can't set global labels from environment

[brettmc]

Describe the bug
Documentation suggests that you can set global labels via the environment variable ELASTIC_APM_GLOBAL_LABELS. When I set this value in an agent, I see no extra labels in APM. Searching the codebase here, I see no reference to the variable in code, just one mention in docs.

To Reproduce
Steps to reproduce the behavior:

1. Set `ELASTIC_APM_GLOBAL_LABELS=foo=bar,baz=bat"
2. Execute the application, causing a trace to be generated
3. View into the transaction's metadata in APM
4. See no extra labels

Expected behavior
Extra labels to be visible in APM.

[intuibase]

Hey @brettmc

I tested it by calling simple test app

ELASTIC_APM_GLOBAL_LABELS=foo=bar,baz=bat php8.2 /var/www/html/curl.php 

and got result:

Could you verify if env variable was set correctly?
It can be done by enabling debug level logs in agent or you can just dump env from PHP app.

Thanks,
Pawel

[brettmc]

Verified that this does work. I was using a quite old version of the agent (1.5), but upgrading to the most recent version fixed it. Sorry for the noise.