GNU envsubst does not handle ${VAR:-default} bash syntax - it leaves
the entire expression unsubstituted. This caused CDC connector
registration to fail with "password authentication failed for user
${POSTGRES_USER:-rwa_user}".
Replace all envsubst calls with a substitute_env_vars() helper that
uses eval+heredoc, which natively supports bash default value syntax.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
hailin
ef663c0c08
