Upgrading an application

Nomad supports different update strategies, all trough the update stanza:

Rolling Upgrades

• A defined number of instances are restarted with a new version of the application.
• Once they are in a healthy state, another set of the same defined number of instances are restarted with the new version, and so on until all instances have been updated.
• Nomad will revert to an older, healthy job if a deployment fails.

Blue/Green Deployment

• Have two different deployments (two instances)
• One is always active (green, production) and one sitting idle (blue or staging)
• Updates are made on the blue instance and then trafic is routed there (turning it green)

Canary

• Releases an application or service incrementally to a subset of users.
• We install the update in our systems and split the users into two groups. A small percentage of them will go to the canary while the rest stay on the old version, as a control.
• As feedback and problems are taken into account, more servers get the canary version