tropostack 0.2.0

Wrapper around the Troposphere lib for CLI management of CloudFormation stacks

tropostack

Wrapper around the excellent Troposphere library for easy creation and management of CloudFormation stacks.

Getting Started

You use tropostack as a library to:

• Consisteny define CloudFormation templates in Python code
• Have a CLI around each stack definition, enabling it to live as a standalone executable

Here is a minimalistic example of a stack that creates a DynamoDB table with a single key:

#!/usr/bin/env python3
from troposphere import Output, Export, Ref, Sub, GetAtt
from troposphere import dynamodb

from tropostack.base import EnvStack
from tropostack.cli import EnvCLI

class DynamoDbStack(EnvStack):
    BASE_NAME = 'example-dynamodb'

    @property
    def o_dynamodb_table_name(self):
        _id = 'TableName'
        return Output(
            _id,
            Description='The name of the DynamoDB table',
            Value=self.r_table.ref(),
            Export=Export(Sub("${AWS::StackName}-%s" % _id))
        )

    @property
    def o_dynamodb_table_arn(self):
        _id = 'TableArn'
        return Output(
            _id,
            Description='The ARN identifier of the DynamoDB table',
            Value=GetAtt(self.r_table, 'Arn'),
            Export=Export(Sub("${AWS::StackName}-%s" % _id))
        )

    @property
    def r_table(self):
        table_name = self.conf['table_name']
        table_key = self.conf['table_key']
        return dynamodb.Table(
            'DynamoDbTable',
            TableName=table_name,
            BillingMode='PAY_PER_REQUEST',
            AttributeDefinitions=[
                dynamodb.AttributeDefinition(
                    AttributeName=table_key,
                    AttributeType='S'
                ),
            ],
            KeySchema=[
                dynamodb.KeySchema(
                    AttributeName=table_key,
                    KeyType='HASH'
                )
            ]
        )

if __name__ == '__main__':
    cli = EnvCLI(DynamoDbStack)

The above already gives you a CLI around your stack definition. Assuming you put it inside an executable file called my_dynamodb.py, you'd be able to call it already:

$ ./my_dynamodb.py -h
usage: my_dynamodb.py [-h]
                    conf_file
                    {apply,create,delete,generate,outputs,update,validate}

positional arguments:
  conf_file
  {apply,create,delete,generate,outputs,update,validate}

optional arguments:
  -h, --help            show this help message and exit

To enable the stack definition to be reused across multiple environments (e.g. def, test, production) with differing details, a configuration file is required (by default). A simple configuration file for the above stack would look like:

env: dev
region: eu-west-1

example-dynamodb:
  table_name: my-test-table
  table_key: my-id

Now we can fire up the CloudFormation stack that would create our DynamoDB table:

$ ./dynamodb_table.py config.yaml apply
Stack creation initiated for: arn:aws:cloudformation:eu-west-1:472799024263:stack/example-dynamodb-dev/2e0f8430-e2a9-11e9-bd25-0aac5439e4be
TIMESTAMP (UTC)          RESOURCE TYPE                              RESOURCE ID                  STATUS                                   REASON
2019-09-29 11:06:26      AWS::CloudFormation::Stack                 example-dynamodb-dev         CREATE_IN_PROGRESS                       User Initiated
2019-09-29 11:06:28      AWS::DynamoDB::Table                       DynamoDbTable                CREATE_IN_PROGRESS                       
2019-09-29 11:06:28      AWS::DynamoDB::Table                       DynamoDbTable                CREATE_IN_PROGRESS                       Resource creation Initiated
2019-09-29 11:06:59      AWS::DynamoDB::Table                       DynamoDbTable                CREATE_COMPLETE                          
2019-09-29 11:07:00      AWS::CloudFormation::Stack                 example-dynamodb-dev         CREATE_COMPLETE                     

(the apply subcommand above is equivalent to create or update)

Stock commands

While the CLI can be expanded for particular stacks, there are several subcommands that come out of the box:

• generate - prints the resulting CloudFormation YAML to the screen
• validate - Sends the CloudFormation template to the AWS API for validation, and reports back result
• create - Initiates the stack creation (should only be used if the stack does not exist yet)
• update - Updates an existing stack (should only be used if the stack exists)
• apply - Idempotently updates or creates a stack, based on whether it exists or not
• outputs - Shows the outputs of an existing stack
• delete - Deletes an existing stack

Installation

pip install tropostack

Compatibility

Licence

See LICENSE file.

Authors

tropostack was written by tie <tropostack /\ morp.org>.