docker swarm 容器内存限制不起作用

Question

我正在尝试强制容器使用比允许的更多的内存，但我无法让它工作。该容器是使用 docker compose 定义的堆栈的一部分，并以群模式部署到 docker。

Docker 允许容器超出我设置的 50M 限制。我期待 docker 终止容器、抛出错误等。

谁能帮我解释为什么 Docker 在这里不强制执行内存限制？

docker-compose.yml 中的容器被定义为具有 50M 的内存限制，然后我设置了一个非常简单的 PHP 测试，它将尝试分配 200M。我已将 PHP 内存限制定义为 128M。

这是我的docker-compose.yml

  version: "3"

  services:
    nginx:
      image: nginx:latest
      restart: unless-stopped
      volumes:
        - ./deploy/nginx/nginx.conf:/etc/nginx/nginx.conf
        - ./public:/usr/share/nginx/html
      ports:
        - "8180:80"
      links:
        - app

    app:
      image: 127.0.0.1:5000/wpdemo
      build:
        context: .
        dockerfile: Dockerfile-app
      restart: unless-stopped
      volumes:
        - .:/var/www/html
      links:
        - mysql
      deploy:
        resources:
          limits:
            cpus: '0.50'
            memory: 50M
          reservations:
            cpus: '0.25'
            memory: 20M

    mysql:
        image: mysql:5.7
        restart: unless-stopped
        ports:
            - "13306:3306"
        environment:
            MYSQL_ALLOW_EMPTY_PASSWORD: 'yes'
        volumes:
            - ~/docker/volumes/mysql:/var/lib/mysql

而不是docker终止容器，它允许它占用尽可能多的内存并且PHP最终停止进程并抛出以下错误：

"PHP message: PHP Fatal error: Allowed memory size of 125829120 bytes exhausted (tried to allocate 67108872 bytes) in /var/www/html/public/index.php on line 4"

我正在使用 Ubuntu 18.04。

uname -a
Linux  4.18.10-041810-generic #201809260332 SMP Wed Sep 26 07:34:01 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Docker version 18.06.1-ce, build e68fc7a

docker-compose version 1.17.1, build unknown docker-py version: 2.5.1 CPython version: 2.7.15rc1 OpenSSL version: OpenSSL 1.1.0g 2 Nov 2017

这是 "docker stats" 在应用程序容器上的输出：

CONTAINER ID        NAME                                        CPU %               MEM USAGE / LIMIT   MEM %               NET I/O             BLOCK I/O           PIDS
679c8495ac1d        stackdemo_app.1.hr3ufwlskhdafre39aqrshxyu   0.00%               43.81MiB / 50MiB    87.62%              106kB / 389kB       2.05GB / 10.6GB     5

这是"docker info"的输出：

Containers: 36
 Running: 5
 Paused: 0
 Stopped: 31
Images: 450
Server Version: 18.06.1-ce
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: active
 NodeID: wnegv5lp41wfs3epfrua489or
 Is Manager: true
 ClusterID: hq7o176yffjglxzb9pu3fiomr
 Managers: 1
 Nodes: 1
 Orchestration:
  Task History Retention Limit: 5
 Raft:
  Snapshot Interval: 10000
  Number of Old Snapshots to Retain: 0
  Heartbeat Tick: 1
  Election Tick: 10
 Dispatcher:
  Heartbeat Period: 5 seconds
 CA Configuration:
  Expiry Duration: 3 months
  Force Rotate: 0
 Autolock Managers: false
 Root Rotation In Progress: false
 Node Address: 192.168.1.120
 Manager Addresses:
  192.168.1.120:2377
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 468a545b9edcd5932818eb9de8e72413e616e86e
runc version: 69663f0bd4b60df09991c08812a60108003fa340
init version: fec3683
Security Options:
 apparmor
 seccomp
  Profile: default
Kernel Version: 4.18.10-041810-generic
Operating System: Ubuntu 18.04.1 LTS
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 15.49GiB
Name: rafxps15
ID: QEX7:FEB3:J76L:DCAQ:SO4S:SWVE:4XPI:PI6R:YM4C:MV4I:C3PM:FLOQ
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

WARNING: No swap limit support

Answer 1

正如您在评论中所说，主机上启用了交换，但尚不支持 cgroups 中的交换限制。

据此启用swap limit support。请注意，重新启动系统是必不可少的。

最后，—-memory-swap 标志应该被设置。如果你想阻止你的 PHP 应用程序访问 swap，你应该将其设置为与 —-memory 相同的值。有关 memory swap settings 的更多详细信息。

docker swarm 容器内存限制不起作用

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