NHS FHIR Middy Error Handler

This repository contains a variant of the Middy Error Handler for use in a FHIR AWS lambda.

Functionality

This repository creates an NPM package that is designed to be used as error handling middleware for a FHIR AWS lambda, returning FHIR compliant error messages as OperationOutcome resources.

Versions

This project has a dependency on @aws-lambda-powertools/logger.
If you are using @aws-lambda-powertools/logger in your project, and you are using version 1.x of @aws-lambda-powertools/logger, then you must use version 1.x of this module.
If you are using @aws-lambda-powertools/logger in your project, and you are using version 2.x of @aws-lambda-powertools/logger, then you must use version 2.x of this module.

Usage

To integrate this into your project, install the package using the following:

npm install @nhs/fhir-middy-error-handler

Then add the following to your middy middleware stack:

import middy from "@middy/core"
import {Logger, injectLambdaContext} from "@aws-lambda-powertools/logger"
import {APIGatewayProxyEvent, APIGatewayProxyResult} from "aws-lambda"
import errorHandler from "@nhs/fhir-middy-error-handler";

const logger = new Logger({serviceName: "myService", logLevel: "INFO"})

const lambdaHandler = async (event: APIGatewayProxyEvent): Promise<APIGatewayProxyResult> => {
  ...
}

export const handler = middy(lambdaHandler)
  .use(injectLambdaContext(logger))
  .use(errorHandler({ logger }));

See a working example in https://github.com/NHSDigital/prescriptionsforpatients/blob/main/packages/getMyPrescriptions/src/getMyPrescriptions.ts

Project Structure

• .devcontainer Contains a dockerfile and vscode devcontainer definition
• .github Contains github workflows that are used for building and deploying from pull requests and releases
• scripts Contains a script to check python licenses
• src Contains the source code for the project
• tests Contains the tests for the project

Contributing

Contributions to this project are welcome from anyone, providing that they conform to the guidelines for contribution and the community code of conduct.

Licensing

This code is dual licensed under the MIT license and the OGL (Open Government License). Any new work added to this repository must conform to the conditions of these licenses. In particular this means that this project may not depend on GPL-licensed or AGPL-licensed libraries, as these would violate the terms of those libraries' licenses.

The contents of this repository are protected by Crown Copyright (C).

Development

It is recommended that you use visual studio code and a devcontainer as this will install all necessary components and correct versions of tools and languages.
See https://code.visualstudio.com/docs/devcontainers/containers for details on how to set this up on your host machine.
There is also a workspace file in .vscode that should be opened once you have started the devcontainer. The workspace file can also be opened outside of a devcontainer if you wish.

All commits must be made using signed commits

Once the steps at the link above have been completed. Add to your ~/.gnupg/gpg.conf as below:

use-agent
pinentry-mode loopback

and to your ~/.gnupg/gpg-agent.conf as below:

allow-loopback-pinentry

As described here: https://stackoverflow.com/a/59170001

You will need to create the files, if they do not already exist. This will ensure that your VSCode bash terminal prompts you for your GPG key password.

You can cache the gpg key passphrase by following instructions at https://superuser.com/questions/624343/keep-gnupg-credentials-cached-for-entire-user-session

CI Setup

The GitHub Actions require a secret to exist on the repo called "SONAR_TOKEN". This can be obtained from SonarCloud as described here. You will need the "Execute Analysis" permission for the project (NHSDigital_nhs-fhir-middy-error-handler) in order for the token to work.

Pre-commit hooks

Some pre-commit hooks are installed as part of the install above, to run basic lint checks and ensure you can't accidentally commit invalid changes. The pre-commit hook uses python package pre-commit and is configured in the file .pre-commit-config.yaml. A combination of these checks are also run in CI.

Make commands

There are make commands that are run as part of the CI pipeline and help alias some functionality during development.

Default target

• make runs the default target which runs deep-clean, install, lint, check-licenses, build, and test

Install targets

• install installs python, pre-commit hooks, and node modules

Clean and deep-clean targets

• clean clears up any files that have been generated by building or testing locally.
• deep-clean runs clean target and also removes any node_modules installed locally.

Linting and testing

• lint runs lint for all code
• test runs all tests

Check licenses

• check-licenses checks licenses for all packages used in node and python

GitHub folder

This .github folder contains workflows and templates related to github

• pull_request_template.yml: Template for pull requests.
• dependabot.yml: Dependabot definition file

Workflows are in the .github/workflows folder

• combine_dependabot_prs.yml: Workflow for combining dependabot pull requests. Runs on demand
• dependabot_auto_approve_and_merge.yml: Workflow to auto merge dependabot updates
• pr_link.yml: Workflow to link Pull Requests to Jira tickets and runs when a pull request is opened.
• pr_title_check.yml: Workflow to check the format of a pull request is compliant with the project standards. See guidelines for contribution for details.
• pull_request.yml: Called when pull request is opened or updated. Runs rename_dependabot_prs.yml, quality_checks, and pr_title_check.yml
• release.yml: Uses semantic-release to release main branch to NPM.
• rename_dependabot_prs.yml: Renames dependabot pull requests to comply with project standards.

Running a Release

Details of running the release can be found in RELEASE.md.