docker

Docker

This section guides you on how to use the Makefile to create (and remove) a docker containers for crcgen!

Note: This section assumes you've already installed docker on your end, and know how to use it!

Installation

To create a new Docker container, use the command:

make docker-gen

You can modify the name and version for the image to be created using the variables IMAGE and VERSION. The above command is equivalent to;

make docker-gen IMAGE=crcgen VERSION=latest

By default, the values for these environment variables are;

IMAGE := crcgen
VERSION := latest

The values of these environment variables can be customized when executing any docker command through the Makefile

make docker-gen IMAGE=<some_name> VERSION=<version_number>

Running docker image

Once you've created a docker container, to run the container, use

docker run crcgen

Cleaning a docker image

To remove a docker image run make clean-docker with VERSION or IMAGE (if needed):

make clean-docker

If you want to target a specific image, you can use the long-form version

make clean-docker IMAGE=<name> VERSION=<specific_version>

Running a simple make clean-docker is the same as

make clean-docker IMAGE=crcgen VERSION=latest

Debug Images

The dockerfile for crcgen uses multistage builds to generate light-weight docker images.

Images generated using the make docker-gen command use scratch as the base image for the final build stage - these images are referred to as production images.

While this allows creating extremely small images, at the same time these images are very minimal, which makes it difficult to debug applications - as an example, the production image cannot be shell-ed into!

To resolve this, the Makefile allows you to create debug-friendly docker images. These images use golang:1.17 as base for the final image. The resulting image is a lot larger compared to production images, at the same time, it comes with the tools you'll need to debug applications inside docker containers!

To create a debug-friendly docker image, use the command

make docker-debug

Similar to docker-gen, you can modify the name/version for the final image using environment variables IMAGE and VERSION. The previous command is the same as

make docker-debug IMAGE=crcgen-debug VERSION=latest

P.S. Notice that for the sake of clarity, debug images will always have their name appended with -debug!

You can run the image generated as

docker run crcgen-debug

You can run a debug image, and directly shell into it with

docker run --rm -it crcgen-debug bash

Cleaning debug images

The command make clean-docker targets production images by default! As a result, you'll have to manually target the debug image using it's name (and version - needed if the version isn't latest).

make clean-docker IMAGE=crcgen-debug VERSION=latest

Additionally, to ensure faster build times, the debug image explicitly caches previous layers as dangling images - allowing faster build times, at the cost of increased storage space! You can list these dangling images with

docker images -f dangling=true

To clear all dangling images, use the command

docker image prune