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checklist-jobspec.md

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New jobspec Entry Checklist

Code

  • Consider similar features in Consul, Kubernetes, and other tools. Is there prior art we should match? Terminology, structure, etc?
  • Add structs/fields to api/ package
    • api/ structs usually have Canonicalize and Copy methods
    • New fields should be added to existing Canonicalize, Copy methods
    • Test the structs/fields via methods mentioned above
  • Add structs/fields to nomad/structs package
    • structs/ structs usually have Copy, Equal, and Validate methods
      • Validate methods in this package must be implemented
      • Equal methods are used when comparing one job to another (e.g. did this thing get updated?)
      • Copy methods ensure modifications do not modify the copy of a job in the state store
        • Use slices.CloneFunc and maps.CloneFunc to ensure creation of deep copies
    • Note that analogous struct field names should match with api/ package
    • Test the structs/fields via methods mentioned above
    • Implement and test other logical methods
  • Add conversion between api/ and nomad/structs/ in command/agent/job_endpoint.go
    • Add test for conversion
  • Determine JSON encoding strategy for responses from RPC (see "JSON Encoding" below)
    • Write nomad/structs/ to api/ conversions if necessary and write tests
  • Implement diff logic for new structs/fields in nomad/structs/diff.go
    • Note that fields must be listed in alphabetical order in FieldDiff slices in nomad/structs/diff_test.go
    • Add test for diff of new structs/fields
  • Add change detection for new structs/fields in scheduler/util.go/tasksUpdated
    • Might be covered by .Equals but might not be, check.
    • Should return true if the task must be replaced as a result of the change.

HCL1 (deprecated)

New jobspec entries should only be added to jobspec2. It makes use of HCL2 and the api package for automatic parsing. Before, additional parsing was required in the original jobspec package.

  • Parse in jobspec/parse.go (HCL1 only)
  • Test in jobspec/parse_test.go (preferably with a jobspec/text-fixtures/<feature>.hcl test file) (HCL1 only)

Docs

JSON Encoding

As a general rule, HTTP endpoints (under command/agent/) will make RPC calls that return structs belonging to nomad/structs/. These handlers ultimately return an object that is encoded by the Nomad HTTP server. The encoded form needs to match the Nomad API; specifically, it should have the form of the corresponding struct from api/. There are a few ways that this can be accomplished:

  • directly return the struct from the RPC call, if it has the same shape as the corresponding struct in api/. This is convenient when possible, resulting in the least work for the developer. Examples of this approach include [GET /v1/evaluation/:id](https://github.com/hashicorp/nomad/blob/v1.0. 0/command/agent/eval_endpoint.go#L88).
  • convert the struct from the RPC call to the appropriate api/ struct. This approach is the most developer effort, but it does have a strong guarantee that the HTTP response matches the API, due to the explicit conversion (assuming proper implementation, which requires tests). Examples of this approach include GET /v1/volume/csi/:id
  • convert to an intermediate struct with the same shape as the api/ struct. This approach strikes a balance between the former two approaches. This conversion can be performed in-situ in the agent HTTP handler, as long as the conversion doesn't need to appear in other handlers. Otherwise, it is possible to register an extension on the JSON encoding used by the HTTP agent; these extensions can be put in nomad/jsonhandles/extensions.go.