Restart policies in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a restart policy in Docker?

A restart policy tells Docker when to automatically restart a container if it stops or crashes.

beginner

Name the four main Docker restart policies.

The four main restart policies are: no, on-failure, always, and unless-stopped.

beginner

What does the 'always' restart policy do?

The 'always' policy restarts the container whenever it stops, no matter the exit status, even after Docker daemon restarts.

beginner

How does the 'on-failure' restart policy work?

The 'on-failure' policy restarts the container only if it exits with a non-zero exit code, indicating an error.

intermediate

What is the difference between 'unless-stopped' and 'always' restart policies?

'Unless-stopped' restarts containers unless you manually stop them. 'Always' restarts containers even after manual stops.

Which Docker restart policy restarts a container only if it crashes with an error?

A always

B on-failure

C no

D unless-stopped

The 'on-failure' policy restarts containers only when they exit with a non-zero error code.

What happens if you set the restart policy to 'no'?

A Docker never restarts the container automatically

B Docker always restarts the container

C Docker restarts only on failure

D Docker restarts unless manually stopped

The 'no' policy means Docker will not restart the container automatically.

Which restart policy will restart a container even after Docker daemon restarts?

A no

B on-failure

C always

D none

The 'always' policy restarts containers even after Docker daemon restarts.

If you want a container to restart unless you manually stop it, which policy do you choose?

A unless-stopped

B always

C on-failure

D no

'Unless-stopped' restarts containers unless you manually stop them.

How do you set a restart policy when running a Docker container?

A docker create --restart-policy=<policy> <image>

B docker start --restart=<policy> <container>

C docker restart --policy=<policy> <container>

D docker run --restart=<policy> <image>

You use 'docker run --restart= ' to set the restart policy.

Explain the purpose of Docker restart policies and list the main types.

Think about what happens when a container stops or crashes.

Describe a scenario where you would use the 'on-failure' restart policy instead of 'always'.

Consider when you want to avoid restarting containers that stopped on purpose.