Docker配置文件在Ubuntu中不起作用的解决办法

环境

1. OS 版本: Ubuntu 16.04 LTS

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04 LTS
Release:	16.04
Codename:	xenial

2. Docker版本: Docker version 1.11.2, build b9f10c9

$ docker -v
Docker version 1.11.2, build b9f10c9

问题描述

最近想使用Docker的Remote API，即使用REST API的形式访问、操作Docker，按照网上的几篇文章配置，发现无法启用Docker的Remote API，于是便有此文。

解决办法

1. 设置Docker开机启动(可选)

sudo systemctl enable docker

2. 配置Docker配置文件，Docker配置文件位于 /etc/default/docker ，配置文件如下：

# Customize location of Docker binary (especially for development testing).
#DOCKER="/usr/local/bin/docker"

# Use DOCKER_OPTS to modify the daemon startup options.
#DOCKER_OPTS="--dns 8.8.8.8 --dns 8.8.4.4"
DOCKER_OPTS="-H=unix:///var/run/docker.sock -H=0.0.0.0:7654"
# If you need Docker to use an HTTP proxy, it can also be specified here.
#export http_proxy="http://127.0.0.1:3128/"

# This is also a handy place to tweak where Docker's temporary files go.
#export TMPDIR="/mnt/bigdrive/docker-tmp"

注意配置文件中的

DOCKER_OPTS="-H=unix:///var/run/docker.sock -H=0.0.0.0:7654"

红色部分即为配置启用Docker Remote API，访问端口为7654

3. 确定 docker.service 文件位置

$ systemctl show --property=FragmentPath docker
FragmentPath=/lib/systemd/system/docker.service

如上，我机器上的docker.service文件位于 /lib/systemd/system/docker.service

4. 修改 docker.service 文件配置

首先查看 docker.service

[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network.target docker.socket
Requires=docker.socket

[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/docker daemon -H fd://
MountFlags=slave
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes

我们需要在 [Service] 部分中加入 EnvironmentFile 配置以及给 ExecStart 配置添加 $DOCKER_OPTS 参数，配置后的配置文件如下：

[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network.target docker.socket
Requires=docker.socket

[Service]
EnvironmentFile=-/etc/default/docker
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/docker daemon -H fd:// $DOCKER_OPTS
MountFlags=slave
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes

5. 重新加载配置文件

systemctl daemon-reload

6. 查看配置参数是否起作用

$ systemctl show docker | grep EnvironmentFile
EnvironmentFile=/etc/default/docker (ignore_errors=yes)

7. 测试 Docker Remote API

curl localhost:7654/info | jq
% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
Dload  Upload   Total   Spent    Left  Speed
100  1381  100  1381    0     0   196k      0 --:--:-- --:--:-- --:--:--  224k
{
"ID": "AMPA:7NQC:J6QJ:SMNQ:CFOR:QA5V:NJY5:SJLP:NLFB:EJA7:KHIO:43TO",
"Containers": 0,
"ContainersRunning": 0,
"ContainersPaused": 0,
"ContainersStopped": 0,
"Images": 7,
"Driver": "aufs",
"DriverStatus": [
[
"Root Dir",
"/var/lib/docker/aufs"
],
[
"Backing Filesystem",
"extfs"
],
[
"Dirs",
"80"
],
[
"Dirperm1 Supported",
"true"
]
],
"SystemStatus": null,
"Plugins": {
"Volume": [
"local"
],
"Network": [
"bridge",
"null",
"host"
],
"Authorization": null
},
"MemoryLimit": true,
"SwapLimit": false,
"KernelMemory": true,
"CpuCfsPeriod": true,
"CpuCfsQuota": true,
"CPUShares": true,
"CPUSet": true,
"IPv4Forwarding": true,
"BridgeNfIptables": true,
"BridgeNfIp6tables": true,
"Debug": false,
"NFd": 14,
"OomKillDisable": true,
"NGoroutines": 33,
"SystemTime": "2016-09-04T21:24:40.951697312+08:00",
"ExecutionDriver": "",
"LoggingDriver": "json-file",
"CgroupDriver": "cgroupfs",
"NEventsListener": 0,
"KernelVersion": "4.4.0-28-generic",
"OperatingSystem": "Ubuntu 16.04 LTS",
"OSType": "linux",
"Architecture": "x86_64",
"IndexServerAddress": "https://index.docker.io/v1/",
"RegistryConfig": {
"InsecureRegistryCIDRs": [
"127.0.0.0/8"
],
"IndexConfigs": {
"docker.io": {
"Name": "docker.io",
"Mirrors": null,
"Secure": true,
"Official": true
}
},
"Mirrors": null
},
"NCPU": 4,
"MemTotal": 4125618176,
"DockerRootDir": "/var/lib/docker",
"HttpProxy": "",
"HttpsProxy": "",
"NoProxy": "",
"Name": "poet-pc",
"Labels": null,
"ExperimentalBuild": false,
"ServerVersion": "1.11.2",
"ClusterStore": "",
"ClusterAdvertise": ""
}

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官方文档链接: https://docs.docker.com/engine/admin/systemd/