Build and provision Docker container with Chef

Example of building and provisioning Docker container with Chef provisioning.

Problem

We have a workstation with Chef and cookbooks and we want to manage Docker container locally. We want to

• create and run Docker container locally;
• provision a Docker container by running a Chef recipe in a container.

Solution

We will use Chef provisioning to create a Docker container.

Workflow:

• build image using Chef provisioning or use existing image
• create and run Docker container running 'chef-client -z' on Workstation
• update running container with Chef

Workstation:

• has ChefDK installed

Settings:

• config/config.json - attributes used to create and provision container
• container.rb - settings for Docker container

Create container:

chef-client -z -j config/config.json container.rb

Provision container:

# copy provision files to container
docker cp ../cookbooks nginx:/opt/provision/

# provision container
docker cp ../config/config.json nginx:/opt/gex/config/
docker exec nginx bash -c 'cd /opt/gex/ && chef-client -z -j /opt/provision/config/config.json -o recipe[nginx::provision]'

• Read more about provisioning Docker container with chef-client - https://gist.github.com/maxivak/167e46b3570a834231be7bbeefe9243a

Workstation:

• install ChefDK

• install gems for Chef provisioning

chef gem install chef-provisioning
chef gem install chef-provisioning-docker

chef gem install docker
chef gem install docker-api

• Setup workstation

• It assumes we have chef-repo on the workstation. This chef-repo contains common cookbooks.

• Also we can have custom cookbooks.

• Directory structure

/path/to/project/
    |__ .chef/ - directory with settings for knife
        |__ knife.rb - settings for knife
    |__ cookbooks/ - directory with cookbooks for the machine
    |_  container.rb
    |_ destroy.rb
    

• chef-repo - directory with cookbooks somewhere on the workstation

/path/to/chef-repo
    |_ cookbooks
       |__ cookbook1
           |__ recipes
               |__ default.rb
               |__ recipe2.rb
           |__ templates    
    ...|__ cookbook2
          |__ ...
    

• edit ./chef/knife.rb:

log_level                :info

root = File.absolute_path(File.dirname(__FILE__))
current_dir = File.dirname(__FILE__)

# specify path to your cookbooks
cookbook_path [ File.join(root, '../cookbooks'), '/another/path/to/your/chef-repo/cookbooks' ]

include paths to cookbooks from chef-repo and to cookbooks in our project.

Create and run a new container

• edit config/config.json with settings for the container

• edit container.rb for additional settings for running Docker container

• run on Workstation to create a container named 'nginx':

chef-client -z -j config/config.json container.rb

• 'config.json' consists of settings for the node (container)

{

  "base":{
    # base directory for shared volumes 
    "dir_data": "/disk3/data/containers/nginx"  
  },
  
  # docker options
  "docker": {
    "ports": ["8080:80"],
    "volumes": ["/var/www/html", "/etc/nginx/conf.d", "/var/log/nginx"]
  },
  
  # specific options for the application
  "nginx":{
    "sitename": "site1.com",
    # place your attributes here
  }

}

• This example creates container for Nginx from base image 'nginx:1.10'.

• If you want to build your own Docker image with Chef - read below "Build Docker image with Chef".

• To destroy the container run this script:

chef-client -z -j config/config.json destroy.rb

Provision a running container

We have a running Docker container and want to modify its state with Chef provisioning.

• Create a chef recipe cookbooks/nginx/recipes/ex1.rb.

Include everything you want to do with the container assuming that this script will be run from inside the container.

• Run provision:

docker cp ../cookbooks nginx:/opt/provision/
docker cp config/config.json nginx:/opt/provision/config/

docker exec nginx bash -c 'cd /opt/provision/ && chef-client -z -j /opt/provision/config/config.json -o recipe[nginx::ex1]'

This will copy cookbooks and config.json to the container and then run chef-client from inside the container.

Workflow:

• it will copy all cookbooks from cookbooks directory to the container If you need more cookbooks, copy them as well.

• it runs chef-client -z in local mode from inside the container.

Build Docker image with Chef