write file

README.md

@@ -105,6 +105,7 @@ Contents:
 		    - [(( read("file.yml") ))](#-readfileyml-)
 		    - [(( exec("command", arg1, arg2) ))](#-execcommand-arg1-arg2-)
             - [(( pipe(data, "command", arg1, arg2) ))](#-pipedata-command-arg1-arg2-)
+		    - [(( write("file.yml", data) ))](#-writefileyml-data-)
 		- [X509 Functions](#x509-functions)
 		    - [(( x509genkey(spec) ))](#-x509genkeyspec-)
 		    - [(( x509publickey(key) ))](#-x509publickeykey-)
@@ -2146,6 +2147,12 @@ Alternatively `pipe` can be called with data and a list argument completely desc
 
 The same command will be executed once, only, even if it is used in multiple expressions.
 
+#### `(( write("file.yml", data) ))`
+
+Write a file and return its content. If the result can be parsed as yaml document,
+the document is returned. An optional 3rd argument can be used to pass the
+file permissions (default is `0644`).
+
 
 ### X509 Functions
 

dynaml/call.go

@@ -138,6 +138,8 @@ func (e CallExpr) Evaluate(binding Binding, locally bool) (interface{}, Evaluati
 		result, sub, ok = func_read(true, values, binding)
 	case "read_uncached":
 		result, sub, ok = func_read(false, values, binding)
+	case "write":
+		result, sub, ok = func_write(values, binding)
 
 	case "format":
 		result, sub, ok = func_format(values, binding)

dynaml/write.go

@@ -0,0 +1,42 @@
+package dynaml
+
+import (
+	"io/ioutil"
+	"os"
+	"strconv"
+)
+
+func func_write(arguments []interface{}, binding Binding) (interface{}, EvaluationInfo, bool) {
+	var err error
+	info := DefaultInfo()
+
+	if len(arguments) < 2 || len(arguments) > 3 {
+		return info.Error("write requires two arguments")
+	}
+	file, ok := getArg(0, arguments[0])
+	if !ok || file == "" {
+		return info.Error("file argument must be a non-empty string")
+	}
+	data, _ := getArg(1, arguments[1])
+	permissions := int64(0644)
+	if len(arguments) == 3 {
+		switch v := arguments[2].(type) {
+		case string:
+			permissions, err = strconv.ParseInt(v, 10, 64)
+			if err != nil {
+				return info.Error("permissions must be given as int or int string: %s", err)
+			}
+		case int64:
+			permissions = v
+		default:
+			return info.Error("permissions must be given as int or int string")
+		}
+	}
+
+	err = ioutil.WriteFile(file, []byte(data), os.FileMode(permissions))
+	if err != nil {
+		return info.Error("cannot write file: %s", err)
+	}
+
+	return convertOutput([]byte(data))
+}