feat(gcp): Dataproc Metastore services

[NitinKumar004]

Summary

New greenfield GCP control-plane service: Dataproc Metastore (metastore.googleapis.com/v1, resource type services). Track-1 control-plane emulation only (no Hive data plane). Real google.golang.org/api/metastore/v1 clients, gcloud, and the Terraform google_dataproc_metastore_service resource hit it unchanged.

Provider tier: GA. google_dataproc_metastore_service is in the STABLE hashicorp/google provider at the default /v1/ path (verified live with provider v8.1.0); the metastore/v1 SDK confirms the GA surface. No beta path needed.

What's covered

• POST .../services?serviceId= · GET (item + list) · PATCH ?updateMask= · DELETE, plus location-scoped operations polls.
• Every mutation returns a google.longrunning.Operation done:true synchronously, resource embedded in response as an Any typed type.googleapis.com/google.cloud.metastore.v1.Service — no LRO hang. Operations flow through the shared lro.Registry; Matches yields operations paths to the shared poller so no sibling GCP service regresses.
• Client-named create via ?serviceId= (body name fallback); 409 dup / 404 missing / 400 bad input.
• Raw passthrough for every caller-supplied body key (encryptionConfig, networkConfig, scalingConfig, maintenanceWindow, hiveMetastoreConfig, labels, …); updateMask top-level replace, unmentioned fields survive.
• COW memstore with deep clone on read; Snapshottable compile-asserted and auto-discovered by persist completeness.

Computed-field stability (drift prevention)

name, state (seeded ACTIVE), stateMessage, uid, endpointUri (deterministic Thrift endpoint from name+port), artifactGcsUri (deterministic gs://…/hive-metastore), createTime/updateTime are minted once at create, stored, and stable across GETs. The Computed port (9083) and provider-defaulted databaseType (MYSQL) / releaseChannel (STABLE) / tier are filled when omitted.

Per the provider schema (terraform providers schema -json), telemetryConfig and hiveMetastoreConfig are Optional, non-Computed nested blocks — so they are carried verbatim and deliberately not server-injected; injecting them was the sole plan-drift source and is avoided.

Live e2e (Terraform, hashicorp/google STABLE, default path)

Ran a real cloudemu serve --gcp-port 18050 + terraform (provider v8.1.0) against a google_dataproc_metastore_service with service_id/location/tier=DEVELOPER, leaving port/database_type/release_channel/telemetry/hive UNSET:

• apply → created, LRO did not hang, state = ACTIVE.
• plan -detailed-exitcode → exit 0, no drift, specifically on the defaulted/computed port, database_type, release_channel, state, endpoint_uri, artifact_gcs_uri, uid, create_time.
• update (add labels + maintenance_window) → in-place PATCH applied; re-plan exit 0 clean.
• destroy → removed; endpoint returns 404.

Gates

go build, full go vet, gofmt, golangci-lint (0 issues), go test -race on new packages, full go test ./server/gcp/... (no sibling operations regression), ./providers/..., ./persist/... (completeness), root ., and go generate idempotency — all green. Docs regenerated (metastore-only diff).

Deferred

metadataImports, backups, federations subcollections, IAM policy verbs, and the real Hive metastore data plane.