Log Driller

Log Driller is a tool to interactively view and filter output from a running application. It's in early development. The main use case is analysing the output from rust applications, but it can be used with any application that writes to stdout or stderr.

It has a very special feature - adding automatic search expressions through your IDE. Once started, Log Driller watches your source folder (by default, the current directory, but you can override this using the --source parameter). Whenever a // is added to the end of a line, any string literal on that line is parsed and added as a search expression. Log Driller then filters the client application output (in real time), only showing matching output lines.

The main use case is debugging complex applications that use rust logging/tracing. Enabling all trace output is likely to yield an overwhelming amount of output. However, using the RUST_LOG environment variable to reduce the output can be tedious, and there is always the risk of accidentally removing log lines that would actually have been interesting.

Using Log Driller, you would typically enable all (or most) log output, then filter by exploring your source code, adding // to the end of lines containing interesting traces, and observing in Log Driller if these occur. Log driller will by default limit the number of captured lines to 1 million, with good performance.

Usage

Make sure logdriller is in your PATH, then use it something like this:

RUST_LOG=trace logdriller -- cargo run test <my test> -- --nocapture

Then, observe your output. Edit lines in the code (adding // at the end) to automatically add search expressions.

Key bindings

Q - Quit

Esc - Quit

Tab - Select filter pane/output pane

A - Manually add search expression

Space - Activate/deactivate current fingerprint(/search expression)

S/Pause - Pause updates (temporarily ignore client application output)

F - Enable/disable filter

O- Scroll to current 'fingerprint'(/search expression).

L - Toggle light mode/dark mode

PgUp/PgDown - Scroll up/down

Up/Down - Scroll up/down

Left/Right - Scroll output left/right

Feature wishlist:

• Search also in un-filtered view
• Properly support target, filenames, namespaces, trace level, and tracing fields, with searching