Dynamic CUE

README.md

Example Usages

Enable feature1

go run ./fill.go "features=[\"feature1\"]" 

Output:

{
        features: ["feature1"]
        application: {
                feature1: "enabled"
        }
}

Insert arbitrary data

go run ./fill.go "arbitrary=\"data\""

Output:

{
        features: [...string]
        arbitrary: "data"
        application: {}
}

base.cue

package main

import (
	"list"
)

features: [...string]
application: {}

if list.Contains(features, "feature1") {
	application: feature1: "enabled"
}

if list.Contains(features, "feature2") {
	application: feature2: "enabled"
}

fill.go

package main

import (
	"cuelang.org/go/cue"
	"cuelang.org/go/cue/cuecontext"
	"cuelang.org/go/cue/load"
	"fmt"
	"os"
	"strings"
)

// Usage:
func main() {
	// We need a cue.Context for building after loading
	ctx := cuecontext.New()

	params := os.Args[1:]

	// Load Cue files into Cue build.Instances slice
	// the second arg is a configuration object, we'll see this later
	bis := load.Instances([]string{"."}, nil)
	bi := bis[0]

	// check for errors on the instance
	// these are typically parsing errors
	if bi.Err != nil {
		fmt.Println("Error during load:", bi.Err)
		os.Exit(1)
	}

	// Use cue.Context.BuildInstance to turn
	// a build.Instance into a cue.Value
	value := ctx.BuildInstance(bi)
	if value.Err() != nil {
		fmt.Println("Error during build:", value.Err())
		os.Exit(1)
	}

	for _, arg := range params {
		split := strings.Split(arg, "=")
		path := split[0]
		argValue := split[1]

		unmarshal := ctx.CompileString(argValue)
		err := unmarshal.Err()
		if err != nil {
			fmt.Println("Unable to compile arg:", err)
			os.Exit(1)
		}

		value = value.FillPath(cue.ParsePath(path), unmarshal)
		err = value.Err()
		if value.Err() != nil {
			fmt.Println("Error during filling:", err)
			os.Exit(1)
		}
	}

	// Validate the value
	err := value.Validate()
	if err != nil {
		fmt.Println("Error during validation:", err)
		os.Exit(1)
	}

	// Print the value
	fmt.Println(value)
}