AppendPath parameter (#476)

* add new append-path parameter

* make fmt

* support specifying the part of the path

pkg/filter/headerlookup/headerlookup.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"regexp"
 	"strings"
 	"time"
 
@@ -55,6 +56,7 @@ type (
 		spec       *Spec
 		etcdPrefix string
 		headerKey  string
+		pathRegExp *regexp.Regexp
 
 		cache   *lru.Cache
 		cluster cluster.Cluster
@@ -71,9 +73,15 @@ type (
 	// Spec defines header key and etcd prefix that form etcd key like /custom-data/{etcdPrefix}/{headerKey's value}.
 	// This /custom-data/{etcdPrefix}/{headerKey's value} is retrieved from etcd and HeaderSetters extract keys from the
 	// from the retrieved etcd item.
+	// When PathRegExp is defined, PathRegExp is used with `regexp.FindStringSubmatch` to identify a group from path.
+	// The first captured group is appended to the etcd key in following format:
+	// /custom-data/{etcdPrefix}/{headerKey's value}-{regex group} . For example, for path
+	// "/api/bananas/33" and pathRegExp: "^/api/([a-z]+)/[0-9]*", the group "bananas" is extracted and etcd key is
+	// /custom-data/{etcdPrefix}/{headerKey's value}-bananas.
 	Spec struct {
 		HeaderKey     string              `yaml:"headerKey" jsonschema:"required"`
 		EtcdPrefix    string              `yaml:"etcdPrefix" jsonschema:"required"`
+		PathRegExp    string              `yaml:"pathRegExp" jsonschema:"omitempty"`
 		HeaderSetters []*HeaderSetterSpec `yaml:"headerSetters" jsonschema:"required"`
 	}
 )
@@ -97,6 +105,10 @@ func (spec Spec) Validate() error {
 			return fmt.Errorf("headerSetters[i].headerKey is required")
 		}
 	}
+
+	if _, err := regexp.Compile(spec.PathRegExp); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -130,6 +142,7 @@ func (hl *HeaderLookup) Init(filterSpec *httppipeline.FilterSpec) {
 	hl.headerKey = http.CanonicalHeaderKey(hl.spec.HeaderKey)
 	hl.cache, _ = lru.New(cacheSize)
 	hl.stopCtx, hl.cancel = context.WithCancel(context.Background())
+	hl.pathRegExp = regexp.MustCompile(hl.spec.PathRegExp)
 	hl.watchChanges()
 }
 
@@ -249,6 +262,12 @@ func (hl *HeaderLookup) handle(ctx httpcontext.HTTPContext) string {
 		logger.Warnf("request does not have header '%s'", hl.spec.HeaderKey)
 		return ""
 	}
+	if hl.spec.PathRegExp != "" {
+		path := ctx.Request().Path()
+		if match := hl.pathRegExp.FindStringSubmatch(path); match != nil && len(match) > 1 {
+			headerVal = headerVal + "-" + match[1]
+		}
+	}
 	headersToAdd, err := hl.lookup(headerVal)
 	if err != nil {
 		logger.Errorf(err.Error())

pkg/filter/headerlookup/headerlookup_test.go

@@ -106,6 +106,24 @@ headerKey: "X-AUTH-USER"
 etcdPrefix: "/credentials/"
 headerSetters:
   - etcdKey: "ext-id"
+`,
+		`
+name: headerLookup
+kind: HeaderLookup
+headerKey: "X-AUTH-USER"
+etcdPrefix: "/credentials/"
+headerSetters:
+  - headerKey: "X-ext-id"
+`,
+		`
+name: headerLookup
+kind: HeaderLookup
+headerKey: "X-AUTH-USER"
+pathRegExp: "**"
+etcdPrefix: "/credentials/"
+headerSetters:
+  - headerKey: "X-ext-id"
+    etcdKey: "ext-id"
 `,
 	}
 
@@ -236,6 +254,73 @@ extra-entry: "extra"
 		}
 	}
 
+	if hl.Status() != nil {
+		t.Errorf("status should be nil")
+	}
+	if len(hl.Description()) == 0 {
+		t.Errorf("description should not be empty")
+	}
+	hl.Close()
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+	clusterInstance.CloseServer(wg)
+	wg.Wait()
+}
+
+func TestHandleWithPath(t *testing.T) {
+	etcdDirName, err := ioutil.TempDir("", "etcd-headerlookup-path-test")
+	check(err)
+	defer os.RemoveAll(etcdDirName)
+	const config = `
+name: headerLookup
+kind: HeaderLookup
+headerKey: "X-AUTH-USER"
+etcdPrefix: "credentials/"
+pathRegExp: "^/api/([a-z]+)/[0-9]*"
+headerSetters:
+  - etcdKey: "ext-id"
+    headerKey: "user-ext-id"
+`
+	clusterInstance := cluster.CreateClusterForTest(etcdDirName)
+	var mockMap sync.Map
+	supervisor := supervisor.NewMock(
+		nil, clusterInstance, mockMap, mockMap, nil, nil, false, nil, nil)
+
+	// let's put data to 'bob'
+	clusterInstance.Put("/custom-data/credentials/bob-bananas",
+		`
+ext-id: 333
+extra-entry: "extra"
+`)
+	clusterInstance.Put("/custom-data/credentials/bob-pearls",
+		`
+ext-id: 4444
+extra-entry: "extra"
+`)
+	hl, err := createHeaderLookup(config, nil, supervisor)
+	check(err)
+
+	ctx, header := prepareCtxAndHeader()
+	header.Set("X-AUTH-USER", "bob")
+	hl.Handle(ctx) // path does not match
+	if header.Get("user-ext-id") != "" {
+		t.Errorf("failed")
+	}
+	ctx.MockedRequest.MockedPath = func() string {
+		return "/api/bananas/9281"
+	}
+	hl.Handle(ctx)
+	if header.Get("user-ext-id") != "333" {
+		t.Errorf("failed")
+	}
+	ctx.MockedRequest.MockedPath = func() string {
+		return "/api/pearls/"
+	}
+	hl.Handle(ctx)
+	if header.Get("user-ext-id") != "4444" {
+		t.Errorf("failed")
+	}
+
 	hl.Close()
 	wg := &sync.WaitGroup{}
 	wg.Add(1)