docker-build-layers

Command line helper to simplify building docker images that have multiple layers.

Why

Sometimes you want to layer your docker images to speed up build process when you don't have to go through every step

Install

npm install --save-dev docker-build-layers

Usage

dbl -h

dbl relies on docker command being present in your PATH.

1. Create docker-build-layers-config.json file with content similar to:

   {
     "prefix": "prefix-string/",
     "afterEach": "gcloud docker push <%= tag %>",
     "images": {
       "base-image": {
         "version": 5,
         "dockerfile": "./Dockerfile-base-image"
       },
       "server": {
         "version": 3,
         "dockerfile": "./Dockerfile-server",
         "isTemplate": true,
         "baseimage": "base-image"
       }
     }
   }

   • prefix: string (optional) A string to prepend to all image names and baseimage names
   • afterEach: string (optional) A command that will be executed after each image build. The command can be a lodash template. A locals of {tag: number} will be applied when compiling the template. tag is the tag of the image just built.
   • images A object of image names to their configurations

     • version: number The version portion of a image tag. The version number will be incremented every time the image it built. When generating an image tag, the version number will be prefixed with a v character. E.g. if image name is demo-image, version is 3, the final tag will become demo-image:v3.

     • dockerfile: string The path to dockerfile of current image.

     • baseimage: string (optional) The baseimage name. Name must point to image configurations under images. This must be specified when isTemplate is true.

     • isTemplate: boolean = false (optional) If true, dockerfile will be treated as a lodash template. A locals of {baseimage_version: number} will be applied. You are responsible to use <%= baseimage_version %> in your dockerfile template. E.g.

       FROM baseimage-name:v<%= baseimage_version %>
       
       ADD index.js /app/index.js
       CMD ["node", "/app/index.js"]

       docker-build-layers will find the baseimage_version according to provided baseimage and use that image configuration's version.

2. Run dbl -l to see a list of available images to build.

3. Run dbl -b <image-name> to build the specific image. Any image with baseimage configuration equals to the name of built image will also be built. The baseimage_version of child images will reflect the new parent image version.

4. At the end docker-build-layers-config.json will be updated with new versions. It is recommended to commit this file to source control.