Mitigate occasional failures in looking up Application Default Credentials on a Google Compute Engine (GCE) Virtual Machine (#110 addresses #109):
- Add retry to the credentials check for the GCE environment
- Use fixed IP address for the GCE VM metadata server used to perform the check (to avoid nameserver lookup)
- Allow skipping the check by setting an environment variable
NO_GCE_CHECK=true
- Use a custom GCE metadata server address by setting the environment variable
GCE_METADATA_HOST=<hostname>