Environment variable replacement is needed so that users don't have to
hardcode their secrets in configuring `tools.yaml`.
Both formats `$ENV_NAME` and `${ENV_NAME}` are standard ways to declare
an environment variable.
However, some database statement placeholders that are already using the
`$ENV_NAME` format.
Therefore, we only support env var declaration using `${ENV_NAME}` to
disambiguate it from other usages.
Fixes issue: https://github.com/googleapis/genai-toolbox/issues/431
Rename existing `authSource` to `authService` through deprecation.
`AuthService` more clearly distinguishes it from `Sources` objects.
`authSources` will be converted into `authServices` after the
unmarshalling process. A warning log is shown if `authSources` are used
(for both within tools parameters and defining auth services):
```
2025-02-20T13:57:51.156025-08:00 WARN "`authSources` is deprecated, use `authServices` for parameters instead"
2025-02-20T13:57:51.156569-08:00 WARN "`authSources` is deprecated, use `authServices` instead"
2025-02-20T13:57:52.047584-08:00 INFO "Initialized 1 sources."
...
```
The manifest generated will continue to use `authSources` to keep
compatibility with the sdks:
```
{
"serverVersion":"0.1.0",
"tools":{
"test_tool2":{
"description":"Use this tool to test\n",
"parameters":[{
"name":"user_id",
"type":"string",
"description":"Auto-populated from Google login",
"authSources":["my-google-auth"]
}]
}
}
}
```
Test cases with `authSources` are kept for compatibility. Will be
removed when `authSources` are no longer supported.
