Continuous Development Environment

using Docker and VSCode - Go version

Directory Structure

|--- .vscode
|       |--- launch.json
|
|--- Dockerfile
|--- Dockerfile.base
|--- Dockerfile.debug
|--- main.go
|--- README.md
|--- request.http

Establish Docker container and integrate with project file in host directory

1. type docker run --rm -it -v ${pwd}:/go/src/app -w /go/src/app -p 3000:3000 golang:1.12
2. to check whether you have bind the volume correctly or not, type ls
3. you should see your local project files inside there
4. run go run main.go

Explanation regarding the Docker command

Command	Explanation
docker run	to create a new Docker container
--rm	delete container after exit, for sanity purpose
-it	to enable interactive mode
-v ${pwd}:/go/src/app	to mount bind between local directory and container directory
-w	to change into a specific directory inside container
-p 3000:3000	to set inbound-outbound port
golang:1.12	base image

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Use Debug module from VSCode

Pre-requisite

1. build the base image first, docker image build -f Dockerfile.base -t go-base .

Main

1. On your VSCode, click ctrl + L shift + p
2. Select/write Go: Install/Update Tools
3. Search dlv
4. Click OK button
5. Set up launch.json file inside .vscode folder
6. For debugging purpose, open up a new port to let dlv listen for changes. i.e. :1234
7. Create a Dockerfile specifically for debugging purpose. i.e. Dockerfile.debug
8. Build it, docker image build -f Dockerfile.debug -t go-debug .
9. Run it, docker run --rm -d -it -v ${pwd}:/go/src/app -w /go/src/app -p 3000:3000 -p 1234:1234 --security-opt=seccomp:unconfined go-debug:latest
10. Run your debugger and start to place your breakpoint

Explanation regarding the Docker command

Command	Explanation
-d	detach, so you will not be directed into the container's CLI
-p 1234:1234	open up another port for debugging purpose
--security-opt=seccomp:unconfined	in order to let dlv run into your container, you need to allow it by without using default secure computing mode (seccomp) profile

Additional explanation about Debug step

1. To know more about dlv CLI command, check here
2. To know more about VSCode debugging, especially in Go, check here

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Separate Docker image between base, debug, and production purpose

1. Create the base image on Dockerfile.base. The purpose of this Dockerfile is to build the standard environment that could be applicable for debug and production
2. Create the debugging-purpose image on Dockerfile.debug. We do not need to have unrelated packages for production, such as go-delve (for debugging purpose) and exposing a new port, which may harm your container.
3. Create the production-purpose image on Dockerfile. We set the standard naming style for production.