Yosukeota Survey Docker Process
09 August 2014
Yosuke OTA
プロセスどうなってるの
[yota@localhost ~]# docker run --name="shell" -t -i -d centos:latest /bin/bash
ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3
[yota@localhost ~]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 0.9 358948 9332 ? Ssl 00:12 0:00 /usr/bin/docker -d --selinux-enabled
root 2602 0.8 0.1 11740 1376 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
~~~ SNIP ~~~
[yota@localhost ~]$ docker run -d -i centos:latest /bin/bash
b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1
[yota@localhost ~]$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 4 seconds ago Up 3 seconds drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 7 minutes ago Up 7 minutes shell
[yota@localhost ~]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 515636 12536 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11740 1376 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 2877 0.0 0.1 11604 1104 ? Ss 01:28 0:00 \_ /bin/bash
~~~ SNIP ~~~
docker -dはdaemon起動なオプション
docker daemonなプロセスに紐づけられたbashなプロセスが2つ存在。
起動時のオプションの違いはTTYを割り当てるかどうか。
ps auxfの結果を見ると明白。
コンテナ内で子プロセス作ってみる
[yota@localhost ~]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 3 minutes ago Up 3 minutes drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 10 minutes ago Up 10 minutes shell
[yota@localhost ~]$ docker attach shell
bash-4.2# while sleep 1; do echo "hello"; done
hello
hello
hello #(補足: ctrl-p ctrl-qでデタッチしてます。)
[yota@localhost ~]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 515636 12536 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1712 pts/1 Ss 01:21 0:00 \_ /bin/bash
root 2944 0.0 0.0 4312 404 pts/1 S+ 01:32 0:00 | \_ sleep 1
root 2877 0.0 0.1 11604 1104 ? Ss 01:28 0:00 \_ /bin/bash
~~~ SNIP ~~~
sleepでecho hello動かすとlogがうざいので何もしないように変更。
ついでにバックグラウンド起動に。
[yota@localhost ~]$ docker attach shell
hello
hello
^C
bash-4.2# while sleep 1; do :; done &
[1] 146
bash-4.2# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.1 11744 1736 ? Ss 06:21 0:00 /bin/bash
root 146 0.5 0.0 11744 696 ? S 06:35 0:00 /bin/bash
root 149 0.0 0.0 4312 404 ? S 06:35 0:00 sleep 1
root 150 0.0 0.1 19748 1208 ? R+ 06:35 0:00 ps aux
もう一つのコンテナでも子プロセス作ってみる。
[yota@localhost ~]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 8 minutes ago Up 8 minutes drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 15 minutes ago Up 15 minutes shell
[yota@localhost ~]$ docker attach drunk_wilson1
while sleep 2; do :; done &
^P
/bin/bash: line 2: $'\020': command not found
^C^C #(補足: このコンテナはctrl-dで抜けた。ctrl-p ctrl-qでは抜けれない。おそらくttyがないからだと思う)
[yota@localhost ~]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 8 minutes ago Up 8 minutes drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 16 minutes ago Up 16 minutes shell
[yota@localhost ~]$ ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.1 515764 11996 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 696 pts/1 S 01:35 0:00 | \_ /bin/bash
root 3238 0.0 0.0 4312 404 pts/1 S 01:37 0:00 | \_ sleep 1
root 2877 0.0 0.1 11604 1300 ? Ss 01:28 0:00 \_ /bin/bash
root 3181 0.1 0.0 11604 720 ? S 01:36 0:00 \_ /bin/bash
root 3237 0.0 0.0 4312 400 ? S 01:37 0:00 \_ sleep 2
~~~ SNIP ~~~
/var/lib/docker見る
何かファイル書き変わってるか調査する
[root@localhost docker]# cd /var/lib/docker
[root@localhost docker]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 17 minutes ago Up 17 minutes drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 24 minutes ago Up 24 minutes shell
[root@localhost docker]# ls -l containers/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1/
total 20
-rw------- 1 root root 117 Aug 9 01:36 b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1-json.log
-rw-r--r-- 1 root root 1365 Aug 9 01:28 config.json
-rw-r--r-- 1 root root 192 Aug 9 01:28 hostconfig.json
-rw-r--r-- 1 root root 13 Aug 9 01:28 hostname
-rw-r--r-- 1 root root 174 Aug 9 01:28 hosts
[root@localhost docker]# cat containers/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1-json.log
{"log":"/bin/bash: line 2: $'\\020': command not found\n","stream":"stderr","time":"2014-08-09T05:36:56.990362511Z"}
コマンドの失敗とかのログはcontainers/[CONTAINER ID]/[CONTAINER ID]-json.logに置いてあるらしい。
ってことはこれもdockerなコマンドで見ることができそう。
docker logs
[yota@localhost ~]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 22 minutes ago Up 22 minutes drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 29 minutes ago Up 29 minutes shell
[yota@localhost ~]$ docker logs drunk_wilson1
/bin/bash: line 2: $'\020': command not found
見れた。
コンテナ内プロセスの表示
このときわざわざcontainerにattachしなくてもdocker topコマンドでpsを見ることができることを知った。
[yota@localhost ~]$ docker top drunk_wilson1
UID PID PPID C STIME TTY TIME CMD
root 2877 857 0 01:28 ? 00:00:00 /bin/bash
root 3181 2877 0 01:36 ? 00:00:00 /bin/bash
root 4600 3181 0 01:51 ? 00:00:00 sleep 2
[yota@localhost ~]$ docker top drunk_wilson1 auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 2877 0.0 0.1 11604 1300 ? Ss 01:28 0:00 \_ /bin/bash
root 3181 0.0 0.0 11604 736 ? S 01:36 0:00 | \_ /bin/bash
root 4782 1.0 0.0 4312 400 ? S 01:53 0:00 | \_ sleep 2
コンテナを殺す
docker killなんてのもある。
[yota@localhost ~]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 25 minutes ago Up 25 minutes drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 33 minutes ago Up 33 minutes shell
[yota@localhost ~]$ docker kill drunk_wilson1
drunk_wilson1
[yota@localhost ~]$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 26 minutes ago Exited (-1) 4 seconds ago drunk_wilson1
ee6b542bf90d centos:latest /bin/bash 33 minutes ago Up 33 minutes shell
docker stopが効かないようなときに無理矢理殺すためのだと思う。
[yota@localhost ~]$ docker kill
Usage: docker kill [OPTIONS] CONTAINER [CONTAINER...]
Kill a running container (send SIGKILL, or specified signal)
-s, --signal="KILL" Signal to send to the container
SIGKILL送るっぽいのでそうだろうなぁ…くらい。
殺しちゃったコンテナの起動
[yota@localhost ~]$ docker start drunk_wilson1
drunk_wilson1
[yota@localhost ~]$ docker top drunk_wilson1
UID PID PPID C STIME TTY TIME CMD
root 5085 857 1 01:56 ? 00:00:00 /bin/bash
立ち上げなおしたらsleepなpsがなくなってた。そりゃそうかー、ってことでもう一度たちあげ。
[yota@localhost ~]$ docker attach drunk_wilson1
while sleep 2; do :; done &
[yota@localhost ~]$ docker top drunk_wilson1
UID PID PPID C STIME TTY TIME CMD
root 5085 857 0 01:56 ? 00:00:00 /bin/bash
root 5247 5085 0 01:58 ? 00:00:00 /bin/bash
root 5266 5247 0 01:58 ? 00:00:00 sleep 2
killコマンド使う
hostからkill送ってみる
[yota@localhost ~]$ ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12680 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 736 pts/1 S 01:35 0:01 | \_ /bin/bash
root 5329 0.0 0.0 4312 400 pts/1 S 01:58 0:00 | \_ sleep 1
root 5085 0.0 0.1 11604 1296 ? Ss 01:56 0:00 \_ /bin/bash
root 5247 0.0 0.0 11604 720 ? S 01:58 0:00 \_ /bin/bash
root 5326 1.0 0.0 4312 400 ? S 01:58 0:00 \_ sleep 2
~~~ SNIP ~~~
[root@localhost docker]# kill 5247
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12644 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 740 pts/1 S 01:35 0:01 | \_ /bin/bash
root 5469 1.0 0.0 4312 404 pts/1 S 02:00 0:00 | \_ sleep 1
root 5085 0.0 0.1 11604 1296 ? Ss 01:56 0:00 \_ /bin/bash
~~~ SNIP ~~~
5247に紐づいてた5326も死んだ。
もう一度起動しよう。
[yota@localhost ~]$ docker attach drunk_wilson1
while sleep 2; do :; done &
[yota@localhost ~]$ ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12408 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 744 pts/1 S 01:35 0:02 | \_ /bin/bash
root 5752 0.0 0.0 4312 404 pts/1 S 02:03 0:00 | \_ sleep 1
root 5085 0.0 0.1 11608 1296 ? Ss 01:56 0:00 \_ /bin/bash
root 5612 0.0 0.0 11604 720 ? S 02:02 0:00 \_ /bin/bash
root 5750 1.0 0.0 4312 404 ? S 02:03 0:00 \_ sleep 2
~~~ SNIP ~~~
sleep 2なプロセス殺してみる。
[root@localhost docker]# kill 5750
-bash: kill: (5750) - No such process
そうだった、sleep 2はps表示してから最大2秒以内にkillしないと新しいプロセスが立ち上がるんだ…。
とりあえずsleepな秒数を少し伸ばして試してみよう。
PIDの隔離確認
[root@localhost docker]# docker top drunk_wilson1
UID PID PPID C STIME TTY TIME CMD
root 5085 857 0 01:56 ? 00:00:00 /bin/bash
root 5612 5085 0 02:02 ? 00:00:00 /bin/bash
root 6007 5612 0 02:06 ? 00:00:00 sleep 2
[root@localhost docker]# docker attach drunk_wilson1
ps
PID TTY TIME CMD
1 ? 00:00:00 bash
76 ? 00:00:00 bash
213 ? 00:00:00 sleep
214 ? 00:00:00 ps
ここでPIDが隔離されていることをようやく確認。
sleepプロセスを殺す
さて5612なプロセスをkillする。それでsleep 20くらいで。
[root@localhost docker]# kill 5612
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12412 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 760 pts/1 S 01:35 0:02 | \_ /bin/bash
root 6424 0.0 0.0 4312 404 pts/1 S 02:10 0:00 | \_ sleep 1
root 5085 0.0 0.1 11608 1344 ? Ss 01:56 0:00 \_ /bin/bash
~~~ SNIP ~~~
[yota@localhost ~]$ docker attach drunk_wilson1
while sleep 20; do :; done &
rootになる。
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12448 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 760 pts/1 S 01:35 0:02 | \_ /bin/bash
root 6547 0.0 0.0 4312 400 pts/1 S 02:12 0:00 | \_ sleep 1
root 5085 0.0 0.1 11608 1344 ? Ss 01:56 0:00 \_ /bin/bash
root 6501 0.0 0.0 11608 612 ? S 02:12 0:00 \_ /bin/bash
root 6544 0.0 0.0 4312 404 ? S 02:12 0:00 \_ sleep 20
~~~ SNIP ~~~
[root@localhost docker]# kill 6544
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12448 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 760 pts/1 S 01:35 0:02 | \_ /bin/bash
root 6556 0.0 0.0 4312 404 pts/1 S 02:12 0:00 | \_ sleep 1
root 5085 0.0 0.1 11608 1344 ? Ss 01:56 0:00 \_ /bin/bash
~~~ SNIP ~~~
sleep動かしてた親なbashも死んだ。
docker killとkill
多分5085なプロセスをkillするってのはdocker killを同じになるはず。
しかしここで間違えてdocker killしてしまったのでもう一度立ち上げ直し。
そのせいでPIDが変わっている。
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12516 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 768 pts/1 S 01:35 0:03 | \_ /bin/bash
root 6858 0.0 0.0 4312 396 pts/1 S 02:16 0:00 | \_ sleep 1
root 6814 0.1 0.1 11604 1096 ? Ss 02:16 0:00 \_ /bin/bash
~~~ SNIP ~~~
[root@localhost docker]# kill 6814
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12516 ? Ssl 00:12 0:01 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 768 pts/1 S 01:35 0:03 | \_ /bin/bash
root 6858 0.0 0.0 4312 396 pts/1 S 02:16 0:00 | \_ sleep 1
root 6814 0.1 0.1 11604 1096 ? Ss 02:16 0:00 \_ /bin/bash
~~~ SNIP ~~~
あれ、死なない。
[root@localhost docker]# kill -KILL 6814
[root@localhost docker]# ps auxf
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
~~~ SNIP ~~~
root 857 0.0 1.2 655032 12628 ? Ssl 00:12 0:02 /usr/bin/docker -d --selinux-enabled
root 2602 0.0 0.1 11744 1736 pts/1 Ss+ 01:21 0:00 \_ /bin/bash
root 3082 0.1 0.0 11744 772 pts/1 S 01:35 0:03 \_ /bin/bash
root 7011 0.0 0.0 4312 400 pts/1 S 02:18 0:00 \_ sleep 1
~~~ SNIP ~~~
死んだ。
killは何も指定しないとSIGTERMだった。
で、docker killはSIGKILLなのねー。
dockerのlog
ちなみにlogsを見てみる。
[yota@localhost ~]$ docker logs drunk_wilson1
/bin/bash: line 2: $'\020': command not found
/bin/bash: line 3: 6 Terminated while sleep 2; do
:;
done
PID TTY TIME CMD
1 ? 00:00:00 bash
76 ? 00:00:00 bash
80 ? 00:00:00 sleep
81 ? 00:00:00 ps
PID TTY TIME CMD
1 ? 00:00:00 bash
76 ? 00:00:00 bash
213 ? 00:00:00 sleep
214 ? 00:00:00 ps
/bin/bash: line 6: 76 Terminated while sleep 2; do
:;
done
/bin/bash: line 5: 341 Terminated sleep 20
jsonもcatしてみよう。
[root@localhost docker]# cat containers/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1-json.log
{"log":"/bin/bash: line 2: $'\\020': command not found\n","stream":"stderr","time":"2014-08-09T05:36:56.990362511Z"}
{"log":"/bin/bash: line 3: 6 Terminated while sleep 2; do\n","stream":"stderr","time":"2014-08-09T06:02:14.007983848Z"}
{"log":" :;\n","stream":"stderr","time":"2014-08-09T06:02:14.007983848Z"}
{"log":"done\n","stream":"stderr","time":"2014-08-09T06:02:14.007983848Z"}
{"log":" PID TTY TIME CMD\n","stream":"stdout","time":"2014-08-09T06:02:21.359330461Z"}
{"log":" 1 ? 00:00:00 bash\n","stream":"stdout","time":"2014-08-09T06:02:21.359330461Z"}
{"log":" 76 ? 00:00:00 bash\n","stream":"stdout","time":"2014-08-09T06:02:21.359330461Z"}
{"log":" 80 ? 00:00:00 sleep\n","stream":"stdout","time":"2014-08-09T06:02:21.359330461Z"}
{"log":" 81 ? 00:00:00 ps\n","stream":"stdout","time":"2014-08-09T06:02:21.359330461Z"}
{"log":" PID TTY TIME CMD\n","stream":"stdout","time":"2014-08-09T06:06:47.073484353Z"}
{"log":" 1 ? 00:00:00 bash\n","stream":"stdout","time":"2014-08-09T06:06:47.073484353Z"}
{"log":" 76 ? 00:00:00 bash\n","stream":"stdout","time":"2014-08-09T06:06:47.073484353Z"}
{"log":" 213 ? 00:00:00 sleep\n","stream":"stdout","time":"2014-08-09T06:06:47.073484353Z"}
{"log":" 214 ? 00:00:00 ps\n","stream":"stdout","time":"2014-08-09T06:06:47.073484353Z"}
{"log":"/bin/bash: line 6: 76 Terminated while sleep 2; do\n","stream":"stderr","time":"2014-08-09T06:12:05.033796079Z"}
{"log":" :;\n","stream":"stderr","time":"2014-08-09T06:12:05.033796079Z"}
{"log":"done\n","stream":"stderr","time":"2014-08-09T06:12:05.033796079Z"}
{"log":"/bin/bash: line 5: 341 Terminated sleep 20\n","stream":"stderr","time":"2014-08-09T06:12:52.285978485Z"}
1行毎にjsonなオブジェクトになってるのね。
mountポジションな場所見る
ちなみにdevicemapper/mnt以下をのぞいてみる。
[root@localhost docker]# ls -l devicemapper/mnt/
total 4
drwxr-xr-x 2 root root 6 Aug 5 05:46 2758ea31b20b87d5a0c29c11414f981edf56d0557f47d91537a204d9642e5731
drwxr-xr-x 2 root root 6 Aug 5 05:46 2abd6cab7b39c5c0c12f0ee2768bb5ce9cce9bf612b38ae3296e6408a62d63da
drwxr-xr-x 2 root root 6 Aug 5 04:39 34e94e67e63a0f079d9336b3c2a52e814d138e5b3f1f614a0cfe273814ed7c0a
drwxr-xr-x 2 root root 6 Aug 5 05:46 3af9d794ad072dc96991f1ab3603d61507f81f0aefa89b81e9cf6eafd774d356
drwxr-xr-x 2 root root 6 Aug 5 05:46 3db9c44f45209632d6050b35958829c3a2aa256d81b9a7be45b362ff85c54710
drwxr-xr-x 2 root root 6 Aug 5 04:39 511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158
drwxr-xr-x 2 root root 6 Aug 5 05:46 9bad880da3d219b10423804147d6982da1a7bb1e285777a4d746afca6215bebb
drwxr-xr-x 2 root root 6 Aug 5 04:39 b157b77b1a65e87b4f49298557677048b98fed36043153dcadc28b1295920373
drwxr-xr-x 2 root root 6 Aug 9 01:28 b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1
drwxr-xr-x 2 root root 6 Aug 9 01:28 b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1-init
drwxr-xr-x 2 root root 6 Aug 5 05:46 bac448df371dc1d40fe2543d8ce3f06eb1cb8457270f5018f67ea76520a72b3b
drwxr-xr-x 4 root root 4096 Aug 5 04:39 ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3
drwxr-xr-x 2 root root 6 Aug 9 01:20 ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3-init
[root@localhost docker]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b1a0060399a7 centos:latest /bin/bash 56 minutes ago Exited (-1) 5 minutes ago drunk_wilson1
ee6b542bf90d centos:latest /bin/bash About an hour ago Up About an hour shell
[root@localhost docker]# ls -l devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3
total 24
-rw------- 1 root root 64 Aug 5 04:39 id
drwx------ 2 root root 16384 Aug 5 04:28 lost+found
dr-xr-xr-x 18 root root 4096 Aug 9 01:21 rootfs
[root@localhost docker]# ls -l devicemapper/mnt/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1
total 0
あれ、b1aなディレクトリの中身は何もない。
コンテナ起動してみよう。
[root@localhost docker]# docker start drunk_wilson1
drunk_wilson1
[root@localhost docker]# ls -l devicemapper/mnt/b1a0060399a759b6ebb6ad29e6de452240e919159c0547b50f25b1ff1b278fd1
total 24
-rw------- 1 root root 64 Aug 5 04:39 id
drwx------ 2 root root 16384 Aug 5 04:28 lost+found
dr-xr-xr-x 18 root root 4096 Aug 9 02:26 rootfs
できた。
てことは、docker stopしてdocker startしなおすとまたまっさらな環境ができあがるってことだろうか…。
試してみよう。
コンテナをstop & start
端末つけて起動している方(--name="shell"な方)でやる。
[yota@localhost ~]$ docker attach shell
bash-4.2# pwd
/
bash-4.2# cd root/
bash-4.2# ls
bash-4.2# echo hello > hogehoge.txt
bash-4.2# [yota@localhost ~]$
ファイルできてるか確認する。
[root@localhost docker]# ls -l devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3/rootfs/root/
total 4
-rw-r--r-- 1 root root 6 Aug 9 02:28 hogehoge.txt
[root@localhost docker]# cat devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3/rootfs/root/hogehoge.txt
hello
できてた。
じゃあstopしてstartしよう。
[yota@localhost ~]$ docker stop shell
shell
[yota@localhost ~]$ docker start shell
shell
ファイルがあるか確認してみる。
[root@localhost docker]# ls -l devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3/rootfs/root/
total 4
-rw-r--r-- 1 root root 6 Aug 9 02:28 hogehoge.txt
[root@localhost docker]# cat devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3/rootfs/root/hogehoge.txt
hello
ある。 さっきの予想は間違っていたみたい。
一度コンテナを止めてみる。
[yota@localhost ~]$ docker stop shell
shell
このときはrootfsみたいなディレクトリはないはず。
[root@localhost docker]# ls -l devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3
total 0
[root@localhost docker]# ls -l devicemapper/mnt/ee6b542bf90de885e7c3b5a92b8d06d84f882943d6807ea824e676c7304bc5a3-init/
total 0
ない。 ここまではオッケー。
stopしてるときの状態はどこに保存されているのか…。
公式ドキュメントを読んでみると、「stopしたときはメモリ状態は保存しないけどファイルシステムは保存される」って書いてた。 どこに…?
とりあえずどこかしらに保存されていて、commitすることでそれが永続化されるようで…。
今回はここまで。
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