Log Viewer

Did you ever struggle with reading the structured logs from a file? If so, the Log Viewer is here to rescue you! It is a GUI that you can run directly in your favorite command line and it will show you your logs in a beautiful colorful way and help you with their browsing and filtering.

Other features that it has are:

• Filtering the log output to show only the logs above a certain level

  • the supported levels are trace, debug, info, warn, error, fatal and panic,

• Support for large files (up to multiple GB)

• If the viewed log file is growing, it can follow the written logs in real-time

• Special handling of certain fields in the structured log:

  • level field is used to derive the level of the log and shown in the log header

  • caller field is shortened to 30 characters and shown in the log header

  • time field is parsed and shown in nanosecond precision at the log beginning

  • message field is shown right after the leader

  • module field is highlighted differently for better readability

What it looks like

Example contents of the log file:

[...]
{"level":"error","module":"loggen","caller":"/github.com/matusvla/logviewer/cmd/loggen/main.go:52","time":"2022-05-22T11:41:36.0627773+02:00","ts":1653212496062777300,"message":"Vestibulum bibendum, urna vitae volutpat porttitor, orci risus consectetur risus, et lobortis urna est vel nulla."}
{"level":"trace","module":"loggen","caller":"/github.com/matusvla/logviewer/cmd/loggen/main.go:52","time":"2022-05-22T11:41:36.0627773+02:00","ts":1653212496062777300,"message":"Aliquam erat volutpat."}
{"level":"debug","module":"loggen","caller":"/github.com/matusvla/logviewer/cmd/loggen/main.go:52","time":"2022-05-22T11:41:36.0628021+02:00","ts":1653212496062802100,"message":"Phasellus bibendum in felis eget fermentum."}
{"level":"info","module":"loggen","caller":"/github.com/matusvla/logviewer/cmd/loggen/main.go:52","time":"2022-05-22T11:41:36.0628021+02:00","ts":1653212496062802100,"message":"Sed vel massa id urna sagittis sodales id id leo."}
{"level":"warn","module":"loggen","caller":"/github.com/matusvla/logviewer/cmd/loggen/main.go:52","time":"2022-05-22T11:41:36.0628021+02:00","ts":1653212496062802100,"message":"Cras accumsan tellus in metus condimentum tempus."}
{"level":"error","module":"loggen","caller":"/github.com/matusvla/logviewer/cmd/loggen/main.go:52","time":"2022-05-22T11:41:36.0628021+02:00","ts":1653212496062802100,"message":"Quisque volutpat in elit facilisis semper."}
[...]

Installation

To install the application clone the repo and run make build command in the root folder.

This will generate two executables in the build folder - viewer and loggen. The viewer is the visual application described above. loggen is a simple CLI application that can be used to generate sample log files to viewable by viewer.