Your LSP Log is Growing

Grow your log file to 100MB+ with this one simple "pragmatic shortcut"

The Problem

My Neovim LSP log file (~/.local/share/nvim/lsp.log) had ballooned to 139MB. I wasn't sure why it was growing so fast, but after inspecting with :LspLog, I saw 300,000+ [ERROR] entries. ~97% of these were from terraform-ls.

Now, I do work with a "Terralith"¹ at work, but I am not sure that we have that many Terraform LSP errors. We do enforce tflint and the works.

Root Cause

This is a known upstream bug in terraform-ls: hashicorp/terraform-ls#1271

terraform-ls writes ALL log messages (INFO, DEBUG, etc.) to stderr instead of using the LSP-standard window/logMessage notification. Neovim's LSP client correctly treats stderr as errors, so every terraform-ls log line becomes an [ERROR] entry in your lsp.log.

The issue has been open since May 2023 - it was a "pragmatic shortcut" taken early in development that never got fixed.

The Fix

Until HashiCorp fixes this upstream, periodic cleanup is the workaround. I added a command to nuke the log from within Neovim:

-- lsp log management
-- Clears the LSP log file (useful due to terraform-ls stderr bug: https://github.com/hashicorp/terraform-ls/issues/1271)
vim.api.nvim_create_user_command('LspLogNuke', function()
    local log_path = vim.lsp.get_log_path()
    local file = io.open(log_path, 'w')
    if file then
        file:close()
        vim.notify('Nuked LSP log: ' .. log_path, vim.log.levels.INFO)
    else
        vim.notify('Failed to nuke LSP log: ' .. log_path, vim.log.levels.ERROR)
    end
end, { desc = 'Clear the LSP log file' })

Now :LspLogNuke clears the log when it gets out of hand.

Conclusion

I'd like to see this fixed upstream of course, this does feel like a misuse of the LSP log. For now, I'm happy with this workaround. See my commit here where I had also changed my Oh-My-ZSH theme to half-life. Serendipitous.