Ever since Docker was introduced to me, the first thing that came to my mind was, Docker is a replacement for Chef. Docker does almost everything that Chef did and provides me with a light weight solution. While Chef just configures the system. Well I was wrong. I read many articles, heard many speeches and came to a conclusion that, it was not Chef vs Docker, it was Chef with Docker. When they work together, you get the most powerful tool to deliver fast, light and efficiently.
I conducted a demo at
Docker-Bangalore meetup #4 to show how integration with Chef and Docker works. More information on the meetup page.
What is Chef?
- Configuration Management Tool.
- Helps write Infrastructure as a code.
- Users write code called ‘recipes’ to help manage and configure servers and applications.
- Runs in client/server as well as stand-alone configuration called chef-solo.
- Ensures each resource is properly configured and is in the desired state.
- More on my blog Learning Chef.
What is Docker?
- Light weight Linux container that packages an application and all its dependencies in a virtual container.
- The container can be packed, shipped and the application can run on any Linux machine on public cloud, private cloud or bare metal.
- Does not include OS.
- Layers the changes made in the container just like a version control system, which allows you to reach any previous state within no time.
- More on my blog Docker.
Why use Chef+Docker, What are the issues with Vagrant+Chef?
- If each project is in its own VM, resource usage is prohibited.
- All the projects in a Single VM, management will be difficult, different versions for same software for different projects.
- Building and Rebuilding takes long time, partial builds or rebuilds are difficult. Unless explicitly snapshot is created at various stages.
- If you rely on external dependencies(which we do), full rebuilds can fail due to one or more broken dependencies.
- If your stack has multiple components (web, db, cache, etc) and they are installed in 1 Vagrant VM, the resulting setup differs from production. Or you could use multiple VMs… but point # 1 holds.
Chef Pros:
- Great at provisioning (knife bootstrap and plugins)
- Configuring services – Writing your infrastructure as a code.
- Testing your Infrastructure
Chef Cons:
- Packaging applications
- Deployments and rollbacks
- Dynamic service delivery
Docker Pros:
- Packaging applications
- Deployments and rollbacks
- Dynamic service delivery
Docker Cons:
- Managing persistent storage
- Complex networking
- Monolithic services
How to get Chef and Docker work together?
The key is understanding the Developers and Operations workflow and making them work together.
Developers own:
- Code and Libraries
- Build and Test Automation
- System Packages
- Runtime Configuration
- Release Management
- Logs monitoring
- Horizontal Scaling
Operations own the Platform:
- Hosts
- Routers
- Monitoring
- Logs
- Security
- Backing Services
Basically,
Developers take the control of the containers
&
Everything outside containers for Operations
Setting up Chef and Docker to work together:
- Install Chef workstation with Omnibus Installer.
- Create an account on manage.opscode.com or create your own chef-server.
- Create a vagrant node or a cloud instance.
- Site install docker community cookbook with site install.
- Create your own cookbook which depends on docker.
- Upload all cookbooks.
- Bootstrap the node.
- Login and verify of the node has the required images.
References:
- Brain Flad's chef-docker cookbook
- Gabriel Monroy's ChefConf presentation
- StackOverflow, Google groups and Quora
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