SegmentStream connections runtime

segmentstream-connections-runtime is the private Cloud Run host for custom OAuth 2.0 connections authored with the SegmentStream SDK. It loads the workspace's connections/connections.py tuple named connections, resolves customer-owned secret references, and performs authorization-code and refresh-token exchanges. Token responses are written directly to a pre-created, per-authorization-attempt Google Secret Manager secret. Authorization and token write operations return only credential metadata. The IAM-private credentials/resolve operation is the sole endpoint that returns token and OAuth client values to the authenticated backend for a capability-scoped local execution context.

The runtime is an infrastructure component, not a public user-facing API. Its Cloud Run service must require IAM authentication.

python -m segmentstream_connections_runtime inspect manifest.json
python -m segmentstream_connections_runtime serve

The server listens on PORT, defaulting to 8080. A declaration such as secret_ref("google-oauth-client-id") is resolved from SEGMENTSTREAM_CONNECTION_SECRET_GOOGLE_OAUTH_CLIENT_ID in the isolated runtime environment. Client secrets use the same mapping convention.

Serving also requires SEGMENTSTREAM_GOOGLE_CLOUD_PROJECT and Cloud Run's automatically injected K_REVISION. The Cloud Run service identity obtains a short-lived access token from the Google metadata server and must have secretmanager.versions.add and secretmanager.versions.access only for each managed ss-oauth-<authorization-attempt-id> secret. The control plane creates the secret and its IAM policy before completing OAuth authorization.

Every authorization, exchange, and refresh request includes the deployment's runtimeRevision. The runtime compares it with K_REVISION before resolving secrets or calling an OAuth provider and returns 409 runtime_revision_mismatch if Cloud Run routed the stable service URL to a different revision. POST /internal/v1/connections/{key}/token/exchange also accepts an authorization-attempt ID, its deterministic credential secret ID, the effective configurationDigest, authorization code, redirect URI, and PKCE verifier. The credential envelope binds its schema-v2 payload to the attempt, connection key, and configuration digest. POST .../token/refresh accepts the authorization-attempt ID, credential secret ID, and exact stored version. Both token operations return only credentialVersion, tokenType, expiresAt, scopes, and hasRefreshToken.

POST /internal/v1/connections/{key}/credentials/resolve additionally requires the exact active credential version and configuration digest. It reads that pinned version, recovers a newer version only when it belongs to the same authorization attempt, key, provider, and digest, and refreshes credentials that are expired or within two minutes of expiry. The response includes the resolved client ID, client secret, access token, optional refresh token, token URL, expiry, scopes, and resulting credential version. This operation must remain IAM-private; it is not a user-facing credential API.

OAuth providers and Secret Manager do not share a transaction. After a token exchange succeeds, the runtime retries retryable credential-version writes a bounded number of times and checks the latest validated version before each retry, so a response-lost successful write is reused instead of duplicated. If every write and recovery attempt fails after a provider has rotated a refresh token, the runtime returns only a sanitized availability failure and the connection may require reauthorization. That persistent provider/storage failure is an unavoidable atomicity limit; token values are never included in the failure. The 5-second metadata, 12-second Secret Manager, and 20-second provider timeouts plus the bounded retry count keep the worst-case credential-resolution budget below 174 seconds. The backend separately bounds workload-identity acquisition at 20 seconds and the whole private invocation at 230 seconds, so it retains the credential row lock throughout that persistence window. OAuth, metadata, and Secret Manager use cancellation-safe async HTTP, cap streamed response bodies, reject content encoding and redirects, and apply one aggregate deadline to connection, write, and read. Slow-drip responses therefore cannot extend the declared per-call budget, and bearer or Basic credentials cannot be forwarded to another origin. The managed one-vCPU service caps instance concurrency at four requests as an additional admission-control boundary. Once a token request begins, provider-result validation and credential persistence are shielded as one bounded operation, so caller cancellation waits for a rotated refresh token to reach durable storage before it propagates. Normalized OAuth token material is capped at 60 KiB of compact UTF-8 JSON, reserving enough space for identifiers and metadata in Secret Manager's 64 KiB credential envelope.

A deterministic token response that is malformed, omits a required refresh token, or grants fewer scopes than the selected connection is rejected as 400 oauth_token_response_invalid before a credential version is written. Definitive provider 4xx rejections return 400 oauth_provider_rejected, while timeouts, rate limits, transport failures, and provider 5xx responses remain 502 oauth_provider_unavailable so an ambiguous exchange can be recovered.

Releases

Releases use the version in pyproject.toml and are published from the connections-runtime-v<version> Git tag by the protected connections-runtime-release.yml workflow. PyPI releases are immutable, so the package version must be incremented before creating another release tag.