From 61f221beb4ee7bfaaf5cbd24cd3c9e49ee80a8c4 Mon Sep 17 00:00:00 2001
From: Matthias Kaeppler <mkaeppler@gitlab.com>
Date: Wed, 23 Feb 2022 15:33:47 +0100
Subject: [PATCH] Add roundtripper to log outbound HTTP requests

This is useful when sending requests to external
parties such as Object Storage providers.
---
 log/outbound_http.go         | 34 +++++++++++++++++++++++++++
 log/outbound_http_options.go | 27 ++++++++++++++++++++++
 log/outbound_http_test.go    | 45 ++++++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 log/outbound_http.go
 create mode 100644 log/outbound_http_options.go
 create mode 100644 log/outbound_http_test.go

diff --git a/log/outbound_http.go b/log/outbound_http.go
new file mode 100644
index 00000000..a50ba59f
--- /dev/null
+++ b/log/outbound_http.go
@@ -0,0 +1,34 @@
+package log
+
+import (
+	"net/http"
+	"time"
+)
+
+type loggingRoundTripper struct {
+	delegate http.RoundTripper
+	config   loggingRoundTripperConfig
+}
+
+func (l loggingRoundTripper) RoundTrip(req *http.Request) (res *http.Response, e error) {
+	started := time.Now()
+	logger := l.config.logger
+
+	defer func() {
+		duration := time.Since(started)
+
+		fields := Fields{}
+		fields[httpRequestMethodField] = req.Method
+		fields[httpResponseStatusCodeField] = res.StatusCode
+		fields[requestDurationField] = int64(duration / time.Millisecond)
+
+		logger.WithFields(fields).Info("outbound_http")
+	}()
+
+	return l.delegate.RoundTrip(req)
+}
+
+func NewLoggingRoundTripper(delegate http.RoundTripper, opts ...LoggingRoundTripperOption) http.RoundTripper {
+	config := applyLoggingRoundTripperOptions(opts)
+	return &loggingRoundTripper{delegate: delegate, config: config}
+}
diff --git a/log/outbound_http_options.go b/log/outbound_http_options.go
new file mode 100644
index 00000000..dc5865d0
--- /dev/null
+++ b/log/outbound_http_options.go
@@ -0,0 +1,27 @@
+package log
+
+import "github.com/sirupsen/logrus"
+
+type loggingRoundTripperConfig struct {
+	logger *logrus.Logger
+}
+
+// LoggingRoundTripperOption will configure a correlation handler.
+// Currently there are no options, but this gives us the option
+// to extend the interface in a backwards compatible way.
+type LoggingRoundTripperOption func(*loggingRoundTripperConfig)
+
+func applyLoggingRoundTripperOptions(opts []LoggingRoundTripperOption) loggingRoundTripperConfig {
+	config := loggingRoundTripperConfig{}
+	for _, v := range opts {
+		v(&config)
+	}
+
+	return config
+}
+
+func WithRoundTripLogger(logger *logrus.Logger) LoggingRoundTripperOption {
+	return func(config *loggingRoundTripperConfig) {
+		config.logger = logger
+	}
+}
diff --git a/log/outbound_http_test.go b/log/outbound_http_test.go
new file mode 100644
index 00000000..9f42912d
--- /dev/null
+++ b/log/outbound_http_test.go
@@ -0,0 +1,45 @@
+package log
+
+import (
+	"bytes"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_logRequest(t *testing.T) {
+	require := require.New(t)
+
+	req, err := http.NewRequest("GET", "http://example.com", nil)
+	require.NoError(err)
+
+	mockTransport := roundTripperFunc(func(req *http.Request) (*http.Response, error) {
+		return &http.Response{StatusCode: 200}, nil
+	})
+
+	buf := &bytes.Buffer{}
+	closer, err := Initialize(WithWriter(buf))
+	require.NoError(err)
+	defer closer.Close()
+
+	roundTripper := NewLoggingRoundTripper(mockTransport, func(lrtc *loggingRoundTripperConfig) {
+		lrtc.logger = logger
+	})
+
+	roundTripper.RoundTrip(req)
+
+	require.Regexp(`^.*level=info msg=outbound_http duration_ms=\d+ method=GET status=200\n$`, buf.String())
+}
+
+type delegatedRoundTripper struct {
+	delegate func(req *http.Request) (*http.Response, error)
+}
+
+func (c delegatedRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	return c.delegate(req)
+}
+
+func roundTripperFunc(delegate func(req *http.Request) (*http.Response, error)) http.RoundTripper {
+	return &delegatedRoundTripper{delegate}
+}
-- 
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