Added trim to available methods in template

Author: Marius Gundersen

README.md

@@ -229,6 +229,7 @@ For example, this is a JSON version of an emitted RuntimeContainer struct:
 * *`split $string $sep`*: Splits `$string` into a slice of substrings delimited by `$sep`. Alias for [`strings.Split`](http://golang.org/pkg/strings/#Split)
 * *`trimPrefix $prefix $string`*: If `$prefix` is a prefix of `$string`, return `$string` with `$prefix` trimmed from the beginning. Otherwise, return `$string` unchanged.
 * *`trimSuffix $suffix $string`*: If `$suffix` is a suffix of `$string`, return `$string` with `$suffix` trimmed from the end. Otherwise, return `$string` unchanged.
+* *`trim $string`*: Removes whitespace from both sides of `$string`.
 * *`where $items $fieldPath $value`*: Filters an array or slice based on the values of a field path expression `$fieldPath`. A field path expression is a dot-delimited list of map keys or struct member names specifying the path from container to a nested value. Returns an array of items having that value.
 * *`whereExist $items $fieldPath`*: Like `where`, but returns only items where `$fieldPath` exists (is not nil).
 * *`whereNotExist $items $fieldPath`*: Like `where`, but returns only items where `$fieldPath` does not exist (is nil).

template.go

@@ -317,12 +317,16 @@ func coalesce(input ...interface{}) interface{} {
 	return nil
 }
 
-// trimPrefix returns whether a given string is a prefix of another string
+func trim(s string) string {
+    return strings.TrimSpace(s)
+}
+
+// trimPrefix returns a string without the prefix, if present
 func trimPrefix(prefix, s string) string {
 	return strings.TrimPrefix(s, prefix)
 }
 
-// trimSuffix returns whether a given string is a suffix of another string
+// trimSuffix returns a string without the suffix, if present
 func trimSuffix(suffix, s string) string {
 	return strings.TrimSuffix(s, suffix)
 }
@@ -352,6 +356,7 @@ func newTemplate(name string) *template.Template {
 		"split":         strings.Split,
 		"trimPrefix":    trimPrefix,
 		"trimSuffix":    trimSuffix,
+        "trim":          trim,
 		"where":         where,
 		"whereExist":    whereExist,
 		"whereNotExist": whereNotExist,

template_test.go

@@ -488,6 +488,15 @@ func TestTrimSuffix(t *testing.T) {
 	}
 }
 
+func TestTrim(t *testing.T) {
+	const str = "  myhost.local  "
+	const trimmed = "myhost.local"
+	got := trim(str)
+	if got != trimmed {
+		t.Fatalf("expected trim(%s) to be %s, got %s", str, trimmed, got)
+	}
+}
+
 func TestDict(t *testing.T) {
 	containers := []*RuntimeContainer{
 		&RuntimeContainer{

templates/nginx.tmpl

@@ -49,7 +49,7 @@ server {
 	access_log /proc/self/fd/1;
 
 	location / {
-		proxy_pass http://{{ $host }};
+		proxy_pass http://{{ trim $host }};
 		proxy_set_header Host $http_host;
 		proxy_set_header X-Real-IP $remote_addr;
 		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;