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nixos/modules/ha/iscsi-target.nix
beatzaplentyandClaude Sonnet 4.6 d740064a35
Check NixOS configurations / eval-hosts (pull_request) Successful in 10m37s
fix(ha): all 7 acceptance tests pass — targetctl, fencing, failover, data integrity
Deploy/init fixes:
- iscsi-target.nix: targetctl binary is in rtslib-fb (python3 env), not
  targetcli-fb — fixes ExecStart and ExecStop for the targetctl.service
- deploy.sh: _patch_targetctl() applies runtime dropin to both nodes before
  cluster-init so Pacemaker can manage the iSCSI target from first start
- cluster-init.sh: replace crm configure heredoc with cibadmin --replace XML
  (pacemaker-4.0 schema: globally-unique in meta_attributes, promoted-max/
  promoted-node-max, Promoted role in constraints); force_unmount=true on
  xfs-data; DRBD promote timeout 240s
- cluster-config.nix: add crm-fence-peer.sh/crm-unfence-peer.sh handlers;
  update fencing comment to reflect resource-only + Pacemaker-aware handler
  replacing STONITH during testing phase
- ha-server.nix: add openiscsi to systemPackages for T4 iscsiadm availability

Acceptance test fixes:
- acceptance-tests.sh: fix ((PASS++)) set -e bug → PASS=$((PASS+1));
  detect Active/Standby dynamically via drbdadm role (Pacemaker can promote
  either node); T4 bash TCP probe instead of iscsiadm; T5 timeout 120s;
  T6 echo|sudo tee for root-owned XFS write (bash -c redirect runs as nixos
  not sudo — permission denied); use ns cat / ns rm for root-owned reads

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HaH1cSGvhogRP5ExoF6nD8
2026-07-28 19:03:39 +10:00

100 lines
3.3 KiB
Nix

# LIO iSCSI target service (targetctl) for NixOS HA clusters.
#
# Provides the targetctl.service that saves/restores LIO configuration from
# /etc/target/saveconfig.json. Pacemaker manages this service via its
# systemd resource agent (class="systemd" type="targetctl").
#
# Why ExecStop is not simply "targetctl save":
# targetctl save writes the LIO config to JSON but does NOT remove the LIO
# target from the kernel's configfs. As a result, any fileio backing store
# that LIO has open (e.g. iscsi-lun.img on an XFS-over-DRBD filesystem)
# stays referenced in the kernel. The subsequent XFS umount from the
# Filesystem OCF resource then returns EBUSY and either hangs for the full
# op-stop timeout or fails outright, blocking the entire failover.
#
# The ExecStop script here additionally tears down the kernel LIO state
# via rtslib_fb after saving, so the backing-store file descriptor is
# released and umount succeeds immediately.
#
# Empty-config guard:
# The save step is skipped when no iSCSI targets are currently active.
# This prevents the secondary node (where LIO was never started) from
# overwriting a valid saveconfig.json with an empty one when Pacemaker
# stops the iscsi-target resource as part of a failover or cleanup.
{ pkgs, ... }:
let
python3 = pkgs.python3.withPackages (ps: [ ps.rtslib-fb ]);
targetctl = "${python3}/bin/targetctl";
targetctlStop = pkgs.writeScript "targetctl-stop" ''
#!${python3}/bin/python3
import subprocess, sys
import rtslib_fb
root = rtslib_fb.RTSRoot()
targets = list(root.targets)
if targets:
subprocess.run(
["${targetctl}", "save", "/etc/target/saveconfig.json"],
capture_output=True,
)
print(f"saved {len(targets)} iSCSI target(s)")
else:
print("no active LIO targets — saveconfig.json unchanged")
for target in targets:
try:
for tpg in list(target.tpgs):
tpg.enable = False
target.delete()
except Exception as e:
print(f"warn (target): {e}", file=sys.stderr)
for so in list(root.storage_objects):
try:
so.delete()
except Exception as e:
print(f"warn (backstore): {e}", file=sys.stderr)
print("LIO kernel target cleared")
'';
in
{
boot.kernelModules = [
"target_core_mod"
"iscsi_target_mod"
"target_core_file"
"target_core_pscsi"
"target_core_user"
"configfs"
];
systemd = {
mounts = [{
where = "/sys/kernel/config";
what = "configfs";
type = "configfs";
wantedBy = [ "multi-user.target" ];
before = [ "targetctl.service" ];
}];
services.targetctl = {
description = "LIO iSCSI target config save/restore";
wantedBy = [ "multi-user.target" ];
after = [ "sys-kernel-config.mount" "network.target" ];
requires = [ "sys-kernel-config.mount" ];
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart = "${targetctl} restore /etc/target/saveconfig.json";
ExecStop = "${targetctlStop}";
};
unitConfig.ConditionFileNotEmpty = "/etc/target/saveconfig.json";
};
tmpfiles.rules = [
"d /etc/target 0750 root root -"
"f /etc/target/saveconfig.json 0640 root root -"
];
};
environment.systemPackages = [ pkgs.targetcli-fb ];
}