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Operating system upgrade procedure

Make sure that the MWS server to be upgraded has at least one hostname other than the mws-[nnnnn].mws3.csx.cam.ac.uk (where [nnnnn] is a string of five digits) name associated with it, and users access each website through one of these hostnames. Testing the upgrade will not be possible without swapping the test and production services if the server is referred to by its MWS name, as the redirection will fail. This is especially true for software like Wordpress, which stores the hostname in its database and creates links to content using the stored hostname.


The general workflow for the upgrade is:

Create test server

Adjust settings/upgrade software

Test using the website redirection

Swap servers

Test with new server in production

Delete test server


Once upgrades are enabled, the panel message area will display a message saying the server is due for an OS update, and there will be a Test OS upgrade button on the main panel page. Clicking that button will bring up a page where the production service can be cloned onto a test service. This will not change anything on the production server, but will create a new test service and copy all files from the production service over to it. This takes some time, during which the Test OS upgrade button will be inactive and display a holding message, and the control panel will display the Your server is being configured message. The page needs to be refreshed for the button to become active once the server configuration indicator turns green.


After having cloned the production service, information about production and test services will be displayed in the status line. Of particular note is the Operating System field, this will be jessie for the current service and stretch for the upgraded service.  Jessie is Debian 8, and stretch is Debian 9.


MWS site administrators can connect to the test server and do any potential  work necessary to bring their websites up and running on the new versions of software. The test server will have an MWS name of the form mws-[nnnnn].mws3.private.cam.ac.uk, which will have a (CUDN-wide) private IP address.


For the purposes of the upgrade, the production service is the one that is visible to the world, while the test service is not. These can be swapped any time by clicking Swap the Test and Production servers button under Test OS upgrade. Only do this when you are sure that all the websites on your server are working correctly in the test service.


The panel will also display a new button titled MWS test server settings. Clicking it will bring up a page where the test service can be configured. Installing PHP libraries and restarting work identically to their corresponding entries in the main configuration panel. The Copy production filesystem to test button starts a sync of user data from the production service to the test service.

This page also displays the list of websites found on the server and has links where you can view the test or production sites without actually swapping them. This works by setting a cookie in your browser and redirecting based on that cookie to the test service, or unsetting the cookie so requests hit the production site. This only has effect for the website on which the link has been clicked and will not interrupt users’ sessions on the production site.

Delete the test server removes the test service. This is a destructive operation, so use it only if you’re satisfied that all files have transferred correctly and the site works under the new operating system.