feat: Add a go plugin to add geo query string to URL

plugins/samples/add_geo_query/BUILD

@@ -0,0 +1,16 @@
+load("//:plugins.bzl", "proxy_wasm_plugin_go", "proxy_wasm_tests")
+
+licenses(["notice"])  # Apache 2
+
+proxy_wasm_plugin_go(
+    name = "plugin_go.wasm",
+    srcs = ["plugin.go"],
+)
+
+proxy_wasm_tests(
+    name = "tests",
+    plugins = [
+        ":plugin_go.wasm",
+    ],
+    tests = ":tests.textpb",
+)

plugins/samples/add_geo_query/plugin.go

@@ -0,0 +1,97 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// [START serviceextensions_plugin_country_query]
+package main
+
+import (
+	"strings"
+
+	"github.com/proxy-wasm/proxy-wasm-go-sdk/proxywasm"
+	"github.com/proxy-wasm/proxy-wasm-go-sdk/proxywasm/types"
+)
+
+func main() {}
+
+func init() {
+	proxywasm.SetVMContext(&vmContext{})
+}
+
+type vmContext struct {
+	types.DefaultVMContext
+}
+
+type pluginContext struct {
+	types.DefaultPluginContext
+}
+
+type httpContext struct {
+	types.DefaultHttpContext
+}
+
+func (*vmContext) NewPluginContext(contextID uint32) types.PluginContext {
+	return &pluginContext{}
+}
+
+func (*pluginContext) NewHttpContext(contextID uint32) types.HttpContext {
+	return &httpContext{}
+}
+
+func (ctx *httpContext) OnHttpRequestHeaders(numHeaders int, endOfStream bool) types.Action {
+	// Get country value from Cloud CDN headers or default to "unknown"
+	countryValue := ctx.getCountryValue()
+
+	// Log the country value for GCP logs
+	proxywasm.LogInfof("country: %s", countryValue)
+
+	// Get current path and add country query parameter
+	path, err := proxywasm.GetHttpRequestHeader(":path")
+	if err != nil {
+		return types.ActionContinue
+	}
+
+	newPath := ctx.addCountryParameter(path, countryValue)
+	proxywasm.ReplaceHttpRequestHeader(":path", newPath)
+
+	return types.ActionContinue
+}
+
+func (ctx *httpContext) getCountryValue() string {
+	// Try common CDN country headers
+	countryHeaders := []string{
+		"X-Country",
+		"CloudFront-Viewer-Country",
+		"X-Client-Geo-Location",
+		"X-AppEngine-Country",
+	}
+
+	for _, header := range countryHeaders {
+		value, err := proxywasm.GetHttpRequestHeader(header)
+		if err == nil && value != "" {
+			return value
+		}
+	}
+
+	return "unknown"
+}
+
+func (ctx *httpContext) addCountryParameter(path, countryValue string) string {
+	// Check if query string already exists
+	if strings.Contains(path, "?") {
+		return path + "&country=" + countryValue
+	}
+	return path + "?country=" + countryValue
+}
+
+// [END serviceextensions_plugin_country_query]

plugins/samples/add_geo_query/tests.textpb

@@ -0,0 +1,149 @@
+# Test basic country parameter addition with X-Country header
+test {
+  name: "AddCountryParameterWithXCountryHeader"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+      header { key: "X-Country" value: "BR" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=BR" }
+      log { regex: ".*country: BR.*" }
+    }
+  }
+}
+
+# Test CloudFront header takes precedence when X-Country missing
+test {
+  name: "UseCloudFrontHeaderWhenXCountryMissing"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+      header { key: "CloudFront-Viewer-Country" value: "US" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=US" }
+      log { regex: ".*country: US.*" }
+    }
+  }
+}
+
+# Test fallback to unknown when no country headers
+test {
+  name: "FallbackToUnknownWhenNoCountryHeaders"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=unknown" }
+      log { regex: ".*country: unknown.*" }
+    }
+  }
+}
+
+# Test appending to existing query string
+test {
+  name: "AppendCountryToExistingQueryString"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data?page=1&limit=10" }
+      header { key: "X-Country" value: "DE" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?page=1&limit=10&country=DE" }
+      log { regex: ".*country: DE.*" }
+    }
+  }
+}
+
+# Test header priority - X-Country should be preferred over CloudFront
+test {
+  name: "XCountryHeaderPriorityOverCloudFront"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+      header { key: "X-Country" value: "FR" }
+      header { key: "CloudFront-Viewer-Country" value: "IT" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=FR" }
+      log { regex: ".*country: FR.*" }
+    }
+  }
+}
+
+# Test X-Client-Geo-Location header as fallback
+test {
+  name: "UseXClientGeoLocationAsThirdOption"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+      header { key: "X-Client-Geo-Location" value: "JP" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=JP" }
+      log { regex: ".*country: JP.*" }
+    }
+  }
+}
+
+# Test X-AppEngine-Country header as fourth option
+test {
+  name: "UseXAppEngineCountryAsFourthOption"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+      header { key: "X-AppEngine-Country" value: "CA" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=CA" }
+      log { regex: ".*country: CA.*" }
+    }
+  }
+}
+
+# Test root path without query string
+test {
+  name: "AddCountryToRootPath"
+  request_headers {
+    input {
+      header { key: ":path" value: "/" }
+      header { key: "X-Country" value: "MX" }
+    }
+    result {
+      has_header { key: ":path" value: "/?country=MX" }
+      log { regex: ".*country: MX.*" }
+    }
+  }
+}
+
+# Test special characters in country code
+test {
+  name: "HandleSpecialCharactersInCountryCode"
+  request_headers {
+    input {
+      header { key: ":path" value: "/api/data" }
+      header { key: "X-Country" value: "UK" }
+    }
+    result {
+      has_header { key: ":path" value: "/api/data?country=UK" }
+      log { regex: ".*country: UK.*" }
+    }
+  }
+}
+
+# Test empty path scenario
+test {
+  name: "HandleEmptyPath"
+  request_headers {
+    input {
+      header { key: ":path" value: "" }
+      header { key: "X-Country" value: "AU" }
+    }
+    result {
+      has_header { key: ":path" value: "?country=AU" }
+      log { regex: ".*country: AU.*" }
+    }
+  }
+}