Ceph
The Ceph Nix package has been hard-pressed to keep up with Ceph, as filesystem concerns are a larger challenge on NixOS than on other Linux lineages. This is a problem seeking a solution; read ahead to see some of the remaining issues this guide should address. Please make a Wiki account and add your experiences, if you made progress running a modern Ceph version.
Here is a quick collection of commands I used on a 3-node Ceph mesh.
Describe your ceph user, alongside your normal login user:
users.users = {
mesh = { isNormalUser = true; extraGroups = [ "wheel" "docker" ]; };
ceph = { isNormalUser = true; extraGroups = [ "wheel" "ceph" ]; };
};
users.groups.ceph = {};
Be sure you rebuild so you can assign some paths to the ceph
user.
Run uuidgen
and assign the response as your fsid
; describe your Ceph nodes:
services.ceph = {
global.fsid = "4b687c5c-5a20-4a77-8774-487989fd0bc7";
osd = {
enable = true;
daemons = ["0"];
};
mon = {
enable = false;
extraConfig = {
"mon initial members" = "mesh-a,mesh-b,mesh-c";
"mon host" = "10.0.0.11,10.0.0.12,10.0.0.13";
};
};
};
Make your OSD volume; run these commands on each node: (based on https://docs.ceph.com/en/quincy/install/manual-deployment/ )
export IP=<your-node-IP-on-local-LAN>
export FSID=4b687c5c-5a20-4a77-8774-487989fd0bc7
sudo -u ceph mkdir -p /etc/ceph
sudo -u ceph mkdir -p /var/lib/ceph/bootstrap-osd
sudo -u ceph mkdir -p /tmp/monmap
sudo -u ceph mkdir -p /var/lib/ceph/mon/ceph-$(hostname)
sudo -u ceph mkdir /var/lib/ceph/mon/ceph-mon-$(hostname)
# Make a keyring!
sudo ceph-authtool --create-keyring /etc/ceph/ceph.client.admin.keyring --gen-key -n client.admin --cap mon 'allow *' --cap osd 'allow *' --cap mds 'allow *' --cap mgr 'allow *'
sudo mkdir -p /var/lib/ceph/bootstrap-osd && sudo ceph-authtool --create-keyring /var/lib/ceph/bootstrap-osd/ceph.keyring --gen-key -n client.bootstrap-osd --cap mon 'profile bootstrap-osd' --cap mgr 'allow r'
sudo ceph-authtool /tmp/ceph.mon.keyring --import-keyring /etc/ceph/ceph.client.admin.keyring sudo ceph-authtool /tmp/ceph.mon.keyring --import-keyring /var/lib/ceph/bootstrap-osd/ceph.keyring
sudo chown ceph:ceph /tmp/ceph.mon.keyring
# Make a monitor!
sudo monmaptool --create --add mesh-a $IP --fsid $FSID /tmp/monmap
sudo -u ceph ceph-mon --mkfs -i mon-$(hostname) --monmap /tmp/monmap --keyring /tmp/ceph.mon.keyring
Bind all Ceph OSD shares using systemd (based on u/imspacekitteh
's example):
systemd.services.ceph-mesh = {
enable = true;
description = "Ceph OSD Bindings";
unitConfig = {
After = "local-fs.target";
Wants = "local-fs.target";
};
serviceConfig = {
Type = "oneshot";
KillMode = "none";
Environment = "CEPH_VOLUME_TIMEOUT=10000 PATH=$PATH:/run/current-system/sw/bin/";
ExecStart = "/bin/sh -c 'timeout $CEPH_VOLUME_TIMEOUT /run/current-system/sw/bin/ceph-volume lvm activate --all --no-systemd'";
TimeoutSec = 0;
};
wantedBy = ["multi-user.target"];
};
Though these commands seem reliable enough, there are some issues...
mesh@mesh-c:~/.build/ > sudo ceph -s Error initializing cluster client: ObjectNotFound('RADOS object not found (error calling conf_read_file)')
Clearly, Ceph is concerned that the `/etc/ceph/ceph.conf` file is missing. So am I! I'd assumed the Nixpkgs module should make that, based on all the extraConfig
options supplied.
So make the necessary config; this should be minimally enough to load Ceph, and we can come back and nixify this soon:
sudo su -c "echo '
[global]
fsid=$FSID
mon initial members = mesh-a
mon host = 10.0.0.11
cluster network = 10.0.0.0/24
' > /etc/ceph/ceph.conf" -
# Double-check!
cat /etc/ceph/ceph.conf
We can now see that Ceph is ready for us to make a volume!
mesh@mesh-a:~/.build/ > sudo systemctl restart ceph-mesh mesh@mesh-a:~/.build/ > sudo systemctl status ceph-mesh ○ ceph-mesh.service - Ceph OSD Bindings Loaded: loaded (/etc/systemd/system/ceph-mesh.service; enabled; preset: enabled) Active: inactive (dead) since Tue 2023-12-19 16:12:51 EST; 4s ago Process: 37570 ExecStart=/bin/sh -c timeout $CEPH_VOLUME_TIMEOUT /run/current-system/sw/bin/ceph-volume lvm activate --all --no-systemd (code=exited, status=0/SUCCESS) Main PID: 37570 (code=exited, status=0/SUCCESS) IP: 0B in, 0B out CPU: 162ms Dec 19 16:12:51 mesh-a systemd[1]: Starting Ceph OSD Bindings... Dec 19 16:12:51 mesh-a sh[37571]: --> Was unable to find any OSDs to activate Dec 19 16:12:51 mesh-a sh[37571]: --> Verify OSDs are present with "ceph-volume lvm list" Dec 19 16:12:51 mesh-a systemd[1]: ceph-mesh.service: Deactivated successfully. Dec 19 16:12:51 mesh-a systemd[1]: Finished Ceph OSD Bindings. mesh@mesh-a:~/.build/ > sudo ceph-volume lvm list No valid Ceph lvm devices found
Go ahead and make one.
mesh@mesh-a:~/.build/ > sudo ceph-volume lvm create --data /dev/nvme0n1p4 --no-systemd Running command: /nix/store/x645fiz9vzkkwyf08agprl9h25fkqw7g-ceph-18.2.0/bin/ceph-authtool --gen-print-key Running command: /nix/store/x645fiz9vzkkwyf08agprl9h25fkqw7g-ceph-18.2.0/bin/ceph --cluster ceph --name client.bootstrap-osd --keyring /var/lib/ceph/bootstrap-osd/ceph.keyring -i - osd new a0d4c3db-cc9c-416a-b209-72b9bad3be40
OOPS! This command hangs endlessly, as does sudo ceph -s
.
Your help is needed to make more progress here!
Many users aspire to run Ceph on NixOS, and recommend varying approaches in different forums online. Here is a collection of links that can lead you along, though please consider; these experiences come from older versions of Ceph, such as v10, while (as of 2023-12) Ceph is on v19.