feat(spanner): support Private Service Connect (PSC) endpoint override#443
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yoshidan merged 1 commit intoJun 23, 2026
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When ClientConfig.endpoint is set to a full HTTPS URL such as https://spanner-nonprod.p.googleapis.com (a GCP Private Service Connect endpoint), use it as both the TLS SNI hostname and the gRPC connection target URL. Previously, GRPCConnectionManager was always called with the hardcoded AUDIENCE constant (https://spanner.googleapis.com/) as the connection target, so configuring a custom endpoint only affected the TLS SNI name but not the actual dial target — PSC connections silently fell back to the public endpoint. This mirrors the behaviour of the Java SDK's SpannerOptions.setHost(): https://cloud.google.com/spanner/docs/private-service-connect Backwards-compatible: when endpoint is a plain hostname (the default), the existing AUDIENCE constant is used unchanged.
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LGTM! |
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Summary
When
ClientConfig.endpointis set to a full HTTPS URL (e.g.https://spanner-nonprod.p.googleapis.com), the existing code only used it for TLS SNI but still dialled the hardcoded publicAUDIENCE(https://spanner.googleapis.com/) as the actual gRPC connection target. Private Service Connect (PSC) connections silently fell back to the public endpoint.This PR mirrors the Java SDK's
SpannerOptions.setHost("https://...")behaviour: when the configured endpoint starts withhttps://, extract the hostname for TLS SNI and use the full URL as the gRPC dial target.Change
spanner/src/apiv1/conn_pool.rs— 16 lines added, 1 line changed, fully backwards-compatible:spanner.googleapis.com): behaviour unchanged,AUDIENCEused as gRPC targethttps://URL: hostname used for TLS SNI, full URL used as gRPC dial targetReference
SpannerOptions.setHost()Testing
Battle-tested in production connecting from Azure AKS to non-prod Google Cloud Spanner via a Walmart PSC endpoint (
https://spanner-nonprod.p.googleapis.com).