Docker - container - restart policy

Policies: 

• always
• unless-stopped
• on-failure

Always

1. Always restart
2. Unless use command to stop it
3. Restart when docker restart, even it has been stopped by command

Ex. docker container run -it {name} --restart always

Ex. After exit the shell, container will stop because the only one process was killed. But it will be restarted right away.

# Run container

Liaos-MBP:scg-control liaoisaac$ docker container run -it ubuntu /bin/bash

# There is only one process -> /bin/bash

root@1888da48ff01:/# ps aux

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND

root         1  1.3  0.1  18504  3352 pts/0    Ss   05:03   0:00 /bin/bash

root        11  0.0  0.1  34396  2912 pts/0    R+   05:03   0:00 ps aux

root@1888da48ff01:/# exit

exit

# Once exit, container will be stopped because there is only one process in container

Liaos-MBP:scg-control liaoisaac$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

Liaos-MBP:scg-control liaoisaac$

# Specify --restart always after “run"

Liaos-MBP:scg-control liaoisaac$ docker container run --restart always -it ubuntu /bin/bash

root@912e47da3142:/# ps aux

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND

root         1  0.5  0.1  18504  3444 pts/0    Ss   05:11   0:00 /bin/bash

root        10  0.0  0.1  34396  2808 pts/0    R+   05:12   0:00 ps aux

root@912e47da3142:/# exit

exit

# Once exit, container will be restarted right away

Liaos-MBP:scg-control liaoisaac$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

912e47da3142        ubuntu              "/bin/bash"         17 seconds ago      Up 2 seconds                            hungry_khorana

Liaos-MBP:scg-control liaoisaac$

Liaos-MBP:scg-control liaoisaac$ docker stop 912e47da3142

912e47da3142

Liaos-MBP:scg-control liaoisaac$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

# After restart docker in Mac, applications will be restarted

Liaos-MBP:scg-control liaoisaac$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

912e47da3142        ubuntu              "/bin/bash"         2 days ago          Up 13 seconds                           hungry_khoran

# After docker restart, container will be restarted again

# Following is ubuntu example

isaac@isaac-KVM:~$ service docker restart

==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===

Authentication is required to restart 'docker.service'.

Authenticating as: isaac,,, (isaac)

Password:

==== AUTHENTICATION COMPLETE ===

isaac@isaac-KVM:~$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

e4403fafa5bb        ubuntu              "/bin/bash"         3 minutes ago       Up 5 seconds                            optimistic_leh                                             mann

unless-stopped

1. Always restart unless it is stopped by command
2. Wont restart when daemon restart
3. Ex. — restart unless-stopped

# Start bash with unless-stopped

isaac@isaac-KVM:~$ docker container run --restart unless-stopped -it ubuntu /bin/bash

root@3be8ac8498a7:/# ps aux

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND

root         1  4.8  0.0  18504  3536 pts/0    Ss   17:53   0:00 /bin/bash

root        10  0.0  0.0  34396  2936 pts/0    R+   17:53   0:00 ps aux

root@3be8ac8498a7:/# exit

exit

# Kill the only one process, container stopped and restart automatically because restart policy is unless-stopped

isaac@isaac-KVM:~$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

3be8ac8498a7        ubuntu              "/bin/bash"         19 seconds ago      Up 7 seconds                            nostalgic_gagarin

# Use command to stop a container

isaac@isaac-KVM:~$ docker container stop 3be8ac8498a7

3be8ac8498a7

isaac@isaac-KVM:~$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

# Container is not started after docker restart because restart policy is unless-stopped

isaac@isaac-KVM:~$ sudo service docker restart

isaac@isaac-KVM:~$ docker container ls

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

isaac@isaac-KVM:~$

on-failure

1. Restart container when it's stopped with non-zero exit code
2. Restart container when docker restart