nomad-driver-containerd

Nomad task driver for launching containers using containerd.

Containerd (containerd.io) is a lightweight container daemon for running and managing container lifecycle.
Docker daemon also uses containerd.

dockerd (docker daemon) --> containerd --> containerd-shim --> runc

nomad-driver-containerd enables nomad client to launch containers directly using containerd, without docker!
Docker daemon is not required on the host system.

nomad-driver-containerd architecture

Requirements

Nomad >=v0.11
Go >=v1.11
Containerd >=1.3

Building nomad-driver-containerd

Make sure your $GOPATH is setup correctly.

$ mkdir -p $GOPATH/src/github.com/Roblox
$ cd $GOPATH/src/github.com/Roblox
$ git clone git@github.com:Roblox/nomad-driver-containerd.git
$ cd nomad-driver-containerd
$ make build (This will build your containerd-driver binary)

Wanna try it out!?

./setup.sh

The setup script will setup containerd 1.3.4 and nomad server+nomad-driver-containerd (nomad server/client should already be installed on your system, and setup.sh only builds the driver) on your system, so you can try out example jobs.

NOTE setup.sh overrides your existing containerd to containerd-1.3.4. This is needed for io.containerd.runc.v2 runtime.
Your original containerd systemd unit file will be backed up at /lib/systemd/system/containerd.service.bkp in case you wanna revert later.

Once setup.sh is complete and the nomad server is up and running, you can check the registered task drivers (which will also show containerd-driver) using:

$ nomad node status (Note down the <node_id>)
$ nomad node status <node_id> | grep containerd-driver

Run Example jobs.

There are few example jobs in the example directory.

$ nomad job run <job_name.nomad>

will launch the job.

NOTE: You need to run setup.sh before trying out the example jobs.
More detailed instructions are in the example README.md

Supported options

Option	Type	Required	Description
image	string	yes	OCI image (docker is also OCI compatible) for your container.
command	string	no	Command to override command defined in the image.
args	[]string	no	Arguments to the command.
privileged	bool	no	Run container in privileged mode. Your container will have all linux capabilities when running in privileged mode.
readonly_rootfs	bool	no	Container root filesystem will be read-only.
cap_add	[]string	no	Add individual capabilities.
cap_drop	[]string	no	Drop invidual capabilities.
devices	[]string	no	A list of devices to be exposed to the container.
mounts	[]block	no	A list of mounts to be mounted in the container. Volume, bind and tmpfs type mounts are supported. fstab style `mount options` are supported.

Mount block
{
- type (string) (Optional): Supported values are volume, bind or tmpfs. Default: volume.
- target (string) (Required): Target path in the container.
- source (string) (Optional): Source path on the host.
- options ([]string) (Optional): fstab style mount options. NOTE: For bind mounts, atleast rbind and ro are required.
}

Bind mount example

mounts = [
           {
                type    = "bind"
                target  = "/target/t1"
                source  = "/src/s1"
                options = ["rbind", "ro"]
           }
        ]

Tests

$ make test

NOTE: These are destructive tests and can leave the system in a changed state.
It is highly recommended to run these tests either as part of a CI/CD system or on a immutable infrastructure e.g VMs.

Cleanup

make clean

This will delete your binary: containerd-driver

License

Licensed under the Apache License, Version 2.0 (the "License"). For more information read the License.

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