Backend variables

CHANGELOG.md

@@ -6,6 +6,7 @@ Unreleased changes are available as `avenga/couper:edge` container.
 
 * **Added**
   * `disable_private_caching` attribute for the [JWT Block](./docs/REFERENCE.md#jwt-block) ([#418](https://github.com/avenga/couper/pull/418))
+  * [`backend_request`](./docs/REFERENCE.md#backend_request) and [`backend_response`](./docs/REFERENCE.md#backend_response) variables ([#430](https://github.com/avenga/couper/pull/430))
 
 * **Fixed**
   * missing upstream log field value for `request.proto` ([#421](https://github.com/avenga/couper/pull/421))

docs/REFERENCE.md

@@ -32,7 +32,9 @@
     - [couper](#couper)
     - [env](#env)
     - [request](#request)
+    - [backend_request](#backend_request)
     - [backend_requests](#backend_requests)
+    - [backend_response](#backend_response)
     - [backend_responses](#backend_responses)
   - [Functions](#functions)
   - [Modifiers](#modifiers)
@@ -649,6 +651,13 @@ and for OIDC additionally:
 - `id_token_claims`: a map of claims from the ID token
 - `userinfo`: a map of claims retrieved from the userinfo endpoint
 
+### `backend_request`
+
+`backend_request` is a list of request variables like `backend_requests.<label>`
+(see [backend_requests](#backend_requests) below). The `backend_request` is only
+available in a [Backend Block](#backend-block) and represents the request of this
+block.
+
 ### `backend_requests`
 
 `backend_requests.<label>` is a list of all backend requests, and their variables.
@@ -674,6 +683,13 @@ To access the HTTP method of the `default` request use `backend_requests.default
 | `port`                           | integer         | Port of the backend request URL                                                                                                                                                                                                                                                      | `443`                                       |
 | `path`                           | string          | Backend request URL path                                                                                                                                                                                                                                                             | `/path/to`                                  |
 
+### `backend_response`
+
+`backend_response` is a list of responses variables like `backend_responses.<label>`
+(see [backend_responses](#backend_responses) below). The `backend_response` is only
+available in a [Backend Block](#backend-block) and represents the response of this
+block.
+
 ### `backend_responses`
 
 `backend_responses.<label>` is a list of all backend responses, and their variables. Same behaviour as for `backend_requests`.

eval/context.go

@@ -166,7 +166,7 @@ func (c *Context) WithClientRequest(req *http.Request) *Context {
 	return ctx
 }
 
-func (c *Context) WithBeresps(beresps ...*http.Response) *Context {
+func (c *Context) WithBeresps(beresp *http.Response) *Context {
 	ctx := &Context{
 		eval:              c.cloneEvalContext(),
 		inner:             c.inner,
@@ -180,14 +180,14 @@ func (c *Context) WithBeresps(beresps ...*http.Response) *Context {
 
 	resps := make(ContextMap)
 	bereqs := make(ContextMap)
-	for _, beresp := range beresps {
-		if beresp == nil {
-			continue
-		}
 
+	if beresp != nil {
 		name, bereqVal, berespVal := newBerespValues(ctx, false, beresp)
 		bereqs[name] = bereqVal
 		resps[name] = berespVal
+
+		ctx.eval.Variables[BackendRequest] = bereqVal
+		ctx.eval.Variables[BackendResponse] = berespVal
 	}
 
 	// Prevent overriding existing variables with successive calls to this method.

eval/sync.go

@@ -1,9 +1,10 @@
 package eval
 
 import (
-	"github.com/zclconf/go-cty/cty"
 	"net/http"
 	"sync"
+
+	"github.com/zclconf/go-cty/cty"
 )
 
 type SyncedVariables struct {

eval/variables.go

@@ -1,7 +1,9 @@
 package eval
 
 const (
+	BackendRequest   = "backend_request"
 	BackendRequests  = "backend_requests"
+	BackendResponse  = "backend_response"
 	BackendResponses = "backend_responses"
 	BackendDefault   = "default"
 	Body             = "body"

logging/hooks/custom_logs.go

@@ -68,7 +68,29 @@ func fire(entry *logrus.Entry, bodyKey request.ContextKey) {
 		return
 	}
 
-	if fields := eval.ApplyCustomLogs(evalCtx.HCLContextSync(), hclBodies, entry); len(fields) > 0 {
+	ctx := evalCtx.HCLContextSync()
+
+	if request.LogCustomUpstream == bodyKey {
+		if _, ok := ctx.Variables[eval.BackendRequests]; ok {
+			for k, v := range ctx.Variables[eval.BackendRequests].AsValueMap() {
+				if k == entry.Context.Value(request.RoundTripName) {
+					ctx.Variables[eval.BackendRequest] = v
+					break
+				}
+			}
+		}
+
+		if _, ok := ctx.Variables[eval.BackendResponses]; ok {
+			for k, v := range ctx.Variables[eval.BackendResponses].AsValueMap() {
+				if k == entry.Context.Value(request.RoundTripName) {
+					ctx.Variables[eval.BackendResponse] = v
+					break
+				}
+			}
+		}
+	}
+
+	if fields := eval.ApplyCustomLogs(ctx, hclBodies, entry); len(fields) > 0 {
 		entry.Data[customLogField] = fields
 	}
 }

server/http_endpoints_test.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/hashicorp/hcl/v2"
+	"github.com/sirupsen/logrus"
 
 	"github.com/avenga/couper/config/configload"
 	"github.com/avenga/couper/internal/test"
@@ -27,6 +28,66 @@ import (
 
 const testdataPath = "testdata/endpoints"
 
+func TestBackend_BackendVariable(t *testing.T) {
+	client := newClient()
+	helper := test.New(t)
+
+	shutdown, hook := newCouper("testdata/integration/backend/01_couper.hcl", helper)
+	defer shutdown()
+
+	req, err := http.NewRequest(http.MethodGet, "http://example.com:8080/", nil)
+	helper.Must(err)
+
+	req.Header.Set("Cookie", "Cookie")
+	req.Header.Set("User-Agent", "Couper")
+
+	hook.Reset()
+	_, err = client.Do(req)
+	helper.Must(err)
+
+	var check int
+
+	for _, entry := range hook.AllEntries() {
+		if entry.Data["type"] != "couper_backend" {
+			continue
+		}
+
+		name := entry.Data["request"].(logging.Fields)["name"]
+		data := entry.Data["custom"].(logrus.Fields)
+		// The Cookie request header is not proxied, so *-req is not set in log.
+
+		if name == "default" {
+			check++
+
+			if len(data) != 2 || data["default-res"] != "application/json" || data["default-ua"] != "Couper" {
+				t.Errorf("unexpected data given: %#v", data)
+			}
+		} else if name == "request" {
+			check++
+
+			if len(data) != 2 || data["request-res"] != "text/plain; charset=utf-8" || data["request-ua"] != "" {
+				t.Errorf("unexpected data given: %#v", data)
+			}
+		} else if name == "r1" {
+			check++
+
+			if len(data) != 2 || data["definitions-res"] != "text/plain; charset=utf-8" || data["definitions-ua"] != "" {
+				t.Errorf("unexpected data given: %#v", data)
+			}
+		} else if name == "r2" {
+			check++
+
+			if len(data) != 2 || data["definitions-res"] != "application/json" || data["definitions-ua"] != "" {
+				t.Errorf("unexpected data given: %#v", data)
+			}
+		}
+	}
+
+	if check != 4 {
+		t.Error("missing 4 backend logs")
+	}
+}
+
 func TestEndpoints_Protected404(t *testing.T) {
 	client := newClient()
 

server/testdata/integration/backend/01_couper.hcl

@@ -0,0 +1,47 @@
+server {
+  endpoint "/" {
+    proxy "default" {
+      url = "${env.COUPER_TEST_BACKEND_ADDR}/anything"
+
+      backend {
+        custom_log_fields = {
+          default-res = backend_response.headers.content-type
+          default-req = backend_request.headers.cookie
+          default-ua  = backend_request.headers.user-agent
+        }
+      }
+    }
+
+    request "request" {
+      url = "${env.COUPER_TEST_BACKEND_ADDR}/small"
+
+      backend { 
+        custom_log_fields = {
+          request-res = backend_response.headers.content-type
+          request-req = backend_request.headers.cookie
+          request-ua  = backend_request.headers.user-agent
+        }
+      }
+    }
+
+    request "r1" {
+      url = "${env.COUPER_TEST_BACKEND_ADDR}/small"
+      backend = "BE"
+    }
+
+    request "r2" {
+      url = "${env.COUPER_TEST_BACKEND_ADDR}/anything"
+      backend = "BE"
+    }
+  }
+}
+
+definitions {
+  backend "BE" {
+    custom_log_fields = {
+      definitions-res = backend_response.headers.content-type
+      definitions-req = backend_request.headers.cookie
+      definitions-ua  = backend_request.headers.user-agent
+    }
+  }
+}