New shutdown flag gives confusing error message

[Stono]

Bug Description

Using the new --exit-zero-on-sigterm does correctly exit with a 0, but gives you an incorrect error:

❯ ./cloud-sql-proxy blah:blah --port=3306 --exit-zero-on-sigterm
2023/08/09 22:05:34 Authorizing with Application Default Credentials
2023/08/09 22:05:34 [blah:blah] Listening on 127.0.0.1:3306
2023/08/09 22:05:34 The proxy has started successfully and is ready for new connections!
2023/08/09 22:05:36 The proxy has encountered a terminal error: SIGTERM signal received

❯ echo $?
0

❯ ./cloud-sql-proxy blah:blah --port=3306 
2023/08/09 22:05:34 Authorizing with Application Default Credentials
2023/08/09 22:05:34 [blah:blah] Listening on 127.0.0.1:3306
2023/08/09 22:05:34 The proxy has started successfully and is ready for new connections!
2023/08/09 22:06:14 SIGTERM signal received. Shutting down...

❯ echo $?
143

So we're correctly getting a 0, but equally it's logging an ERROR The proxy has encountered a terminal error: SIGTERM signal received which feels wrong.

Structured logs shows the log level too:

{"severity":"INFO","timestamp":"2023-08-09T22:10:21.009+0100","message":"Authorizing with Application Default Credentials"}
{"severity":"INFO","timestamp":"2023-08-09T22:10:21.177+0100","message":"[blah:blah] Listening on 127.0.0.1:3306"}
{"severity":"INFO","timestamp":"2023-08-09T22:10:21.177+0100","message":"The proxy has started successfully and is ready for new connections!"}
{"severity":"ERROR","timestamp":"2023-08-09T22:10:22.965+0100","message":"The proxy has encountered a terminal error: SIGTERM signal received"}

In both shutdown scenarios, the message should be 2023/08/09 22:06:14 SIGTERM signal received. Shutting down...

Example code (or command)

No response

Stacktrace

No response

Steps to reproduce?

See above

Environment

1. OS type and version: macosx
2. Cloud SQL Proxy version (./cloud-sql-proxy --version): 2.6.0
3. Proxy invocation command (for example, ./cloud-sql-proxy --port 5432 INSTANCE_CONNECTION_NAME): see above

Additional Details

No response

[enocom]

Thanks, @Stono. We'll fix this.