Actual disk space requirements for Azure AppService docker containers

Question

Hi,
We started to run into problems with disk space on our multi-container Azure AppService instance. We have two slots (staging/prod) on an app with 5 docker containers each (rails, rails, node, ngnix, redis) and started to get errors during startup due to no space left for docker images. The «Linux - Host Disk Space Usage» reports near 100% usage.

Here https://github.com/projectkudu/kudu/wiki/Understanding-the-Azure-App-Service-file-system I read, that depending on the App Service Plan the quota varies. But I fear this information is outdated, as we are on a P2V3 plan and seem to still hit a limit of 15 GB.

Can you give us an update on the current quotas with the up-to-date PxV3 plans? Also, once we hit such a limit, what is the quickest way to clean up the disk space, as the service typically starts and endless restart loop that is not quite easy to stop.

Thanks for your help!

Answer 1

@Stefan N , Thanks for reaching out. As per the documentation if you are using the P2V3 app service plan they you will get 250GB file system storage as shown below

App service on [Linux offers] (https://learn.microsoft.com/en-us/troubleshoot/azure/general/faqs-app-service-linux#my-container-fails-to-start-with--no-space-left-on-device---what-does-this-error-mean-) two types of storage:
1.File System Storage: It's used when files are saved to the persistent storage that's rooted in the /home directory.
2.**Host disk space: ** The host disk space is used to store container images on worker. It's managed by the platform through the docker storage driver. It's not expandable and there is a 15 GB limit for each instance.

If the container's writable layer saves data outside of the /home directory or a mounted azure storage path, the host disk space will also be consumed. If the container writes a large quantity of data to other /home directory, then you may land up with runtime exceptions once the host disk limit is exceeded.

It's recommended that you keep your container images as small as possible and write data to the persistent storage or BYOS(Bring your own storage) when running on Linux App Service. If not possible, you must split the App Service plan because the host disk space is fixed and shared between all containers in the App Service Plan.