LogViewer

A Ruby gem that converts NDJSON log files into a readable HTML format for easy viewing in your browser.

• Converts NDJSON log files to HTML tables
• Filters logs by minimum level (trace, debug, info, notice, warning, error, critical)
• Displays key fields: date, level, tag, file, line, function, and text
• Human-readable timestamp formatting (MM/DD HH:MM:SS)
• Simplified file paths (shows only filename, not full path)
• Color-coded log levels for easy identification
• Large, readable fonts throughout the interface (18px base size)
• Interactive dynamic filtering by log level and tags in the browser
• Dark mode interface with optimized colors for comfortable viewing
• Responsive design that works well in any browser
• Automatically opens the generated HTML file in your default browser

Install the gem from RubyGems:

gem install logviewer

# With a specific file
logviewer example.ndjson

# Without specifying a file (auto-detects most recent .ndjson file)
logviewer

This will:

1. Parse the NDJSON file
2. Include all log levels (trace and above by default)
3. Generate an HTML file in /tmp/
4. Open the HTML file in your default browser (initially filtered to debug+)

logviewer --level info example.ndjson

Only includes log entries with level "info" and above in the HTML file. You can then use the interactive dropdown in the browser to filter within those entries.

When no file is specified, LogViewer automatically searches the current directory for .ndjson files and uses the one with the most recent modification date:

logviewer --level info

This will find the most recent .ndjson file in the current directory and apply the specified log level filter.

• -l, --level LEVEL: Set minimum log level (trace, debug, info, notice, warning, error, critical)
• -v, --version: Show version
• -h, --help: Show help message

# Show all logs from a specific file
logviewer app.ndjson

# Auto-detect most recent .ndjson file and show all logs
logviewer

# Auto-detect most recent .ndjson file and show only warnings and above
logviewer --level warning

# Show only errors and fatal logs from specific file
logviewer -l error system.ndjson

# Show version
logviewer --version

The tool expects NDJSON (newline-delimited JSON) files where each line contains a JSON object with these fields:

• timestamp: Unix timestamp in milliseconds since epoch (displayed as MM/DD HH:MM:SS)
• levelName: Log level (trace, debug, info, notice, warning, error, critical)
• subsystem and category: Combined to create tag display (e.g., "Play/avPlayer")
• message: The log message
• file: Source file path (displayed as filename only)
• function: Function/method name

Example log entry:

{"timestamp":1749926447359,"levelName":"debug","subsystem":"Play","category":"avPlayer","message":"pausing","file":"PodHaven/PodAVPlayer.swift","function":"pause(overwritePreSeekStatus:)","line":136}

The generated HTML file will be saved in /tmp/ with a timestamp and automatically opened in your browser. The HTML includes:

• A wide, responsive table layout (2000px max width) with columns in order: date, level, tag, file, line, function, text
• Interactive log level filtering dropdown for dynamic filtering in the browser
• Multi-select tag filter to show only specific subsystem/category combinations
• Dark mode theme with comfortable dark backgrounds and light text
• Human-readable timestamps (MM/DD HH:MM:SS format)
• Color-coded log levels optimized for dark backgrounds
• Sticky header for easy navigation
• Hover effects for better readability
• Large fonts (18px base size) for excellent readability
• Simplified file display (filename only, not full paths)
• Optimized column widths with expanded text area for log messages
• Date, file, line, and function names in monospace font
• Color-coded tags for easy categorization

Once the HTML file opens in your browser, you can:

• Use the level dropdown in the header to dynamically filter log entries by minimum level
• Filter changes are applied instantly without page reload
• Command line level controls what entries are included in the HTML file
• Browser initially shows debug+ level by default, regardless of command line level

• Use the multi-select tag filter to choose which subsystem/category combinations to display
• All tags are selected by default (showing all entries)
• Use "Select All" and "Clear All" buttons for quick selection changes
• Tags are built from subsystem/category fields (e.g., "Play/avPlayer", "Database/queue")

• Log level and tag filters work together - entries must match both criteria to be visible
• Entry counts update automatically to show how many entries match the current filters
• Header shows selected filter status including number of tags when filtered

After checking out the repo, run the following commands to set up development:

# Install dependencies
bundle install

# Build the gem
rake build

# Install locally for testing
rake install

# Clean build artifacts
rake clean

# Build the gem
rake build

# Install locally
rake install

# Push to RubyGems (requires authentication)
rake push

• Ruby 2.5.0 or higher
• macOS (uses open command to launch browser)

MIT