php - 为什么 Docker Compose 重启可能会越来越多地渲染容器输出？

Question

我正在编写一个基于 Docker Compose 的 Web 应用程序，它有许多后台系统——一个 HTTP API、一个 HTTP 代理和一个队列。一切都在 PHP 5.6 或 7.0 的 Alpine 容器中。

我最初在 API 容器内的 Supervisor 中设置了队列，效果很好。然而，Supervisor/Python 使容器比它们应该的要胖得多(80M 而不是 25M)，所以我将队列移到了它自己的容器中。它会存活约 5 分钟并退出以重新启动，而我在 Supervisor 中使用自动重启系统，因此我已切换到 Docker Compose 中的重启系统。我使用的是 Compose YAML 格式的第 2 版。

当队列启动时，它会向标准输出呈现一条简单的消息:

queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)

当我最初执行 docker-compose up 时，这很好。但是，每次重新启动时，我都会收到三个这样的消息，然后是五个，依此类推，没有限制。如果我执行 docker ps 则表明只有一个队列在运行:

halfer@machine:~/proximate-app$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
a9c94558769d        proximate-app       "/tmp/container-st..."   2 hours ago         Up 2 hours          0.0.0.0:8084->8084/tcp   app_instance
7e48d6aec459        proximate-api       "sh /tmp/bin/web-s..."   2 hours ago         Up 2 hours          0.0.0.0:8080->8080/tcp   api_instance
86c564becadf        proximate-queue     "sh /var/app/bin/c..."   2 hours ago         Up About a minute                            queue_instance
20c2145f80e4        proximate-proxy     "sh /var/proxy/con..."   2 hours ago         Up 2 hours          0.0.0.0:8081->8081/tcp   proxy_instance

这是我的 Compose 文件:

version: '2'
services:

  proximate-app:
    container_name: "app_instance"
    image: proximate-app
    ports:
    - "8084:8084"
    links:
    - proximate-api

  # @todo Remove external ports once everything is happy
  proximate-api:
    container_name: "api_instance"
    image: proximate-api
    ports:
    - "8080:8080"
    links:
    - proximate-proxy
    - proximate-queue
    volumes:
    - proximate-volume:/remote/cache
    - proximate-q-volume:/remote/queue
    # Use time and TZ from the host, could alternatively use env vars and set it
    # manually in the container, see https://wiki.alpinelinux.org/wiki/Setting_the_timezone
    - /etc/localtime:/etc/localtime:ro
    - /etc/timezone:/etc/timezone:ro
    # Should perhaps pass this as a var to docker-compose so as not to hardwire it,
    # but it is fine for now
    environment:
    - PHP_TIMEZONE=Europe/London

  proximate-queue:
    container_name: "queue_instance"
    image: proximate-queue
    restart: always
    links:
    - proximate-proxy
    volumes:
    - proximate-volume:/remote/cache
    - proximate-q-volume:/remote/queue
    environment:
    - PROXY_ADDRESS=proximate-proxy:8081

  # @todo Remove external ports once everything is happy
  proximate-proxy:
    container_name: "proxy_instance"
    image: proximate-proxy
    ports:
    - "8081:8081"
    volumes:
    - proximate-volume:/remote/cache
    environment:
    - PROXY_LOG_PATH=/remote/cache/proxy.log

volumes:
  proximate-volume:
  proximate-q-volume:

相关的容器是proximate-queue。

我很确定我的容器本身不会造成这种奇怪现象。我的 Dockerfile 这样输入:

ENTRYPOINT ["sh", "/var/app/bin/container-start.sh"]

这只是调用一个启动脚本:

#!/bin/sh

php \
    /var/app/bin/queue.php \
    --queue-path /remote/queue \
    --proxy-address ${PROXY_ADDRESS}

运行队列进程:

#!/usr/bin/env php
<?php

use Proximate\Service\File;
use Proximate\Service\SiteFetcher as SiteFetcherService;
use Proximate\Queue\Read as QueueReader;

$root = realpath(__DIR__ . '/..');
require_once $root . '/vendor/autoload.php';

$actions = getopt('p:q:', ['proxy-address:', 'queue-path:']);

$queuePath = isset($actions['queue-path']) ? $actions['queue-path'] : (isset($actions['q']) ? $actions['q'] : null);
$proxyAddress = isset($actions['proxy-address']) ? $actions['proxy-address'] : (isset($actions['p']) ? $actions['p'] : null);

if (!$queuePath || !$proxyAddress)
{
    $command = __FILE__;
    die(
        sprintf("Syntax: %s --proxy-address <proxy:port> --queue-path <queue-path>\n", $command)
    );
}

if (!file_exists($queuePath))
{
    die(
        sprintf("Error: the supplied queue path `%s` does not exist\n", $queuePath)
    );
}

echo sprintf(
    "Starting queue watcher (path=%s, proxying to %s)\n",
    $queuePath,
    $proxyAddress
);

$queue = new QueueReader($queuePath, new File());
$queue->
    setFetcher(new SiteFetcherService($proxyAddress))->
    process();

如您所见，echo sprintf() 是宣布启动的内容，在我这边没有什么比循环更能做到这一点了。这可能是 Docker Compose 中的错误吗？我在 Ubuntu 14.04 上使用 docker-compose 版本 1.9.0, build 2585387。

作为引用，Docker Compose 标准输出如下所示(队列中重复的行可见):

halfer@machine:~/proximate-app$ docker-compose up
Creating network "proximateapp_default" with the default driver
Creating proxy_instance
Creating queue_instance
Creating api_instance
Creating app_instance
Attaching to proxy_instance, queue_instance, api_instance, app_instance
proxy_instance     | Teeing proxy logs also to /remote/cache/proxy.log
proxy_instance     | [2017-05-10 09:18:42] stdout.INFO: Setting up queue at `/remote/cache/data` [] []
proxy_instance     | [2017-05-10 09:18:42] stdout.INFO: Starting proxy listener on 172.18.0.2:8081 [] []
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
api_instance       | PHP 7.0.16 Development Server started at Wed May 10 10:19:00 2017
app_instance       | PHP 5.6.29 Development Server started at Wed May 10 09:19:10 2017
app_instance       | PHP 5.6.29 Development Server started at Wed May 10 09:19:10 2017
queue_instance exited with code 0
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance exited with code 0
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)
queue_instance     | Starting queue watcher (path=/remote/queue, proxying to proximate-proxy:8081)

我可以尝试的一件事是让应用程序进入休眠状态并且什么都不做，以证明某些奇怪的退出处理程序或某些东西不会造成严重破坏。但是，我希望它会做同样的事情。

更新

我已将队列替换为打印时间信息然后休眠 20 秒的脚本。这是我得到的:

halfer@machine:~/proximate-app$ docker-compose up
Creating network "proximateapp_default" with the default driver
Creating proxy_instance
Creating queue_instance
Creating api_instance
Creating app_instance
Attaching to proxy_instance, queue_instance, api_instance, app_instance
proxy_instance     | Teeing proxy logs also to /remote/cache/proxy.log
proxy_instance     | [2017-05-10 11:51:17] stdout.INFO: Setting up queue at `/remote/cache/data` [] []
proxy_instance     | [2017-05-10 11:51:17] stdout.INFO: Starting proxy listener on 172.18.0.2:8081 [] []
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:51:27 +0000. Microtime=1494417087.107185
api_instance       | PHP 7.0.16 Development Server started at Wed May 10 12:51:37 2017
app_instance       | PHP 5.6.29 Development Server started at Wed May 10 11:51:46 2017
app_instance       | PHP 5.6.29 Development Server started at Wed May 10 11:51:46 2017
queue_instance exited with code 0
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:51:27 +0000. Microtime=1494417087.107185
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:51:55 +0000. Microtime=1494417115.178871
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:52:22 +0000. Microtime=1494417142.409513
queue_instance exited with code 0
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:51:27 +0000. Microtime=1494417087.107185
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:51:55 +0000. Microtime=1494417115.178871
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:52:22 +0000. Microtime=1494417142.409513
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:52:49 +0000. Microtime=1494417169.612523
queue_instance     | Hello everyone! Time=Wed, 10 May 2017 11:53:17 +0000. Microtime=1494417197.826749

这似乎表明:

• 仅每隔一次重新启动报告一次重新启动
• 我的任务将需要 20 秒，但 Compose 会非常缓慢地重新启动它们(接近每 30 秒)。这并没有让我太困扰，但可能是一个有用的观察
• 在重复行的地方，它们实际上是旧的重启报告。

发生了什么事？

Answer 1

我总结了我们的发现。

累积输出是由于容器在每次退出时都没有被移除。因此，docker-compose 再次启动它，向您显示来自再次启动的同一容器的 docker logs -f。这按预期工作。

我没有找到一种方法让 docker-compose 在重新启动之前删除容器 inside 相同的 docker-compose up

我喜欢你的基于队列的架构，但我认为如果你使用一个长生命周期的容器而不是一个启动/退出/启动/退出的容器会更好......你可以通过一个简单的当真；做./queue-app-blabla.php；睡20；在 shell 脚本中完成。

Anyone that need to reproduce this, can use the following docker-compose.yml

version: "2"

services:
  ui:
    image: ubuntu
    command: tail -f /dev/null
    links:
      - queue
  queue:
    image: ubuntu
    command: sh -c "date; echo Sleeping...; sleep 20; echo exit."
    restart: always

输出:

queue_1  | Mon May 15 04:32:12 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
docker_queue_1 exited with code 0
queue_1  | Mon May 15 04:32:12 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
queue_1  | Mon May 15 04:32:33 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
queue_1  | Mon May 15 04:32:54 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
docker_queue_1 exited with code 0
queue_1  | Mon May 15 04:32:12 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
queue_1  | Mon May 15 04:32:33 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
queue_1  | Mon May 15 04:32:54 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
queue_1  | Mon May 15 04:33:17 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.
queue_1  | Mon May 15 04:33:38 UTC 2017
queue_1  | Sleeping...
queue_1  | exit.

我提出的解决方案:

version: "2"

services:
  ui:
    image: ubuntu
    command: tail -f /dev/null
    links:
      - queue
  queue:
    image: ubuntu
    command: sh -c "while true; do date; echo Sleeping...; sleep 20; echo loop.; done"
    restart: always

输出:

Attaching to docker_queue_1, docker_ui_1
queue_1  | Mon May 15 04:36:16 UTC 2017
queue_1  | Sleeping...
queue_1  | loop.
queue_1  | Mon May 15 04:36:36 UTC 2017
queue_1  | Sleeping...
queue_1  | loop.
queue_1  | Mon May 15 04:36:56 UTC 2017
queue_1  | Sleeping...
queue_1  | loop.
queue_1  | Mon May 15 04:37:16 UTC 2017
queue_1  | Sleeping...

IMO，最好看到容器启动和工作，而不是摆动启动/退出容器。 Docker 对具有这种行为的容器进行了特殊处理，请参阅 docker docs . “在每次重新启动之前添加一个不断增加的延迟(之前延迟的两倍，从 100 毫秒开始)，以防止服务器泛滥。”(但它不适用于您的情况，因为您的容器正在运行 > 10 秒。

---

编辑:

检查可能的错误并退出。这可能很有用:

#!/bin/bash

PERIOD=10 # seconds

while true; do
  echo Starting process...

  date # the process
  STATUS=$?

  if [ $STATUS -ne 0 ]; then
        echo "Error found. Exiting" >&2
        exit $STATUS
  fi

  echo End process. Sleeping ${PERIOD}s
  sleep $PERIOD
done

输出:

▶ ./script.sh
Starting process...
Mon May 15 11:43:06 ART 2017
End process. Sleeping 10s
Starting process...
Mon May 15 11:43:16 ART 2017
End process. Sleeping 10s
Starting process...
Mon May 15 11:43:26 ART 2017
End process. Sleeping 10s
Starting process...
Mon May 15 11:43:36 ART 2017
End process. Sleeping 10s
Starting process...
Mon May 15 11:43:46 ART 2017
End process. Sleeping 10s