Prolog/Epilog Hooks

Setting up Prolog/Epilog hooks for immediate job notification
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Prolog/Epilog hook setup is optional but recommended for immediate job notification, which reduces latency compared to relying solely on periodic polling.

Prerequisites

  • Daemon must be running (see Daemon Setup)
  • Hook script must be accessible from slurmctld
  • Hook script must exit with code 0 to avoid rejecting job allocations

1. Create Hook Script

Create /opt/cc-slurm-adapter/hook.sh:

#!/bin/sh
/opt/cc-slurm-adapter/cc-slurm-adapter
exit 0

Make it executable:

sudo chmod +x /opt/cc-slurm-adapter/hook.sh

Important: Always exit with 0. Non-zero exit codes will reject job allocations.

2. Configure Slurm

Add to slurm.conf:

PrEpPlugins=prep/script
PrologSlurmctld=/opt/cc-slurm-adapter/hook.sh
EpilogSlurmctld=/opt/cc-slurm-adapter/hook.sh

3. Restart slurmctld

sudo systemctl restart slurmctld

Note: If using non-default socket path, add -config /path/to/config.json to hook.sh. The config file must be readable by the slurm user/group.

Multi-Cluster Setup

For multiple slurmctld nodes, use TCP sockets instead of UNIX sockets:

{
  "prepSockListenPath": "tcp:0.0.0.0:12345",
  "prepSockConnectPath": "tcp:slurmctld-host:12345"
}

This allows Prolog/Epilog hooks on different nodes to connect to the daemon over the network.

How It Works

  1. Job Event: Slurm triggers Prolog/Epilog hook when a job starts or stops
  2. Socket Message: Hook sends job ID to daemon via socket
  3. Immediate Query: Daemon queries Slurm for that specific job
  4. Fast Submission: Job submitted to cc-backend with minimal delay

This reduces the job notification latency from up to 60 seconds (default poll interval) to just a few seconds.