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Developing Azure Functions in a Docker Container

Developer Tools
by: Patrick Bacon
Improve Your Dev Experience with Dockerized Postgres

Article summary

Of late, I’ve become enamored with using Docker containers for anything and everything (I recently posted about doing development in a Docker container). So when I needed to do some work on a small Azure Functions project, the first thing I investigated was whether or not I could do my development/testing in a Docker container running on my MacBook Pro.

I was pleasantly surprised to find out that I could! As of Version 2 of the Azure Functions Runtime, it is cross-platform (thanks to .NET core), with support for Windows, Mac, and Linux.

There’s even some official Microsoft documentation that shows how to configure a Docker container to run a Node.js based Azure Functions project:


FROM mcr.microsoft.com/azure-functions/node:2.0
ENV AzureWebJobsScriptRoot=/home/site/wwwroot
COPY . /home/site/wwwroot

or for a C# project, Mark Heath provides an example:


FROM microsoft/azure-functions-dotnet-core2.0:2.0
ENV AzureWebJobsScriptRoot=/home/site/wwwroot
COPY ./bin/Release/netstandard2.0 /home/site/wwwroot

Development Environment

Those containers are great for running the app. But I wanted to use a container that would allow me to edit the code in the container and run the server without having to rebuild the container every single time (as I described in the post I mentioned earlier).

I pieced together the necessary Linux installation instructions from various web pages and was able to come up with a Dockerfile that has all of the necessary .NET and Azure Functions parts:


FROM ubuntu:18.04

RUN apt-get update && apt-get install -y \
  curl \
  gnupg \
  git \
  vim \
  lsb-release

RUN curl https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor > microsoft.gpg \
  && mv microsoft.gpg /etc/apt/trusted.gpg.d/microsoft.gpg \
  && echo "deb [arch=amd64] https://packages.microsoft.com/repos/microsoft-ubuntu-$(lsb_release -cs)-prod $(lsb_release -cs) main" > /etc/apt/sources.list.d/dotnetdev.list

RUN apt-get update && apt-get install -y \
  azure-functions-core-tools \
  dotnet-sdk-2.1

# Development environment utilities
RUN apt-get install -y \
  telnet \
  net-tools \
  iputils-ping \
  htop \
  bash-completion \
  time

RUN groupadd -g 1000 dev && \
    adduser --uid 1000 --gid 1000 --disabled-password dev

USER dev
RUN mkdir -p /home/dev/app
WORKDIR /home/dev/app

You can easily change the version of the dotnet-sdk to whatever you need.

With this as a starting point, you simply need to get the source code into your running container (clone the repository, ideally). From there, you should be able to run func start --build to run the app. As noted in my earlier post, it’s a good idea to mount a named volume so when you check out the source code it won’t get blown away when the container is recreated.

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