This is a Go library for parsing config files for VyOS router configs.

VyOS's configs are similar (but not exactly the same) to Juniper's Junos configs; they're hierarchial and block-structured. Like Junos, there are two main forms for configs:

• The version returned from show configuration (or just show in config mode)
• A version that consists of set commands that can re-create any given configuration. In VyOS, you get generate this form via show | commands in config mode.

The second mode has the advantage of being trivial to cut and paste into a router, but it's generally a bit harder to read and much harder to edit.

VyOS also adds a third config format, although it's mostly hidden behind the scenes; it stores its boot config in /config/config.boot in almost the same format as "show" outputs, but with different quoting rules.

This library supports reading and writing all three formats. Here's a quick example that will read a "show" format config from a file and print the "set" equivalent to stdout:

  package main
  
  import (
      "fmt"
      "os"
      
      "github.com/scottlaird/vyos-parser/syntax"
      "github.com/scottlaird/vyos-parser/parser"
  )
  
  func main() {
      // Error checking omitted
      configModel, _ := syntax.GetDefaultConfigModel()
      config, _ := os.ReadFile("my-show-config.txt")
      ast, _ := parser.ParseShowFormat(string(config), configModel)
      setConfig, _ := parser.WriteSetFormat(ast)
      fmt.Println(setConfig)
  }

At least for trivial configs, this library should be able to produce byte-for-byte identical output that matches what VyOS 1.5-rolling-202501060800 produces, with the exception of version migration comments at the end of config.boot.

Syntax

This library uses VyOS's own syntax definitions in parsing. They're extracted from vyos-1x/interface-definitions, parsed, and dropped into syntax/vyos*.json.gz. To produce a newer syntax definition, run git pull in the vyos-1x subdirectory, then run make in the vyos-parser root directory. This will produce a new definition file in synatax/, named using the date of the most recent commit to vyos-1x. To make this the default, edit syntax/default.version.