Prometheus

Prometheus is the metrics collector and TSDB at the heart of most monitoring stacks. This image wraps the upstream binary in the same bootstrap as every container here: you configure it with PROMETHEUS_* environment variables, the entrypoint seeds a config file if you have not mounted one, and ezx supervises the process, rotates the logs and probes readiness.

Quickstart

bash

docker run -d \
  --name prometheus \
  -v prometheus-data:/opt/containers/data \
  -v prometheus-config:/opt/containers/config \
  -p 9090:9090 \
  ghcr.io/supanadit/containers/prometheus

With no mounted config, the image seeds the bundled default prometheus.yml into /opt/containers/config so the container starts out of the box. To bring your own scrape configuration, mount a file at /opt/containers/config/prometheus.yml.

yaml

services:
  prometheus:
    image: ghcr.io/supanadit/containers/prometheus
    volumes:
      - prometheus-data:/opt/containers/data
      - ./prometheus.yml:/opt/containers/config/prometheus.yml:ro
    ports:
      - "9090:9090"

volumes:
  prometheus-data:

Configuration

Variable	Default	Description
`PROMETHEUS_PORT`	`9090`	Web UI and API listen port.
`PROMETHEUS_CONFIG_FILE`	`/opt/containers/config/prometheus.yml`	Path to the scrape config.
`PROMETHEUS_DATA_DIR`	`/opt/containers/data`	TSDB data directory.
`PROMETHEUS_CONFIG_DIR`	`/opt/containers/config`	Configuration directory.
`PROMETHEUS_STORAGE_TSDB_RETENTION_TIME`	(unset)	TSDB time-based retention (e.g. `15d`).
`PROMETHEUS_STORAGE_TSDB_RETENTION_SIZE`	(unset)	TSDB size-based retention (e.g. `10GB`).
`PROMETHEUS_STORAGE_TSDB_MIN_BLOCK_DURATION`	(unset)	Minimum TSDB block duration.
`PROMETHEUS_STORAGE_TSDB_MAX_BLOCK_DURATION`	(unset)	Maximum TSDB block duration.
`PROMETHEUS_WEB_CONFIG_FILE`	(unset)	TLS/basic-auth web config file (`--web.config.file`).
`LOG_LEVEL`	`info`	Log verbosity.

Retention and block-duration flags are only added to the command line when their variable is set — unset never becomes an empty --flag=.

Feature toggles

Web endpoints and --enable-feature gates are plain booleans (true/false/1/0/yes/no):

Variable	Enables
`PROMETHEUS_ENABLE_WEB_LIFECYCLE`	`/-/reload` and `/-/quit` endpoints
`PROMETHEUS_ENABLE_WEB_REMOTE_WRITE_RECEIVER`	Remote-write receiver API
`PROMETHEUS_ENABLE_WEB_OTLP_RECEIVER`	OTLP ingestion receiver
`PROMETHEUS_ENABLE_NATIVE_HISTOGRAM`	`native-histograms`
`PROMETHEUS_ENABLE_EXEMPLAR_STORAGE`	`exemplar-storage`
`PROMETHEUS_ENABLE_PROMQL_FUNCTIONS`	`promql-experimental-functions`
`PROMETHEUS_ENABLE_AUTO_RELOAD_CONFIG`	`auto-reload-config`

That is a selection — the full set of PROMETHEUS_ENABLE_* flags lives in entrypoint.d/bootstrap/env.js in the repository.

Readiness tuning

Variable	Default	Description
`PROMETHEUS_READY_MAX_ATTEMPTS`	`30`	Readiness probe attempts.
`PROMETHEUS_READY_ATTEMPT_INTERVAL`	`1`	Seconds between probe attempts.

Custom scrape configuration

The config file is the only thing Prometheus needs beyond env vars. When the path is the container default and nothing is mounted, the entrypoint copies the bundled default config into place; a custom path you set with PROMETHEUS_CONFIG_FILE is never fabricated — if it does not exist, the container fails fast with a validation error instead of guessing.

Health

The composite health endpoint runs on the shared health server (default port 8080). It reports healthy when Prometheus answers /-/ready, the supervised process is alive, the data directory has free space and there are no zombie children.

bash

curl -s http://localhost:8080/health
curl -s http://localhost:8080/health/comprehensive | jq

Next steps

Ship metrics long-term with Mimir or Thanos.
Visualize them with Grafana.
Configuration explains the env-var conventions.