Docker Compose Resource Optimization

Configures resource allocation, constraints, and scaling for PHP application stacks.

Resource Allocation Overview

┌─────────────────────────────────────────────────────────────────┐
│            PHP STACK RESOURCE DISTRIBUTION (4GB Host)            │
├─────────────────────────────────────────────────────────────────┤
│  PHP-FPM:   ████████████████████░░░░░░░░░░  1024MB  (25%)     │
│  MySQL:     ████████████████████████░░░░░░  1536MB  (38%)     │
│  Redis:     ████████░░░░░░░░░░░░░░░░░░░░░░   512MB  (13%)    │
│  Nginx:     ████░░░░░░░░░░░░░░░░░░░░░░░░░░   256MB   (6%)    │
│  RabbitMQ:  ████████░░░░░░░░░░░░░░░░░░░░░░   512MB  (13%)    │
│  System:    ████░░░░░░░░░░░░░░░░░░░░░░░░░░   256MB   (6%)    │
└─────────────────────────────────────────────────────────────────┘

Recommended Resource Limits

Service	Memory Limit	Memory Reservation	CPU Limit	CPU Reservation
PHP-FPM	512MB-1GB	256MB	1.0	0.25
Nginx	128MB-256MB	64MB	0.5	0.1
MySQL	1GB-2GB	512MB	1.5	0.5
PostgreSQL	1GB-2GB	512MB	1.5	0.5
Redis	256MB-512MB	128MB	0.5	0.1
RabbitMQ	512MB-1GB	256MB	1.0	0.25

Service Configurations

PHP-FPM

  php-fpm:
    deploy:
      resources:
        limits: { cpus: "1.0", memory: 1024M }
        reservations: { cpus: "0.25", memory: 256M }
      replicas: 2
    tmpfs: ["/tmp:size=64M"]
    healthcheck:
      test: ["CMD", "php-fpm-healthcheck"]
      interval: 30s
      timeout: 5s
      start_period: 10s

MySQL

  mysql:
    deploy:
      resources:
        limits: { cpus: "1.5", memory: 2048M }
        reservations: { cpus: "0.5", memory: 512M }
    shm_size: "256m"
    command: >
      --innodb-buffer-pool-size=1G --innodb-log-file-size=256M
      --max-connections=200 --tmp-table-size=64M
    ulimits:
      nofile: { soft: 65536, hard: 65536 }

Redis

  redis:
    deploy:
      resources:
        limits: { cpus: "0.5", memory: 512M }
        reservations: { cpus: "0.1", memory: 128M }
    command: redis-server --maxmemory 384mb --maxmemory-policy allkeys-lru --save "" --appendonly no
    tmpfs: ["/data:size=384M"]

RabbitMQ

  rabbitmq:
    deploy:
      resources:
        limits: { cpus: "1.0", memory: 1024M }
        reservations: { cpus: "0.25", memory: 256M }
    environment:
      RABBITMQ_VM_MEMORY_HIGH_WATERMARK: 0.6
      RABBITMQ_DISK_FREE_LIMIT: 128MB

Logging Configuration

    logging:
      driver: json-file
      options:
        max-size: "10m"
        max-file: "3"

Service	max-size	max-file	Total Disk
PHP-FPM	10m	3	30MB
Nginx	20m	5	100MB
MySQL	10m	3	30MB
Redis	5m	2	10MB

tmpfs for Ephemeral Data

    tmpfs:
      - /tmp:size=64M,mode=1777
      - /app/var/cache:size=128M
      - /app/var/log:size=32M

Benefits: faster I/O, no disk writes, auto-cleaned on restart.

shm_size for Databases

  postgres:
    shm_size: "256m"   # shared_buffers, WAL buffers, lock tables
  mysql:
    shm_size: "256m"   # InnoDB buffer pool, temp tables

ulimits Configuration

ulimit	Default	Recommended	Purpose
nofile	1024	65536	Max open files/sockets
nproc	1024	4096	Max processes
memlock	64KB	unlimited	Memory locking (Redis)

Scaling with Replicas

  php-fpm:
    deploy:
      replicas: 3
      endpoint_mode: dnsrr
      resources:
        limits: { cpus: "0.5", memory: 512M }
    # Total: 1.5 CPU, 1536M memory across 3 replicas
    # Nginx resolves php-fpm to all replicas via DNS round-robin

Before/After Comparison

Metric	No Limits	With Limits	Improvement
OOM kills	Frequent	Rare	Predictable
Noisy neighbor	Common	Prevented	Isolated
Memory waste	30-50%	< 10%	-80% waste
Log disk usage	Unbounded	< 200MB	Controlled
Recovery time	Minutes	Seconds	Faster restarts

Generation Instructions

1. Inventory services: List all containers in the stack
2. Assess host resources: Total CPU and memory available
3. Allocate proportionally: Database > App > Cache > Proxy
4. Set limits and reservations: Limits cap usage, reservations guarantee minimum
5. Configure logging: Prevent unbounded disk growth
6. Add health checks: Enable automatic recovery
7. Test under load: Verify no OOM kills or throttling