Merge pull request #10 from google/martian-logger

General request/response logging to stdout as a modifier.

README.md

@@ -26,6 +26,8 @@ flag:
 
     go run examples/main.go -- -v=0
 
+For logging of requests and responses a [logging modifier](https://github.com/google/martian/wiki/Modifier-Reference#logging) is available
+
 By default, Martian will be running on port 8080. The port can be specified via
 a flag:
 

examples/main.go

@@ -57,6 +57,35 @@ matches "www.example.com"
 the "modifier" key within the "url.Filter" JSON object contains another
 modifier message of the type header.Modifier to run iff the filter passes
 
+groups may also be used to run multiple modifiers sequentially; for example to
+log requests and responses after adding the "Martian-Test" header to the
+request, but only when the host matches www.example.com:
+
+  {
+    "url.Filter": {
+      "host": "www.example.com",
+      "modifier": {
+        "fifo.Group": {
+          "modifiers": [
+            {
+              "header.Modifier": {
+                "scope": ["request"],
+                "name": "Martian-Test",
+                "value": "true"
+              }
+            },
+            {
+              "log.Logger": { }
+            }
+          ]
+        }
+      }
+    }
+  }
+
+modifiers are designed to be composed together in ways that allow the user to
+write a single JSON structure to accomplish a variety of functionality
+
 	GET host:port/martian/verify
 
 retrieves the verifications errors as JSON with the following structure:

log/logger.go

@@ -0,0 +1,129 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// 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.
+
+// Package log provides a Martian modifier that logs the request and response.
+package log
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/google/martian"
+	"github.com/google/martian/parse"
+)
+
+// Logger is a modifier that logs requests and responses.
+type Logger struct {
+	log func(line string)
+}
+
+type loggerJSON struct {
+	Scope []parse.ModifierType `json:"scope"`
+}
+
+func init() {
+	parse.Register("log.Logger", loggerFromJSON)
+}
+
+// NewLogger returns a logger that logs requests and responses. Log function defaults to martian.Infof.
+func NewLogger() *Logger {
+	return &Logger{
+		log: func(line string) {
+			martian.Infof(line)
+		},
+	}
+}
+
+// SetLogFunc sets the logging function for the logger.
+func (l *Logger) SetLogFunc(logFunc func(line string)) {
+	l.log = logFunc
+}
+
+// ModifyRequest logs the request. Note that the body of the request is not logged.
+//
+// The format logged is:
+// --------------------------------------------------------------------------------
+// Request to http://www.google.com/path?querystring
+// --------------------------------------------------------------------------------
+// GET /path?querystring HTTP/1.1
+// Host: www.google.com
+// Connection: close
+// Other-Header: values
+// --------------------------------------------------------------------------------
+func (l *Logger) ModifyRequest(ctx *martian.Context, req *http.Request) error {
+	b := &bytes.Buffer{}
+
+	fmt.Fprintln(b, "")
+	fmt.Fprintln(b, strings.Repeat("-", 80))
+	fmt.Fprintf(b, "Request to %s\n", req.URL)
+	fmt.Fprintln(b, strings.Repeat("-", 80))
+	fmt.Fprintf(b, "%s %s %s\r\n", req.Method, req.RequestURI, req.Proto)
+	fmt.Fprintf(b, "Host: %s\r\n", req.Host)
+
+	if req.Close {
+		fmt.Fprint(b, "Connection: close\r\n")
+	}
+
+	req.Header.Write(b)
+	fmt.Fprintln(b, strings.Repeat("-", 80))
+
+	l.log(b.String())
+
+	return nil
+}
+
+// ModifyResponse logs the response. Note that the body of the response is not logged.
+//
+// The format logged is:
+// --------------------------------------------------------------------------------
+// Response from http://www.google.com/path?querystring
+// --------------------------------------------------------------------------------
+// HTTP/1.1 200 OK
+// Date: Tue, 15 Nov 1994 08:12:31 GMT
+// Other-Header: values
+// --------------------------------------------------------------------------------
+func (l *Logger) ModifyResponse(ctx *martian.Context, res *http.Response) error {
+	b := &bytes.Buffer{}
+	fmt.Fprintln(b, "")
+	fmt.Fprintln(b, strings.Repeat("-", 80))
+	fmt.Fprintf(b, "Response from %s\n", res.Request.URL)
+	fmt.Fprintln(b, strings.Repeat("-", 80))
+	fmt.Fprintf(b, "%s %s\r\n", res.Proto, res.Status)
+	res.Header.Write(b)
+	fmt.Fprintln(b, strings.Repeat("-", 80))
+
+	l.log(b.String())
+
+	return nil
+}
+
+// loggerFromJSON builds a logger from JSON.
+//
+// Example JSON:
+// {
+//   "log.Logger": {
+//     "scope": ["request", "response"]
+//   }
+// }
+func loggerFromJSON(b []byte) (*parse.Result, error) {
+	msg := &loggerJSON{}
+	if err := json.Unmarshal(b, msg); err != nil {
+		return nil, err
+	}
+
+	return parse.NewResult(NewLogger(), msg.Scope)
+}

log/logger_test.go

@@ -0,0 +1,103 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// 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.
+
+package log
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/google/martian"
+	"github.com/google/martian/parse"
+	"github.com/google/martian/proxyutil"
+)
+
+func ExampleLogger() {
+	l := NewLogger()
+	l.SetLogFunc(func(line string) {
+		// Remove \r to make it easier to test with examples.
+		fmt.Print(strings.Replace(line, "\r", "", -1))
+	})
+
+	req, err := http.NewRequest("GET", "http://example.com/path?querystring", strings.NewReader("body"))
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	req.RequestURI = req.URL.RequestURI()
+	req.Header.Set("Other-Header", "values")
+	req.Close = true
+
+	if err := l.ModifyRequest(martian.NewContext(), req); err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	res := proxyutil.NewResponse(200, strings.NewReader("body"), req)
+	res.Header.Set("Date", "Tue, 15 Nov 1994 08:12:31 GMT")
+	res.Header.Set("Other-Header", "values")
+
+	if err := l.ModifyResponse(martian.NewContext(), res); err != nil {
+		fmt.Println(err)
+		return
+	}
+	// Output:
+	// --------------------------------------------------------------------------------
+	// Request to http://example.com/path?querystring
+	// --------------------------------------------------------------------------------
+	// GET /path?querystring HTTP/1.1
+	// Host: example.com
+	// Connection: close
+	// Other-Header: values
+	// --------------------------------------------------------------------------------
+	//
+	// --------------------------------------------------------------------------------
+	// Response from http://example.com/path?querystring
+	// --------------------------------------------------------------------------------
+	// HTTP/1.1 200 OK
+	// Date: Tue, 15 Nov 1994 08:12:31 GMT
+	// Other-Header: values
+	// --------------------------------------------------------------------------------
+}
+
+func TestLoggerFromJSON(t *testing.T) {
+	msg := []byte(`{
+		"log.Logger": {
+			"scope": ["request", "response"]
+		}
+	}`)
+
+	r, err := parse.FromJSON(msg)
+	if err != nil {
+		t.Fatalf("parse.FromJSON(): got %v, want no error", err)
+	}
+
+	reqmod := r.RequestModifier()
+	if reqmod == nil {
+		t.Fatal("r.RequestModifier(): got nil, want not nil")
+	}
+	if _, ok := reqmod.(*Logger); !ok {
+		t.Error("reqmod.(*Logger): got !ok, want ok")
+	}
+
+	resmod := r.ResponseModifier()
+	if resmod == nil {
+		t.Fatal("r.ResponseModifier(): got nil, want not nil")
+	}
+	if _, ok := resmod.(*Logger); !ok {
+		t.Error("resmod.(*Logger); got !ok, want ok")
+	}
+}