Google Cloud Function for proxying requests to OIDC-authenticated endpoints. For example, this can be used to make authenticated requests to resources protected by a GCP Identity Aware Proxy (IAP) using a service account.

$ gcloud functions deploy gcp-oidc-proxy \
    --runtime python37 \
    --entry-point handle_request \
    --trigger-http

• The service account for the Cloud Function needs the "Service Account Actor IAM" role.
• A CLIENT_ID environment variable needs to be set containing the OAuth2 client ID, e.g. the client ID used by IAP.
• A WHITELIST environment variable needs to be set containing a comma-separated list of paths to allow requests for. A value of * will whitelist all paths.
• The service account for the Cloud Function needs to be added as a member of the protected resource with appropriate roles configured.
• Optionally, Basic authentication can be enabled by setting AUTH_USERNAME and AUTH_PASSWORD environment variables. If either of these is not set, authentication is disabled.

You can run the function locally with:

$ python test.py

This will start an HTTP server which maps requests to the Cloud Function. This requires setting the GOOGLE_APPLICATION_CREDENTIALS environment variable to a service account credentials file which has the IAM roles described above.