Multi-Service Deployment

• In this model, we deploy new changes to multiple services simultaneously.
• This approach is easy to implement. But since all the services are upgraded at the same time, it is hard to manage and test dependencies.
• It’s also hard to rollback safely.

Blue-Green Deployment

• With blue-green deployment, we have two identical environments: one is staging (blue) and the other is production (green).
• The staging environment is one version ahead of production.
• Once testing is done in the staging environment, user traffic is switched to the staging environment, and the staging becomes the production.
• This deployment strategy is simple to perform rollback, but having two identical production quality environments could be expensive.

Canary Deployment

• A canary deployment upgrades services gradually, each time to a subset of users.
• It is cheaper than blue-green deployment and easy to perform rollback. However, since there is no staging environment, we have to test on production.
• This process is more complicated because we need to monitor the canary while gradually migrating more and more users away from the old version.

A/B Test

• In the A/B test, different versions of services run in production simultaneously.
• Each version runs an “experiment” for a subset of users.
• A/B test is a cheap method to test new features in production.
• We need to control the deployment process in case some features are pushed to users by accident.