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Loki ​

Introduction ​

Grafana Loki is an open-source, horizontally scalable, multi-tenant log aggregation system inspired by Prometheus. Unlike traditional log systems, Loki indexes only metadata labels (not the log content itself), which keeps storage costs low and operational overhead minimal. Logs are typically collected by Promtail, Grafana Alloy, or Fluent Bit, stored in object storage (S3, GCS, Azure Blob), and queried via the LogQL query language directly inside Grafana — making Loki a natural pairing with Prometheus metrics and Tempo traces in the Grafana observability stack.

How to Install ​

Starting via Binary ​

Quick Start ​

bash
# download and decompression
cd /opt && wget https://github.com/grafana/loki/releases/download/v3.0.1/loki-linux-amd64.zip
unzip loki-linux-amd64.zip && rm -f loki-linux-amd64.zip
mkdir /opt/loki/{bin,config}

# soft link
mv /opt/loki/loki-linux-amd64 /opt/loki/bin/loki

# configure
wget https://raw.githubusercontent.com/grafana/loki/main/examples/getting-started/loki-config.yaml -O /opt/loki/config/loki-config.yaml

# start
/opt/loki/bin/loki -config.file=/opt/loki/config/loki-config.yaml

# logcli
# download
LOGCLI_VERSION=v3.4.2
wget https://github.com/grafana/loki/releases/download/${LOGCLI_VERSION}/logcli-linux-amd64.zip
unzip logcli-linux-amd64.zip && rm -f logcli-linux-amd64.zip
chmod +x logcli-linux-amd64 && mv logcli-linux-amd64 /usr/bin/logcli
# query
export LOKI_ADDR=http://localhost:3100
kubectl port-forward services/loki-query -n logging 3100:3100
logcli query --limit 10 '{namespace="default",instance="my-app"} |= "kube-probe"'
logcli query --limit 10 --since=1h '{namespace="default",instance="my-app"} |= "kube-probe"'
logcli query --limit 10 --from="2025-01-01T00:00:00Z" --to="2025-01-01T08:00:00Z" '{namespace="default",instance="my-app"} |= "kube-probe"'

Config and Boot ​

Config ​
bash
# loki config
cat > /opt/loki/config/loki-config.yaml << "EOF"
...
EOF

# promtail config
cat > /opt/observability/promtail/config.yml << "EOF"
server:
  log_level: info
  log_format: logfmt
  http_listen_port: 3101

clients:
  - url: http://loki-gateway.revosurge-uat.com/loki/api/v1/push

positions:
  filename: /tmp/positions.yaml

scrape_configs:
- job_name: docker-containers-debug
  docker_sd_configs:
    - host: unix:///var/run/docker.sock
      refresh_interval: 5s
      port: 80

  # Use the Docker Compose service name as the 'app' label
  relabel_configs:
  - source_labels: [__meta_docker_container_label_com_docker_compose_service]
    target_label: app
  - source_labels: [__meta_docker_container_name]
    regex: '/(.+)'
    target_label: container_name
    replacement: '$1'

  # Add static labels
  - target_label: namespace
    replacement: 'revosurge'
  - target_label: node_name
    replacement: '${HOSTNAME:-unknow_node}'

  # Filter out Promtail's own logs to prevent loops
  - source_labels: [__meta_docker_container_name]
    regex: '.*promtail.*'
    action: drop

  pipeline_stages:
  - docker: {}
EOF
Boot(systemd) ​
bash
cat > /etc/systemd/system/loki.service << "EOF"
[Unit]
Description=Grafana Loki
Documentation=https://grafana.com/docs/loki
Wants=network-online.target
After=network-online.target

[Service]
ExecStart=/opt/loki/bin/loki --config.file /etc/loki/loki-all.yaml
ExecReload=/bin/kill -s HUP $MAINPID
ExecStop=/bin/kill -s TERM $MAINPID
LimitNOFILE=65535
LimitNPROC=4096
LimitAS=infinity
LimitFSIZE=infinity
KillSignal=SIGTERM
KillMode=process
PrivateTmp=yes
Restart=on-failure
RestartSec=5s
SendSIGKILL=no
StandardError=inherit
StandardOutput=journal
SuccessExitStatus=143
TimeoutStartSec=60
TimeoutStopSec=30
Type=simple
User=loki
Group=loki

[Install]
WantedBy=multi-user.target
EOF


chown loki:loki /opt/loki -R
systemctl daemon-reload
systemctl start loki.service
systemctl enable loki.service

Starting via Docker ​

bash
# Using by docker
# get loki and promtail config
wget https://raw.githubusercontent.com/grafana/loki/v3.0.0/cmd/loki/loki-local-config.yaml -O loki-config.yaml
wget https://raw.githubusercontent.com/grafana/loki/v3.0.0/clients/cmd/promtail/promtail-docker-config.yaml -O promtail-config.yaml
# run container
docker run --name loki -d -v $(pwd):/mnt/config -p 3100:3100 grafana/loki:3.0.0 -config.file=/mnt/config/loki-config.yaml
docker run --name promtail -d -v $(pwd):/mnt/config -v /var/log:/var/log --link loki grafana/promtail:3.0.0 -config.file=/mnt/config/promtail-config.yaml


# Using by docker compose
wget https://raw.githubusercontent.com/grafana/loki/main/examples/getting-started/docker-compose.yaml -O docker-compose.yaml
docker compose up -d

Starting via Kubernetes ​

bash
# Add and update repo
helm repo add grafana https://grafana.github.io/helm-charts --force-update

# Get charts package
helm pull grafana/loki-simple-scalable --untar
cd loki-simple-scalable

# Configure and run
vim values.yaml
deploymentMode: SimpleScalable  # single-binary, simple-scalable, distributed(microservices)
loki:
  auth_enabled: false
  server:
    http_listen_port: 3100
    grpc_listen_port: 9095
    http_server_read_timeout: 600s
    http_server_write_timeout: 600s
  limits_config:
    ingestion_rate_mb: 10
    ingestion_burst_size_mb: 20
    max_label_names_per_series: 15
    reject_old_samples: true
    reject_old_samples_max_age: 1w
    max_line_size: 256KB
    max_line_size_truncate: true
    max_streams_per_user: 10000
    max_global_streams_per_user: 50000
    per_stream_rate_limit: 3MB
    per_stream_rate_limit_burst: 15MB
    max_chunks_per_query: 2000000
    max_query_length: 30d1h
    max_query_parallelism: 32
    query_timeout: 1m
    split_queries_by_interval: 1h
    retention_period: 30d
  storage:
    bucketNames:
      chunks: loki-chunks
      ruler: loki-ruler
      admin: loki-admin
    type: s3 # s3, gcs, filesystem etc..
    s3:
      s3: null
      endpoint: "oss-ap-southeast-1.aliyuncs.com"
      region: "your_region"
      accessKeyId: "access_key"
      secretAccessKey: "secret_key"
      signatureVersion: null
      s3ForcePathStyle: false
      insecure: false
      http_config: {}
      backoff_config: {}
      disable_dualstack: false
    # gcs:
    #   chunkBufferSize: 0
    #   requestTimeout: "0s"
    #   enableHttp2: true
    # filesystem:
    #   chunks_directory: /var/loki/chunks
    #   rules_directory: /var/loki/rules
    #   admin_api_directory: /var/loki/admin
    object_store:
      type: s3
  schemaConfig:
    configs:
      - from: 2024-04-01
        store: tsdb
        object_store: s3 # s3, gcs, filesystem etc..
        schema: v13
        index:
          prefix: loki_index_
          period: 24h
        chunks:
          prefix: loki_chunks_
          period: 24h
  useTestSchema: false
  testSchemaConfig: {}
  rulerConfig:
    storage:
      type: local
      local:
        directory: /var/loki/rules
    wal:
      dir: /var/loki/ruler-wal
  query_scheduler: {}
  storage_config:
    tsdb_shipper:
      index_gateway_client:
        server_address: '{{ include "loki.indexGatewayAddress" . }}'
    hedging:
      at: "250ms"
      max_per_second: 20
      up_to: 3
  compactor:
    working_directory: /var/loki/compactor
    retention_enabled: true
    retention_delete_delay: 2h
    delete_request_store: s3 # s3, gcs, filesystem etc..
  querier:
    max_concurrent: 4
  ingester:
    chunk_retain_period: 0s
    chunk_idle_period: 30m
    chunk_block_size: 262144
    chunk_target_size: 1572864
    chunk_encoding: snappy
  index_gateway:
    mode: simple
  distributor: {}
  tracing:
    enabled: false
test:
  enabled: false
lokiCanary:
  enabled: false
networkPolicy:
  enabled: false
gateway:
  enabled: true
  replicas: 3
  nodeSelector:
    tier: middleware
ingress:
  enabled: false
singleBinary:
  replicas: 0
write:
  replicas: 3
  nodeSelector:
    tier: middleware
read:
  replicas: 3
  nodeSelector:
    tier: middleware
backend:
  replicas: 3
  resources:
      requests:
        cpu: 2000m
        memory: 4Gi
      limits:
        cpu: 4000m
        memory: 8Gi
    persistence:
      volumeClaimsEnabled: true
      size: 100Gi
      storageClass: premium-rwo
  nodeSelector:
    tier: middleware
ingester:
  replicas: 0
distributor:
  replicas: 0
querier:
  replicas: 0
queryFrontend:
  replicas: 0
queryScheduler:
  replicas: 0
indexGateway:
  replicas: 0
compactor:
  replicas: 0
bloomGateway:
  replicas: 0
bloomPlanner:
  replicas: 0
bloomBuilder:
  replicas: 0
ruler:
  enabled: false
  replicas: 0
memcached:
  enabled: true
resultsCache:
  enabled: true
  defaultValidity: 12h
  timeout: 500ms
  replicas: 1
  writebackSizeLimit: 500MB
  writebackBuffer: 500000
  writebackParallelism: 5
  nodeSelector:
    tier: middleware
chunksCache:
  enabled: true
  batchSize: 4
  parallelism: 5
  timeout: 2000ms
  defaultValidity: 0s
  replicas: 1
  writebackSizeLimit: 500MB
  writebackBuffer: 500000
  writebackParallelism: 5
  nodeSelector:
    tier: middleware
minio:
  enabled: false

# install promtail
helm install promtail grafana/promtail -f values.yaml -n logging
# install loki
helm install loki grafana/loki -f values.yaml -n logging

Reference:

  1. Official Website
  2. Repository

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