Differences between Azure Functions Docker images on Docker Hub?

Question

My team is upgrading Azure Functions runtime from 3.x to 4.x to support .NET 6. We noticed that there are 4 Docker image tags available. What are the differences between these tags?

Link to Docker Hub: https://hub.docker.com/_/microsoft-azure-functions-dotnet?tab=description

Bonus question: what is .NET isolated images? (https://hub.docker.com/_/microsoft-azure-functions-dotnet-isolated)

Thanks.

Answer 1

@Pitawat ,

Thanks for reaching out to Q&A.

The following are the differences between the available tags. Images and their uses are also listed below

4 – This is the “standard” image for dotnet support. This includes the full package of dependencies. But, does not include ssh configuration that makes connecting to a production application over kudu possible. This image is a good image to build off of when custom dependencies are necessary. Here is the definition file of that image.

https://github.com/Azure/azure-functions-docker/blob/dev/host/4/bullseye/amd64/dotnet/dotnet-inproc/dotnet.Dockerfile

4-slim – In most cases, this is the smallest available image for a specific language. In general, it cuts out unnecessary but commonly used dependencies. For dotnet, we do not have any unused dependencies so this slim image is equivalent to the above image ‘4’. This image is not preferred in any cases.

https://github.com/Azure/azure-functions-docker/blob/dev/host/4/bullseye/amd64/dotnet/dotnet-inproc/dotnet-slim.Dockerfile

4-appservice – By default, this is the image that most customers use. It includes all necessary dependencies, the Functions Host, and tools for ssh’ing into an application using Kudu. In most cases, unless a customer has to download specific dependencies for their app this is the preferred image. A definition can be found here attached to the latest release under <version>-appservice

https://github.com/Azure/azure-functions-docker/releases/tag/4.1.3

4-dotnet6-appservice – Equal to above 4-appservice image. For other languages, the customer can select a specific runtime version. For example if the customer wanted to use java. The customer could select a specific runtime version such as java:4-java8-appservice or they could go for the default image (java:4-appservice) which is java11. However, for dotnet there are no other versions available. So this image is equivalent to the above 4-appservice image.

I hope this helps!

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