A working efm language server config for janet/lua

plugin_opts.lua

require('lspconfig').efm.setup {
    init_options = {
            documentFormatting = true,
            hover = true,
            documentSymbol = true,
            codeAction = true, completion = true
    },
    settings = {
        rootMarkers = {".git/"},
        languages = {
            lua = {{formatCommand = "lua-format -i", formatStdin = true}},
            janet = {
                {
                    formatCommand = "jfmt",
                    formatStdin = true,
                    lintCommand = "janet -k -s",
                    lintStdin = true,
                    lintIgnoreExitCode = true,
                    lintFormats = {'%f:%l:%c: %m'}
                }
            }
        }
    },
    filetypes = {'janet', 'lua'}
}

A winner is you!