Jackalambda

Mythical lambda creature.

Description

Toolkit for writing production ready Lambda functions.

Jackalambda provides a consistent way to write Lambda handlers that let you focus on the business logic of you function and none of the boilerplate.

With Jackalambda, you get:

• Consistent JSON logging.
• Cached remote secrets and configuration.
• AWS event detection and parsing.
• X-Ray enhanced clients for common AWS services.
• Distributed request id support.
• Isolated side effects for fully testable handlers.
• AVA logging integration.

All Jackalambda handlers follow a clear execution path:

1. Resolve and validate all required configuration, or fail with a clear error.
2. Isolate all side-effect producing dependencies in a container with their configuration.
3. Run a processor function with a reference to the container.
4. Ensure the logger is always available, scoped per-request, and always logs failures, event fatal ones.

Example

This project is a fully working, real world, example of using Jackalambda. Just check out the handlers folder.

Creating your first handler is this simple:

import { createHandler } from '@meltwater/jackalambda'

export handler = createHandler({
  createProcessor: ({ log }) => (event, context) => {
    log.info({ meta: event }, 'I 💖 Jackalambda')
    return { success: true }
  }
})

And here is how to add a side-effect that calls another lambda where the lambda ARN is stored in SSM:

import { createHandler, LambdaClient } from '@meltwater/jackalambda'
import { createSsmStringConfigurationRequest } from '@meltwater/aws-configuration-fetcher'

export handler = createHandler({
  configurationRequests: [
    createSsmStringConfigurationRequest(
      'otherLambdaArn',
      process.env.OTHER_LAMBDA_ARN_SSM_PATH
    )
  ],
  createContainer: (ctx, { otherLambdaArn }) => ({
    otherLambdaClient: new LambdaClient({ arn: otherLambdaArn, ...ctx })
  }),
  createProcessor: ({ log }, { otherLambdaClient }) => (event, context) => {
    log.info({ meta: event }, 'I 💖 Jackalambda')
    return otherLambdaClient.invokeJson(event)
  }
})

Installation

Add this as a dependency to your project using npm with

$ npm install @meltwater/jackalambda

or using Yarn with

$ yarn add @meltwater/jackalambda

Usage

For a full set of documentation check out the docs!

Development and Testing

Quickstart

$ git clone https://github.com/meltwater/jackalambda.git serverless-nodejs
$ cd serverless-nodejs
$ nvm install
$ yarn install

Run each command below in a separate terminal window:

$ yarn run offline
$ yarn run test:watch

Primary development tasks are defined under scripts in package.json and available via yarn run. View them with

$ yarn run

Source code

The source code is hosted on GitHub. Clone the project with

$ git clone git@github.com:meltwater/jackalambda.git

Requirements

You will need Node.js with npm, Yarn, and a Node.js debugging client.

Be sure that all commands run under the correct Node version, e.g., if using nvm, install the correct version with

$ nvm install

Set the active version for each shell session with

$ nvm use

Install the development dependencies with

$ yarn install

Drone

Drone should already be configured: this section is for reference only.

The following secrets must be set on Drone. These may be set manually or by running the script ./.drone/secrets.sh.

Note the Drone config path must be set to .drone/config.yml after the repo is activated.

npm

• npm_token_ro: npm token for installing packages.
• npm_token_rw: npm token for publishing packages.
• npm_team: npm team to grant read-only package access (format org:team, optional).

Slack

• slack_webhook: Slack webhook for build notifications.

Drone Promotion

When the drone build publishes a new package version it can trigger a promotion event on a Drone repo.

• drone_server: Drone server.
• drone_token: Drone token.

AWS S3 Release

• aws_assume_role_arn_staging: The AWS role to assume for staging.
• aws_assume_role_external_id_staging: The external ID for the AWS role for staging.
• aws_assume_role_arn_production: The AWS role to assume for production.
• aws_assume_role_external_id_production: The external ID for the AWS role for production.

Publishing

Use the npm version command to release a new version. This will push a new git tag which will trigger a CI publish job.

Contributing

Please submit and comment on bug reports and feature requests.

To submit a patch:

1. Fork it (https://github.com/meltwater/jackalambda/fork).
2. Create your feature branch (git checkout -b my-new-feature).
3. Make changes.
4. Commit your changes (git commit -am 'Add some feature').
5. Push to the branch (git push origin my-new-feature).
6. Create a new Pull Request.

License

This npm package is licensed under the MIT license.

Warranty

This software is provided by the copyright holders and contributors "as is" and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. In no event shall the copyright holder or contributors be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited to, procurement of substitute goods or services; loss of use, data, or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of the use of this software, even if advised of the possibility of such damage.