remove header appending, and the last header defined always wins

README.md

@@ -132,6 +132,25 @@ For example, to enable CORS for all resources, you just need to enable it for al
 }
 ```
 
+##### Precedence
+When there are header conflicts, the last header definition always wins. The headers do not get appended. For example,
+
+```json
+{
+  "headers": {
+    "/**": {
+      "X-Foo": "bar",
+      "X-Bar": "baz"
+    },
+    "/foo": {
+      "X-Foo": "foo"
+    }
+  }
+}
+```
+
+when accessing `/foo`, `X-Foo` will have the value `"foo"` and `X-Bar` will not be present.
+
 ### Route Ordering
 
 * Root Files

scripts/config/lib/ngx_mruby/headers.rb

@@ -9,12 +9,13 @@ req    = Nginx::Request.new
 uri    = req.var.uri
 
 if config["headers"]
-  config["headers"].each do |route, header_hash|
+  config["headers"].to_a.reverse.each do |route, header_hash|
     if Regexp.compile("^#{NginxConfigUtil.to_regex(route)}$") =~ uri
       header_hash.each do |key, value|
         # value must be a string
         req.headers_out[key] = value.to_s
       end
+      break
     end
   end
 end

spec/fixtures/custom_headers_no_append/public_html/foo.html

+foo

spec/fixtures/custom_headers_no_append/public_html/index.html

+index

spec/fixtures/custom_headers_no_append/static.json

+{
+  "headers": {
+    "/": {
+      "Cache-Control": "no-cache"
+    },
+    "/**": {
+      "X-Foo": "false",
+      "X-Bar": "blah"
+    },
+    "/foo.html": {
+      "X-Foo": "true"
+    }
+  },
+  "clean_urls": true
+}

spec/simple_spec.rb

@@ -216,6 +216,18 @@ STATIC_JSON
       end
     end
 
+    describe "conflicting headers" do
+      let(:name) { "custom_headers_no_append" }
+
+      it "should not append headers" do
+        response = app.get("/foo.html")
+        expect(response["X-Foo"]).to eq("true")
+        expect(response["X-Bar"]).to eq(nil)
+        expect(response.code).to eq("200")
+        expect(response.body.chomp).to eq("foo")
+      end
+    end
+
     describe "wildcard paths" do
       let(:name) { "custom_headers_wildcard" }