support relative callbacks in template

.gitignore

@@ -2,3 +2,4 @@
 terraformer
 dist
 .DS_Store
+gen

README.md

@@ -116,7 +116,7 @@ Go template processing is can be easily extended by special functions. The first
 | feature | description | example |
 |---------|-------------|---------|
 | tfStringListFormater | formats a list with quoted elements | [1,2,3] -> ["1","2","3"] |
-| tfCallback | call a script which prints to stdout | read dynamic values in tf.template |
+| tfCallback | call a script which prints to stdout (relative to the template file) | read dynamic values in tf.template |
 | more to come | provide a pull request | f(x)  |
 
 ## try out 

examples/aws/tf.template

@@ -13,5 +13,5 @@ resource "aws_route53_record" "some-dns-record" {
 }
 
 resource "dummy" {
-  callback = "{{ tfCallback "examples/aws/callback.sh"  }}"
+  callback = "{{ tfCallback "callback.sh"  }}"
 }

runSamples.sh

@@ -0,0 +1,16 @@
+mkdir -p gen/examples
+
+go run terraformer.go ctx > gen/examples/context1.yml
+go run terraformer.go ctx --state=./examples/context/terraform.tfstate > gen/examples/context2.yml
+go run terraformer.go ctx --callback=./examples/context/callback.sh > gen/examples/context3.yml
+go run terraformer.go ctx ./examples/context/config1.yml > gen/examples/context4.yml
+
+go run terraformer.go gen ./examples/aws/tf.template ./examples/aws/context.yml > gen/examples/tf.main
+
+error=$(cat gen/examples/* | grep error)
+
+if [ "$error" == "" ]; then
+  ls -al gen/examples
+else
+  echo "--$error--"
+fi

terraformer.go

@@ -20,21 +20,24 @@ var (
 	date    string = "unknown"
 )
 
+var (
+	app = kingpin.New("terraformer", "A go program that generates terraform files using go templates")
+
+	commandGenerate = app.Command("generate", "generate a terraform file (main.tf), alias=gen").Alias("gen")
+	templateFile    = commandGenerate.Arg("terraform-template", "path to a go template file").Required().ExistingFile()
+	contextFile     = commandGenerate.Arg("context", "path to a yaml file").Required().ExistingFile()
+
+	commandGenerateContext = app.Command("generate-context", "generate a context yaml file, alias=ctx").Alias("ctx")
+	stateFlag              = commandGenerateContext.Flag("state", "(optional) path to a terraform.tfsate file").Short('s').ExistingFile()
+	templateFlag           = commandGenerateContext.Flag("template", "(optional) path to a go template file").Short('t').ExistingFile()
+	callbackFlag           = commandGenerateContext.Flag("callback", "(optional) list of executable script file printing YAML to stdout").Short('c').ExistingFile()
+	configFiles            = commandGenerateContext.Arg("config-files", "(optional) list of yaml files").ExistingFiles()
+)
+
 func main() {
-	app := kingpin.New("terraformer", "A go program that generates terraform files using go templates")
 	app.Version(printVersion()).Author("Stephan Klevenz")
 	app.HelpFlag.Short('h')
 
-	commandGenerate := app.Command("generate", "generate a terraform file (main.tf), alias=gen").Alias("gen")
-	templateFile := commandGenerate.Arg("terraform-template", "path to a go template file").Required().ExistingFile()
-	contextFile := commandGenerate.Arg("context", "path to a yaml file").Required().ExistingFile()
-
-	commandGenerateContext := app.Command("generate-context", "generate a context yaml file, alias=ctx").Alias("ctx")
-	stateFlag := commandGenerateContext.Flag("state", "(optional) path to a terraform.tfsate file").Short('s').ExistingFile()
-	templateFlag := commandGenerateContext.Flag("template", "(optional) path to a go template file").Short('t').ExistingFile()
-	callbackFlag := commandGenerateContext.Flag("callback", "(optional) list of executable script file printing YAML to stdout").Short('c').ExistingFile()
-	configFiles := commandGenerateContext.Arg("config-files", "(optional) list of yaml files").ExistingFiles()
-
 	s := kingpin.MustParse(app.Parse(os.Args[1:]))
 
 	switch s {
@@ -51,7 +54,7 @@ func main() {
 func generate(templateFile string, contextFile string) {
 	funcMap := template.FuncMap{
 		"tfStringListFormater": tfStringListFormater,
-		"tfCallback": tfCallback,
+		"tfCallback":           tfCallback,
 	}
 
 	templateName := path.Base(templateFile)
@@ -137,7 +140,7 @@ func readYamlFile(filePath string) interface{} {
 func readYamlCallback(scriptFile string) interface{} {
 	var err error
 	yamlBytes, err := exec.Command(scriptFile).Output()
-	if (err != nil){
+	if err != nil {
 		fmt.Printf("error: %v\n", err)
 	}
 
@@ -195,8 +198,11 @@ func printVersion() string {
 
 func tfCallback(scriptFile string) string {
 
+	// call script relative to template file
+	scriptFile = path.Join(path.Dir(*templateFile), scriptFile)
+
 	out, err := exec.Command(scriptFile).Output()
-	if (err != nil){
+	if err != nil {
 		fmt.Printf("error: %v\n", err)
 	}
 	return strings.TrimSuffix(string(out), "\n")

terraformer_test.go

@@ -65,12 +65,10 @@ func TestTfCallback(t *testing.T) {
 	// var array []interface{}{1, 2, "4", 1.4}
 	var result string
 
-	result = tfCallback("examples/unit-testing/callback-value.sh")
+	result = tfCallback("callback-value.sh")
 	assert.Equal(t, "4711", result)
 }
 
-
-
 func captureStdout(f func()) string {
 	old := os.Stdout
 	r, w, _ := os.Pipe()