Merge pull request #533 from Azure/vsts-sidecar

Blog for VSTS tasks for sidecars

Author: tulikac

_posts/2025-10-29-VSTS-tasks-for-sidecars.md

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+---
+title: "Azure Pipeline samples: add sidecars to Azure App Service for Linux"
+author_name: "Tulika Chaudharie"
+toc: true
+toc_sticky: true
+---
+
+Sidecars on Azure App Service let you attach extra containers — logging, telemetry, lightweight APIs, caches, AI inference helpers — alongside your main app, in the same App Service. They start and run with your app, but you don’t have to bake that logic into your main code.
+
+We’re publishing two Azure Pipelines (Azure DevOps / VSTS) YAML samples to make this easy. 
+
+## VSTS samples
+
+* **[`vsts-blessed-sitecontainers.yml`](https://github.com/Azure/actions-workflow-samples/blob/master/AppService/vsts-blessed-sitecontainers.yml)** 
+  For built-in runtimes on App Service for Linux (for example, Python or Node on the built-in stack).
+  * Builds your app, zips it, and deploys it using `AzureWebApp@1`.
+  * In the same deploy step, it sends a `sitecontainersConfig` payload that defines one or more sidecar containers by image, port, and config.
+  * Your app keeps running on the App Service runtime; the sidecars run next to it.
+
+* **[`vsts-only-sitecontainers.yml`](https://github.com/Azure/actions-workflow-samples/blob/master/AppService/vsts-only-sitecontainers.yml)** 
+  For containerized apps (Web App for Containers style).
+  * Builds and pushes multiple images (main app container + sidecars) to your container registry.
+  * Uses `AzureWebAppContainer@1` to deploy them all together to App Service for Linux.
+  * One container is marked `"isMain": true`; the rest are `"isMain": false`.
+
+Both samples assume Azure App Service for Linux and the sidecar model, where containers in the same app can talk to each other over localhost.
+
+## How the pipelines work
+
+1. **Build and Publish**
+   * `vsts-blessed-sitecontainers.yml`: sets up your language/runtime, installs dependencies, and produces a ZIP artifact of your app. It also uses Docker tasks to build and publish the sidecar container.
+   * `vsts-only-sitecontainers.yml`: uses Docker tasks to build and push multiple container images.
+
+2. **Deploy to App Service for Linux**
+   * Code-based flow: `AzureWebApp@1` deploys the ZIP and sidecar containers defined in `sitecontainersConfig`.
+   * Container flow: `AzureWebAppContainer@1` deploys your main container and sidecars, defined in `sitecontainersConfig`.
+
+That’s it: one pipeline run builds, packages, and deploys your main app plus its helper containers.
+
+## Quick start
+
+1. **Pick a template**
+   * Built-in runtime on App Service for Linux? Use `vsts-blessed-sitecontainers.yml`.
+   * Already running containers? Use `vsts-only-sitecontainers.yml`.
+
+2. **Add it to your repo**
+   Save the YAML as `azure-pipelines.yml` (or add it as a new pipeline in Azure DevOps).
+
+3. **Fill in the placeholders**
+   * `azureServiceConnectionId` / `azureSubscription`: your Azure RM service connection.
+   * `webAppName` / `appName`: the target App Service for Linux app.
+   * `resourceGroup`: where that app lives.
+   * `containerRegistry`, image names, and ports for each container in the multi-container case.
+   * Each container in `sitecontainersConfig` declares its port and whether it’s the main app or a sidecar.
+
+4. **Run it in Azure DevOps**
+   Create a new pipeline from YAML, authorize the service connections, and run.
+
+5. **Check your app**
+   In the Azure portal, go to Deployment Center->Containers and your App Service will now show your primary app plus the sidecar containers defined in the pipeline.
+
+## Customize to fit
+
+These YAMLs are starting points. You can:
+* Add test/lint stages before deployment so you only ship good builds.
+* Swap the agent pool (`ubuntu-latest` vs your own self-hosted pool).
+* Deploy to a staging slot first, then swap to production.
+* Tune each sidecar in `sitecontainersConfig`: env vars, ports, credentials, etc.
+
+You don’t have to redesign CI/CD every time you want to add observability, a cache container, or a small inference helper next to your app — you just describe the containers and ship.
+
+
+## Learn more
+
+* **Deploy to Azure App Service using Azure Pipelines**
+  Full walkthrough for setting up [Azure Pipelines with App Service](https://learn.microsoft.com/en-us/azure/app-service/deploy-azure-pipelines?tabs=yaml), including service connections and the `AzureWebApp@1` / `AzureWebAppContainer@1` tasks.
+
+* **Sidecars on App Service for Linux**
+  [How sidecars work](https://learn.microsoft.com/en-us/azure/app-service/overview-sidecar), how `isMain` is used, networking rules (localhost between containers), and common patterns like telemetry/OTEL agents, API helpers, and lightweight caches.
+
+Drop these templates into your pipeline, point them at your app, and you’ve got repeatable CI/CD for multi-containers in App Service.