User experience: starting the collector without config file yields a cryptic message

[jpkrohling]

When running the collector without specifying a config file, the error message that is returned doesn't immediately make it clear to users what the problem is:

$ ./bin/otelcorecol_linux_amd64 
Error: invalid map resolver config: no URIs
2022/07/07 16:08:11 collector server run finished with error: invalid map resolver config: no URIs

I would prefer to have a validation somewhere before this error, stating that a configuration file is required to run the collector. I believe we even had this a few releases ago.

[josephwoodward]

Feel free to assign this to me.

[svrnm]

I am wondering if instead of throwing an error the collector could just start with a minimal configuration (otlp receivers, debug logging exporters for all signals)? Or would this be unexpected behavior / lead to more confusion ?

[mx-psi]

I am wondering if instead of throwing an error the collector could just start with a minimal configuration (otlp receivers, debug logging exporters for all signals)? Or would this be unexpected behavior / lead to more confusion ?

We have that on the Helm chart, and it seems to have mixed feedback: open-telemetry/opentelemetry-helm-charts#90. We also have it on the Docker images, for which I have heard anecdotal negative feedback when open-telemetry/opentelemetry-collector-releases/issues/59 happened (since the Collector did not fail to start, just started with a different configuration).

IMO it's hard to agree on what this minimal configuration should be: different people have different ideas and use cases in mind, and the official binaries should probably be neutral in this regard and just provide high-quality examples outside of the binary.

[svrnm]

I share those mixed feeling, but I thought asking/exploring that would be helpful. From the perspective of a user that's just getting started having some easy defaults would be great, but for someone using the collector in production such a behavior might be harmful (especially what you said about the collector starting with a different/unexpected config vs just failing).

There are probably better ways to serve new comers (and I might raise another issue for that), so my question got answered. Thanks!

[josephwoodward]

Started looking into this and can confirm it used to error with the following message:

$ ./otelcol-dev
Error: failed to get config: invalid configuration: no enabled receivers specified in config
2022/08/13 00:30:23 collector server run finished with error: failed to get config: invalid configuration: no enabled receivers specified in config

It looks like it fails the way it does because the error is returned when creating a new config provider before it's even able to try and validate the configuration and get the friendlier error message.

[TylerHelmuth]

@jpkrohling when you said "configuration file is required to run the collector" do you mean an actual configuration file, or do you mean configuration provided via any valid source?

[TylerHelmuth]

@josephwoodward I think we can check for the presence of a --config flag here, and if there are not any we can error accordingly. Let me know if you are still working on it. If not, I can pick this up.

[jpkrohling]

Sorry, I meant a configuration provided from any valid source.