ASP.NET 5 Docker language stack with Kestrel

This blog post presents a Docker Language Stack for creating and running ASP.NET 5 (née vNext) apps. It’s based on my work last week to run ASP.NET 5 on Google Container Engine.

I the interim, the ASP.NET team has released their own Docker image. It’s not really up to spec for being a Docker language stack though, so I forked it, added what was missing and published it on Docker Hub.

Other people already sent PRs to add onbuild support to the ASP.NET repo, but there’s apparently some uncertainty about how ASP.NET 5 apps are going to get built, so they’re holding off on merging. I hope that eventually the work presented here will get folded into the official repo, just like it happened with the Mono stack I created a month ago. That’s the base for what’s now the official Mono Docker language stack, which, incidentally, is what the ASP.NET docker image derives from!

How to use

Using the onbuild image is pretty simple. To run HelloWeb sample, clone that repo and add this Dockerfile in the HelloWeb dir, next to the project.json:

FROM friism/aspnet:1.0.0-beta1-onbuild
EXPOSE 5004

Now build the image:

docker build -t my-app .

And finally run the app, exposing the site on port 80 on your local machine:

docker run -t -p 80:5004 my-app

Note that the -t option is currently required when invoking docker run. This is because there’s some sort of bug in Kestrel that requires the process to have a functional tty to write to – without a tty, Kestrel hangs on start.

One thought on “ASP.NET 5 Docker language stack with Kestrel”

  • Hi Michael,

    As a supplement to your last note about running docker with the -t (tty) option: If you must run without the -t option, for example when using fig for Orchestration, then you can wrap the execution of kestrel with script to emulate a tty. I.e.:

    $ cat host.sh
    #!/bin/bash
    script -c “k kestrel” /tmp/kestrel

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