HOCON (Human-Optimized Config Object Notation)
Configuration library for working with the Lightbend's HOCON format. HOCON is a human-friendly JSON superset
Features of HOCON
- Comments, with
#or// - Allow omitting the
{}around a root object - Allow
=as a synonym for: - Allow omitting the
=or:before a{sofoo { a : 42 } - Allow omitting commas as long as there's a newline
- Allow trailing commas after last element in objects and arrays
- Allow unquoted strings for keys and values
- Unquoted keys can use dot-notation for nested objects,
foo.bar=42meansfoo { bar : 42 } - Duplicate keys are allowed; later values override earlier, except for object-valued keys where the two objects are merged recursively
includefeature merges root object in another file into current object, sofoo { include "bar.json" }merges keys inbar.jsoninto the objectfoo- substitutions
foo : ${a.b}sets keyfooto the same value as thebfield in theaobject - substitutions concatenate into unquoted strings,
foo : the quick ${colors.fox} jumped - substitutions fall back to environment variables if they don't
resolve in the config itself, so
${HOME}would work as you expect. - substitutions normally cause an error if unresolved, but
there is a syntax
${?a.b}to permit them to be missing. +=syntax to append elements to arrays,path += "/bin"- multi-line strings with triple quotes as in Python or Scala
see the documentation for more details about the HOCON https://github.com/lightbend/config/blob/master/HOCON.md
Installation
go get -u github.com/gurkankaymak/hocon
Usage
package main
import (
"fmt"
"log"
"github.com/gurkankaymak/hocon"
)
func main() {
hoconString := `
booleans {
trueVal: true
trueValAgain: ${booleans.trueVal}
trueWithYes: yes
falseWithNo: no
}
// this is a comment
# this is also a comment
numbers {
intVal: 3
floatVal: 1.0
}
strings {
a: "a"
b: "b"
c: "c"
}
arrays {
empty: []
ofInt: [1, 2, 3]
ofString: [${strings.a}, ${strings.b}, ${strings.c}]
ofDuration: [1 second, 2h, 3 days]
}
durations {
second: 1s
halfSecond: 0.5 second
minutes: 5 minutes
hours: 2hours
day: 1d
}
objects {
valueObject {
mandatoryValue: "mandatoryValue"
arrayValue: ${arrays.ofInt}
nullValue: null
}
}`
conf, err := hocon.ParseResource(hoconString)
if err != nil {
log.Fatal("error while parsing configuration: ", err)
}
objectValue := conf.GetObject("objects.valueObject")
arrayValue := conf.GetArray("arrays.ofInt")
stringValue := conf.GetString("strings.a")
intValue := conf.GetInt("numbers.intVal")
floatValue := conf.GetFloat64("numbers.floatVal")
durationValue := conf.GetDuration("durations.second")
fmt.Println("objectValue:", objectValue) // {mandatoryValue:mandatoryValue, arrayValue:[1,2,3], nullValue:null}
fmt.Println("arrayValue:", arrayValue) // [1,2,3]
fmt.Println("stringValue:", stringValue) // a
fmt.Println("intValue:", intValue) // 3
fmt.Println("floatValue:", floatValue) // 1.0
fmt.Println("durationValue:", durationValue) // 1s
fmt.Println("all configuration:", conf)
}