Panic when loading config referencing non-existent environment variable about signalfx-agent HOT 3 CLOSED

Thanks for reporting this @jalaziz, even after finding the solution. The referenced PR should fix the panic and also provide clear context in the config file as to the error. I suspect you had a variable that was getting interpreted as YAML but had some kind of parse error, as I could not reproduce it with an unset or blank envvar. Either way, it should be easier to diagnose config errors after this PR is released.

Also, I would recommend using the following syntax to put in envvars:

globalDimensions:
  env: {"#from": "env:ENV_NAME", raw: true}
  region: {"#from": "env:REGION", raw: true}

This will prevent the values from attempting to be parsed as YAML.

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@keitwb Thanks for the info. You are right, it was a different block that was causing the panic:

- type: collectd/kafka
   serviceURL: service:jmx:rmi:///jndi/rmi://{{.Host}}:9999/jmxrmi
   clusterName: ${ENV_NAME}-${REGION}
   discoveryRule: container_name == "kafka" && port == 9092

Looks like the - was being interpreted as a list? Adding quotes around the value doesn't seem to help.

Unfortunately, I don't believe the {"#from"} block works for this use case unless there's an undocumented trick?

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Ah ok, that makes sense. The resolved value was just - if both envvars were blank, which I think gets interpreted as the start of a list, resulting in a syntax error. I just tested my PR with that particular combination and it will now give a better error message.

Yes, you are right that #from isn't powerful enough to combine values in an arbitrary template. The ${} will work fine but just remember that it pastes in the envvar values before parsing it as YAML.

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