Azure App Service on Linux FAQ

With the release of App Service on Linux, we're working on adding features and making improvements to our platform. This article provides answers to questions that our customers have been asking us recently.

If you have a question, comment on the article and we'll answer it as soon as possible.

Built-in images

I want to fork the built-in Docker containers that the platform provides. Where can I find those files?

You can find all Docker files on GitHub. You can find all Docker containers on Docker Hub.

What are the expected values for the Startup File section when I configure the runtime stack?

For Node.js, you specify the PM2 configuration file or your script file. For .NET Core, specify your compiled DLL name. For Ruby, you can specify the Ruby script that you want to initialize your app with.

Management

What happens when I press the restart button in the Azure portal?

This action is the same as a Docker restart.

Can I use Secure Shell (SSH) to connect to the app container virtual machine (VM)?

Yes, you can do that through the source control management (SCM) site.

How can I create a Linux App Service plan through an SDK or an Azure Resource Manager template?

You need to set the reserved field of the app service to true.

Continuous integration and deployment

My web app still uses an old Docker container image after I've updated the image on Docker Hub. Do you support continuous integration and deployment of custom containers?

To set up continuous integration/deployment for Azure Container Registry or DockerHub images by check the following article Continuous Deployment with Web App for Containers. For private registries, you can refresh the container by stopping and then starting your web app. Or you can change or add a dummy application setting to force a refresh of your container.

Do you support staging environments?

Yes.

Can I use web deploy to deploy my web app?

Yes, you need to set an app setting called WEBSITE_WEBDEPLOY_USE_SCM to false.

Git deployment of my application fails when using Linux web app. How can I workaround the issue?

If Git deployment fails to your Linux web app, you can choose the following alternate options to deploy your application code:

  • Use the Continuous Delivery (Preview) feature: You can store your app’s source code in a Team Services Git repo or GitHub repo to use Azure Continuous Delivery. For more details, see How to configure Continuous Delivery for Linux web app.

  • Use the ZIP deploy API: To use this API, SSH into your web app and go to the folder where you want to deploy your code. Run the following:

    curl -X POST -u <user> --data-binary @<zipfile> https://{your-sitename}.scm.azurewebsites.net/api/zipdeploy
    

    If you get an error that the curl command is not found, make sure you install curl by using apt-get install curl before you run the previous curl command.

Language support

I want to use websockets in my Node.js application, any special settings or configurations to set?

Yes, disable perMessageDeflate in your server side Node.js code. For example, if you are using socket.io, do the following:

var io = require('socket.io')(server,{
  perMessageDeflate :false
});

Do you support uncompiled .NET Core apps?

Yes.

Do you support Composer as a dependency manager for PHP apps?

Yes. During a Git deployment, Kudu should detect that you are deploying a PHP application (thanks to the presence of a composer.lock file), and Kudu will then trigger a composer install for you.

Custom containers

I'm using my own custom container. I want the platform to mount an SMB share to the /home/ directory.

You can do that by setting the WEBSITES_ENABLE_APP_SERVICE_STORAGE app setting to true or by removing the app setting entirely. Keep in mind that doing this will cause container restarts when the platform storage goes through a change.

Note

If the WEBSITES_ENABLE_APP_SERVICE_STORAGE setting is false, the /home/ directory will not be shared across scale instances, and files that are written there will not be persisted across restarts.

My custom container takes a long time to start, and the platform restarts the container before it finishes starting up.

You can configure the amount of time the platform will wait before it restarts your container. To do so, set the WEBSITES_CONTAINER_START_TIME_LIMIT app setting to the value you want. The default value is 230 seconds, and the maximum value is 600 seconds.

What is the format for the private registry server URL?

Provide the full registry URL, including http:// or https://.

What is the format for the image name in the private registry option?

Add the full image name, including the private registry URL (for example, myacr.azurecr.io/dotnet:latest). Image names that use a custom port cannot be entered through the portal. To set docker-custom-image-name, use the az command-line tool.

Can I expose more than one port on my custom container image?

We do not currently support exposing more than one port.

Can I bring my own storage?

We do not currently support bringing your own storage.

Why can't I browse my custom container's file system or running processes from the SCM site?

The SCM site runs in a separate container. You can't check the file system or running processes of the app container.

My custom container listens to a port other than port 80. How can I configure my app to route requests to that port?

We have automatic port detection. You can also specify an app setting called WEBSITES_PORT and give it the value of the expected port number. Previously, the platform used the PORT app setting. We are planning to deprecate this app setting and to use WEBSITES_PORT exclusively.

Do I need to implement HTTPS in my custom container?

No, the platform handles HTTPS termination at the shared front ends.

Pricing and SLA

What is the pricing, now that the service is generally available?

You are charged the normal Azure App Service pricing for the number of hours that your app runs.

Other questions

What are the supported characters in application settings names?

You can use only letters (A-Z, a-z), numbers (0-9), and the underscore character (_) for application settings.

Where can I request new features?

You can submit your idea at the Web Apps feedback forum. Add "[Linux]" to the title of your idea.

Next steps