[opentelemetry-collector] Pod fails to start when node name is digits only

[ebostijancicunwired]

The pod fails to start with the following error message when deployed on a node which hostname contains only digits:

Error: invalid configuration: service::telemetry::resource: legacy resource attribute "host.name" must be string or null

A workaround for this error is setting the resource attributes host.name and k8s.node.name to null

resource:
  k8s.node.name: 'null'
  host.name: 'null'

unfortunately this is not a satisfying solution, as information is lost.

According to RFC1123 §2.1 hostnames with digits only are allowed.

[TylerHelmuth]

@ebostijancicunwired is the issue happening with some of our out-of-the-box resource attributes or with your values.yaml file? If there is something wrong in our default values we should wrap them in "". If it is coming from your values.yaml file, is something like str!! enough to solve the issue?

[ebostijancicunwired]

@TylerHelmuth I have set this in my values.yaml and it solves the issue:

service:
  telemetry:
    resource:
      k8s.node.name: str!! ${env:OTEL_K8S_NODE_NAME}
      host.name: str!! ${env:OTEL_K8S_NODE_NAME}

However it would be benefical to have this fix already in the default values.yaml so that it works out-of-the-box for this corner case.

[TylerHelmuth]

@kshitizj03 if you're interested in solving this issue please address it with this fix directly in the values.yaml

[kshitizj03]

Thanks @TylerHelmuth. I tried it directly in values.yaml, but the chart renders config through toYaml, which quotes anything starting with !. So host.name: "!!str ${env:OTEL_K8S_NODE_NAME}" comes out as:

host.name: '!!str ${env:OTEL_K8S_NODE_NAME}'

Once it's quoted, !!str is just literal text, so the collector resolves host.name to !!str 12345 instead of 12345. The reporter's str!! form has the same issue (host.name becomes str!! 12345).

From what I can tell, the tag only takes effect if it's applied unquoted at render time, which is what the helper does:

host.name: !!str ${env:OTEL_K8S_NODE_NAME}

Happy to go whichever way you prefer here. If the generic pass feels too broad, I can scope it to just host.name/k8s.node.name. And if there's a simpler values.yaml approach I haven't thought of, glad to take the pointer.

[TylerHelmuth]

@kshitizj03 when I set the chart's default values.yaml to

config:
  service:
      telemetry:
        resource:
          k8s.node.name: str!! ${env:OTEL_K8S_NODE_NAME}
          host.name: str!! ${env:OTEL_K8S_NODE_NAME}

and run helm template testing ./charts/opentelemetry-collector --set mode=deployment --set image.repository=test I see

        resource:
          host.name: str!! ${env:OTEL_K8S_NODE_NAME}
          k8s.node.name: str!! ${env:OTEL_K8S_NODE_NAME}

in the output configmap as expected