Tuesday, February 2, 2021

Deploying Docker images to Azure App Services

Deploying Docker images to Azure App Services is simple. Learn how to deploy your Docker images to Azure App Services using Azure Container Registry (ACR)
Photo by Glenn Carstens-Peters on Unsplash

We've been discussing Docker, containers and microservices for some time on the blog. On previous posts we learned how to create our own ASP.NET Docker images and how to push them to Azure Container Registry. Today we'll learn how to deploy these same Docker images on Azure App Services.

On this post we will:


As requirements, please make sure you have:
If you want to follow along, please check the previous tutorials discussing how to:

    About Azure App Services

    Azure developers are quite familiar with Azure App Services. But for those who don't know, App services are:
    HTTP-based services for hosting web applications, REST APIs, and mobile back ends. You can develop in your favorite language, be it .NET, .NET Core, Java, Ruby, Node.js, PHP, or Python. Applications run and scale with ease on both Windows and Linux-based environments.

    Why use App Services

    And why use Azure App Services? Essentially because App Services:
    • support multiple languages and frameworks: such as ASP.NET, Java, Ruby, Python and Node.js
    • can be easily plugged into your CI/CD pipelines, for example to deploy from Docker Hub or Azure Container Registries
    • can be used as serverless services
    • runs webjobs allowing us to deploy backend services without any additional costs
    • have a very powerful and intuitive admin interface 
    • are integrated with other Azure services

    Creating our App Service

    So let's get started and create our App Service. While this shouldn't be new to anyone, I'd like to review the workflow so readers understand the step-by-step. To create your App Service, in Azure, click Create -> App Service:
    On this screen, make sure you select:
    • Publish: Docker Container
    • OS: Linux

    Select the free plan

    Click on Change Plan to choose the free one (by default you're set on a paid one). Click Dev/Test and select F1:

    Selecting Docker Container/Linux

    Review the info and don't forget to select Docker Container/Linux for Publish and Operating System:

    Specifying Container Information

    Next, we specify the container information. On this step we will choose:
    • Options: Single Container
    • Image Source: Azure Container Registry
    • Registry: Choose yours
    Change Image Source to Azure Container Registry:
    On this step, Azure should auto-populate your repository. However, if you do not have admin user enabled (I didn't), you'll get this error:

    Enabling Admin in your Azure Container Registry

    To enable admin access to your registry, open it using the portal and on the Identity tab, change from Disable:
    To Enable and Azure will auto-generate the credentials for you:

    Specify your Container

    Back to the creation screen, as soon as the admin access is enabled on your registry, Azure should auto-populate the required information with your registry, image and tag (if one exists):
    Startup Command allows you to specify additional commands for the image (for example environment vars, volumes, configurations, etc).

    Review and Confirm

    Review and confirm. The deployment should take less than 1 second:

    Accessing our App Service in Azure

    As seen above, as soon as confirm, the deployment starts. It shouldn't take more than 1 minute to have it complete.

    Accessing our Web Application

    Let's check if our image is running. From the above image you can see my image's URL highlighted in yellow. Open that on a browser to confirm the site is accessible:

    Container Features

    To finish, let's summarize some features that Azure offers us to easily manage our containers. 

    Container Settings

    Azure still offers a Container Settings tab that allows us to inspect, change container settings for our web app.

    Container Logs

    We can inspect logs for our containers to easily troubleshoot them.
    As an example, here's an excerpt of what I got for my own container log:
    2020-04-10 04:32:51.913 INFO  -  Status: Downloaded newer image for hildenco.azurecr.io/webapp:v1
    2020-04-10 04:32:52.548 INFO  - Pull Image successful, Time taken: 0 Minutes and 47 Seconds
    2020-04-10 04:32:52.627 INFO  - Starting container for site
    2020-04-10 04:32:52.627 INFO  - docker run -d -p 5021:80 --name hildenco-docker_0_e1384f56 -e WEBSITES_ENABLE_APP_SERVICE_STORAGE=false -e WEBSITE_SITE_NAME=hildenco-docker -e WEBSITE_AUTH_ENABLED=False -e PORT=80 -e WEBSITE_ROLE_INSTANCE_ID=0 -e WEBSITE_HOSTNAME=hildenco-docker.azurewebsites.net -e WEBSITE_INSTANCE_ID=[redacted] hildenco.azurecr.io/webapp:v1 
    2020-04-10 04:32:52.627 INFO  - Logging is not enabled for this container.
    Please use https://aka.ms/linux-diagnostics to enable logging to see container logs here.
    2020-04-10 04:32:57.601 INFO  - Initiating warmup request to container hildenco-docker_0_e1384f56 for site hildenco-docker
    2020-04-10 04:33:02.177 INFO  - Container hildenco-docker_0_e1384f56 for site hildenco-docker initialized successfully and is ready to serve requests.

    Continuous Deployment (CD)

    Another excellent feature that you should explore in the future is enabling continuous deployment on your web apps. Enabling continuous deployment is essential to help your team gain agility by releasing faster and often. We'll try to cover this fantastic topic in the future, keep tuned.


    On this post we reviewed how to create an Azure App Service and learned how to deploy our own Docker Images from our very own Azure Container Registry (ACR) to it. By using ACR greatly simplified the integration between our own Docker Images and our App Services. From here I'd urge you to explore continuous integration to automatically push your images to your App Services as code lands in your git repository.


    See Also

    About the Author

    Bruno Hildenbrand      
    Principal Architect, HildenCo Solutions.