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⚙️ Shared Config

Shared Docker Compose Anchors

The following shared anchors are used across services in your docker-compose.yml file to ensure consistent configuration for logging, labeling, and resource limits.

Standardized Logging for Docker services

The following shared anchors are used across services in your docker-compose.yml file to ensure consistent configuration for logging, labeling, and resource limits.

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x-logging: &default-logging
  driver: "loki" # (1)
  options: &default-logging-options
    loki-url: https://loki.${SYNOLOGY_BASIC_URL}/loki/api/v1/push # (2)
    loki-retries: 5 # (3)
    loki-batch-size: 400 # (4)
    loki-batch-wait: 2s # (5)
    loki-timeout: 10s # (6)
    loki-max-backoff: 5s # (7)
    loki-min-backoff: 1s # (8)
    loki-tenant-id: default # (9)
  1. → Uses Grafana Loki for log aggregation
  2. → Dynamic URL using environment variable
  3. → Maximum 5 retries on failure
  4. → 400 log lines per batch maximum
  5. → 2 second wait for partial batches
  6. → 10 second request timeout
  7. → 5 seconds maximum between retries
  8. → 1 second minimum between retries
  9. → Default tenant identifier

Remember

  • The SYNOLOGY_BASIC_URL must be set in your environment or replaced with your direct Loki URL
  • These settings can be adjusted as needed, but the shown values are recommended by Loki docs for:
  • Balanced performance (batch size 400)
  • Reliable delivery (retries 5)
  • Network resilience (timeout 10s)
  • For production environments, consider:
  • Increasing batch size if high log volume
  • Adjusting timeouts based on network latency

Standardized labels for Docker services

The following shared anchors ensure consistent behavior across your docker-compose.yml:

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x-labels: &default-labels
  com.centurylinklabs.watchtower.enable: true  # (1)
  recreat.container: true                      # (2)
  container.label.group: setup                 # (3)
  1. → Enables Watchtower to auto-update this container
  2. → Custom marker for deployment-triggered recreation
  3. → Categorizes containers (e.g., proxy, db, monitoring)

Remember

  • Update container.label.group per service
  • Groups enable bulk operations via:
    docker ps --filter "label=container.label.group=setup"

Standardized Resource Limits for Docker services

The following shared anchors ensure consistent behavior across your docker-compose.yml:

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x-resource-limits: &default-resource-limits
  deploy:
    resources:
      limits:
        cpus: '0.50'  # (1)
        memory: 512M  # (2)
      reservations:
        cpus: '0.25'  # (3)
        memory: 256M  # (4)
  1. → Container won't exceed 50% of a CPU core
  2. → Hard memory cap of 512MB (OOM kill if exceeded)
  3. → Guaranteed 25% of a CPU core
  4. → Always allocated 256MB memory buffer

Remember

  • Adjust values based on your host machine capacity
  • Monitor usage with
    docker stats --format "table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}"

Example Usage

Here's how to implement these shared anchors in a service definition:

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version: '3.8'

services:
  nginx:
    image: nginx:latest
    <<: *default-labels
    <<: *default-resource-limits
    logging: *default-logging
    ports:
      - "80:80"
    environment:
      - SYNOLOGY_BASIC_URL=yourdomain.com  # Required for Loki URL

  postgres:
    image: postgres:15
    <<: *default-labels
    <<: *default-resource-limits
    logging: *default-logging
    environment:
      POSTGRES_PASSWORD: example
      - SYNOLOGY_BASIC_URL=yourdomain.com
    volumes:
      - pgdata:/var/lib/postgresql/data

x-logging: &default-logging
  driver: "loki"
  options: &default-logging-options
    loki-url: https://loki.${SYNOLOGY_BASIC_URL}/loki/api/v1/push
    loki-retries: 5
    loki-batch-size: 400
    loki-batch-wait: 2s
    loki-timeout: 10s
    loki-max-backoff: 5s
    loki-min-backoff: 1s
    loki-tenant-id: default

x-labels: &default-labels
  com.centurylinklabs.watchtower.enable: true
  recreat.container: true
  container.label.group: setup

x-resource-limits: &default-resource-limits
  deploy:
    resources:
      limits:
        cpus: '0.50'
        memory: 512M
      reservations:
        cpus: '0.25'
        memory: 256M

volumes:
  pgdata: