Deploy a code change to production
First, you need your change to be merged in the master branch. Cherry-pick your change to the relevant wmf/ branch.
Such deployment should normally occur during the SWAT deploys, windows 3 times per day from Monday to Thursday where you can ask code to be pushed to the production servers.
We normally don't deploy Fridays or week-end. If there is an emergency, you can ask for an exemption on #wikimedia-operations: ping greg-g or absent, RainbowSprinkles. One of these deployers can then deploy your change.
Please stay on #wikimedia-operations and other relevant channels after deployment, to be able to react if there is any issue.