Rolling updates in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a rolling update in Docker?

A rolling update gradually replaces old containers with new ones without downtime, updating services smoothly.

beginner

Which Docker command is used to perform a rolling update on a service?

The command docker service update is used to perform rolling updates on Docker services.

intermediate

What does the --update-parallelism option control during a rolling update?

It controls how many containers are updated at the same time during the rolling update.

beginner

Why are rolling updates preferred over stopping all containers and starting new ones at once?

Because rolling updates avoid downtime by updating containers gradually, keeping the service available.

intermediate

What happens if a rolling update fails in Docker?

Docker can pause or rollback the update to keep the service stable and avoid downtime.

Which command updates a Docker service with a new image using rolling update?

A docker update service --image newimage:tag

B docker container update --image newimage:tag

C docker service create --image newimage:tag

D docker service update --image newimage:tag servicename

The correct command is docker service update --image newimage:tag servicename to update the service image.

What does the --update-delay option do in a rolling update?

A Sets the number of containers to update at once

B Sets the total time for the update

C Sets the time to wait between updating groups of containers

D Sets the timeout for container startup

--update-delay sets the wait time between updating batches of containers.

Why is rolling update important for production services?

A It ensures zero downtime during updates

B It deletes all containers before updating

C It updates all containers at once

D It requires manual restart of containers

Rolling updates help keep services running without downtime by updating containers gradually.

If a rolling update fails, what can Docker do automatically?

A Delete all containers

B Rollback to the previous stable version

C Ignore the failure and continue

D Stop the Docker daemon

Docker can rollback the update to the previous stable version to keep the service stable.

Which option controls how many containers update at the same time?

A --update-parallelism

B --update-delay

C --replicas

D --restart-condition

--update-parallelism sets how many containers update simultaneously.

Explain what a rolling update is and why it is useful in Docker services.

Think about how to update a running service without stopping it all at once.

Describe the key Docker service update options that control rolling updates and their effects.

Focus on options that manage how many containers update and timing between updates.