Loki

Grafana Loki is a log aggregation system that indexes labels instead of full log lines, making it cheap to run. This image reduces Loki's large YAML configuration to a handful of GRAFANA_LOKI_* environment variables: at boot the entrypoint renders the full loki.yaml (schema, storage, ring, compactor, ruler) deterministically and starts Loki under ezx supervision.

Quickstart

Single-node filesystem Loki:

bash

docker run -d \
  --name loki \
  -v loki-data:/opt/containers/data \
  -p 3100:3100 \
  ghcr.io/supanadit/containers/grafana-loki

Query it and check readiness:

bash

curl -s http://localhost:3100/ready
curl -s http://localhost:8080/health

Configuration

Variable	Default	Description
`GRAFANA_LOKI_CONFIG`	`/opt/containers/config/loki.yaml`	Where the generated config is written.
`GRAFANA_LOKI_DATA_DIR`	`/opt/containers/data`	Chunks, rules and retention data.
`GRAFANA_LOKI_TARGET`	(unset = `all`)	Component target: `read`, `write` or `backend`.
`GRAFANA_LOKI_LISTEN_PORT_HTTP`	`3100`	HTTP API port.
`GRAFANA_LOKI_LISTEN_PORT_GRPC`	`9096`	gRPC port.
`GRAFANA_LOKI_STORAGE_BACKEND`	`filesystem`	`filesystem` or `s3`.
`GRAFANA_LOKI_MEMBERLIST`	(unset)	Comma-separated memberlist peers; enables clustering.
`GRAFANA_LOKI_INSTANCE_ADDRESS`	(unset)	Advertised instance address.
`GRAFANA_LOKI_COMPACTOR_ADDRESS`	(unset)	Compactor address for the cluster.
`GRAFANA_LOKI_USER` / `_GROUP`	`loki`	Unprivileged account the process runs as.
`GRAFANA_LOKI_READY_MAX_ATTEMPTS`	`30`	Readiness probe attempts.
`GRAFANA_LOKI_READY_ATTEMPT_INTERVAL`	`1`	Seconds between probe attempts.

The config is regenerated on every start from these variables — mount a file at GRAFANA_LOKI_CONFIG's path only if you want to inspect it, not to edit it, because Loki is configured from the environment, not the file.

S3 storage

Set GRAFANA_LOKI_STORAGE_BACKEND=s3 and the object storage moves from the local disk to S3 (or any S3-compatible store such as MinIO):

Variable	Default
`GRAFANA_LOKI_S3_BUCKET`	`loki`
`GRAFANA_LOKI_S3_ENDPOINT`	`s3.amazonaws.com`
`GRAFANA_LOKI_S3_ACCESS_KEY`	`your-access-key`
`GRAFANA_LOKI_S3_SECRET_KEY`	`your-secret-key`
`GRAFANA_LOKI_S3_REGION`	`us-east-1`
`GRAFANA_LOKI_S3_FORCE_PATH_STYLE`	`true`
`GRAFANA_LOKI_S3_INSECURE`	`false`

yaml

environment:
  GRAFANA_LOKI_STORAGE_BACKEND: s3
  GRAFANA_LOKI_S3_ENDPOINT: minio:9000
  GRAFANA_LOKI_S3_BUCKET: loki
  GRAFANA_LOKI_S3_ACCESS_KEY: minio
  GRAFANA_LOKI_S3_SECRET_KEY: minio123
  GRAFANA_LOKI_S3_INSECURE: "true"

Clustering

Set GRAFANA_LOKI_MEMBERLIST to a comma-separated list of peer addresses and the entrypoint renders a memberlist: block (port 7946, gossip) and switches the ring KV store from inmemory to memberlist. Split roles across replicas with GRAFANA_LOKI_TARGET=read / write / backend.

yaml

environment:
  GRAFANA_LOKI_MEMBERLIST: loki-1:7946,loki-2:7946,loki-3:7946

Health

The composite health endpoint runs on the shared health server (default port 8080): Loki must answer /ready, the process must be alive, the data directory must have free space and there must be no zombie children.

bash

curl -s http://localhost:8080/health
curl -s http://localhost:8080/loki/ready

Next steps

Visualize logs with Grafana.
Collect metrics with Prometheus.
Volumes explains what to persist.