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SLURM Emulator - Time Travel Edition

A comprehensive SLURM command emulator with time manipulation capabilities for testing periodic limits and decay calculations.

Features

  • 🎮 Interactive CLI - Full command-line interface with time travel
  • ⏰ Time Manipulation - Advance time by days, months, or quarters
  • 💾 Usage Injection - Add specific node-hour usage at any time point
  • 🔄 Decay Calculations - 15-day half-life fairshare decay simulation
  • 🎯 QoS Management - Threshold-based QoS switching (normal → slowdown → blocked)
  • 📊 Periodic Limits - Quarterly allocation with carryover logic
  • 🎬 Scenario Runner - Complete SLURM_PERIODIC_LIMITS_SEQUENCE.md validation
  • 🔌 API Integration - REST API for waldur-site-agent integration
  • 💾 State Management - Checkpoint/restore functionality for testing

Quick Start

Installation

# Clone the repository
git clone https://github.com/waldur/slurm-emulator.git
cd slurm-emulator

# Install dependencies using uv
uv sync

Interactive CLI (CMD-based)

# Run with default configuration
uv run slurm-emulator

# Run with SLURM configuration file
uv run slurm-emulator --config examples/slurm.conf

# Advanced features work the same way
uv run slurm-emulator --config examples/custom_slurm.conf

# Validate configuration only
uv run slurm-emulator --validate-only --config /etc/slurm/slurm.conf

🎮 SLURM Emulator - Time Travel Edition (CMD Interface)
Type 'help' or '?' for commands. TAB for auto-completion.
Type 'help <command>' for detailed help on specific commands.

slurm-emulator> help
# Shows all available commands

slurm-emulator> help time_advance
# Shows detailed help for specific command

slurm-emulator> time_advance 2 months
⏭️  Advanced 2 months

slurm-emulator> account_create test "Test Account" 1000
✅ Created account test with 1000Nh allocation

slurm-emulator> account create test-account "Test Account" 1000
✅ Created account test-account with 1000Nh allocation

slurm-emulator> usage inject user1 200 test-account
💾 Injected 200.0Nh usage for user1 in test-account at 2024-01-01 00:00:00

slurm-emulator> time advance 2 months
⏭️  Advanced 2 months
⏰ New time: 2024-03-01 00:00:00

slurm-emulator> usage inject user1 400 test-account
💾 Injected 400.0Nh usage for user1 in test-account at 2024-03-01 00:00:00

slurm-emulator> limits calculate test-account
📊 Periodic Limits for test-account:
   Period: 2024-Q1
   Base allocation: 1000Nh
   Total allocation: 1000.0Nh
   Fairshare: 333
   QoS threshold: 1200.0Nh
   Grace limit: 1200.0Nh
   Billing minutes: 60000

Complete Sequence Scenario

Run the full scenario from SLURM_PERIODIC_LIMITS_SEQUENCE.md:

slurm-emulator> scenario run sequence --interactive

🎬 Starting SLURM Periodic Limits Sequence Scenario
============================================================

⏸️  Press Enter to execute Step 1: Initial Q1 setup...

📍 Step 1: Initial Q1 2024 Setup
   Setting up 1000Nh quarterly allocation with 20% grace period
   ⚖️  Set fairshare to 333
   🚫 Set GrpTRESMins to 72000 billing-minutes
   🎯 QoS threshold set to 1200.0Nh
   💾 Checkpoint 'initial_setup' created

# ... continues through all 9 steps of the sequence

Direct SLURM Commands

The emulator intercepts and emulates real SLURM commands:

slurm-emulator> sacctmgr add account test-account description="Test"
 Adding Account(s)
  test-account
 Settings
  Parent     = root
  Description = Test

slurm-emulator> sacctmgr modify account test-account set fairshare=333
 Modified account...
  test-account
 Settings
  fairshare=333

slurm-emulator> sacctmgr modify account test-account set GrpTRESMins=billing=72000
 Modified account...
  test-account
 Settings
  GrpTRESMins=billing=72000

slurm-emulator> sacct --accounts=test-account --starttime=2024-01-01 --endtime=2024-12-31
test-account|cpu=12800,mem=102400,gres/gpu=800|08:00:00|user1

API Integration

Start the API server for waldur-site-agent integration:

# From the slurm-emulator directory
uv run uvicorn emulator.api.emulator_server:app --host 0.0.0.0 --port 8080

API Endpoints

  • POST /api/apply-periodic-settings - Apply periodic limits settings
  • POST /api/downscale-resource - Set QoS to slowdown
  • POST /api/restore-resource - Restore QoS to normal
  • POST /api/submit-report - Submit usage reports
  • GET /api/status - Get emulator status
  • POST /api/time/advance - Advance emulator time

Example API Usage

# Apply periodic settings (from Waldur Mastermind)
curl -X POST http://localhost:8080/api/apply-periodic-settings \\
  -H "Content-Type: application/json" \\
  -d '{
    "resource_id": "slurm_account_123",
    "fairshare": 333,
    "grp_tres_mins": {"billing": 72000},
    "qos_threshold": {"billing": 1000}
  }'

# Submit usage report (from site agent)
curl -X POST http://localhost:8080/api/submit-report \\
  -H "Content-Type: application/json" \\
  -d '{
    "resource_id": "slurm_account_123",
    "usage": {"billing": 167},
    "billing_period": "2024-01-01",
    "date": "2024-01-31T23:59:59Z",
    "users": {
      "user1": {"billing": 100},
      "user2": {"billing": 67}
    }
  }'

# Advance time for testing
curl -X POST "http://localhost:8080/api/time/advance?months=3"

Waldur Site Agent Integration

Configure waldur-site-agent to use the emulator:

# waldur-site-agent-config.yaml
offerings:
  - name: "SLURM HPC Cluster - Emulator"
    backend_type: "slurm"
    backend_settings:
      # Enable emulator mode
      emulator_mode: true
      emulator_base_url: "http://localhost:8080"

      # Override SLURM commands to use emulator
      command_prefix: ["python", "/path/to/slurm-emulator/emulator/commands/dispatcher.py"]

      # Periodic limits configuration
      periodic_limits:
        enabled: true
        limit_type: "GrpTRESMins"
        tres_billing_enabled: true
        tres_billing_weights:
          CPU: 0.015625
          Mem: 0.001953125G
          "GRES/gpu": 0.25
        fairshare_decay_half_life: 15
        api_endpoints:
          apply_periodic_settings: "http://localhost:8080/api/apply-periodic-settings"
          downscale_resource: "http://localhost:8080/api/downscale-resource"
          restore_resource: "http://localhost:8080/api/restore-resource"

SLURM Configuration Support

The emulator now supports real SLURM configuration files to match actual deployment behavior:

Loading Configuration

# Use system SLURM configuration
uv run slurm-emulator --config /etc/slurm/slurm.conf

# Use custom configuration
uv run slurm-emulator --config examples/slurm.conf

# Validate configuration
uv run slurm-emulator --validate-only --config slurm.conf

Supported Configuration Parameters

The emulator parses and applies these SLURM configuration parameters:

Priority and Decay Settings:

  • PriorityDecayHalfLife - Fairshare decay half-life (e.g., "15-00:00:00")
  • PriorityUsageResetPeriod - Usage reset period ("None" for manual reset)
  • PriorityWeightFairShare - Fairshare weight for priority calculations
  • PriorityWeightQOS - QoS weight for priority calculations
  • FairShareDampeningFactor - Dampening factor for fairshare

TRES Billing:

  • TRESBillingWeights - Billing weights (e.g., "CPU=0.015625,Mem=0.001953125G,GRES/gpu=0.25")

Priority Flags:

  • PriorityFlags - Priority calculation flags (e.g., "MAX_TRES,NO_NORMAL_ASSOC")

Example Configuration

# SLURM Configuration
PriorityDecayHalfLife   = 15-00:00:00
PriorityUsageResetPeriod = None # manual reset via sacctmgr RawUsage=0
PriorityWeightFairShare = 259200
PriorityWeightQOS       = 500000
FairShareDampeningFactor = 3
TRESBillingWeights="CPU=0.015625,Mem=0.001953125G,GRES/gpu=0.25"
PriorityFlags=MAX_TRES,NO_NORMAL_ASSOC

Understanding Decay Calculations

The emulator implements SLURM's fairshare decay using the configured half-life:

# Decay formula matches SLURM's implementation
decay_factor = 2 ** (-days_elapsed / half_life_days)

# With default 15-day half-life, after 90 days (1 quarter):
decay_factor = 2 ** (-90 / 15) = 0.0156 (1.56%)

# With 7-day half-life, after 90 days:
decay_factor = 2 ** (-90 / 7) = 0.000135 (0.01%)

Example with 15-day half-life: User consumes 2000 hours in Q1. After Q1 ends (90 days later):

  • Original impact: 2000 hours
  • Decayed impact: 2000 × 0.0156 = 31 hours equivalent
  • Q2 allocation: 1000 + (1000 - 31) = 1969 hours available

Key Commands Reference

Time Manipulation

time_show                             # Show current time and period
time_advance <amount> <unit>          # Advance time (units: days, months, quarters)
time_set YYYY-MM-DD [HH:MM:SS]       # Set specific date/time

# Examples:
time_advance 2 months
time_advance 30 days
time_set 2024-05-20

Usage Simulation

usage_inject <user> <amount> [account]  # Inject node-hour usage
usage_show [account] [period]           # Show usage summary with user breakdown

# Examples:
usage_inject user1 200 test-account
usage_show test-account
usage_show test-account 2024-Q1

Account Management

account_create <name> [description] [allocation]  # Create account
account_list                                      # List all accounts with status
account_show <name>                               # Show detailed account info
account_delete <name>                             # Delete account

# Examples:
account_create test "Test Account" 1000
account_show test
account_list

QoS Management

qos_show [account]                    # Show QoS status and details
qos_set <account> <qos>              # Set QoS level (normal/slowdown/blocked)
qos_check [account]                  # Check thresholds and auto-update QoS

# Examples:
qos_check test-account
qos_set test-account slowdown
qos_show test-account

Limits Calculation

limits_calculate [account]           # Calculate and display periodic limits

# Example:
limits_calculate test-account

Scenario Management

scenario_list [type]                 # List scenarios (optionally filter by type)
scenario_describe <name>             # Show detailed description and learning objectives
scenario_steps <name>                # Show step-by-step command breakdown
scenario_run <name>                  # Run scenario automatically
scenario_run <name> --interactive    # Run with confirmation prompts
scenario_run <name> --step-by-step   # Run with detailed step output
scenario_search <query>              # Search scenarios by keyword

# Examples:
scenario_list qos_management
scenario_describe qos_thresholds
scenario_run qos_thresholds --step-by-step
scenario_search decay

Configuration Management

config_show                          # Show current SLURM configuration
config_reload <path>                 # Hot-reload configuration file

# Examples:
config_show
config_reload examples/slurm.conf

State Management

cleanup_all                          # Clean all accounts and reset to fresh state
cleanup_scenario <name>              # Clean specific scenario accounts
cleanup_account <name>               # Clean specific account completely

# Examples:
cleanup_all
cleanup_scenario qos_thresholds
cleanup_account test-account

SLURM Commands

sacctmgr <args>                      # Run sacctmgr command
sacct <args>                         # Run sacct command
sinfo <args>                         # Run sinfo command

# Examples:
sacctmgr list accounts
sacctmgr modify account test set fairshare=333
sacct --accounts=test --format=Account,User,Elapsed

Testing Scenarios

Basic Usage Pattern

# Setup with specific configuration
uv run slurm-emulator --config examples/slurm.conf

# In emulator CLI:
time set 2024-01-01
account create test-account "Test" 1000

# Month 1: Light usage
usage inject user1 100 test-account
time advance 1 months

# Month 2: Heavy usage
usage inject user1 600 test-account
limits calculate test-account
qos check test-account

# Quarter transition
time advance 1 months
limits apply test-account

Configuration Testing

# Test different decay rates
uv run slurm-emulator --config examples/custom_slurm.conf

# Compare configurations
uv run slurm-emulator --validate-only --config examples/slurm.conf
uv run slurm-emulator --validate-only --config examples/custom_slurm.conf

Decay Validation

# Q1: Heavy usage
time set 2024-01-01
account create test-account "Test" 1000
usage inject user1 1500 test-account

# Q2: Check decay impact
time set 2024-04-01
limits calculate test-account
# Should show ~23Nh effective previous usage (1500 * 0.0156)

QoS Threshold Testing

# Setup with 1000Nh allocation (1200Nh threshold with 20% grace)
account create test-account "Test" 1000
qos show test-account  # Should show "normal"

usage inject user1 1100 test-account
qos check test-account  # Should show approaching threshold

usage inject user1 200 test-account  # Total: 1300Nh
qos check test-account  # Should trigger slowdown QoS

Architecture

slurm-emulator/
├── emulator/
│   ├── core/
│   │   ├── time_engine.py          # Time manipulation
│   │   ├── database.py             # In-memory state
│   │   ├── slurm_config.py         # SLURM config parsing
│   │   └── usage_simulator.py      # Usage injection
│   ├── commands/
│   │   ├── sacctmgr.py             # sacctmgr emulator
│   │   ├── sacct.py                # sacct emulator
│   │   └── dispatcher.py           # Command routing
│   ├── periodic_limits/
│   │   ├── calculator.py           # Decay & carryover
│   │   └── qos_manager.py          # QoS management
│   ├── scenarios/
│   │   ├── sequence_scenario.py    # Complete scenario
│   │   ├── scenario_registry.py    # Scenario discovery & running
│   │   └── limits_configuration_scenarios.py
│   ├── cli/
│   │   ├── main.py                 # Interactive CLI
│   │   └── cmd_cli.py              # CMD-based CLI
│   └── api/
│       └── emulator_server.py      # REST API
├── scripts/
│   ├── release.py                  # Release management
│   ├── changelog.sh                # Changelog generation
│   ├── generate_changelog_data.py  # Commit data collection
│   └── prompts/
│       └── changelog-prompt.md     # Changelog prompt template
└── tests/                          # Test suites

Development

Running Tests

uv run pytest

Releasing

# Full release: update version, generate changelog, tag, push
uv run scripts/release.py release X.Y.Z

# Skip changelog generation
uv run scripts/release.py release X.Y.Z --skip-changelog

Pushing the tag triggers GitHub Actions for testing and PyPI publishing.

Adding New Scenarios

# Create new scenario class
class CustomScenario:
    def __init__(self, time_engine, database):
        self.time_engine = time_engine
        self.database = database

    def run_scenario(self):
        # Implement scenario steps
        pass

Extending Commands

# Add new SLURM command support
class NewCommandEmulator:
    def handle_command(self, args):
        # Implement command logic
        return "command output"

Troubleshooting

State Persistence

Emulator state is saved to:

  • /tmp/slurm_emulator_time.json - Current time
  • /tmp/slurm_emulator_db.json - Database state

Common Issues

"Account not found": Create account first with account create "No usage records": Inject usage with usage inject "Time not advancing": Check time with time command "API connection failed": Ensure server is running on port 8080

Reset Emulator

rm /tmp/slurm_emulator_*.json
slurm-emulator
# Start fresh

License

MIT License - See LICENSE file for details.

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Initial release Latest
Nov 6, 2025

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