zappa deployment `can be found
here <>`__.

If you only need to add a few permissions to the default Zappa execution
policy, you can use the ``extra_permissions`` setting like so:

.. code:: javascript

"dev": {
"extra_permissions": [{ // Attach any extra permissions to this policy.
"Effect": "Allow",
"Action": ["rekognition:*"], // AWS Service ARN
"Resource": "*"

Globally Available Server-less Architectures

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Click to see slides from ServerlessConf London!

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During the ``init`` process, you will be given the option to deploy your
application "globally." This will allow you to deploy your application
to all available AWS regions simultaneously in order to provide a
consistent global speed, increased redundancy, data isolation, and legal
compliance. You can also choose to deploy only to "primary" locations,
the AWS regions with ``-1`` in their names.

To learn more about these capabilities, see `these
slides <>`__
from ServerlessConf London.

Raising AWS Service Limits

Out of the box, AWS sets a limit of `1000 concurrent
executions <>`__
for your functions. If you start to breach these limits, you may start
to see errors like
``ClientError: An error occurred (LimitExceededException) when calling the PutTargets.."``
or something similar.

To avoid this, you can file a `service
ticket <>`__ with Amazon to
raise your limits up to the many tens of thousands of concurrent
executions which you may need. This is a fairly common practice with
Amazon, designed to prevent you from accidentally creating extremely
expensive bug reports. So, before raising your service limits, make sure
that you don't have any rogue scripts which could accidentally create
tens of thousands of parallel executions that you don't want to pay for.

Using Zappa With Docker

If Docker is part of your team's CI, testing, or deployments, you may
want to check out `this handy
guide <>`__
on using Zappa with Docker.

Dead Letter Queues

If you want to utilise `AWS Lambda's Dead Letter Queue
feature <>`__ simply
add the key ``dead_letter_arn``, with the value being the complete ARN
to the corresponding SNS topic or SQS queue in your

You must have already created the corresponding SNS/SQS topic/queue, and
the Lambda function execution role must have been provisioned with
read/publish/sendMessage access to the DLQ resource.

Zappa Guides

- `Django-Zappa tutorial
(screencast) <>`__.
- `Using Django-Zappa, Part
1 <>`__.
- `Using Django-Zappa, Part 2:
VPCs <>`__.
- `Building Serverless Microservices with Zappa and
Flask <>`__
- `Zappa で Hello World するまで
(Japanese) <>`__
- `How to Deploy Zappa with CloudFront, RDS and
VPC <>`__
- `Secure 'Serverless' File Uploads with AWS Lambda, S3, and
Zappa <>`__
- `First Steps with AWS Lambda, Zappa and
Python <>`__
- `Deploy a Serverless WSGI App using Zappa, CloudFront, RDS, and
VPC <>`__
- `AWS: Deploy Alexa Ask Skills with Flask-Ask and
Zappa <>`__
- `Guide to using Django with
Zappa <>`__
- `Apex and WWW Domains with
Zappa <>`__
- *Your guide here?*

Zappa in the Press

- *`Zappa Serves Python, Minus the
Servers <>`__*
- *`Zappa lyfter serverlösa applikationer med
Python <>`__*
- *`Interview: Rich Jones on
Zappa <>`__*
- `Top 10 Python Libraries of
2016 <>`__

Sites Using Zappa

- ` <>`__ - A simple Zappa homepage
- `Zappatista! <>`__ - The official Zappa blog!
- `Mailchimp Signup
Utility <>`__ - A
microservice for adding people to a mailing list via API.
- `Zappa Slack
Inviter <>`__ - A
tiny, server-less service for inviting new users to your Slack
- `Serverless Image
Host <>`__ - A
thumbnailing service with Flask, Zappa and Pillow.
- `Gigger <>`__ - The live music industry's
search engine
- `Zappa BitTorrent
Tracker <>`__ -
An experimental server-less BitTorrent tracker. Work in progress.
- `JankyGlance <>`__ - A
server-less Yahoo! Pipes replacement.
- `LambdaMailer <>`__ - A
server-less endpoint for processing a contact form.
- `Voter Registration
Microservice <>`__
- Official backup to to the Virginia Department of Elections portal.
- `FreePoll Online <>`__ - A simple and
awesome say for groups to make decisions.
- `PasteOfCode <>`__ - A Zappa-powered paste
- And many more, including banks, governments, startups, enterprises
and schools!

Are you using Zappa? Let us know and we'll list your site here!

Related Projects

- `lambda-packages <>`__ -
Precompiled C-extension packages for AWS Lambda. Used automatically
by Zappa.
- `Mackenzie <>`__ - AWS Lambda
Infection Toolkit
- `NoDB <>`__ - A simple, server-less,
Pythonic object store based on S3.
- `zappa-cms <>`__ - A tiny
server-less CMS for busy hackers. Work in progress.
- `zappa-django-utils <>`__
- Utility commands to help Django deployments.
- `flask-ask <>`__ - A
framework for building Amazon Alexa applications. Uses Zappa for
- `zappa-file-widget <>`__
- A Django plugin for supporting binary file uploads in Django on
- `zops <>`__ - Utilities for teams
and continuous integrations using Zappa.
- `cookiecutter-mobile-backend <>`__
- A ``cookiecutter`` Django project with Zappa and S3 uploads
- `zappa-examples <>`__ -
Flask, Django, image uploads, and more!
- `zappa-hug-example <>`__
- Example of a Hug application using Zappa.
- `Zappa Docker Image <>`__ - A
Docker image for running Zappa locally, based on Lambda Docker.
- `zappa-dashing <>`__ - Monitor
your AWS environment (health/metrics) with Zappa and CloudWatch.
- `s3env <>`__ - Manipulate a
remote Zappa environment variable key/value JSON object file in an S3
bucket through the CLI.
- `zappa\_resize\_image\_on\_fly <>`__
- Resize images on the fly using Flask, Zappa, Pillow, and
- `gdrive-lambda <>`__ -
pass json data to a csv file for end users who use Gdrive across the
- `travis-build-repeat <>`__
- Repeat TravisCI builds to avoid stale test results.
- `wunderskill-alexa-skill <>`__
- An Alexa skill for adding to a Wunderlist.
- `xrayvision <>`__ - Utilities and
wrappers for using AWS X-Ray with Zappa.


Zappa goes quite far beyond what Lambda and API Gateway were ever
intended to handle. As a result, there are quite a few hacks in here
that allow it to work. Some of those include, but aren't limited to..

- :sub:`[STRIKEOUT:Using VTL to map body, headers, method, params and
query strings into JSON, and then turning that into valid WSGI.]`
- :sub:`[STRIKEOUT:Attaching response codes to response bodies, Base64
encoding the whole thing, using that as a regex to route the response
code, decoding the body in VTL, and mapping the response body to
- :sub:`[STRIKEOUT:Packing and *Base58* encoding multiple cookies into
a single cookie because we can only map one kind.]`
- Forcing the case permutations of "Set-Cookie" in order to return
multiple headers at the same time.
- :sub:`[STRIKEOUT:Turning cookie-setting 301/302 responses into 200
responses with HTML redirects, because we have no way to set headers
on redirects.]`


This project is still young, so there is still plenty to be done.
Contributions are more than welcome!

Please file tickets for discussion before submitting patches. Pull
requests should target ``master`` and should leave Zappa in a
"shippable" state if merged.

If you are adding a non-trivial amount of new code, please include a
functioning test in your PR. For AWS calls, we use the ``placebo``
library, which you can learn to use `in their
README <>`__. The
test suite will be run by `Travis
CI <>`__ once you open a pull

Please include the GitHub issue or pull request URL that has discussion
related to your changes as a comment in the code
(`example <>`__).
This greatly helps for project maintainability, as it allows us to trace
back use cases and explain decision making. Similarly, please make sure
that you meet all of the requiments listed in the `pull request
template <>`__.

Please feel free to work on any open ticket, especially any ticket
marked with the "help-wanted" label. If you get stuck or want to discuss
an issue further, please join `our Slack
channel <>`__, where you'll find a community of
smart and interesting people working dilligently on hard problems.

Using a Local Repo

To use the git HEAD, you *probably can't* use ``pip install -e``.
Instead, you should clone the repo to your machine and then
``pip install /path/to/zappa/repo`` or
``ln -s /path/to/zappa/repo/zappa zappa`` in your local project.


If you or your company uses **Zappa**, please consider giving what you
can to support the ongoing development of the project!

You can become a patron by **`visiting our Patreon
page <>`__**.

Zappa is currently supported by these awesome individuals and companies:

- Nathan Lawrence
- LaunchLab
- Sean Paley

Thank you very, very much!


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Support / Development / Training / Consulting

Do you need help with..

- Porting existing Flask and Django applications to Zappa?
- Building new applications and services that scale infinitely?
- Reducing your operations and hosting costs?
- Adding new custom features into Zappa?
- Training your team to use AWS and other server-less paradigms?

Good news! We're currently available for remote and on-site consulting
for small, large and enterprise teams. Please contact
with your needs and let's work together!

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