In the middle of writing my blog engine dynocator, I wondered about the best possible way to read data from a config file. My first approach was to read line by line from the file and use the wonderful strings package to parse the data I want. Another approach revolved around using regexp to seek out the info from the file. But these approaches were both very hacky and involved dealing with a lot of string operations, which I’m not a big fan of.
When examining Hugo, I realized that it reads settings data from a TOML config file. My first impression was “Oh god, not another markup language”, but as it turned out, I really like TOML. Here’s some exaple TOML data:
# This is a TOML document. Boom.
title = "TOML Example"
[owner]
name = "Lance Uppercut"
dob = 1979-05-27T07:32:00-08:00 # First class dates? Why not?
[database]
server = "192.168.1.1"
ports = [ 8001, 8001, 8002 ]
connection_max = 5000
enabled = true
[servers]
# You can indent as you please. Tabs or spaces. TOML don't care.
[servers.alpha]
ip = "10.0.0.1"
dc = "eqdc10"
[servers.beta]
ip = "10.0.0.2"
dc = "eqdc10"
[clients]
data = [ ["gamma", "delta"], [1, 2] ]
# Line breaks are OK when inside arrays
hosts = [
"alpha",
"omega"
]
I wanted to go ahead and write my own TOML parser but then I stumbled upon this great package. The idea is to have TOML data relate directly to Go structs. Here’s some config data from my config file:
baseurl="http://localhost:1414"
title="My Beautiful Site"
templates="templates"
posts="posts"
public="public"
admin="admin"
metadata="metadata"
index="default"
And here’s how to read it:
// Info from config file
type Config struct {
Baseurl string
Title string
Templates string
Posts string
Public string
Admin string
Metadata string
Index string
}
// Reads info from config file
func ReadConfig() Config {
var configfile = flags.Configfile
_, err := os.Stat(configfile)
if err != nil {
log.Fatal("Config file is missing: ", configfile)
}
var config Config
if _, err := toml.DecodeFile(configfile, &config); err != nil {
log.Fatal(err)
}
//log.Print(config.Index)
return config
}
Now I can access all my config data very easily like this:
var config = ReadConfig()
fmt.Print(config.Title)