lambda-budgets

Lambda that runs on a cron to create AWS Budgets.

Development

Contributions

Contributions are welcome.

Setup Development Environment

Install the following applications:

• AWS CLI
• AWS SAM CLI
• pre-commit
• pipenv

Install Requirements

Run pipenv install --dev to install both production and development requirements, and pipenv shell to activate the virtual environment. For more information see the pipenv docs.

After activating the virtual environment, run pre-commit install to install the pre-commit git hook.

Update Requirements

First, make any needed updates to the base requirements in Pipfile, then use pipenv to regenerate both Pipfile.lock and requirements.txt.

$ pipenv update --dev

We use pipenv to control versions in testing, but sam relies on requirements.txt directly for building the lambda artifact, so we dynamically generate requirements.txt from Pipfile.lock before building the artifact. The file must be created in the CodeUri directory specified in template.yaml.

$ pipenv requirements > requirements.txt

Additionally, pre-commit manages its own requirements.

$ pre-commit autoupdate

Environment Variables

The lambda requires certain environment varibles:

• NOTIFICATION_TOPIC_ARN: an SNS topic that the AWS budgets API will use to send notifications to users.
• AWS_ACCOUNT_ID: the account where the lambda runs. This is used to construct role ARNs and work with budgets. The assumption is that there will be no cross-account budget creation.
• END_USER_ROLE_NAME: the name of the AWS IAM role used to access the service catalog by users who require that a budget be made. The assumption is that there will only be one such named role.
• BUDGET_RULES: a yaml-format string that contains the rules used for budget creation. To get an idea of what this should look like, see _budget_rules_schema in config.py.
• THRESHOLDS: a yaml-format string that defines threshold levels used to send notifications. To get an idea of what this should look like, see _thresholds_schema in config.py.

The example file sam-local-envvars.json at the root of this project, which is used to run the lambda function locally, contains examples of the environment variables. For a real deployment the variables are defined in template.yaml; some are derived or have defaults, but others require configuration.

Note: When the Lambda runs, config.py validates that the required parameters are present and, if not, stops the Lambda.

Create a local build

Use a Lambda-like docker container to build the Lambda artifact

$ sam build --use-container

Run unit tests

Tests are defined in the tests folder in this project, and dependencies are managed with pipenv. Install the development dependencies and run the tests using coverage.

$ pipenv run coverage run -m pytest tests/ -svv

Automated testing will upload coverage results to Coveralls.

Run locally

Run the command below, where my-profile is an AWS profile with the correct permissions, and you've edited the sam-local-envvars.json file to have meaningful values for the required environment variables.

$ sam local invoke BudgetMakerFunction --event events/event.json --profile my-profile -n sam-local-envvars.json

Deployment

Build

sam build

Deploy Lambda to S3

This requires the correct permissions to upload to bucket bootstrap-awss3cloudformationbucket-19qromfd235z9 and essentials-awss3lambdaartifactsbucket-x29ftznj6pqw

sam package --template-file .aws-sam/build/template.yaml \
  --s3-bucket essentials-awss3lambdaartifactsbucket-x29ftznj6pqw \
  --output-template-file .aws-sam/build/lambda-budgets.yaml

aws s3 cp .aws-sam/build/lambda-budgets.yaml s3://bootstrap-awss3cloudformationbucket-19qromfd235z9/lambda-budgets/master/

Install Lambda into AWS

Create the following sceptre file

config/prod/lambda-template.yaml

template_path: "remote/lambda-budgets.yaml"
stack_name: "lambda-budgets"
stack_tags:
  Department: "Platform"
  Project: "Infrastructure"
  OwnerEmail: "it@sagebase.org"
hooks:
  before_launch:
    - !cmd "curl https://s3.amazonaws.com/bootstrap-awss3cloudformationbucket-19qromfd235z9/lambda-template/master/lambda-budgets.yaml --create-dirs -o templates/remote/lambda-budgets.yaml"

Install the lambda using sceptre:

sceptre --var "profile=my-profile" --var "region=us-east-1" launch prod/lambda-budgets.yaml

Author

Your Name Here.