Merge pull request #3046 from alphagov/msw/restart-an-app

Document restarting an app

source/manual/restart-application.html.md

@@ -6,6 +6,32 @@ layout: manual_layout
 section: Deployment
 ---
 
-To restart an application go to the Deploy app Jenkins job in [AWS](https://deploy.blue.production.govuk.digital/job/Deploy_App/build), choose your app, the **[current release]** and select `app:hard_restart`.
+### Restarting one instance of an app
 
+To restart an application on one machine, SSH into the machine then
+run:
+
+```bash
+sudo service <app> restart
+```
+
+This will terminate any active requests to that instance of the app,
+and so may cause a few errors.  Other instances of the app on
+different machines will not restart.
+
+### Restarting all instances of an app
+
+To restart an application on all machines:
+
+1. Go to the [Deploy_App Jenkins job][]
+   - For `TARGET_APPLICATION`, choose the app to restart
+   - For `DEPLOY_TASK`, choose `deploy:with_hard_restart`
+   - For `TAG`, choose the [current release][]
+2. Click "Build"
+
+All the instances of the app will restart at roughly the same time, so
+any pages served by the app will be briefly unavailable, and there
+will be a spike of 5xx errors.
+
+[Deploy_App Jenkins job]: https://deploy.blue.production.govuk.digital/job/Deploy_App/build
 [current release]:https://release.publishing.service.gov.uk/applications