# Azure Devops Deployments For zero downtime deployments, Deployment slots are a great tool to use. The process goes as follows: 1. Deployment to `stage` slot 2. Warming up of `stage` slot 3. Shifting of traffic from `production` to `stage` slot, effectively swapping the two The warming up in Step 2 also works as a health-check so we are only swapping to a healthy Deployment slot to avoid taking the site offline. In order for this health-check to work the Azure DevOps Release Pipeline needs to have access to the `stage` slot. Without access, you might get this error: ![[Pasted image 20231010161818.png]] ## Access Restriction on AppService To grant access, instead of whitelisting individual IPs or the Azure IP range directly, there are ServiceTags that can be used to grant access: `App Service > Deployment Slot 'stage' > Networking > Access Restrictions` ![[azure-devops-deployments-servicetag-1.png]] ![[azure-devops-deployments-servicetag-2.png]]