Collector

The shape is always the same on every platform:

The CloudWatch Agent is the primary collector (Step 2); upstream otelcol-contrib is the backup. The app-side wiring is identical either way.

Pick the platform guide for deployment and app wiring:

Lambda is not here. A Lambda execution environment has nowhere to run a collector short of a custom extension, and it does not need one: the ADOT layer exports to the environment’s own X-Ray receiver under active tracing. See the lambda-*.md guides.

Step 1: The destination — CloudWatch’s own OTLP endpoints, per signal

Omni reads CloudWatch’s data; it has no store of its own. Telemetry lands in CloudWatch first, in OTLP form — log groups for logs, aws/spans for traces, and the account’s CloudWatch Dataset for metrics. A dataset integration copies logs and traces into the Dataset, and the Space reads the Dataset.

The collector exports to CloudWatch’s own OTLP endpoints — three endpoints, one per signal. This is the standard path and what the CloudWatch Agent uses.

CloudWatchAgentServerPolicy covers all three and is what AWS’s own collector docs recommend.

cloudwatch:PutMetricData in that table is the IAM action the OTLP metrics endpoint authorizes against — it does not mean the collector calls the PutMetricData API. A metric that arrives through the OTLP endpoint stays OpenTelemetry-native, carries its resource attributes ("@resource.service.name"), and is PromQL-queryable in Omni. A metric published with the PutMetricData API itself, or with EMF log lines, is a CloudWatch metric and is not — see instrumentation.md (§ Custom metrics).

Three things that are easy to get wrong:

• Transaction Search must be enabled in the Region before traces work. This is a real prerequisite for Omni generally, not just for this endpoint — Omni only understands OpenTelemetry, and Transaction Search is what routes incoming spans into the aws/spans CloudWatch Logs group that Omni reads. Without it the traces endpoint rejects spans. It is an account-level, per-Region change: the user enables it with aws xray update-trace-segment-destination --destination CloudWatchLogs --region <region> (which also requires a CloudWatch Logs resource policy letting xray.amazonaws.com call logs:PutLogEvents on aws/spans). That resource policy grants a service principal, so it MUST carry the confused-deputy conditions the Transaction Search documentation shows: aws:SourceAccount equal to the account and aws:SourceArn matched with ArnLike against arn:aws:xray:<region>:<account-id>:* — never a bare grant to the principal. Tell the user to enable it; do not enable it for them. Spans carry request attributes, so treat aws/spans (and any custom trace log group) as a log group holding application data: CloudWatch Logs encrypts it at rest with a service-owned key by default, and a customer who must use their own key associates a symmetric KMS key with aws logs associate-kms-key. That key policy grants the CloudWatch Logs service principal (logs.<region>.amazonaws.com) the encrypt, decrypt, and data-key actions, and — like every service-principal grant in this file — it MUST be scoped, not bare: the CloudWatch Logs documentation’s statement conditions it with ArnLike on kms:EncryptionContext:aws:logs:arn matching arn:aws:logs:<region>:<account-id>:log-group:* (or the one log group), so the key can only be used for that account’s log groups. Recommend it where the customer’s data classification calls for it; do not associate a key or edit a key policy for them.
• Each signal needs its OWN sigv4auth extension, because the service differs (xray vs monitoring vs logs). One shared extension cannot sign for more than one.
• The logs endpoint needs x-aws-log-group and x-aws-log-stream headers. The log group must already exist.

Step 2: Choose the collector

The CloudWatch Agent is the primary collector. Since 1.300070 it builds an OTLP pipeline straight from its JSON config via a root-level opentelemetry section, so it needs no hand-written collector YAML at all:

That is the whole configuration. The agent derives the three destination endpoints from agent.region and builds the sigv4auth extensions, batch processors and pipelines itself. It also adds resource detection, entity correlation (cloud.resource_id), log-group routing, and retry plus sending queues — none of which the hand-written pipeline below has.

This stays inside Omni’s scope. The opentelemetry section pulls in no Application Signals, ServiceEvents or Dynamic Instrumentation components. Those live in the agent’s separate logs.metrics_collected.application_signals and traces.traces_collected.application_signals sections, which you MUST NOT add. Leave span_metrics_enabled unset — it defaults to false, and turning it on generates span metrics this reference does not cover.

resource_attributes sits alongside collect if extra resource attributes are needed, but prefer OTEL_RESOURCE_ATTRIBUTES on the application so they travel with the app rather than the host.

Verify the version first. An agent older than 1.300070 reports Configuration validation succeeded, status: running and configstatus: configured while starting no OTLP listener and generating no collector YAML. The only check that catches it is looking for listeners on 4317/4318. Note the Amazon Linux 2023 repo package is currently 1.300069.1, so install the current build from S3 rather than the distro repo.

The host package and the container image use different version schemes. Compare the 1.3000NN middle component, not a full string:

There is no v-prefixed tag and no 1.300070.1 tag in that repository — the nearest published tag is 1.300070.0b1586. Pin a real tag; do not float :latest. To enumerate tags, use the public-ECR token endpoint plus /v2/<repo>/tags/list (aws ecr-public describe-images does not work against public.ecr.aws without a registry id). On EKS, chart 6.6.0 already defaults agent.image.tag to a build past the floor, so pinning is optional there.

One limit decides when you cannot use it:

1. Batch sizes are fixed — traces and logs 10000/30s, metrics 1000/10s. Not tunable from JSON. The endpoints derive from agent.region; the JSON schema has no endpoint, URL, token or auth field anywhere under opentelemetry — which is fine, since the per-signal CloudWatch endpoints are exactly what the agent targets.

Backup: upstream OTel Collector Contrib

Use otelcol-contrib when batch sizing matters, or when the customer will not run the CloudWatch Agent. otelcol-contrib on a host, otel/opentelemetry-collector-contrib:<version> as a container.

Contrib, not core. sigv4auth is a contrib component; the core build refuses to start with unknown extension "sigv4auth". Pin a version from opentelemetry-collector-releases (opens in a new tab) rather than floating latest.

Step 3: Write the collector config (otelcol-contrib only)

Skip this entire step if you are using the CloudWatch Agent — its JSON above is the config.

CloudWatch’s own endpoints, traces + metrics. Each signal needs its own exporter and its own sigv4auth, because the signing service differs:

Why the config looks like this

• otlphttp, never otlp, on the exporter. The CloudWatch OTLP endpoints are HTTP/1.1 only — gRPC is not supported. The otlp exporter speaks gRPC.
• Both receiver protocols are enabled — gRPC on 4317 and HTTP on 4318. That is the OTel default pair, and it is what the CloudWatch Agent listens on too. It matters here because SDK defaults differ: the Java agent defaults to gRPC on 4317 while the Python, Node.js and .NET distros default to HTTP on 4318. Listening on both means an app works whichever default it has, and OTEL_EXPORTER_OTLP_PROTOCOL becomes a correctness detail rather than a hard requirement. Dropping one protocol is a deliberate narrowing, not a simplification. Note this is the inbound side only — the exporter to CloudWatch is HTTP-only regardless.
• extensions sits at service.extensions. AWS’s “OpenTelemetry Collector” page shows it nested under service.telemetry.extensions, which is not a real config key — the collector fails to start on it. AWS’s CloudWatch-agent page has it in the right place. Use service.extensions.
• send_batch_size: 200 keeps requests under the metrics endpoint’s limits: 1 MB and 1,000 data points per request, 500 TPS per account. Traces allow 5 MB and 10,000 spans, so 200 is comfortable for both.
• compression: gzip — the endpoints accept gzip or none and nothing else.
• Spans older than 14 days or more than 2 hours in the future are rejected. Only matters if the user replays telemetry.

Step 4: Wire the app to the collector

Set on the application, per the platform guide’s mechanism (systemd Environment=, container environment, pod env):

Set OTEL_EXPORTER_OTLP_PROTOCOL explicitly. SDK defaults differ — the Java agent defaults to gRPC, so pointing it at 4318 without this produces a port that is listening and telemetry that silently never arrives. This is the single most common failure in this setup.

Nothing else about the instrumentation changes. Do not revisit the loader variables.

IAM: the collector needs permissions, the app still does not

The instrumentation guides say instrumentation adds no IAM, and that stays true — the SDK only talks to the collector. The collector is what calls AWS, so it needs credentials.

What to grant: CloudWatchAgentServerPolicy, which covers all three CloudWatch OTLP signals (xray, monitoring, logs).

Where that grant attaches, per platform:

On ECS the execution role additionally needs ssm:GetParameters if the config comes from Parameter Store — a different role for a different reason. Getting these two backwards is the usual cause of an ECS collector that starts and then 403s.

Do NOT

• Do not use CloudWatch Agent port 4316, and do not install the amazon-cloudwatch-observability EKS add-on. Both wire up Application Signals. This is not a ban on the CloudWatch Agent itself — Step 2 makes it the primary collector, and its opentelemetry section pulls in no Application Signals components. What is banned is the Application Signals configuration, not the agent.
• Do not enable Application Signals, ServiceEvents, or Dynamic Instrumentation in the collector config.
• Do not modify application source. This is all IaC and collector config.
• Do not deploy. Present the diff and let the user apply it.

Verify (optional, and only after the user deploys)

None of this is part of the change you present. Every check here inspects a running collector, so it belongs to the conversation after the user applies — and on EC2 the change takes effect only when the instance is replaced, since UserData runs at first boot only.

Do not run these unprompted, and do not treat them as a gate on completing the task. Hand the relevant few to the user, or run them if they ask you to verify after applying.

The checks differ by collector AND by platform. Pick the row that matches what you deployed. Several checks that work on an EC2 host are impossible in a container, and vice versa.

CloudWatch Agent (primary)

Three things about the agent’s own diagnostics:

• The log is a file only on a host install. There, journalctl -u amazon-cloudwatch-agent is near-empty and will hide the errors, so read the file. In a container the file is never populated — the agent runs with logtarget = "lumberjack" and writes to stdout, so the awslogs stream (ECS) or kubectl logs (EKS) is the log.
• You cannot exec into the agent container. The image is distroless: no ss, no sh, no printenv. Read the endpoints from the API server instead of poking inside the pod.
• There is no 8888 endpoint. The agent generates service.telemetry.metrics.level: None and logs Skipped telemetry setup.. On EKS the operator still creates a cloudwatch-agent-monitoring Service on 8888 with endpoints, so the check looks available and then refuses the connection.

Benign noise you will see on a healthy collector — do not grep for E! or Error, grep for Exporting failed / dropped_items:

• On Fargate: two E! [EC2] Fetch hostname / identity document from EC2 metadata fail lines against 169.254.169.254, followed by I! Detected the instance is ECS. There is no IMDS in a task.
• Cannot access /etc/cwagentconfig: no such file or directory when the config comes from CW_CONFIG_CONTENT.
• E! ... "msg":"using deprecated field \blocking`”` with a ~2.5 KB Go stacktrace, once per exporter — an upstream collector deprecation, not your problem.

otelcol-contrib (backup)

otelcol_receiver_accepted_* rising with otelcol_exporter_sent_* at zero means the destination is rejecting; both at zero means the app never sent anything — check OTEL_EXPORTER_OTLP_PROTOCOL.

On ECS Fargate neither curl check is reachable — there is no host shell and no route into the task’s network namespace without enableExecuteCommand plus ssmmessages:* on the task role. Use the collector’s log stream instead: it dumps its generated pipelines at startup and logs Everything is ready. Begin running and processing data.. See collector-ecs.md.

Optional: confirm telemetry arrived at the destination

Everything above establishes that the collector is healthy, which is this guide’s job. Confirming the data landed is a query task and belongs to the aws-observability skill — route there rather than reproducing query recipes here. Two facts a reader needs in order to look in the right place:

• Traces land in the CloudWatch Logs group aws/spans (via Transaction Search), not in the CloudWatch X-Ray traces view. In the console that is CloudWatch → Transaction Search.
• Metrics land in CloudWatch’s Metrics V2 store and are not visible to list-metrics or get-metric-statistics, which only see V1. They are queried with PromQL over https://monitoring.<region>.amazonaws.com.

Allow 1–2 minutes for either to appear. If aws/spans stays empty while the collector logs no export errors, the usual cause is Transaction Search not being enabled on the account.

One trap worth stating, because it invites an account-wide change for no reason: aws xray get-indexing-rules reports a probabilistic DesiredSamplingPercentage that defaults to 1%. It governs X-Ray-side indexing for trace-summary search — it does not reduce what reaches aws/spans, which is unsampled. Do not raise it to debug missing spans.

Also do not treat traces.span.metrics.calls / .duration as evidence the metrics pipeline works. CloudWatch derives those from ingested spans, so they appear even when metric export is failing entirely. They carry @instrumentation.@name="cloudwatch.aws/xray/span-metrics"; the SDK’s own metrics carry @instrumentation.cloudwatch.source="cloudwatch-agent".

• references/cloudwatch-omni/instrumentation/collector.md(opens in a new tab)
• Raw file(opens in a new tab)
• aws/agent-toolkit-for-aws(opens in a new tab)