Give system admins ability to clear caches (#834)

* Give system admins ability to clear caches In some situations, a system admin may want to clear the caches, either for development/testing or because a misconfiguration has made it into the system. This introduces a way for system admins to perform cache resets. This required a bit of a refactor of the cacher, separating the namespace property from the actual key value. * Update descriptions * Use public_keys
google · Oct 15, 2020 · 7a6fb4a · 7a6fb4a
1 parent c29b6a2
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Showing 32 changed files with 393 additions and 156 deletions.
diff --git a/cmd/adminapi/main.go b/cmd/adminapi/main.go
@@ -85,10 +85,7 @@ func realMain(ctx context.Context) error {
 	logger.Infow("observability exporter", "config", oeConfig)
 
 	// Setup cacher
-	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.MultiKeyFunc(
-		cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey),
-		cache.PrefixKeyFunc("cache:"),
-	))
+	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey))
 	if err != nil {
 		return fmt.Errorf("failed to create cacher: %w", err)
 	}

diff --git a/cmd/apiserver/main.go b/cmd/apiserver/main.go
@@ -88,10 +88,7 @@ func realMain(ctx context.Context) error {
 	logger.Infow("observability exporter", "config", oeConfig)
 
 	// Setup cacher
-	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.MultiKeyFunc(
-		cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey),
-		cache.PrefixKeyFunc("cache:"),
-	))
+	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey))
 	if err != nil {
 		return fmt.Errorf("failed to create cacher: %w", err)
 	}

diff --git a/cmd/enx-redirect/main.go b/cmd/enx-redirect/main.go
@@ -80,10 +80,7 @@ func realMain(ctx context.Context) error {
 	logger.Infow("observability exporter", "config", oeConfig)
 
 	// Setup cacher
-	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.MultiKeyFunc(
-		cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey),
-		cache.PrefixKeyFunc("cache:"),
-	))
+	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey))
 	if err != nil {
 		return fmt.Errorf("failed to create cacher: %w", err)
 	}

diff --git a/cmd/modeler/main.go b/cmd/modeler/main.go
@@ -79,10 +79,7 @@ func realMain(ctx context.Context) error {
 	logger.Infow("observability exporter", "config", oeConfig)
 
 	// Setup cacher
-	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.MultiKeyFunc(
-		cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey),
-		cache.PrefixKeyFunc("cache:"),
-	))
+	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey))
 	if err != nil {
 		return fmt.Errorf("failed to create cacher: %w", err)
 	}

diff --git a/cmd/server/assets/admin/_nav.html b/cmd/server/assets/admin/_nav.html
@@ -34,6 +34,10 @@
     <a class="nav-link{{if .currentPath.IsDir "/admin/sms"}} active{{end}}" href="/admin/sms">SMS</a>
   </li>
 
+  <li class="nav-item">
+    <a class="nav-link{{if .currentPath.IsDir "/admin/caches"}} active{{end}}" href="/admin/caches">Caches</a>
+  </li>
+
   <li class="nav-item">
     <a class="nav-link{{if .currentPath.IsDir "/admin/info"}} active{{end}}" href="/admin/info">Info</a>
   </li>

diff --git a/cmd/server/assets/admin/caches/index.html b/cmd/server/assets/admin/caches/index.html
@@ -0,0 +1,41 @@
+{{define "admin/caches/index"}}
+
+{{$caches := .caches}}
+
+<!doctype html>
+<html lang="en">
+<head>
+  {{template "head" .}}
+</head>
+
+<body class="tab-content">
+  {{template "admin/navbar" .}}
+
+  <main role="main" class="container">
+    {{template "flash" .}}
+
+    <div class="card mb-3 shadow-sm">
+      <div class="card-header">Caches</div>
+      <ul class="list-group list-group-flush">
+        {{range $k, $cache := $caches}}
+          <li class="list-group-item d-flex justify-content-between align-items-center">
+            <div>
+              <h5 class="mb-1">{{$cache.Name}}</h5>
+              <small>{{$cache.Description}}</small>
+            </div>
+            <a href="/admin/caches/clear/{{$k}}"
+              data-method="POST"
+              data-confirm="Are you sure you want to clear the {{$cache.Name}} cache?"
+              class="btn btn-danger">
+              Clear
+            </a>
+          </li>
+        {{end}}
+      </ul>
+    </div>
+  </main>
+
+  {{template "scripts" .}}
+</body>
+</html>
+{{end}}
diff --git a/cmd/server/main.go b/cmd/server/main.go
@@ -106,10 +106,7 @@ func realMain(ctx context.Context) error {
 	sessions.Options.SameSite = http.SameSiteStrictMode
 
 	// Setup cacher
-	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.MultiKeyFunc(
-		cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey),
-		cache.PrefixKeyFunc("cache:"),
-	))
+	cacher, err := cache.CacherFor(ctx, &cfg.Cache, cache.HMACKeyFunc(sha1.New, cfg.Cache.HMACKey))
 	if err != nil {
 		return fmt.Errorf("failed to create cacher: %w", err)
 	}
@@ -444,7 +441,7 @@ func realMain(ctx context.Context) error {
 		adminSub.Use(requireSystemAdmin)
 		adminSub.Use(rateLimit)
 
-		adminController := admin.New(ctx, cfg, db, auth, h)
+		adminController := admin.New(ctx, cfg, cacher, db, auth, h)
 		adminSub.Handle("", http.RedirectHandler("/admin/realms", http.StatusSeeOther)).Methods("GET")
 		adminSub.Handle("/realms", adminController.HandleRealmsIndex()).Methods("GET")
 		adminSub.Handle("/realms", adminController.HandleRealmsCreate()).Methods("POST")
@@ -461,6 +458,9 @@ func realMain(ctx context.Context) error {
 		adminSub.Handle("/users/new", adminController.HandleUsersCreate()).Methods("GET")
 		adminSub.Handle("/users/{id:[0-9]+}", adminController.HandleUsersDelete()).Methods("DELETE")
 
+		adminSub.Handle("/caches", adminController.HandleCachesIndex()).Methods("GET")
+		adminSub.Handle("/caches/clear/{id}", adminController.HandleCachesClear()).Methods("POST")
+
 		adminSub.Handle("/info", adminController.HandleInfoShow()).Methods("GET")
 	}
 

diff --git a/pkg/cache/cacher.go b/pkg/cache/cacher.go
@@ -33,6 +33,33 @@ var (
 // FetchFunc is a function used to Fetch in a cacher.
 type FetchFunc func() (interface{}, error)
 
+// Key is a cache key. It has an optional Namespace. Any KeyFunc are applied to
+// the Key, but not the Namespace.
+type Key struct {
+	Namespace string
+	Key       string
+}
+
+// Compute builds the final value of the key. If f is not nil, it is called on
+// the value of Key. If Namespace is not "", the result is prefixed with
+// Namespace + ":".
+func (k *Key) Compute(f KeyFunc) (string, error) {
+	key := k.Key
+
+	if f != nil {
+		var err error
+		key, err = f(key)
+		if err != nil {
+			return "", err
+		}
+	}
+
+	if k.Namespace != "" {
+		return k.Namespace + ":" + key, nil
+	}
+	return key, nil
+}
+
 // KeyFunc is a function that mutates the provided cache key before storing it
 // in Redis. This can be used to hash or HMAC values to prevent their plaintext
 // from appearing in Redis. A good example might be an API key lookup that you
@@ -58,17 +85,6 @@ func MultiKeyFunc(fns ...KeyFunc) KeyFunc {
 	}
 }
 
-// PrefixKeyFunc returns a KeyFunc that prefixes the key with the given constant
-// before passing it to the cacher for storage.
-func PrefixKeyFunc(prefix string) KeyFunc {
-	return func(in string) (string, error) {
-		if prefix != "" {
-			in = prefix + in
-		}
-		return in, nil
-	}
-}
-
 // HashKeyFunc returns a KeyFunc that hashes the provided key before passing it
 // to the cacher for storage.
 func HashKeyFunc(hasher func() hash.Hash) KeyFunc {
@@ -105,16 +121,20 @@ type Cacher interface {
 	// it calls FetchFunc to create the item. If FetchFunc returns an error, the
 	// error is bubbled up the stack and no value is cached. If FetchFunc
 	// succeeds, the value is cached for the provided TTL.
-	Fetch(context.Context, string, interface{}, time.Duration, FetchFunc) error
+	Fetch(context.Context, *Key, interface{}, time.Duration, FetchFunc) error
 
 	// Read gets an item from the cache and reads it into the provided interface.
 	// If it does not exist, it returns ErrNotFound.
-	Read(context.Context, string, interface{}) error
+	Read(context.Context, *Key, interface{}) error
 
 	// Write adds an item to the cache, overwriting if it already exists, caching
 	// for TTL. It returns any errors that occur on writing.
-	Write(context.Context, string, interface{}, time.Duration) error
+	Write(context.Context, *Key, interface{}, time.Duration) error
 
 	// Delete removes an item from the cache, returning any errors that occur.
-	Delete(context.Context, string) error
+	Delete(context.Context, *Key) error
+
+	// DeletePrefix removes all items from the cache that begin with the given
+	// value.
+	DeletePrefix(context.Context, string) error
 }
diff --git a/pkg/cache/cacher_test.go b/pkg/cache/cacher_test.go
@@ -114,16 +114,21 @@ func exerciseCacher(t *testing.T, cacher Cacher) {
 			t.Fatal(err)
 		}
 
-		if err := cacher.Read(ctx, "foo", nil); !errors.Is(err, ErrStopped) {
+		key := &Key{
+			Namespace: "foo",
+			Key:       "bar",
+		}
+
+		if err := cacher.Read(ctx, key, nil); !errors.Is(err, ErrStopped) {
 			t.Errorf("expected %#v to be %#v", err, ErrStopped)
 		}
-		if err := cacher.Write(ctx, "foo", nil, 0); !errors.Is(err, ErrStopped) {
+		if err := cacher.Write(ctx, key, nil, 0); !errors.Is(err, ErrStopped) {
 			t.Errorf("expected %#v to be %#v", err, ErrStopped)
 		}
-		if err := cacher.Delete(ctx, "foo"); !errors.Is(err, ErrStopped) {
+		if err := cacher.Delete(ctx, key); !errors.Is(err, ErrStopped) {
 			t.Errorf("expected %#v to be %#v", err, ErrStopped)
 		}
-		if err := cacher.Fetch(ctx, "foo", nil, 0, nil); !errors.Is(err, ErrStopped) {
+		if err := cacher.Fetch(ctx, key, nil, 0, nil); !errors.Is(err, ErrStopped) {
 			t.Errorf("expected %#v to be %#v", err, ErrStopped)
 		}
 
@@ -138,7 +143,10 @@ func exerciseType(tb testing.TB, cacher Cacher, in, out interface{}) {
 	tb.Helper()
 
 	ctx := context.Background()
-	key := testRandomKey(tb)
+	key := &Key{
+		Namespace: testRandomKey(tb),
+		Key:       testRandomKey(tb),
+	}
 
 	// Ensure the value isn't cached already
 	if err := cacher.Read(ctx, key, out); !errors.Is(err, ErrNotFound) {
@@ -188,4 +196,30 @@ func exerciseType(tb testing.TB, cacher Cacher, in, out interface{}) {
 	if err := cacher.Delete(ctx, key); err != nil {
 		tb.Fatal(err)
 	}
+
+	// Ensure value is deleted
+	if err := cacher.Read(ctx, key, out); !errors.Is(err, ErrNotFound) {
+		tb.Fatalf("expected %#v to be %#v", err, ErrNotFound)
+	}
+
+	// Create caches with the same namespace
+	for i := 0; i < 10; i++ {
+		key = &Key{
+			Namespace: key.Namespace,
+			Key:       testRandomKey(tb),
+		}
+		if err := cacher.Write(ctx, key, in, 5*time.Minute); err != nil {
+			tb.Fatal(err)
+		}
+	}
+
+	// Delete the prefix
+	if err := cacher.DeletePrefix(ctx, key.Namespace); err != nil {
+		tb.Fatal(err)
+	}
+
+	// Ensure value is deleted
+	if err := cacher.Read(ctx, key, out); !errors.Is(err, ErrNotFound) {
+		tb.Fatalf("expected %#v to be %#v", err, ErrNotFound)
+	}
 }