terraform/config/interpolate_funcs.go

72 lines
1.6 KiB
Go

package config
import (
"bytes"
"fmt"
"io/ioutil"
"strings"
)
// Funcs is the mapping of built-in functions for configuration.
var Funcs map[string]InterpolationFunc
func init() {
Funcs = map[string]InterpolationFunc{
"concat": interpolationFuncConcat,
"file": interpolationFuncFile,
"lookup": interpolationFuncLookup,
}
}
// interpolationFuncConcat implements the "concat" function that allows
// strings to be joined together.
func interpolationFuncConcat(
vs map[string]string, args ...string) (string, error) {
var buf bytes.Buffer
for _, a := range args {
if _, err := buf.WriteString(a); err != nil {
return "", err
}
}
return buf.String(), nil
}
// interpolationFuncFile implements the "file" function that allows
// loading contents from a file.
func interpolationFuncFile(
vs map[string]string, args ...string) (string, error) {
if len(args) != 1 {
return "", fmt.Errorf(
"file expects 1 arguments, got %d", len(args))
}
data, err := ioutil.ReadFile(args[0])
if err != nil {
return "", err
}
return string(data), nil
}
// interpolationFuncLookup implements the "lookup" function that allows
// dynamic lookups of map types within a Terraform configuration.
func interpolationFuncLookup(
vs map[string]string, args ...string) (string, error) {
if len(args) != 2 {
return "", fmt.Errorf(
"lookup expects 2 arguments, got %d", len(args))
}
k := fmt.Sprintf("var.%s", strings.Join(args, "."))
v, ok := vs[k]
if !ok {
return "", fmt.Errorf(
"lookup in '%s' failed to find '%s'",
args[0], args[1])
}
return v, nil
}