Server attributes env var interpolation is broken

[ju2wheels]

We upgraded from Docker image scalyr/scalyr-agent-docker-syslog:2.1.10 to scalyr/scalyr-agent-docker-syslog:2.1.27-alpine .

We were previously setting our server attributes with a config file that looks similar to this:

{
  "import_vars": ["SCALYR_DEVICE", "SCALYR_DEVICE_DOMINANCE"],
  "server_attributes": {
    "device": "$SCALYR_DEVICE",
    "dominance":"$SCALYR_DEVICE_DOMINANCE"
  }
}

With 2.1.10, if we set env vars as following:

SCALYR_DEVICE="mydevice"
SCALYR_DEVICE_DOMINANCE="primary"

Then the server attributes on forwarded messages were correctly set as expected:

device=mydevice
dominance=primary

However, with 2.1.27-alpine, instead what we get is this:

device=mydevice
dominance=mydevice_DOMINANCE

It appears that scalyr is having variable interpolation issues because both variables start with the same prefix. I even tried the following change to see if it would help interpolation but it ended up with the same result:

{
  "import_vars": ["SCALYR_DEVICE", "SCALYR_DEVICE_DOMINANCE"],
  "server_attributes": {
    "device": "${SCALYR_DEVICE}",
    "dominance":"${SCALYR_DEVICE_DOMINANCE}"
  }
}

[ajtcode]

@ju2wheels,

Thank you for bringing this to our attention and documenting your observations.

I duplicated this behavior and have raised it with our Engineering team for further investigation. I will follow up with updates as they become available.

Kindly note that this behavior will not occur if the environment variable name is unique. For example, if SCALYR_DVCE_DOMINANCE were specified instead of SCALYR_DEVICE_DOMINANCE, it would be interpreted correctly, as the SCALYR_DEVICE environment variable is not matched. You may also wish to change the SCALYR_ prefix to reduce potential ambiguity, as the SCALYR_ prefix is used to define Agent specific parameters (https://app.scalyr.com/help/scalyr-agent-env-aware).

[Kami]

Thanks for reporting this.

#935 should fix this bug.

[ju2wheels]

Confirming fix works for me with 2.1.32-alpine.

Thanks,