CCM-12649 Get Status healthcheck endpoint

[stevebux]

Description

Context

Healthcheck endpoint

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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[francisco-videira-nhs]

A couple points:

Response payload
I raised this this ticket originally thinking we'd only need to return 200 OK if pass and 400/500 if not, but looks like we need to do this like described in https://nhsd-confluence.digital.nhs.uk/spaces/APM/pages/158433407/_status+endpoint (payload links to the healthcheck RFC)?

I'm not aware if we can simplify it though... Any thoughts @masl2 ?

If we do need to return a payload like described in there it might prove tricky with the current error mapping logic involving mapToErrorResponse.

Proxygen
I wonder if we need to do something additional with proxygen too? Is it already supporting this? @nhsd-david-wass

OAS / Sandbox
Currently the _status endpoint inly has a 200 OK. We might want to build up on that depending on the answers above?

[stevebux]

Proxygen I wonder if we need to do something additional with proxygen too? Is it already supporting this? @nhsd-david-wass

Am I right in thinking openapi.yaml is the proxygen configuration? If so, it's already configured:

x-nhsd-apim:
  temporary: true
  monitoring: false
  access: []
  target:
    type: hosted
    healthcheck: /_status

[masl2]

So by the information in https://nhsd-confluence.digital.nhs.uk/spaces/APM/pages/158433407/_status+endpoint

The status response should always return 200 if the check is triggered and contain a response with a status content (looks like we're currently returning empty)

Also - the setup for running the health checks will use a manually created product to routinely poll the healthcheck (using apikey auth) in order to report the proxy status; so we can't attach the standard auth pattern for suppliers to the healthcheck

[stevebux]

So by the information in https://nhsd-confluence.digital.nhs.uk/spaces/APM/pages/158433407/_status+endpoint

The status response should always return 200 if the check is triggered and contain a response with a status content (looks like we're currently returning empty)

According to @nhsd-david-wass, the status JSON described there will be created for us for free by a default proxy policy - all we have to do is return 200

[stevebux]

Also - the setup for running the health checks will use a manually created product to routinely poll the healthcheck (using apikey auth) in order to report the proxy status; so we can't attach the standard auth pattern for suppliers to the healthcheck

Ah OK, I wasn't sure on that point. I can remove that. Can we get away with no authorisation at all in that case?

[francisco-videira-nhs]

LGTM ✔️