Docker

An OpenTelemetry Collector on the Docker host reads the log files of every container and forwards them to Squasher. The same Collector can receive traces and logs from your apps. For host and container resource metrics, use Host and Docker metrics.

Prerequisites

A Linux host that runs Docker with the default json-file log driver.
Docker Compose.
An ingest key in the environment as SQUASHER_API_KEY. See Create an ingest key.

Set up the Collector

Configure the Collector

The second json_parser reads the level from container lines that are JSON. Plain-text lines have no level.

otel-config.yaml

receivers:
  filelog/docker:
    include: [/var/lib/docker/containers/*/*-json.log]
    operators:
      - type: json_parser
        timestamp:
          parse_from: attributes.time
          layout_type: gotime
          layout: "2006-01-02T15:04:05.999999999Z07:00"
      - type: move
        from: attributes.log
        to: body
      - type: move
        from: attributes.stream
        to: attributes["log.iostream"]
      - type: json_parser
        if: 'body matches "^\\s*\\{"'
        parse_from: body
        parse_to: attributes
        severity:
          parse_from: attributes.level
  otlp:
    protocols:
      http:
        endpoint: 0.0.0.0:4318

processors:
  resource:
    attributes:
      - { key: service.name, value: docker-host, action: insert }
      - { key: deployment.environment.name, value: production, action: insert }
  batch: {}

exporters:
  otlphttp/squasher:
    endpoint: https://ingest.squasher.ai
    headers:
      x-squasher-key: "${env:SQUASHER_API_KEY}"

service:
  pipelines:
    logs:
      receivers: [filelog/docker, otlp]
      processors: [resource, batch]
      exporters: [otlphttp/squasher]
    traces:
      receivers: [otlp]
      processors: [resource, batch]
      exporters: [otlphttp/squasher]

Add the Collector to Docker Compose

The Collector runs as root so that it can read the container log files.

docker-compose.yml

services:
  otel-collector:
    image: otel/opentelemetry-collector-contrib:latest
    user: "0:0"
    environment:
      SQUASHER_API_KEY: ${SQUASHER_API_KEY}
    volumes:
      - ./otel-config.yaml:/etc/otelcol-contrib/config.yaml:ro
      - /var/lib/docker/containers:/var/lib/docker/containers:ro
    restart: unless-stopped

Start it

docker compose up -d otel-collector

To send traces from your apps, set OTEL_EXPORTER_OTLP_ENDPOINT=http://otel-collector:4318 in their containers. See OpenTelemetry for each language.

What Squasher keeps from each record

Container log field	Squasher field
`log`	Log body and issue title
`time`	Time
`stream`	The `log.iostream` attribute: `stdout` or `stderr`
`level` in a JSON line	Level. `error` and `fatal` create issues.
Other keys in a JSON line	Attributes

Every container line gets the service name docker-host and the environment production from the resource processor. Apps that send OTLP keep their own values.

Verify

In a container, write the line {"level":"error","msg":"Squasher test error"} to stdout.
In Squasher, select Issues in the sidebar. The error is at the top of the list.
Select Logs in the sidebar to see the other container lines.

Limits

Plain-text lines have no level, so they create no issues, even on stderr.
Docker Desktop on macOS and Windows keeps container logs inside a virtual machine. Run this setup on a Linux host.

Get started

Guides

Prerequisites

Set up the Collector

What Squasher keeps from each record

Verify

Limits

Next steps

Host and Docker metrics

Kubernetes

​Prerequisites

​Set up the Collector

​What Squasher keeps from each record

​Verify

​Limits

​Next steps

Host and Docker metrics

Kubernetes

Prerequisites

Set up the Collector

What Squasher keeps from each record

Verify

Limits

Next steps