Web App for Containers: Unable to Access or Edit Files in Deployed Container Image

Question

Web App for Containers: Unable to Access or Edit Files in Deployed Container Image

andycahn-6863 0

Problem description

I am trying to find and edit JavaScript files within my deployed container image for a Linux Web App running on Azure. The container is pulled from a registry and is configured as a single container pulling from Azure Container Registry with Managed Identity. I want to modify files in the a folder called "feeds" to add or update some files, but I cannot access them directly through the typical App Service content editing methods.

Environment

Web App for Containers, Linux, Azure, region not specified in case information

What I've already tried

I reviewed the deployment source and configuration in the Azure portal. I confirmed that the app uses a container image deployed from Azure Container Registry. I understand that the application files are built into the container image and are not editable directly in the live App Service environment.

I have also asked the Microsoft Support that I pay for to help me with this issue, and for some reason they say I have to post this here to continue, even though their last reply said they would continue to help me solve this issue.

Current status

I am seeking guidance on how to modify or update the JavaScript files within the container image, or how to access the 'feeds' folder if it is mounted as a persistent storage, so I can make the necessary edits. I am also waiting for the Microsoft Support reply to make good on its offer to "help [me] determine whether the feeds content is baked into the container or read from a mounted storage path, and then outline the supported update path for that design."

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2 answers

Your answer

Answer 1

Hi @andycahn-6863

Thanks for reaching out in Microsoft Q&A forum,

Based on the Web App for Containers deployment model, application files that are packaged as part of the deployed container image are not intended to be modified directly within the running container. The application runs from the container image deployed to the App Service.

Although it may be possible to access and modify files within a running container instance, changes made directly to the container's local filesystem are temporary and may be lost when the container is restarted, scaled out, redeployed, or recreated by the platform. This is expected behavior for containerized applications.

If you need to update the JavaScript files located in the feeds folder and those files are part of the deployed application image, the recommended approach is to update the application source code, rebuild the container image with the required changes, and then redeploy the updated image to Azure App Service.

If the application instead requires files to persist independently of the container lifecycle, persistent storage, such as Azure Storage mounted to the Web App, can be used. This is generally intended for persistent application data or files rather than for modifying application code within the deployed container image.

For additional information, please refer to the following Microsoft documentation:

Kindly let us know if the above helps or you need further assistance on this issue.

Please do not forget to and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

Answer 2

Hi andycahn-6863 & thx for join me at Q&A platform,

For Web App for Containers, the application files inside the image aren't intended to be edited through App Service. The container image is effectively the deployment artifact, so changes made manually inside a running container would also be lost when the container restarts, scales, or App Service pulls a new instance. The first thing to determine is where feeds actually lives. You can use the App Service SSH/console to inspect the running container and check the path containing that directory. If feeds is simply part of the image filesystem, the supported approach is to modify the JavaScript files in the source/build context, rebuild the image, push the new image to ACR, and redeploy/restart the Web App using the new image.

If feeds needs to be updated independently of application deployments, it shouldn't be baked into the image. Move it to persistent storage instead, for example an Azure Storage mount configured for the Web App, and have the application read the files from that mounted path. Then updates to those files can persist independently of container replacement.

So the key distinction is whether feeds is an image directory or a mounted volume. SSH into the container and run mount and df -h, then inspect the path to feeds. If you can share the container configuration and the actual path to that folder, it should be possible to tell which case you have and what the cleanest update path is.

rgds,

Alex