Rollbacks

Rollbacks are a powerful feature that allows you to easily revert changes to your application. This is particularly useful when you encounter issues or want to revert to a previous version of your application.

Requirements

1. Have a /health endpoint in your application.

Steps to Rollback

Let's suppose we have a NodeJS application that has a health check route /api/health that returns a 200 status code and running in the port 3000.

1. In your application is necessary to have a Path or Health Route to be able to achieve zero downtime deployments eg. in the case of a NodeJS app you can have a route /api/health that returns a 200 status code.
2. Go to Advanced Tab and go to Cluster Settings and enter to Swarm Settings
3. There are a couple options that you can use, in this case we will focus on Health Check and Update Config.
4. Paste this code in the health check field: Make sure the API Route exists in your application

{
  "Test": [
    "CMD",
    "curl",
    "-f",
    "http://localhost:3000/api/health"
  ],
  "Interval": 30000000000,
  "Timeout": 10000000000,
  "StartPeriod": 30000000000,
  "Retries": 3
}

5. Now in the Update Config

Now when the application is getting unhealthy response from the health check, the container will rollback to the previous version.

Paste the following code:

{
  "Parallelism": 1,
  "Delay": 10000000000,
  "FailureAction": "rollback",
  "Order": "start-first"
}