Add DeveloperConnectSource to Vertex ReasoningEngine

[rileykarson]

Fixes hashicorp/terraform-provider-google#25931

Followup test issue: hashicorp/terraform-provider-google#26007

I've omitted testing for now. This is complicated because we need a properly set up Git repo with developer connect set up- so wrangling external credentials, specific files, etc. Let me know what you'd look for for this!

I could probably get it set up manually, but it's a bit of a pain following policy since the path of least resistance is a personal Git repo.

Sending it in a request:

2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: ---[ REQUEST ]---------------------------------------
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: POST /v1beta1/projects/graphite-test-rileykarson/locations/us-central1/reasoningEngines?alt=json HTTP/1.1
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: Host: us-central1-aiplatform.googleapis.com
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: User-Agent: Terraform/1.5.7 (+https://www.terraform.io) Terraform-Plugin-SDK/2.38.1 terraform-provider-google-beta/dev7
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: Content-Length: 511
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: Content-Type: application/json
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: Accept-Encoding: gzip
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta: {
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:  "description": "A basic reasoning engine",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:  "displayName": "reasoning-engine",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:  "spec": {
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:   "sourceCodeSpec": {
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:    "developerConnectSource": {
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:     "config": {
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:      "dir": "src",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:      "gitRepositoryLink": "projects/ci-test-project-nightly-beta/locations/us-central1/connections/tf-test-my-connectiony31n360y2w/gitRepositoryLinks/tf-test-my-repositoryy31n360y2w",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:      "revision": "main"
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:     }
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:    },
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:    "pythonSpec": {
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:     "entrypointModule": "simple_agent",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:     "entrypointObject": "fixed_name_generator",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:     "requirementsFile": "./test-fixtures/requirements.txt",
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:     "version": "3.11"
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:    }
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:   }
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:  }
2026-02-05T14:17:20.454-0800 [DEBUG] provider.terraform-provider-google-beta:

I get a domain-specific error:

Error: Error waiting to create ReasoningEngine: Error waiting for Creating ReasoningEngine: Error code 3, message: Build failed. The issue might be caused by incorrect code, requirements.txt file or other dependencies.

where without the field configured I get:

Error message required oneof field 'source' must have one initialized field doesn't match the format of [error-reason] public-message

Release Note Template for Downstream PRs (will be copied)

See Write release notes for guidance.

vertexai: added support for `developer_connect_source` to `spec.source_code_spec` in `google_vertex_ai_reasoning_engine`

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 3 files changed, 186 insertions(+))
google-beta provider: Diff ( 3 files changed, 186 insertions(+))
terraform-google-conversion: Diff ( 1 file changed, 77 insertions(+))

Missing test report

Your PR includes resource fields which are not covered by any test.

Resource: google_vertex_ai_reasoning_engine (7 total tests)
Please add an acceptance test which includes these fields. The test should include the following:

resource "google_vertex_ai_reasoning_engine" "primary" {
  spec {
    source_code_spec {
      developer_connect_source {
        config {
          dir                 = # value needed
          git_repository_link = # value needed
          revision            = # value needed
        }
      }
    }
  }
}

[modular-magician]

Tests analytics

Total tests: 83
Passed tests: 80
Skipped tests: 3
Affected tests: 0

Click here to see the affected service packages

• vertexai

🟢 All tests passed!

View the build log

[rileykarson]

Discussed offline; the schema is simple and unlikely to have issues, the API accepts the request and fails for domain-specific reasons. I'll follow up with a test per issue hashicorp/terraform-provider-google#26007

[c2thorn]

Discussed testing offline, LGTM.