sam-slash-slack 0.1.2

A SAM python framework for slack slash bots.

sam-slash-slack

A python framework for building slack slash bots using AWS SAM. Get input parsing and validation, command routing, async responses, auto-generated help dialog, response visibility, and response message formatting all for free.

sam-slash-slack utilizes the AWS Serverless Application Model (SAM) to generate serverless resources to run your sam-slash-slack bot. The sam-slash-slack bot consists of two lambda functions and one SQS queue. The api_handler lambda function receives the POST request from slack enqueues the request in the SQS queue for async processing, and immediately responds. Slack requires a response within 3 seconds. This architecture enables your slash commands to take longer than that to respond. The async_handler receives messages from the api_handler and executes the given command.

Most of the code for sam-slash-slack is shared from slash-slack.

View Slack slash command documentation here.

# EX: /slash-slack math 10 * 10
# Response: 100.0
import os

from sam_slash_slack import Flag, Float, SAMSlashSlack, String

slash = SAMSlashSlack(signing_secret=os.environ['SLACK_SIGNING_SECRET'])
api_handler = slash.get_api_handler()
async_handler = slash.get_async_handler()


@slash.command("math")
def math_fn(
    x: float = Float(),
    symbol: str = Enum(values={"*", "+", "-", "/"}),
    y: float = Float(),
):
    if symbol == "*":
        return x * y
    if symbol == "+":
        return x + y
    if symbol == "-":
        return x - y
    if symbol == "/":
        return x / y

Why use sam-slash-slack?

Building a slack slash bot can seem very straightforward at first, however there are some complexities that make it difficult. sam-slash-slack handles all of the complexities for you letting you focus on the bot response handlers.

You don't have to worry about deployment, as you can let SAM and lambda functions do the heavy lifting.

Webhook signature verification

slash-slack will verify that incoming requests were made by slack by validating the request signature. To disable signature verification use the dev=True option when creating the SAMSlashSlack object.

Command Response Timeout/Async responses

Slack requires that the slash bot webhook be responded to within 3 seconds.

Often times the action being taken by the bot will depend on external services which might not respond within 3 seconds.

sam-slash-slack sends an immediate 200 response to the webhook request, and runs the command function asynchronously. When the command function finishes, the response is sent back to slack using the response_url from the request.

You can optionally add content to the immediate response to let your user know that something is being done in the background. A global/default response can be set with the acknowledge_response parameter on the SAMSlashSlack class, or at the command level with the acknowledge_response parameter on the command decorator. The value passed to acknowledge_response will be passed to blocks._make_block_message and can be a str, block, list[str], or list[block] where a block is a block kit block. See the example for example usage.

Input Arg/Flag parsing

sam-slash-slack takes care of parsing command input into pre-defined args and flags which let you focus on writing the command function, and not wrangling the content into the format that you need.

Auto-generated help

sam-slash-slack provides help dialog auto-generated from your commands, args, and flags. Additional details can be embedded directly into the command decorator and arg/flag initializers.

To request global help:

/slash-slack help

To request command specific help:

/slash-slack command --help

Response visibility

Slack slash command responses can be made visible only to the requestor, or to the entire channel. sam-slash-slack adds the ability for any command to be made visible with the --visible flag.

Response formatting

Slack expects responses to be in the Slack Block Kit format. sam-slash-slack will automatically convert your string responses into slack mrkdown blocks.

Deployment

sam-slash-slack utilizes SAM to generate and deploy the underlying AWS infrastructure. To initialize a new sam-slash-slack app. Run init-sam-slash-slack in the project directory. This will bootstrap the SAM template, and app.py file. You must expose the underlying api_handler, and async_handler methods from the SAMSlashSlack bot.

sam build
sam deploy

Command Inputs

The inputs and parsing for each command is determined by the parameters to the function. SAMSlashSlack parses the function parameters and generates an input schema.

When a request is made to a given command, SAMSlashSlack attempts to parse the input text into the command input schema.

Flags

Flags are boolean options that can be added to commands anywhere within the request. During the input parsing, flags are parsed and removed, and then args are parsed.

There is no difference in doing /slash-slack command arg --flag and /slash-slack command --flag arg.

Global Flags

There are 2 global flags: --visible and --help.

The --visible flag will make the response visible in the channel that the request was made. By default, responses are only visible to the user which made the request.

The --help flag will indicate that the SlashSlack app should return the relevant help message. Whether that is app level /slash-slack --help, or command level /slash-slack command --help.

Args

All non-flag arguments to the command function make up the input schema for the command function. This means that the # of words in the command request must match up with the # of non-flag arguments. (With two exceptions: String, UnknownLengthList).

String

When the only non-flag parameter for the function is a String() then the entire argument body (with flags removed) will be passed into that parameter.

# EX: /slash-slack echo hello --upper world
# Response: HELLO WORLD
@slash.command("echo")
def echo(s: str, upper: bool = Flag()):
    return s

Unknown Length List

To collect an arbitrary # of args from the user use the UnknownLengthList arg type. This arg type will be passed a list of all of the values passed to it parsed into the given type.

Because this consumes args till the end of the arg list, this must be the last non-flag param for the command function.

# EX: /slash-slack avg 10, 20, 30
# Response: 20.0
@slash.command("avg")
def avg(numbers = UnknownLengthList(arg_type=Float())):
    return sum(numbers) / len(numbers)

SlashSlackRequest

If you want to have access to the complete request as sent from the slack servers. Add a param with the type annotation of SlashSlackRequest to the command function.

# EX: /slash-slack echo hello world
# Response: hello world This request was made by John Doe
@slash.command("echo")
def echo(content: str, slash_slack_request: SlashSlackRequest):
    return f"{content} This request was made by {slash_slack_request.user_name}"