Golang and Docker for development and production

Josh McMenemy
Feb 12, 2017 · 3 min read
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Why you would want to use Docker for dev and production:

  • Quick on-boarding (anyone with Docker installed can start coding without setting up any other dependencies or GOPATH variables);
  • Dev environment is the same as production.

What you will learn in this article:

  • How to write a single Dockerfile that allows you to build a dev container that will reload code changes you make locally (without rebuilding the container) and a production container that serves the binary build;
  • This is done using shared volumes, pilu/fresh, and build arguments.

How to do it:

To get started run the following commands in Terminal:

$ mkdir myGoDockerApp
$ cd myGoDockerApp
$ mkdir app
$ cd app
$ touch app.go
$ cd .. 
$ touch Dockerfile
  • ARG app_env => allows app_env to be set during build (defaults to empty string)
  • ENV APP_ENV $app_env => sets an environment variable to app_env argument, this way the variable will persist in the container for use in code
  • COPY ./app /go/src/github.com/user/myProject/app => copy the local project code into a directory in the container’s GOPATH
  • WORKDIR /go/src/github.com/user/myProject/app => set this to the working directory so all subsequent commands will run from this directory
  • RUN go get ./ => install all dependencies
  • RUN go build => build the binary
  • CMD if … => If arg_env was set to production run the binary otherwise use pilu/fresh to hot reload the code when it changes
  • EXPOSE 8080 => This is the port the app was programed to serve on
$ docker build ./
$ pwd
$ docker run -it -p 8080:8080 -v [put your path here]/app:/go/src/github.com/user/myProject/app [image id]
$ docker build ./ --build-arg app_env=production
$ docker run -i -t -p 8080:8080 [image id]

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