canoe

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Development

Use it with pipenv. pytest should be installed in the virtualenv. See build.sh for a full deployment to aws.

See env.json.sample for required environment variables.

Running Tests

1. Export all required environment variables
2. pipenv shell
3. Verify pytest is running from pipenv: which pytest, if no then uninstall pytest outside of the pipenv by running pip uninstall pytest
4. pipenv install
5. pytest

Requirements

• AWS CLI with Administrator permission
• Python 3 installed
• Pipenv installed
  • pip install pipenv
• Docker installed
• SAM Local installed

As you've chosen the experimental Makefile we can use Make to automate Packaging and Building steps as follows:

        ...::: Installs all required packages as defined in the Pipfile :::...
        make install

        ...::: Run Pytest under tests/ with pipenv :::...
        make test

        ...::: Creates local dev environment for Python hot-reloading w/ packages:::...
        make build SERVICE="canoe"

        ...::: Run SAM Local API Gateway :::...
        make run

        # or

        ...::: Run SAM Invoke Function :::...
        make invoke SERVICE="FirstFunction" EVENT="events/canoe_event.json"

Testing

Pytest is used to discover tests created under tests folder - Here's how you can run tests our initial unit tests:

make test

Packaging

AWS Lambda Python runtime requires a flat folder with all dependencies including the application. To facilitate this process, the pre-made SAM template expects this structure to be under canoe/build/:

...
    FirstFunction:
        Type: AWS::Serverless::Function
        Properties:
            CodeUri: canoe/build/
            ...

With that in mind, we will:

1. Generate a hashed requirements.txt out of our Pipfile dep file
2. Install all dependencies directly to build sub-folder
3. Copy our function (app.py) into build sub-folder

Given that you've chosen a Makefile these steps are automated by simply running: make build SERVICE="canoe"

Local development

Given that you followed Packaging instructions then run the following to invoke your function locally:

Invoking function locally without API Gateway

echo '{"lambda": "payload"}' | sam local invoke FirstFunction

You can also specify a event.json file with the payload you'd like to invoke your function with:

sam local invoke -e event.json FirstFunction

Deployment

First and foremost, we need a S3 bucket where we can upload our Lambda functions packaged as ZIP before we deploy anything - If you don't have a S3 bucket to store code artifacts then this is a good time to create one:

aws s3 mb s3://BUCKET_NAME

Provided you have a S3 bucket created, run the following command to package our Lambda function to S3:

aws cloudformation package \
    --template-file template.yaml \
    --output-template-file packaged.yaml \
    --s3-bucket REPLACE_THIS_WITH_YOUR_S3_BUCKET_NAME

Next, the following command will create a Cloudformation Stack and deploy your SAM resources.

aws cloudformation deploy \
    --template-file packaged.yaml \
    --stack-name canoe \
    --capabilities CAPABILITY_IAM

See Serverless Application Model (SAM) HOWTO Guide for more details in how to get started.

Appendix

Makefile

It is important that the Makefile created only works on OSX/Linux but the tasks above can easily be turned into a Powershell or any scripting language you may want too.

The following make targets will automate that we went through above:

• Find all available targets: make
• Install all deps and clone (OS hard link) our lambda function to /build: make build SERVICE="canoe"
  • SERVICE="canoe" tells Make to start the building process from there
  • By creating a hard link we no longer need to keep copying our app over to Build and keeps it tidy and clean
• Run Pytest against all tests found under tests folder: make test
• Install all deps and builds a ZIP file ready to be deployed: make package SERVICE="canoe"
  • You can also build deps and a ZIP file within a Docker Lambda container: make package SERVICE="canoe" DOCKER=1
  • This is particularly useful when using C-extensions that if built on your OS may not work when deployed to Lambda (different OS)

AWS CLI commands

AWS CLI commands to package, deploy and describe outputs defined within the cloudformation stack:

aws cloudformation package \
    --template-file template.yaml \
    --output-template-file packaged.yaml \
    --s3-bucket REPLACE_THIS_WITH_YOUR_S3_BUCKET_NAME

aws cloudformation deploy \
    --template-file packaged.yaml \
    --stack-name canoe \
    --capabilities CAPABILITY_IAM \
    --parameter-overrides MyParameterSample=MySampleValue

aws cloudformation describe-stacks \
    --stack-name canoe --query 'Stacks[].Outputs'

Adding it to Slack

• Create Slack Application Integration
• Add Oauth Scope chat:write
• Copy generated API token
• Change API token for UpdatesNotificationsFunction on Amazon Lambda / London function
• Invite the new app to the room you want to post