Develop Lambda functions

Develop a new Lambda

To develop a new lambda from a sample, create a new folder in cumulus/tasks/ and run npm init:

$ cd ../cumulus/tasks
$ mkdir new-lambda
$ cd new-lambda
$ npm init

Or copy an existing lambda function to customize:

$ cd ../cumulus/tasks
$ cp discover-pdrs new-lambda

Modify package.json:

• name
• version
• description
• test script
• dependencies (NOT devDependencies)

Build a Lambda

To build node.js lambda functions, use webpack to pack into single .js with dependencies:

$ npm run build

Alternatively, to monitor for changes and auto-rebuild:

$ npm run watch

For non-node lambdas not included in Cumulus repo, upload .zip to s3 and modify lambdas.yml as previously shown.

Deploy a Lambda

For new lambdas, update <daac>-deploy/lambdas.yml by adding a new entry. E.g.: node.js sample for '../cumulus/cumulus/tasks/sample-lambda' in the Cumulus repo):

<LambdaName>:                                       # eg:  LambdaSample (does not need to conform to dirname)
  handler: <dir>.<function>                                # eg:  sample-lambda.handler (assuming file has module.exports.handler = <someFunc>)
  timeout: <ms>                                            # eg:  300
  source: 'node_modules/@cumulus/<dir>/dist/'  # eg:  '../cumulus/cumulus/tasks/sample-lambda/dist/index.js'

For non-node.js lambda code (e.g. python) uploaded as a .zip to an S3 bucket:

PyLambda:
  handler: <file.py>.<function>               # eg:  lambda_handler.handler for lambda_handler.py with:  def handler(event, context):
  timeout: <ms>
  s3Source:
    bucket: '{{buckets.internal.name}}'       # refers to bucket set in config.yml
    key: deploy/cumulus-process/<dir>/<file>  # eg: deploy/cumulus-process/modis/0.3.0b3.zip
  runtime: python2.7                          # Node is default, otherwise specify.

To deploy all changes to /tasks/ and lambdas.yml:

$ kes cf deploy --kes-folder app --template ../cumulus/packages/deployment/app --region <region> --deployment <deployment-name> --role <arn:deployerRole>

To deploy modifications to a single lambda package:

$ kes lambda <LambdaName> --kes-folder app --template ../cumulus/packages/deployment/app --deployment <deployment-name> --role <arn:deployerRole>