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Upgrade

All instructions to upgrade this project from one release to the next will be documented in this file. Upgrades must be run sequentially, meaning you should not skip minor/major releases while upgrading (fix releases can be skipped).

The format is inspired from Keep a Changelog, and this project adheres to Semantic Versioning.

Unreleased

Static services

This version introduces Static services and it is a breaking change in the blue/green deployment process. The switch playbook is patching static services instead of routes. And the deployment_stamp of the deployed stacks is no longer stored in routes, but in static services instead.

In order to migrate to this new system, you have to apply the following upgrade process. This will not cause any downtime, but it implies a redeployment of your applications.

Upgrade Procedure

This procedure must be applied for every arnold application deployed.

The current stack of your application (before applying this procedure) will be referred to as BEFORE-UPGRADE-VERSION.

1. Upgrade your arnold version
2. Execute the create_services ansible playbook :
bin/ansible-playbook create_services.yml -e "apps_filter=your-application"

It will create the static services required by your application. Each variant of these static services (previous, current, next) will target nothing after this step.

3. Execute the deploy ansible playbook :
bin/deploy -e "apps_filter=your-application"

It will deploy your application and the next static services will target this stack.

This step does not affect routes. So your BEFORE-UPGRADE-VERSION stays unchanged and available via the current route. On the other hand, the next stack you just deployed will not be reachable by any route.

4. Execute the switch ansible playbook :
bin/switch -e "apps_filter=your-application"

The switch will be done at the static services level. So, the stack you just deployed will be considered as the current by static services and by the ansible playbooks.

But again, this step does not affect routes. So your BEFORE-UPGRADE-VERSION stack stays unchanged and available via the current route.

5. Execute the create_routes playbook :
bin/ansible-playbook create_routes.yml -e "apps_filter=your-application"

This will patch the routes to target the corresponding static services. After this step, your BEFORE-UPGRADE-VERSION will be unavailable and will be replaced by the current stack you just deployed.

6. Check and clean

Check that everything is OK and execute the clean playbook to remove unreferenced stacks :

bin/clean -e "apps_filter=your-application"