propellor-2.8.1: property-based host configuration management in haskell

Safe HaskellNone




Docker support for propellor

The existance of a docker container is just another Property of a system, which propellor can set up. See config.hs for an example.


Host properties

configured :: Property HasInfo Source

Configures docker with an authentication file, so that images can be pushed to Optional.

container :: ContainerName -> Image -> Container Source

Defines a Container with a given name, image, and properties. Properties can be added to configure the Container.

container "web-server" "debian"
   & publish "80:80"
   & Apt.installed {"apache2"]
   & ...

docked :: Container -> RevertableProperty Source

Ensures that a docker container is set up and running.

The container has its own Properties which are handled by running propellor inside the container.

When the container's Properties include DNS info, such as a CNAME, that is propigated to the Info of the Host it's docked in.

Reverting this property ensures that the container is stopped and removed.

imageBuilt :: HasImage c => FilePath -> c -> Property NoInfo Source

Build the image from a directory containing a Dockerfile.

imagePulled :: HasImage c => c -> Property NoInfo Source

Pull the image from the standard Docker Hub registry.

memoryLimited :: Property NoInfo Source

Configures the kernel to respect docker memory limits.

This assumes the system boots using grub 2. And that you don't need any other GRUB_CMDLINE_LINUX_DEFAULT settings.

Only takes effect after reboot. (Not automated.)

garbageCollected :: Property NoInfo Source

Causes *any* docker images that are not in use by running containers to be deleted. And deletes any containers that propellor has set up before that are not currently running. Does not delete any containers that were not set up using propellor.

Generally, should come after the properties for the desired containers.

tweaked :: Property NoInfo Source

Tweaks a container to work well with docker.

Currently, this consists of making pam_loginuid lines optional in the pam config, to work around which affects docker 1.2.0.

data Image Source

A docker image, that can be used to run a container. The user has to specify a name and can provide an optional tag. See Docker Image Documention for more information.



latestImage :: String -> Image Source

Defines a Docker image without any tag. This is considered by Docker as the latest image of the provided repository.

type ContainerName = String Source

A short descriptive name for a container. Should not contain whitespace or other unusual characters, only [a-zA-Z0-9_-] are allowed

data Container Source

A docker container.


Container Image Host 

Container configuration

dns :: String -> Property HasInfo Source

Set custom dns server for container.

hostname :: String -> Property HasInfo Source

Set container host name.

class Publishable p Source

Minimal complete definition



Publishable String Source

string format: ip:hostPort:containerPort | ip::containerPort | hostPort:containerPort

Publishable (Bound Port) Source 

publish :: Publishable p => p -> Property HasInfo Source

Publish a container's port to the host

expose :: String -> Property HasInfo Source

Expose a container's port without publishing it.

user :: String -> Property HasInfo Source

Username or UID for container.

class Mountable p Source

Minimal complete definition



Mountable String Source

string format: [host-dir]:[container-dir]:[rw|ro]

With just a directory, creates a volume in the container.

Mountable (Bound FilePath) Source 

volume :: Mountable v => v -> Property HasInfo Source

Mount a volume

volumes_from :: ContainerName -> Property HasInfo Source

Mount a volume from the specified container into the current container.

workdir :: String -> Property HasInfo Source

Work dir inside the container.

memory :: String -> Property HasInfo Source

Memory limit for container. Format: numberunit, where unit = b, k, m or g

Note: Only takes effect when the host has the memoryLimited property enabled.

cpuShares :: Int -> Property HasInfo Source

CPU shares (relative weight).

By default, all containers run at the same priority, but you can tell the kernel to give more CPU time to a container using this property.

link :: ContainerName -> ContainerAlias -> Property HasInfo Source

Link with another container on the same host.

environment :: (String, String) -> Property HasInfo Source

Set environment variable with a tuple composed by the environment variable name and its value.

type ContainerAlias = String Source

A short alias for a linked container. Each container has its own alias namespace.

restartAlways :: Property HasInfo Source

This property is enabled by default for docker containers configured by propellor; as well as keeping badly behaved containers running, it ensures that containers get started back up after reboot or after docker is upgraded.

restartOnFailure :: Maybe Int -> Property HasInfo Source

Docker will restart the container if it exits nonzero. If a number is provided, it will be restarted only up to that many times.

restartNever :: Property HasInfo Source

Makes docker not restart a container when it exits Note that this includes not restarting it on boot!

Internal use

init :: String -> IO () Source

Called when propellor is running inside a docker container. The string should be the container's ContainerId.

This process is effectively init inside the container. It even needs to wait on zombie processes!

In the foreground, run an interactive bash (or sh) shell, so that the user can interact with it when attached to the container.

When the system reboots, docker restarts the container, and this is run again. So, to make the necessary services get started on boot, this needs to provision the container then. However, if the container is already being provisioned by the calling propellor, it would be redundant and problimatic to also provisoon it here, when not booting up.

The solution is a flag file. If the flag file exists, then the container was already provisioned. So, it must be a reboot, and time to provision again. If the flag file doesn't exist, don't provision here.

chain :: [Host] -> HostName -> String -> IO () Source