Templates: Normal

A normal template is for the most part exactly like any other Docker template except it has queryable data and a context that we create for that data before allowing Docker to create it's own context.

Dockerfile

Just like any Docker image, you have a Dockerfile, it can be transformed using variables and other stuff on a per-tag/group basis because we run all your Dockerfile's through ERB before creating your context for Docker.

Variables

• @metadata: A Metadata class holding all of the opts.yml data.
• You have full access to Ruby and it's context from within ERB as well.

Example

Lets build an image that installs prosody on both Alpine and Ubuntu with each tag respectively having base packages shared across them and one having it's own unique package (bash) because Alpine is an embedded OS driven at simplicity, it has no bash. This image uses the default base image of envygeeks/ubuntu:latest which provides runit in place of other run systems and provides extra stuff, you can read more about this image here: https://github.com/envygeeks/docker/tree/master/repos/ubuntu

The Layout

• opts.yml
• repos/prosody
  • opts.yml
  • Dockerfile
  • copy/

Opts.yml (Metadata)

/opts.yml

maintainer: Your Name <[email protected]>
user: random

/repos/prosody/opts.yml

tags:
  ubuntu: ubuntu
  alpine: alpine

aliases:
  latest: alpine

images:
  tag:
    ubuntu: "envygeeks/ubuntu:latest"
    alpine: "envygeeks/alpine:latest"

packages:
  all:
    - prosody

  group:
    alpine:
      - bash

package_commands:
  group:
    ubuntu: "apt-get update && apt-get install --no-install-recommends -y"
    alpine: "apk --update add"

The Dockerfile

MAINTAINER <% @metadata.maintainer %>
FROM <%= @metadata.image %>
RUN <%= @metadata.package_command + " " + @metadata.packages %>
COPY copy /

Final Outputs

alpine

MAINTAINER Your Name <[email protected]>
FROM envygeeks/alpine:latest
RUN apk --update add prosody bash
COPY copy /

ubuntu

MAINTAINER Your Name <[email protected]>
FROM envygeeks/ubuntu:latest
RUN apt-get update && apt-get install --no-install-recommends -y prosody
COPY copy /

/repos/prosody/copy/etc/startup3.d/prosody/run

sed -ri "s/__HOSTNAME__/$HOSTNAME/" \
  /etc/prosody/prosody.cfg.lua

ssl_lines() {
  grep -nE '\s+-{2}\s+enable:ssl$' /etc/prosody/prosody.cfg.lua | awk -F: '{
    print $1
  }'
}

if [ "$ENABLE_SSL" ]; then
  for v in $(ssl_lines); do
    sed -ri "${v}s/(\s*)-{2}\s+/\1/" /etc/prosody/prosody.cfg.lua
    sed -ri "${v}s/\s+-{2}\s+enable:ssl\$//" \
      /etc/prosody/prosody.cfg.lua
  done
else
  while { l=$(ssl_lines | head -n1); test -n "$l"; } do sed -i "${l}d" /etc/prosody/prosody.cfg.lua; done
  for v in $(grep -nE '\s+-{2}\s+disable:ssl$' /etc/prosody/prosody.cfg.lua | awk -F: '{ print $1 }'); do
    sed -ri "${v}s/(\s*)-{2}\s+/\1/" /etc/prosody/prosody.cfg.lua
    sed -ri "${v}s/\s+-{2}\s+disable:ssl\$//" \
      /etc/prosody/prosody.cfg.lua
  done
fi

exec chpst -u prosody:prosody \
  prosody

Building

Upon building, you will get three images, random/prosody:ubuntu, random/prosody:latest, random/prosody:alpine, and random/prosody:latest will point to the image id of random/prosody:alpine.

docker-template build prosody
docker-template build prosody:ubuntu
docker-template build prosody:alpine

Running

docker-template run --rm -it random/prosody:alpine
docker-template run --rm -it random/prosody:ubuntu
docker-template run --rm -it random/prosody:latest