add distributed cache support via redis

README.md

@@ -113,6 +113,8 @@ _this is the recommended way to run remark42_
 | admin.shared.email      | ADMIN_SHARED_EMAIL      | `admin@${REMARK_URL}`    | admin email                                     |
 | backup                  | BACKUP_PATH             | `./var/backup`           | backups location                                |
 | max-back                | MAX_BACKUP_FILES        | `10`                     | max backup files to keep                        |
+| cache.type              | CACHE_TYPE              | `mem`                    | type of cache, `redis` or `mem` or `none`       |
+| cache.redis_addr        | CACHE_REDIS_ADDR        | `127.0.0.1:6379`         | address of redis cache, turn redis cache on for distributed cache |
 | cache.max.items         | CACHE_MAX_ITEMS         | `1000`                   | max number of cached items, `0` - unlimited     |
 | cache.max.value         | CACHE_MAX_VALUE         | `65536`                  | max size of cached value, `0` - unlimited       |
 | cache.max.size          | CACHE_MAX_SIZE          | `50000000`               | max size of all cached values, `0` - unlimited  |

backend/app/cmd/server.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/dgrijalva/jwt-go"
 	"github.com/go-pkgz/jrpc"
+	"github.com/go-pkgz/lcw/eventbus"
 	log "github.com/go-pkgz/lgr"
 	"github.com/kyokomi/emoji"
 	"github.com/pkg/errors"
@@ -159,8 +160,9 @@ type AvatarGroup struct {
 
 // CacheGroup defines options group for cache params
 type CacheGroup struct {
-	Type string `long:"type" env:"TYPE" description:"type of cache" choice:"mem" choice:"none" default:"mem"` // nolint
-	Max  struct {
+	Type      string `long:"type" env:"TYPE" description:"type of cache" choice:"redis" choice:"mem" choice:"none" default:"mem"` // nolint
+	RedisAddr string `long:"redis_addr" env:"REDIS_ADDR" default:"127.0.0.1:6379" description:"address of redis cache, turn redis cache on for distributed cache"`
+	Max       struct {
 		Items int   `long:"items" env:"ITEMS" default:"1000" description:"max cached items"`
 		Value int   `long:"value" env:"VALUE" default:"65536" description:"max size of cached value"`
 		Size  int64 `long:"size" env:"SIZE" default:"50000000" description:"max size of total cache"`
@@ -669,6 +671,17 @@ func (s *ServerCommand) makeAdminStore() (admin.Store, error) {
 func (s *ServerCommand) makeCache() (LoadingCache, error) {
 	log.Printf("[INFO] make cache, type=%s", s.Cache.Type)
 	switch s.Cache.Type {
+	case "redis":
+		redisPubSub, err := eventbus.NewRedisPubSub(s.Cache.RedisAddr, "remark42-cache")
+		if err != nil {
+			return nil, errors.Wrap(err, "cache backend initialization, redis PubSub initialisation")
+		}
+		backend, err := cache.NewLruCache(cache.MaxCacheSize(s.Cache.Max.Size), cache.MaxValSize(s.Cache.Max.Value),
+			cache.MaxKeys(s.Cache.Max.Items), cache.EventBus(redisPubSub))
+		if err != nil {
+			return nil, errors.Wrap(err, "cache backend initialization")
+		}
+		return cache.NewScache(backend), nil
 	case "mem":
 		backend, err := cache.NewLruCache(cache.MaxCacheSize(s.Cache.Max.Size), cache.MaxValSize(s.Cache.Max.Value),
 			cache.MaxKeys(s.Cache.Max.Items))

backend/app/cmd/server_test.go

@@ -329,6 +329,19 @@ func TestServerApp_Failed(t *testing.T) {
 	_, err = opts.newServerApp()
 	assert.EqualError(t, err, "failed to make data store engine: unsupported store type blah")
 	t.Log(err)
+
+	// wrong redis location
+	opts = ServerCommand{}
+	opts.SetCommon(CommonOpts{RemarkURL: "https://demo.remark42.com", SharedSecret: "123456"})
+	p = flags.NewParser(&opts, flags.Default)
+	_, err = p.ParseArgs([]string{"--store.bolt.path=/tmp", "--cache.type=redis", "--cache.redis_addr=wrong_address"})
+	assert.NoError(t, err)
+	_, err = opts.newServerApp()
+	assert.EqualError(t, err,
+		"failed to make cache: cache backend initialization, redis PubSub initialisation: "+
+			"problem subscribing to channel remark42-cache on address wrong_address: "+
+			"dial tcp: address wrong_address: missing port in address")
+	t.Log(err)
 }
 
 func TestServerApp_Shutdown(t *testing.T) {

backend/go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/go-chi/render v1.0.1
 	github.com/go-pkgz/auth v0.10.2
 	github.com/go-pkgz/jrpc v0.2.0
-	github.com/go-pkgz/lcw v0.6.1
+	github.com/go-pkgz/lcw v0.7.1
 	github.com/go-pkgz/lgr v0.7.0
 	github.com/go-pkgz/repeater v1.1.3
 	github.com/go-pkgz/rest v1.5.0

backend/go.sum

@@ -64,6 +64,10 @@ github.com/go-pkgz/jrpc v0.2.0 h1:CLy/eZyekjraVrxZV18N2R1mYLMJ/nWrgdfyIOGPY/E=
 github.com/go-pkgz/jrpc v0.2.0/go.mod h1:wd8vtQ4CgtCnuqua6x2b1SKIgv0VSOh5Dn0uUITbiUE=
 github.com/go-pkgz/lcw v0.6.1 h1:hb1v9oFaP6MiGSvROoVTiTmcyU/qHzGebUOhA74l4xU=
 github.com/go-pkgz/lcw v0.6.1/go.mod h1:vovP88gZLeuIWn5cm0NlgPYFyGGkv3m2OcKMOOaHhj0=
+github.com/go-pkgz/lcw v0.7.0 h1:O6UY2btJIgarMK9/5AdnbaWc+eP/OMPkwFvForKfwHQ=
+github.com/go-pkgz/lcw v0.7.0/go.mod h1:3P6g9QrJsDePXEMe42ywO+tW08L17tBJGwIDdI7lZ6g=
+github.com/go-pkgz/lcw v0.7.1 h1:2Q2k1am6xb2KgxZG84kL072q66rlWFUR+MvgPcDcJXA=
+github.com/go-pkgz/lcw v0.7.1/go.mod h1:3P6g9QrJsDePXEMe42ywO+tW08L17tBJGwIDdI7lZ6g=
 github.com/go-pkgz/lgr v0.7.0 h1:S/AAPwt/RE9a5mNJskA7dGVp+Dq6SMIW6LYjG3ITxY8=
 github.com/go-pkgz/lgr v0.7.0/go.mod h1:yMgxU+GobMRJgIEbSzDKy/67W18S7qmGx/7BVL5AB8Q=
 github.com/go-pkgz/repeater v1.1.3 h1:q6+JQF14ESSy28Dd7F+wRelY4F+41HJ0LEy/szNnMiE=