redis: prefixed routing

DEPRECATED.md

@@ -7,6 +7,7 @@ The following features have been DEPRECATED and will be removed in the specified
 A logged warning is expected for each deprecated item that is in deprecation window.
 
 ## Version 1.11.0 (Pending)
+* Use of `cluster`, found in [redis-proxy.proto](https://github.com/envoyproxy/envoy/blob/master/api/envoy/config/filter/network/redis_proxy/v2/redis_proxy.proto) is deprecated. Set a `PrefixRoutes.catch_all_cluster` instead.
 
 ## Version 1.10.0 (Apr 5, 2019)
 * Use of `use_alpha` in [Ext-Authz Authorization Service](https://github.com/envoyproxy/envoy/blob/master/api/envoy/service/auth/v2/external_auth.proto) is deprecated. It should be used for a short time, and only when transitioning from alpha to V2 release version.

api/envoy/config/filter/network/redis_proxy/v2/redis_proxy.proto

@@ -22,7 +22,13 @@ message RedisProxy {
   // Name of cluster from cluster manager. See the :ref:`configuration section
   // <arch_overview_redis_configuration>` of the architecture overview for recommendations on
   // configuring the backing cluster.
-  string cluster = 2 [(validate.rules).string.min_bytes = 1];
+  //
+  // .. attention::
+  //
+  //   This field is deprecated. Use a :ref:`catch-all
+  //   cluster<envoy_api_field_config.filter.network.redis_proxy.v2.RedisProxy.PrefixRoutes.catch_all_cluster>`
+  //   instead.
+  string cluster = 2 [deprecated = true];
 
   // Redis connection pool settings.
   message ConnPoolSettings {
@@ -55,10 +61,63 @@ message RedisProxy {
     bool enable_redirection = 3;
   }
 
-  // Network settings for the connection pool to the upstream cluster.
+  // Network settings for the connection pool to the upstream clusters.
   ConnPoolSettings settings = 3 [(validate.rules).message.required = true];
 
   // Indicates that latency stat should be computed in microseconds. By default it is computed in
   // milliseconds.
   bool latency_in_micros = 4;
+
+  message PrefixRoutes {
+    message Route {
+      // String prefix that must match the beginning of the keys. Envoy will always favor the
+      // longest match.
+      string prefix = 1 [(validate.rules).string.min_bytes = 1];
+
+      // Indicates if the prefix needs to be removed from the key when forwarded.
+      bool remove_prefix = 2;
+
+      // Upstream cluster to forward the command to.
+      string cluster = 3 [(validate.rules).string.min_bytes = 1];
+    }
+
+    // List of prefix routes.
+    repeated Route routes = 1 [(gogoproto.nullable) = false];
+
+    // Indicates that prefix matching should be case insensitive.
+    bool case_insensitive = 2;
+
+    // Optional catch-all route to forward commands that doesn't match any of the routes. The
+    // catch-all route becomes required when no routes are specified.
+    string catch_all_cluster = 3;
+  }
+
+  // List of **unique** prefixes used to separate keys from different workloads to different
+  // clusters. Envoy will always favor the longest match first in case of overlap. A catch-all
+  // cluster can be used to forward commands when there is no match. Time complexity of the
+  // lookups are in O(min(longest key prefix, key length)).
+  //
+  // Example:
+  //
+  // .. code-block:: yaml
+  //
+  //    prefix_routes:
+  //      routes:
+  //        - prefix: "ab"
+  //          cluster: "cluster_a"
+  //        - prefix: "abc"
+  //          cluster: "cluster_b"
+  //
+  // When using the above routes, the following prefixes would be sent to:
+  //
+  // * 'get abc:users' would retrive the key 'abc:users' from cluster_b.
+  // * 'get ab:users' would retrive the key 'ab:users' from cluster_a.
+  // * 'get z:users' would return a NoUpstreamHost error. A :ref:`catch-all
+  //   cluster<envoy_api_field_config.filter.network.redis_proxy.v2.RedisProxy.PrefixRoutes.catch_all_cluster>`
+  //   would have retrieved the key from that cluster instead.
+  //
+  // See the :ref:`configuration section
+  // <arch_overview_redis_configuration>` of the architecture overview for recommendations on
+  // configuring the backing clusters.
+  PrefixRoutes prefix_routes = 5 [(gogoproto.nullable) = false];
 }

docs/root/intro/arch_overview/redis.rst

@@ -8,7 +8,9 @@ In this mode, the goals of Envoy are to maintain availability and partition tole
 over consistency. This is the key point when comparing Envoy to `Redis Cluster
 <https://redis.io/topics/cluster-spec>`_. Envoy is designed as a best-effort cache,
 meaning that it will not try to reconcile inconsistent data or keep a globally consistent
-view of cluster membership.
+view of cluster membership. It also supports routing commands from different workload to
+different to different upstream clusters based on their access patterns, eviction, or isolation
+requirements.
 
 The Redis project offers a thorough reference on partitioning as it relates to Redis. See
 "`Partitioning: how to split data among multiple Redis instances
@@ -22,6 +24,7 @@ The Redis project offers a thorough reference on partitioning as it relates to R
 * Detailed command statistics.
 * Active and passive healthchecking.
 * Hash tagging.
+* Prefix routing.
 
 **Planned future enhancements**:
 

docs/root/intro/version_history.rst

@@ -60,6 +60,7 @@ Version history
 * ratelimit: removed deprecated rate limit configuration from bootstrap.
 * redis: added :ref:`hashtagging <envoy_api_field_config.filter.network.redis_proxy.v2.RedisProxy.ConnPoolSettings.enable_hashtagging>` to guarantee a given key's upstream.
 * redis: added :ref:`latency stats <config_network_filters_redis_proxy_per_command_stats>` for commands.
+* redis: added :ref:`prefix routing <envoy_api_field_config.filter.network.redis_proxy.v2.RedisProxy.prefix_routes>` to enable routing commands based on their key's prefix to different upstream.
 * redis: added :ref:`success and error stats <config_network_filters_redis_proxy_per_command_stats>` for commands.
 * redis: migrate hash function for host selection to `MurmurHash2 <https://sites.google.com/site/murmurhash>`_ from std::hash. MurmurHash2 is compatible with std::hash in GNU libstdc++ 3.4.20 or above. This is typically the case when compiled on Linux and not macOS.
 * redis: added :ref:`latency_in_micros <envoy_api_field_config.filter.network.redis_proxy.v2.RedisProxy.latency_in_micros>` to specify the redis commands stats time unit in microseconds.

source/common/common/utility.h

@@ -568,8 +568,11 @@ template <class Value> struct TrieLookupTable {
    * Adds an entry to the Trie at the given Key.
    * @param key the key used to add the entry.
    * @param value the value to be associated with the key.
+   * @param overwrite_existing will overwrite the value when the value for a given key already
+   * exists.
+   * @return false when a value already exists for the given key.
    */
-  void add(const char* key, Value value) {
+  bool add(const char* key, Value value, bool overwrite_existing = true) {
     TrieEntry<Value>* current = &root_;
     while (uint8_t c = *key) {
       if (!current->entries_[c]) {
@@ -578,7 +581,11 @@ template <class Value> struct TrieLookupTable {
       current = current->entries_[c].get();
       key++;
     }
+    if (current->value_ && !overwrite_existing) {
+      return false;
+    }
     current->value_ = value;
+    return true;
   }
 
   /**
@@ -599,6 +606,31 @@ template <class Value> struct TrieLookupTable {
     return current->value_;
   }
 
+  /**
+   * Finds the entry associated with the longest prefix. Complexity is O(min(longest key prefix, key
+   * length))
+   * @param key the key used to find.
+   * @return the value matching the longest prefix based on the key.
+   */
+  Value findLongestPrefix(const char* key) const {
+    const TrieEntry<Value>* current = &root_;
+    const TrieEntry<Value>* result = nullptr;
+    while (uint8_t c = *key) {
+      if (current->value_) {
+        result = current;
+      }
+
+      // https://github.com/facebook/mcrouter/blob/master/mcrouter/lib/fbi/cpp/Trie-inl.h#L126-L143
+      current = current->entries_[c].get();
+      if (current == nullptr) {
+        return result ? result->value_ : nullptr;
+      }
+
+      key++;
+    }
+    return current ? current->value_ : result->value_;
+  }
+
   TrieEntry<Value> root_;
 };
 

source/extensions/filters/network/redis_proxy/BUILD

@@ -30,13 +30,22 @@ envoy_cc_library(
     ],
 )
 
+envoy_cc_library(
+    name = "router_interface",
+    hdrs = ["router.h"],
+    deps = [
+        ":conn_pool_interface",
+        "@envoy_api//envoy/config/filter/network/redis_proxy/v2:redis_proxy_cc",
+    ],
+)
+
 envoy_cc_library(
     name = "command_splitter_lib",
     srcs = ["command_splitter_impl.cc"],
     hdrs = ["command_splitter_impl.h"],
     deps = [
         ":command_splitter_interface",
-        ":conn_pool_interface",
+        ":router_interface",
         "//include/envoy/stats:stats_macros",
         "//include/envoy/stats:timespan",
         "//source/common/common:assert_lib",
@@ -54,7 +63,6 @@ envoy_cc_library(
     hdrs = ["conn_pool_impl.h"],
     deps = [
         ":conn_pool_interface",
-        "//include/envoy/router:router_interface",
         "//include/envoy/thread_local:thread_local_interface",
         "//include/envoy/upstream:cluster_manager_interface",
         "//source/common/buffer:buffer_lib",
@@ -97,7 +105,21 @@ envoy_cc_library(
         "//source/extensions/filters/network/common:factory_base_lib",
         "//source/extensions/filters/network/common/redis:codec_lib",
         "//source/extensions/filters/network/redis_proxy:command_splitter_lib",
-        "//source/extensions/filters/network/redis_proxy:conn_pool_lib",
         "//source/extensions/filters/network/redis_proxy:proxy_filter_lib",
+        "//source/extensions/filters/network/redis_proxy:router_lib",
+    ],
+)
+
+envoy_cc_library(
+    name = "router_lib",
+    srcs = ["router_impl.cc"],
+    hdrs = ["router_impl.h"],
+    deps = [
+        ":router_interface",
+        "//include/envoy/thread_local:thread_local_interface",
+        "//include/envoy/upstream:cluster_manager_interface",
+        "//source/common/common:to_lower_table_lib",
+        "//source/extensions/filters/network/redis_proxy:conn_pool_lib",
+        "@envoy_api//envoy/config/filter/network/redis_proxy/v2:redis_proxy_cc",
     ],
 )