Add on-disk log preservation, configurable install prefix, and log output command

[rkoshy]

Summary

This PR adds three related features that improve troubleshooting workflows and make Laminar more accessible to command-line tools and AI coding assistants.

Features

1. On-Disk Log Preservation (LAMINAR_ON_DISK_LOGS)

• Problem: Logs are only stored compressed in SQLite database, making them inaccessible to standard Unix tools
• Solution: Optional uncompressed log files alongside database storage
• Configuration: LAMINAR_ON_DISK_LOGS=N environment variable
• Behavior:
  • Writes logs to ${LAMINAR_HOME}/archive/JOB/RUN/log
  • Keeps N most recent logs per job with automatic rotation
  • Independent of LAMINAR_KEEP_RUNDIRS (important for remote build scenarios)
  • Backward compatible (disabled by default when N=0)

2. Configurable Default LAMINAR_HOME

• Problem: Default LAMINAR_HOME is hardcoded to /var/lib/laminar, requiring manual configuration for custom installations
• Solution: Use CMAKE_INSTALL_PREFIX to set intelligent default
• Behavior:
  • Defaults to ${CMAKE_INSTALL_PREFIX}/var (e.g., /opt/laminar/var)
  • Falls back to /var/lib/laminar if not set
  • Enables self-contained installations without extra configuration

3. Log Output Command (laminarc output-log)

• Problem: No simple way to view logs from command line for scripting/automation
• Solution: New command to output logs to stdout
• Usage: laminarc output-log JOB [RUN]
• Features:
  • Defaults to latest run if RUN not specified
  • Shows header with actual run number
  • Outputs to stdout for piping to grep, less, etc.

Motivation

Command-Line CI/CD Workflows

When running builds from command line (not through web UI):

• Database-only logs require SQL queries and decompression for access
• Standard Unix tools (grep, tail, less) cannot be used directly
• Troubleshooting requires either web UI or manual database extraction

AI Coding Assistant Integration

Modern AI coding assistants (Claude, GitHub Copilot, etc.) work best with:

• Simple file access patterns
• Standard command-line tools
• Direct log output without intermediate processing

This PR makes Laminar logs accessible through standard patterns these tools understand.

Example Usage

Enable on-disk logs (in /etc/laminar.conf):

LAMINAR_ON_DISK_LOGS=4  # Keep 4 most recent logs per job

View logs from command line:

# View latest log
laminarc output-log my-build

# View specific run
laminarc output-log my-build 42

# Use with standard tools
laminarc output-log my-build | grep ERROR
laminarc output-log my-build | less

# Direct file access (if on-disk logs enabled)
grep -r "error" ${LAMINAR_HOME}/archive/my-build/

Custom installation path:

cmake .. -DCMAKE_INSTALL_PREFIX=/opt/laminar
make install
# Now /opt/laminar/var is the default LAMINAR_HOME

Implementation Details

• Files Modified: 7 files, 87 insertions, 1 deletion
• Breaking Changes: None - all features are opt-in
• Performance Impact: Minimal (only when LAMINAR_ON_DISK_LOGS > 0)
• Tested: Successfully tested with custom /opt/laminar installation

Benefits

✅ Direct log access with standard Unix tools
✅ Better troubleshooting workflow for CI/CD debugging
✅ Easier integration with log analysis tools and AI assistants
✅ More flexible installation options
✅ No breaking changes to existing deployments
✅ Self-contained installations without manual configuration

Related Discussion

This addresses the common need for easier log access in command-line workflows, particularly for:

• Headless CI/CD servers
• Remote troubleshooting scenarios
• Integration with modern development tools
• Automated log analysis