enhancement(http_client source): add support for request body

[benjamin-awd]

Summary

This PR allows a request body to be sent via the http_client source with additional support for VRL.

Vector configuration

As a raw string:

sources:
  api:
    type: http_client
    endpoint: https://foobar.com/api/audit/search
    method: POST
    headers:
      Accept:
        - application/json
    auth:
      strategy: bearer
      token: ${API_TOKEN}
    body: |
      {
          "searchStatements": [{
              "column": "auditAction",
              "operator": "=",
              "value": "DELETE"
          }]"
      }

with VRL:

sources:
  api:
    type: http_client
    endpoint: https://foobar.com/api/audit/search
    method: POST
    headers:
      Accept:
        - application/json
    auth:
      strategy: bearer
      token: ${API_TOKEN}
    body:
      value: |
        encode_json({
          "searchStatements": [{"column": "auditAction", "operator": "=", "value": "DELETE"}],
          "timestamp": now()
        })
      type: vrl

How did you test this PR?

Change Type

• [ ] Bug fix
• [x] New feature
• [ ] Non-functional (chore, refactoring, docs)
• [ ] Performance

Is this a breaking change?

• [ ] Yes
• [x] No

Does this PR include user facing changes?

• [x] Yes. Please add a changelog fragment based on our guidelines.
• [ ] No. A maintainer will apply the no-changelog label to this PR.

References

• Closes #14758

Notes

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[benjamin-awd]

Hi @pront,

Have added a note about the default content type in 64721f7d9.

I think the current unit tests should provide enough coverage, so will leave the integration test suite as-is. Failing docs check should be addressed by 83a4621f8 🙏

[benjamin-awd]

hey @thomasqueirozb, any blockers on this one? would like to merge before any drift occurs 🙏

[thomasqueirozb]

Hi @benjamin-awd. We missed this one, sorry. Since pront gave the approval and had even queued it I'll make an exception and include it in the release tomorrow since it should've been merged quite some time ago.