Send APM data through the agent

With this route, applications send OpenTelemetry data to the Logcore agent on the same server. The agent forwards it to Logcore with its own API key, so your apps need no key.

 app ──OTLP──▶ localhost:4317 / :4318 (logcore-agent) ──HTTPS + gzip──▶ Logcore

1. Enable APM in the agent

The installer writes the APM block into logcore.yaml commented out. Remove the # from those lines:

Before

# apm:
#   enabled: true
#   otlp_grpc_addr: "127.0.0.1:4317"   # OTLP/gRPC from local apps ("off" disables)
#   otlp_http_addr: "127.0.0.1:4318"   # OTLP/HTTP; "0.0.0.0:4318" to accept apps in containers

After

apm:
  enabled: true
  otlp_grpc_addr: "127.0.0.1:4317"   # OTLP/gRPC from local apps ("off" disables)
  otlp_http_addr: "127.0.0.1:4318"   # OTLP/HTTP; "0.0.0.0:4318" to accept apps in containers

Uncommenting only apm: and enabled: true is enough; the addresses shown are the defaults.

Then restart the agent and check it:

Linux

sudo systemctl restart logcore-agent
sudo logcore-agent status      # look for the "APM (OpenTelemetry)" section

Windows

logcore-agent service restart
logcore-agent status

Do it at install time

Add LOGCORE_APM=true to the install command to install with APM already enabled. Running the installer again with LOGCORE_APM=true also enables it on an existing installation.

2. Point your app at the agent

OTEL_SERVICE_NAME=checkout
OTEL_RESOURCE_ATTRIBUTES=deployment.environment=production
OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318
OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf
OTEL_TRACES_EXPORTER=otlp
OTEL_METRICS_EXPORTER=otlp
OTEL_LOGS_EXPORTER=otlp

For gRPC, use OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4317 and OTEL_EXPORTER_OTLP_PROTOCOL=grpc.

Don't set OTEL_EXPORTER_OTLP_HEADERS. The agent adds the key itself.

Next, add OpenTelemetry to your app: Language setup.

What the agent adds

If your app doesn't set them, the agent adds these resource attributes:

Attribute	Value
host.name	the agent's hostname
deployment.environment	the value of the agent's env: tag, for example env:prod gives prod

So traces line up with the host in Infrastructure and its environment without any extra configuration.

Apps in Docker on the same host

By default the agent listens on 127.0.0.1 only. To accept data from containers:

apm:
  enabled: true
  otlp_http_addr: "0.0.0.0:4318"

Then in the container use the host's address:

# docker-compose.yml
services:
  api:
    environment:
      OTEL_EXPORTER_OTLP_ENDPOINT: http://host.docker.internal:4318
    extra_hosts:
      - "host.docker.internal:host-gateway"

WARNING

0.0.0.0 listens on every interface. Block port 4318 from outside the host with your firewall, because anyone who can reach it can send data to your organization.

Ports already in use

If another program, such as an OpenTelemetry Collector, already uses 4317 or 4318, choose other ports, or turn one protocol off:

apm:
  enabled: true
  otlp_grpc_addr: "off"
  otlp_http_addr: "127.0.0.1:14318"

and point apps at http://localhost:14318.

When Logcore is unreachable

The agent passes the failure back to the app as a retryable error (HTTP 503 or gRPC UNAVAILABLE). OpenTelemetry SDKs then retry with backoff, so short outages don't lose data.