Add GCE support

[jefchien]

Description of changes

Depends on amazon-contributing/opentelemetry-collector-contrib#634 (will need to update go.mod once merged)

Adds GCE (Google Compute Engine) as a host mode to the agent translator with a corresponding detector. The detector uses cloud.google.com/go/compute/metadata (which is already brought in as a transitive dependency by the resourcedetection processor and promoted to a direct dependency). When detected, the mode is set to ModeGCE which branches the translator in a couple ways:

• The resourcedetection processor is set up with detectors: [env, gcp] so telemetry is enriched with GCP related attributes.
• A new version of the identity transform processor is used (transform_identity_gce.yaml), which sets the cloud.resource_id resource attribute to the derived GCP Full Resource Name (https://docs.cloud.google.com/iam/docs/full-resource-names): //compute.googleapis.com/projects/{cloud.account.id}/zones/{cloud.availability_zone}/instances/{host.name} (Note: The page says the last part is INSTANCE_ID, but confirmed by looking at the Asset Inventory resource information that the last part is the VM display/host name)
• Sets the provider to gcp for the oidctoken extension to support authentication.

License

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Tests

• Added unit tests and a sample config for the default:otel config on GCE.
• Built and tested on a GCE instance with mode set to auto.
  • Mode was auto-detected as GCE (after attempting to reach EC2 IMDS)
  • The oidctoken extension fetched and wrote the token to the expected file
  • Host metrics reached CloudWatch with the expected resource attributes

Resource Attribute	Value
cloud.provider	gcp
cloud.platform	gcp_compute_engine
cloud.region	us-east1
cloud.availability_zone	us-east1-b
cloud.account.id	{{project-id}}
cloud.resource_id	//compute.googleapis.com/projects/{{project-id}}/zones/us-east1-b/instances/cwagent-otel-gce
host.type	projects/{{project-number}}/machineTypes/e2-medium
host.name	cwagent-otel-gce
host.id	{{instance-id}}
deployment.environment.name	gcp_compute_engine:{{project-id}}

Requirements

Before commiting your code, please do the following steps.

1. Run make fmt and make fmt-sh
2. Run make lint

---

Integration Tests

To run integration tests against this PR, add the ready for testing label.

[github-actions]

Binary Size Report

linux/amd64

Binary	PR	vs main (660543b)	vs v1.300072.0
amazon-cloudwatch-agent	194.8 MB	${\color{red}▲}$ +12.3 KB (+0.0%)	${\color{red}▲}$ +1.5 MB (+0.8%)
amazon-cloudwatch-agent-config-wizard	2.0 MB	+0 B	+0 B
config-downloader	2.0 MB	+0 B	+0 B
config-translator	2.0 MB	+0 B	+0 B
start-amazon-cloudwatch-agent	2.5 MB	+0 B	+0 B
workload-discovery	3.0 MB	+0 B	+0 B
Total	206.4 MB	${\color{red}▲}$ +12.3 KB (+0.0%)	${\color{red}▲}$ +1.5 MB (+0.7%)

linux/amd64 amazon-cloudwatch-agent (last 9 main commits + this PR)

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 MB  └────────────────────────────────────────
      ca8av1.300072.0                     PR

Notable changes:

• +1.5 MB at 2b4d0a1

linux/arm64

Binary	PR	vs main (660543b)	vs v1.300072.0
amazon-cloudwatch-agent	178.6 MB	+0 B	${\color{red}▲}$ +1.5 MB (+0.9%)
amazon-cloudwatch-agent-config-wizard	2.0 MB	+0 B	+0 B
config-downloader	2.0 MB	+0 B	+0 B
config-translator	2.0 MB	+0 B	+0 B
start-amazon-cloudwatch-agent	2.4 MB	+0 B	+0 B
workload-discovery	2.9 MB	+0 B	+0 B
Total	189.9 MB	+0 B	${\color{red}▲}$ +1.5 MB (+0.8%)

windows/amd64

Binary	PR	vs main (660543b)	vs v1.300072.0
amazon-cloudwatch-agent.exe	197.6 MB	${\color{red}▲}$ +18.4 KB (+0.0%)	${\color{red}▲}$ +1.5 MB (+0.8%)
amazon-cloudwatch-agent-config-wizard.exe	2.1 MB	+0 B	+0 B
config-downloader.exe	2.1 MB	+0 B	+0 B
config-translator.exe	2.1 MB	+0 B	+0 B
start-amazon-cloudwatch-agent.exe	2.3 MB	+0 B	+0 B
workload-discovery.exe	2.9 MB	+0 B	${\color{red}▲}$ +512 B (+0.0%)
Total	209.3 MB	${\color{red}▲}$ +18.4 KB (+0.0%)	${\color{red}▲}$ +1.5 MB (+0.7%)

Investigating size changes

Use go-size-analyzer to compare binaries:

GOEXPERIMENT=jsonv2 go install github.com/Zxilly/go-size-analyzer/cmd/gsa@latest
gsa diff --old <baseline-binary> --new <new-binary>