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Containerd

Liquid Metal uses containerd to download and manage the images which are mounted into MicroVMs as kernel and OS volumes.

Download the all-in-one provision script:

wget https://raw.githubusercontent.com/weaveworks-liquidmetal/flintlock/main/hack/scripts/provision.sh
chmod +x provision.sh

Create thinpool​

Flintlock relies on containerd's devicemapper snapshotter to provide filesystem devices for Firecracker microvms. This is how the images are stored. In a production we would use a dedicated disk, but here we will use a loopback device.

Run the script to create the thinpool:

sudo ./provision.sh devpool
Output
[flintlock provision.sh] Creating containerd directory /var/lib/containerd-dev/snapshotter/devmapper
[flintlock provision.sh] Creating containerd directory /run/containerd-dev
[flintlock provision.sh] Creating containerd directory /etc/containerd
[flintlock provision.sh] All containerd directories created
[flintlock provision.sh] Will create loop-back thinpool flintlock-dev-thinpool
[flintlock provision.sh] Creating sparse file /var/lib/containerd-dev/snapshotter/devmapper/data of size 100G
[flintlock provision.sh] Sparse file /var/lib/containerd-dev/snapshotter/devmapper/data created
[flintlock provision.sh] Creating sparse file /var/lib/containerd-dev/snapshotter/devmapper/metadata of size 10G
[flintlock provision.sh] Sparse file /var/lib/containerd-dev/snapshotter/devmapper/metadata created
[flintlock provision.sh] Associating loop devices with sparse files
[flintlock provision.sh] Loop devices /dev/loop13 and /dev/loop20 associated
[flintlock provision.sh] Creating thinpool flintlock-dev-thinpool with devices /dev/loop13 and /dev/loop20
[flintlock provision.sh] Thinpool flintlock-dev-thinpool created
[flintlock provision.sh] Dev thinpool creation complete
[flintlock provision.sh] remember to set pool_name to flintlock-dev-thinpool in your containerd config

Verify that the device has been created with sudo dmsetup ls:

flintlock-dev-thinpool  (253:0)

Configure and start containerd​

caution

This section will start containerd as a service. If you run docker locally, you may already have a containerd service running. This new service will run parallel to that service and should not affect it. If you have any doubts or encounter problems, you can disable the original service.

Run the script to install containerd in dev mode:

sudo ./provision.sh containerd --dev

This command will:

  • Install the latest version of containerd
  • Create various state dirs
  • Save a development config file under /etc/containerd/config-dev.toml
  • Start containerd as a systemd service
Output
[flintlock provision.sh] Creating containerd directory /var/lib/containerd-dev/snapshotter/devmapper
[flintlock provision.sh] Creating containerd directory /run/containerd-dev
[flintlock provision.sh] Creating containerd directory /etc/containerd
[flintlock provision.sh] All containerd directories created
[flintlock provision.sh] Installing containerd version latest to /usr/local/bin
[flintlock provision.sh] Containerd version v1.6.8 successfully installed
[flintlock provision.sh] Writing containerd config to /etc/containerd/config-dev.toml
[flintlock provision.sh] Containerd config saved
[flintlock provision.sh] Starting containerd service with /etc/systemd/system/containerd-dev.service
[flintlock provision.sh] Containerd running

Verify that the service started with systemctl status containerd-dev.service.

Output
● containerd-dev.service - containerd container runtime
     Loaded: loaded (/etc/systemd/system/containerd-dev.service; disabled; vendor preset: enabled)
     Active: active (running) since Tue 2022-09-27 13:02:53 BST; 1s ago
       Docs: https://containerd.io
    Process: 777843 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
   Main PID: 777844 (containerd)
      Tasks: 14
     Memory: 19.6M
        CPU: 101ms
     CGroup: /system.slice/containerd-dev.service
             └─777844 /usr/local/bin/containerd --config /etc/containerd/config-dev.toml

Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048720119+01:00" level=info msg="Start snapshots syncer"
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048728525+01:00" level=info msg="Start cni network conf syncer for default"
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048735830+01:00" level=info msg="Start streaming server"
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048741460+01:00" level=info msg=serving... address="127.0.0.1:1338"
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048804854+01:00" level=info msg=serving... address=/run/containerd-dev/containerd.sock.ttrpc
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048845976+01:00" level=info msg=serving... address=/run/containerd-dev/containerd.sock
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048894187+01:00" level=debug msg="sd notification" error="<nil>" notified=true state="READY=1"
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.048917346+01:00" level=info msg="containerd successfully booted in 0.033546s"
Sep 27 13:02:53 callisto-XPS systemd[1]: Started containerd container runtime.
Sep 27 13:02:53 callisto-XPS containerd[777844]: time="2022-09-27T13:02:53.154115708+01:00" level=debug msg="garbage collected" d=6.658119ms
...

Now we can move on to installing flintlock.