lnav/src/tailer

Tailer

This directory contains the functionality for monitoring remote files. The name "tailer" refers to the binary that is transferred to the remote host that takes care of tailing files and sending the contents back to the host that is running the main lnav binary. To ease integration with lnav's existing functionality, the remote files are mirrored locally. The tailer also supports interactive use by providing previews of file contents and TAB-completion possibilities.

Files

The important files in this directory are:

• tailer.main.c - The main() implementation for the tailer.
• tailer.looper.hh - The service in the main lnav binary that transfers tailers to hosts and communicates with them.
• tailer.h and tailerpp.hh - Utility libraries for the tailer protocol.
• tailer.ape - The αcτµαlly pδrταblε εxεcµταblε build of the tailer. This binary is produced by a GitHub Action and checked in so the build process doesn't need to be supported on lots of platforms.

Flow

When a remote-path is passed to lnav, the file_collection.hh logic forwards the request to the tailer::looper service. This service makes two connections to the remote host using the ssh command so that the user's custom configurations will be used. The first connection is used to transfer the "tailer.ape" binary and make it executable. The second connection starts the tailer and uses stdin/stdout for a binary protocol and stderr for logging. The tailer then waits for requests to open files, preview files, and get possible paths for TAB-completions.