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azlin batch command

Execute shell commands on multiple VMs simultaneously.

Synopsis

azlin batch command COMMAND [OPTIONS]

Description

Execute a shell command on multiple VMs in parallel. Filter VMs by tags, name patterns, or run on all VMs. Output can be shown inline or summarized.

Arguments

COMMAND - Shell command to execute (required)

Options

Option Description
--tag TEXT Filter VMs by tag (format: key=value)
--vm-pattern TEXT Filter VMs by name pattern (glob)
--all Select all VMs in resource group
--resource-group, --rg TEXT Resource group
--config PATH Config file path
--max-workers INTEGER Maximum parallel workers (default: 10)
--timeout INTEGER Command timeout in seconds (default: 300)
--show-output Show command output from each VM
-h, --help Show help message

Examples

Execute on All VMs

# Run command on all VMs
azlin batch command 'uptime' --all

# Show detailed output
azlin batch command 'df -h' --all --show-output

Filter by Tag

# Run on VMs with specific tag
azlin batch command 'git pull' --tag 'env=dev'

# Multiple filters (OR logic)
azlin batch command 'systemctl restart nginx' --tag 'app=web'

Filter by Pattern

# Wildcard patterns
azlin batch command 'docker ps' --vm-pattern 'web-*'

# Multiple patterns
azlin batch command 'uptime' --vm-pattern '*-prod'

Resource Group

# Specific resource group
azlin batch command 'free -h' --all --rg production-rg

Parallelism Control

# More parallel workers (faster)
azlin batch command 'apt update' --all --max-workers 20

# Sequential execution
azlin batch command 'systemctl restart app' --all --max-workers 1

Timeout Control

# Longer timeout for slow commands
azlin batch command 'npm install' --all --timeout 600

# Short timeout
azlin batch command 'hostname' --all --timeout 10

Use Cases

Code Deployment

# Pull latest code on all app servers
azlin batch command 'cd ~/myapp && git pull origin main' --tag 'app=web' --show-output

Service Management

# Restart service across fleet
azlin batch command 'sudo systemctl restart myapp' --all

# Check service status
azlin batch command 'systemctl status myapp' --all --show-output

System Administration

# Update packages
azlin batch command 'sudo apt update && sudo apt upgrade -y' --all --timeout 900

# Check disk space
azlin batch command 'df -h | grep -E "/$|/home"' --all --show-output

# Clear temp files
azlin batch command 'sudo rm -rf /tmp/*' --all

Monitoring

# Check running processes
azlin batch command 'ps aux | grep myapp' --all --show-output

# Network connectivity
azlin batch command 'ping -c 3 google.com' --all --show-output

# Check logs
azlin batch command 'tail -20 /var/log/myapp.log' --tag 'env=prod' --show-output

Configuration Management

# Copy config file
azlin batch command 'cp /tmp/new-config.json /etc/myapp/config.json' --all

# Verify configuration
azlin batch command 'cat /etc/myapp/config.json | jq .version' --all --show-output

# Reload configuration
azlin batch command 'sudo systemctl reload myapp' --all

Output Formats

Summary (Default)

$ azlin batch command 'uptime' --all

Output: 

Executing on 3 VMs...

✓ web-01: Success (0.3s)
✓ web-02: Success (0.2s)
✗ web-03: Failed (connection timeout)

2/3 succeeded

Detailed Output

$ azlin batch command 'hostname' --all --show-output

Output: 

=== web-01 ===
web-01.internal

=== web-02 ===
web-02.internal

=== web-03 ===
web-03.internal

3/3 succeeded

Selection Methods

All VMs

# Every VM in resource group
azlin batch command 'uptime' --all

By Tag

# VMs matching tag
azlin batch command 'git pull' --tag 'env=production'
azlin batch command 'systemctl status' --tag 'app=api'

Tags set via: azlin tag my-vm --add env=production

By Pattern

# Glob patterns
azlin batch command 'uptime' --vm-pattern 'api-*'
azlin batch command 'df -h' --vm-pattern '*-test'
azlin batch command 'free -m' --vm-pattern 'web-*-prod'

Patterns support wildcards: *, ?, [abc]

Performance

Workers Best For Notes
1 Sequential operations requiring order Slowest, most controlled
10 (default) General use Good balance
20-50 Fast operations on many VMs May hit SSH limits

Error Handling

Connection Failures

Failed VMs are logged but don't stop execution:

✓ vm-01: Success
✗ vm-02: Connection timeout
✓ vm-03: Success

2/3 succeeded

Command Failures

Non-zero exit codes are reported:

✓ vm-01: Success
✗ vm-02: Command failed (exit code 1)
✓ vm-03: Success

Troubleshooting

No VMs Selected

# Check VMs exist
azlin list

# Verify tags
azlin list --tag 'env=dev'

# Test pattern
azlin list | grep 'web-*'

Timeouts

# Increase timeout
azlin batch command 'slow-command' --all --timeout 900

# Test connectivity
azlin w

SSH Errors

# Verify SSH access
azlin connect test-vm

# Check keys
azlin keys list

Best Practices

Test First

# Test on one VM
azlin connect test-vm --command 'mycommand'

# Then batch
azlin batch command 'mycommand' --all

Use Show-Output for Verification

# Always use --show-output for important operations
azlin batch command 'critical-command' --all --show-output

Control Parallelism

# Sequential for order-dependent operations
azlin batch command 'db-migration' --all --max-workers 1

# Parallel for independent operations
azlin batch command 'git pull' --all --max-workers 20

Set Appropriate Timeouts

# Quick commands: short timeout
azlin batch command 'hostname' --all --timeout 10

# Long operations: long timeout
azlin batch command 'npm install' --all --timeout 900

See Also