caddyfile: Allow partial directive env var expansion (#2253)

caddyfile/parse.go

@@ -343,7 +343,7 @@ func (p *parser) doSingleImport(importFile string) ([]Token, error) {
 // are loaded into the current server block for later use
 // by directive setup functions.
 func (p *parser) directive() error {
-	dir := p.Val()
+	dir := replaceEnvVars(p.Val())
 	nesting := 0
 
 	// TODO: More helpful error message ("did you mean..." or "maybe you need to install its server type")

caddyfile/parse_test.go

@@ -452,6 +452,7 @@ func TestEnvironmentReplacement(t *testing.T) {
 	os.Setenv("PORT", "8080")
 	os.Setenv("ADDRESS", "servername.com")
 	os.Setenv("FOOBAR", "foobar")
+	os.Setenv("PARTIAL_DIR", "r1")
 
 	// basic test; unix-style env vars
 	p := testParser(`{$ADDRESS}`)
@@ -460,6 +461,13 @@ func TestEnvironmentReplacement(t *testing.T) {
 		t.Errorf("Expected key to be '%s' but was '%s'", expected, actual)
 	}
 
+	// basic test; unix-style env vars
+	p = testParser(`di{$PARTIAL_DIR}`)
+	blocks, _ = p.parseAll()
+	if actual, expected := blocks[0].Keys[0], "dir1"; expected != actual {
+		t.Errorf("Expected key to be '%s' but was '%s'", expected, actual)
+	}
+
 	// multiple vars per token
 	p = testParser(`{$ADDRESS}:{$PORT}`)
 	blocks, _ = p.parseAll()