OverlayBD Artifact Streaming
Installation
Flatcar Container Linux offers support for the installation and customization of containerd’s
accelerated container image
artifact streaming.
Both
accelerated-container-image
and the
overlaybd
back-end are combined in an optional,
system dependent sysext
.
The sysext can be provisioned simply by adding the line overlaybd to /etc/flatcar/enabled-sysext.conf.
Since these sysexts are system dependent (compiled against the system’s C library), they will be updated automatically in lockstep with the operating system.
Example Butane configuration:
---
# config.yaml
# butane < config.yaml > config.json
variant: flatcar
version: 1.0.0
storage:
files:
- path: /etc/flatcar/enabled-sysext.conf
contents:
inline: |
overlaybd
Usage
The below usage largely follows upstream’s Getting started guide .
The sysext includes upstream’s
overlaybd.json
and
config.json
and will populate /etc/overlaybd/ and /etc/overlaybd-snapshotter/
at extension merge time.
Containerd configuration needs to be
amended
to use overlaybd and the snapshotter plugin.
Since Flatcar does not support containerd drop-in configuration at the time of writing, our Butane config needs to include the full containerd toml:
---
# config.yaml
# butane < config.yaml > config.json
variant: flatcar
version: 1.0.0
storage:
files:
- path: /etc/flatcar/enabled-sysext.conf
contents:
inline: |
overlaybd
- path: /etc/containerd/config.toml
contents:
inline: |
version = 2
# persistent data location
root = "/var/lib/containerd"
# runtime state information
state = "/run/containerd"
# set containerd as a subreaper on linux when it is not running as PID 1
subreaper = true
# set containerd's OOM score
oom_score = -999
disabled_plugins = []
# grpc configuration
[grpc]
address = "/run/containerd/containerd.sock"
# socket uid
uid = 0
# socket gid
gid = 0
[plugins."io.containerd.runtime.v1.linux"]
# shim binary name/path
shim = "containerd-shim"
# runtime binary name/path
runtime = "runc"
# do not use a shim when starting containers, saves on memory but
# live restore is not supported
no_shim = false
[plugins."io.containerd.grpc.v1.cri"]
# enable SELinux labeling
enable_selinux = true
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
# setting runc.options unsets parent settings
runtime_type = "io.containerd.runc.v2"
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
SystemdCgroup = true
[proxy_plugins.overlaybd]
type = "snapshot"
address = "/run/overlaybd-snapshotter/overlaybd.sock"
systemd:
units:
- name: containerd.service
dropins:
- name: 10-configtoml.conf
contents: |
[Service]
ExecStart=
ExecStart=/usr/bin/containerd --config /etc/containerd/config.toml
After the instance provisioned successfully, accelerated container images can be started in accordance with upstream’s guilde :
sudo /opt/overlaybd/snapshotter/ctr rpull -u {user}:{pass} registry.hub.docker.com/overlaybd/redis:6.2.1_obd
sudo ctr run --net-host --snapshotter=overlaybd --rm -t registry.hub.docker.com/overlaybd/redis:6.2.1_obd demo