frontail – streaming logs to the browser

frontail is a Node.js application for streaming logs to the browser. It’s a tail -F with UI.

Quick start

• npm i frontail -g or download a binary file from Releases page
• frontail /var/log/syslog
• visit http://127.0.0.1:9001

Features

• log rotation (not on Windows)
• auto-scrolling
• marking logs
• pausing logs
• number of unread logs in favicon
• themes (default, dark)
• highlighting
• search (Tab to focus, Esc to clear)
• set filter from url parameter filter
• tailing multiple files and stdin
• basic authentication

Installation options

• download a binary file from Releases pagegit st
• using npm package: npm i frontail -g
• using Docker image: docker run -d -P -v /var/log:/log mthenw/frontail /log/syslog

Usage

frontail [options] [file ...]

Options:

  -V, --version                 output the version number
  -h, --host <host>             listening host, default 0.0.0.0
  -p, --port <port>             listening port, default 9001
  -n, --number <number>         starting lines number, default 10
  -l, --lines <lines>           number on lines stored in browser, default 2000
  -t, --theme <theme>           name of the theme (default, dark)
  -d, --daemonize               run as daemon
  -U, --user <username>         Basic Authentication username, option works only along with -P option
  -P, --password <password>     Basic Authentication password, option works only along with -U option
  -k, --key <key.pem>           Private Key for HTTPS, option works only along with -c option
  -c, --certificate <cert.pem>  Certificate for HTTPS, option works only along with -k option
  --pid-path <path>             if run as daemon file that will store the process id, default /var/run/frontail.pid
  --log-path <path>             if run as daemon file that will be used as a log, default /dev/null
  --url-path <path>             URL path for the browser application, default /
  --ui-hide-topbar              hide topbar (log file name and search box)
  --ui-no-indent                don't indent log lines
  --ui-highlight                highlight words or lines if defined string found in logs, default preset
  --ui-highlight-preset <path>  custom preset for highlighting (see ./preset/default.json)
  --path <path>                 prefix path for the running application, default /
  --disable-usage-stats         disable gathering usage statistics
  --help                        output usage information

Web interface runs on http://[host]:[port].

Tailing multiple files

[file ...] accepts multiple paths, *, ? and other shell special characters(Wildcards, Quotes, Back Quotes and Apostrophes in shell commands).

stdin

Use - for streaming stdin:

./server | frontail -

Highlighting

--ui-highlight option turns on highlighting in UI. By default preset from ./preset/default.json is used:

{
    "words": {
        "err": "color: red;"
    },
    "lines": {
        "err": "font-weight: bold;"
    }
}

which means that every “err” string will be in red and every line containing “err” will be bolded.

New presets are very welcome. If you don’t like default or you would like to share yours, please create PR with json file.

Available presets:

• default
• npmlog
• python

Running behind nginx

Using the --url-path option frontail can run behind nginx with the example configuration

Using frontail with --url-path /frontail

events {
    worker_connections 1024;
}

http {
    server {
        listen      8080;
        server_name localhost;

        location /frontail {
            proxy_pass http://127.0.0.1:9001/frontail;

            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
        }
    }
}

Usage statistics

frontail by default (from v4.5.0) gathers anonymous usage statistics in Google Analytics. It can be disabled with
--disable-usage-stats.

The data is used to help me understand how frontail is used and I can make it better.