When no STS configuration is provided in the IAM config file, the STS
service was not being initialized, causing temporary credentials from
AssumeRole to be rejected with "InvalidAccessKeyId" errors.
This commit adds a DefaultSTSConfig() function that provides sensible
defaults (1h token duration, 12h max session, secure random signing key)
and updates the IAM manager to use these defaults when no explicit STS
configuration is provided.
Changes:
- Add DefaultSTSConfig() with secure random signing key generation
- Update IAM manager to use default config when config.STS is nil
- Add tests verifying initialization with and without explicit config
Fixes#8312
Chris Lu
5fc2fefb4a