Add DD_AGENT_IPC_* env vars

[mackjmr]

What does this PR do?

This PR adds DD_AGENT_IPC_PORT and DD_AGENT_IPC_CONFIG_REFRESH_INTERVAL env vars in otel agent and core agent. It does not override them if they are added by the user. This is necessary for the otel-agent to pull the api key from core config in the case where backend secrets are used.

Motivation

OTEL-2323

Additional Notes

I have an open question about test, see PR comment.

Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

Run the otel-agent without API Key in otel collector config, and by providing api key in core agent via backend secret.

Setup 1:

kubectl create secret generic datadog-secret-deux --from-literal api_key=xxx

operator config:

  global:
    secretBackend:
      command: /readsecret_multiple_providers.sh
      enableGlobalPermissions: true
    kubelet:
      tlsVerify: false
    credentials:
      apiKey: ENC[k8s_secret@system/datadog-secret-deux/api_key]

Validate config can be fetched by the otel agent by checking otel-agent logs contain:

2025-01-07 12:57:02 UTC | OTELCOL | INFO | (/usr/local/go/src/reflect/value.go:581 in call) | configsync enabled (agent_ipc 'localhost:5009' | agent_ipc.config_refresh_interval: 60)
2025-01-07 12:57:02 UTC | OTELCOL | INFO | (comp/core/configsync/configsyncimpl/module.go:68 in newComponent) | triggering configsync on init (will retry for 30s)
2025-01-07 12:57:04 UTC | OTELCOL | INFO | (comp/core/configsync/configsyncimpl/module.go:100 in newConfigSync) | Succeeded to fetch config from core agent

Setup 2:

Same as above but user provided env vars, make sure these are not overriden.

Operator config:

spec:
  override:
    nodeAgent:
      containers: 
        agent:
          env:
            - name: DD_AGENT_IPC_PORT
              value: "3333"
            - name: DD_AGENT_IPC_CONFIG_REFRESH_INTERVAL
              value: "21"
        otel-agent:
          env:
            - name: DD_AGENT_IPC_PORT
              value: "3333"
            - name: DD_AGENT_IPC_CONFIG_REFRESH_INTERVAL
              value: "21"

Validate config can be fetched by the otel agent by checking otel-agent logs contain:

2025-01-07 12:57:02 UTC | OTELCOL | INFO | (/usr/local/go/src/reflect/value.go:581 in call) | configsync enabled (agent_ipc 'localhost:3333' | agent_ipc.config_refresh_interval: 21)
2025-01-07 12:57:02 UTC | OTELCOL | INFO | (comp/core/configsync/configsyncimpl/module.go:68 in newComponent) | triggering configsync on init (will retry for 30s)
2025-01-07 12:57:04 UTC | OTELCOL | INFO | (comp/core/configsync/configsyncimpl/module.go:100 in newConfigSync) | Succeeded to fetch config from core agent

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[mackjmr]

I don't think this can be tested by the current test framework, as the env vars added via WithEnvVars helper don't make it into container env vars.

e.g.

		{
			Name: "otel agent user provided ipc port",
			DDA: testutils.NewDatadogAgentBuilder().
				WithOTelCollectorEnabled(true).
				WithEnvVars([]corev1.EnvVar{
					{
						Name:  v2alpha1.DDAgentIpcPort,
						Value: "3333",
					},
				}).
				Build(),
			WantConfigure:        true,
			WantDependenciesFunc: testExpectedDepsCreatedCM,
			Agent: testExpectedAgent(apicommon.OtelAgent, defaultExpectedPorts, defaultLocalObjectReferenceName,
				expectedEnvVars{
					agent_ipc_port: expectedEnvVar{
						present: true,
						value:   "3333",
					},
					agent_ipc_refresh: expectedEnvVar{
						present: true,
						value:   "60",
					},
				},
			),
		},

will fail.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 48.97%. Comparing base (87f8143) to head (9d48e2a).

Files with missing lines	Patch %	Lines
...ller/datadogagent/feature/otelcollector/feature.go	81.25%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1604      +/-   ##
==========================================
+ Coverage   48.94%   48.97%   +0.02%     
==========================================
  Files         227      227              
  Lines       20636    20652      +16     
==========================================
+ Hits        10101    10114      +13     
- Misses      10010    10012       +2     
- Partials      525      526       +1     

Flag	Coverage Δ
unittests	48.97% <81.25%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ller/datadogagent/feature/otelcollector/feature.go	88.05% <81.25%> (-0.77%)	⬇️

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