feat(origin detection): send both container ID and Entity ID

[wdhif]

What does this PR do?

We would like customers to be able to retrieve container tags even when DD_ENTITY_ID is set. Currently the library does not send the container ID if the Entity ID is set.

For those who do not want container tags, several alternatives are possible:

• Send the tag dd.internal.card=none.
• Inject DD_ORIGIN_DETECTION_ENABLED=false to the application pod.

Description of the Change

Remove checks for DD_ENTITY_ID when resolving container ID.

Possible Drawbacks

Verification Process

To make sure that this is working as intended, create a new pod with the following manifest:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: dummy-dogstatsd-udp-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: dummy-dogstatsd-udp-app
  template:
    metadata:
      labels:
        app: dummy-dogstatsd-udp-app
    spec:
      containers:
      - name: dummy-dogstatsd-udp-app
        image: wdhifdatadog/dummy_dogstatsd_udp
        imagePullPolicy: Always
        env:
        - name: DD_AGENT_HOST
          valueFrom:
            fieldRef:
              fieldPath: status.hostIP
        - name: DD_ENTITY_ID
          valueFrom:
            fieldRef:
              fieldPath: metadata.uid

You should still be able to get the following metrics with container tags such as container_id:

• dummy_dsd_udp_python.increment
• dummy_dsd_udp_python.decrement

We can see that, with an agent cardinality set as high:

• With the old behaviour, we don't get container tags.
• With the old behaviour and dd.internal.card:low, we don't get container tags (only pod tags).
• With the new behaviour, we get container tags.
• With the new behaviour and dd.internal.card:low, we don't get container tags (only pod tags).

Review checklist (to be filled by reviewers)

• Feature or bug fix MUST have appropriate tests (unit, integration, etc...)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have one changelog/ label attached. If applicable it should have the backward-incompatible label attached.
• PR should not have do-not-merge/ label attached.
• If Applicable, issue must have kind/ and severity/ labels attached at least.

[wdhif]

Links to DataDog/datadog-go#300

[wdhif]

I've added a unit test showing both Entity ID and container ID in the same metric.

[wdhif]

/merge

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[wdhif]

/merge

[dd-devflow]

🚂 MergeQueue

Pull request added to the queue.

This build is going to start soon! (estimated merge in less than 0s)

Use /merge -c to cancel this operation!

[dd-devflow]

🚨 MergeQueue

Gitlab pipeline didn't start on its own and we were unable to create it... Please retry.

If you need support, contact us on Slack #devflow with those details!