Live Log Viewer

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A VS Code extension that opens .log and .log.gz files in a viewer with per-level colors, text / regex / level filters, live tail and, for JSON logs, a Kibana-like table with field filters.

Features

• Opens *.log and *.log.gz by default. The normal text editor is still available via Reopen Editor With….
• Level colors: FATAL (also CRITICAL), ERROR (ERR), WARN (WARNING), INFO, DEBUG, TRACE. The level is taken from the JSON fields level / severity / log.level, or from a level word in plain text. Lines without a level (stack traces, continuation lines) inherit the level of the line above.
• Filters: text, regex (.*), level dropdown; the counter shows shown / total.
• Live tail: the file is polled every 0.5 s and only new lines are appended. A truncated or rotated file is reloaded.
• Raw mode: line numbers (stay visible when scrolling horizontally), horizontal + vertical scroll, click a line to wrap / unwrap it.
• Table mode for JSON logs (Kibana Discover style): field sidebar, columns, expandable rows, ⊕ / ⊖ cell filters, filter pills, "+ Add filter" with is one of / is not one of.
• .log.gz: decompressed in memory (streaming), never extracted to disk.
• Status bar Logs: N with a quick list / full list of all log files in the workspace.

Installation

From source:

npm install
npm run install:local   # builds the VSIX and installs it if the version changed (add -- --force to reinstall)

Then run Developer: Reload Window.

Or build the package and install it manually:

npm run package
code --install-extension live-log-viewer-<version>.vsix

Usage

1. Open a log file

Open any *.log or *.log.gz file from the Explorer; it opens in Live Log Viewer. To see the plain text instead, use Reopen Editor With… → Text Editor.

The toolbar, from left to right:

2. Raw mode, filters and Live

Type in the filter box, tick .* for a regex, and pick a level. Stack-trace lines inherit the level of the line above, so filtering on ERROR keeps each exception together with its stack trace. Uncheck Live to stop the view from jumping to the end while you read.

Click a line to wrap it (click again to unwrap). Line numbers stay visible when you scroll sideways.

3. Table mode (JSON logs)

Click Table. The left sidebar lists Selected fields (the columns) and Available fields, each with the number of lines that have it. Tick a field to add it as a column, untick to remove it. Reset in the Selected fields header restores the default columns (timestamp, level, message). The table scrolls horizontally inside its own area and the header stays visible.

Click a row to expand it as pretty-printed JSON; click again to collapse.

4. Field filters: ⊕ / ⊖ and pills

Hover a cell to show ⊕ (filter for this value) and ⊖ (filter out this value). Each filter appears as a pill under the toolbar and matching cells are highlighted.

• Click a pill to toggle it between include and NOT.
• Click × on a pill to remove it.
• Long pills are cut with … ; hover for the full text.

Field filters also apply in Raw mode (non-JSON lines such as stack traces follow the JSON line above them).

5. "+ Add filter": is one of / is not one of

Click + Add filter, choose a field and an operator (is one of or is not one of), then tick one or more values. Values are listed most frequent first (top 500) with their counts; use Search values… to find one. Click Add filter.

6. Reset buttons

• Reset filters (toolbar): removes all pills and clears the text, regex and level filters.
• Reset (Selected fields header): restores the default columns.

7. .log.gz archives

.log.gz files open the same way. They are decompressed in memory and never extracted to disk. Archives do not change, so they are not watched (Live has no effect).

8. Status bar and the log file list

The status bar shows Logs: N, the number of *.log / *.log.gz files in the workspace (node_modules excluded, max 5000). It is hidden when there are none and updates when log files are created or deleted.

Click it:

• 10 files or fewer: a quick pick with name, folder, size and modified time (newest first), plus an Open full view… entry.
• More than 10 files: the Log Files tab opens directly. Files are grouped by folder with size and modified time; use the search box to filter and Refresh to rescan. Click a file to open it in the viewer.

9. Commands

Errors are written to the Live Log Viewer output channel (View → Output).

Limitations

• Only the last 20 MB of a file is read when it is opened (also the last 20 MB of a decompressed .gz).
• The viewer keeps the last 100,000 lines and renders them without virtual scrolling.
• Table mode shows top-level JSON fields only; nested objects are shown as JSON text.
• The "+ Add filter" popup lists the top 500 values of a field (use ⊕ / ⊖ for others).
• Only the *.log.gz pattern is recognized, not names like app.log.1.gz.
• Filter pills, the view mode and the columns are not remembered after the tab is closed.

Development

npm install
npm run compile          # TypeScript -> out/
npm run watch            # compile on change
npm test                 # compile + unit tests (node --test)
npm run package          # build the .vsix (vsce)
npm run install:local    # build + install into your local VS Code (add -- --force to reinstall the same version)

License

MIT