feat(disvocery): Add zookeeper discovery

Makefile

@@ -281,14 +281,15 @@ install: runtime
 
 	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/discovery
 	$(ENV_INSTALL) apisix/discovery/*.lua $(ENV_INST_LUADIR)/apisix/discovery/
-	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/discovery/{consul,consul_kv,dns,eureka,nacos,kubernetes,tars}
+	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/discovery/{consul,consul_kv,dns,eureka,nacos,kubernetes,tars,zookeeper}
 	$(ENV_INSTALL) apisix/discovery/consul/*.lua $(ENV_INST_LUADIR)/apisix/discovery/consul
 	$(ENV_INSTALL) apisix/discovery/consul_kv/*.lua $(ENV_INST_LUADIR)/apisix/discovery/consul_kv
 	$(ENV_INSTALL) apisix/discovery/dns/*.lua $(ENV_INST_LUADIR)/apisix/discovery/dns
 	$(ENV_INSTALL) apisix/discovery/eureka/*.lua $(ENV_INST_LUADIR)/apisix/discovery/eureka
 	$(ENV_INSTALL) apisix/discovery/kubernetes/*.lua $(ENV_INST_LUADIR)/apisix/discovery/kubernetes
 	$(ENV_INSTALL) apisix/discovery/nacos/*.lua $(ENV_INST_LUADIR)/apisix/discovery/nacos
 	$(ENV_INSTALL) apisix/discovery/tars/*.lua $(ENV_INST_LUADIR)/apisix/discovery/tars
+	$(ENV_INSTALL) apisix/discovery/zookeeper/*.lua $(ENV_INST_LUADIR)/apisix/discovery/zookeeper
 
 	$(ENV_INSTALL) -d $(ENV_INST_LUADIR)/apisix/http
 	$(ENV_INSTALL) apisix/http/*.lua $(ENV_INST_LUADIR)/apisix/http/

apisix/discovery/zookeeper/init.lua

@@ -0,0 +1,209 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+
+local core = require("apisix.core")
+local utils = require("apisix.discovery.zookeeper.utils")
+local schema = require("apisix.discovery.zookeeper.schema")
+local table = require("apisix.core.table")
+local ngx = ngx
+local ipairs = ipairs
+local log = core.log
+
+local _M = {
+    version = 0.1,
+    priority = 1000,
+    name = "zookeeper",
+    schema = schema.schema,
+}
+
+-- Global Configuration
+local local_conf
+-- Service Instance Cache（service_name -> {nodes, expire_time}）
+local instance_cache = core.lrucache.new({
+    ttl = 3600,
+    count = 1024
+})
+
+-- Timer Identifier
+local fetch_timer
+
+-- The instance list of a single service from ZooKeeper
+local function fetch_service_instances(conf, service_name)
+    -- 1. Init connect
+    local client, err = utils.new_zk_client(conf)
+    if not client then
+        return nil, err
+    end
+
+    -- 2. TODO: Create path
+    local service_path = conf.root_path .. "/" .. service_name
+    local ok, err = utils.create_zk_path(client, service_path)
+    if not ok then
+        utils.close_zk_client(client)
+        return nil, err
+    end
+
+    -- 3. All instance nodes under a service
+    local children, err = client:get_children(service_path)
+    if not children then
+        utils.close_zk_client(client)
+        if err == "not exists" then
+            log.warn("service path not exists: ", service_path)
+            return {}
+        end
+        log.error("get zk children failed: ", err)
+        return nil, err
+    end
+
+    -- 4. Parse the data of each instance node one by one
+    local instances = {}
+    for _, child in ipairs(children) do
+        local instance_path = service_path .. "/" .. child
+        local data, stat, err = client:get(instance_path)
+        if not data then
+            log.error("get instance data failed: ", instance_path, " stat:", stat, " err: ", err)
+            goto continue
+        end
+
+        -- Parse instance data
+        local instance = utils.parse_instance_data(data)
+        if instance then
+            table.insert(instances, instance)
+        end
+
+        ::continue::
+    end
+
+    -- 5. Close connects
+    utils.close_zk_client(client)
+
+    log.debug("fetch service instances: ", service_name, " count: ", #instances)
+    return instances
+end
+
+-- Scheduled fetch of all service instances (full cache update)）
+local function fetch_all_services()
+    if not local_conf then
+        log.warn("zookeeper discovery config not loaded")
+        return
+    end
+
+    -- 1. Init Zookeeper client
+    local client, err = utils.new_zk_client(local_conf)
+    if not client then
+        log.error("init zk client failed: ", err)
+        return
+    end
+
+    -- 2.  All instance nodes under a service
+    local services, err = client:get_children(local_conf.root_path)
+    if not services then
+        utils.close_zk_client(client)
+        log.error("get zk root children failed: ", err)
+        return
+    end
+
+    -- 3. Fetch the instances of each service and update the cache
+    local now = ngx.time()
+    for _, service in ipairs(services) do
+        local instances, err = fetch_service_instances(local_conf, service)
+        if instances then
+            instance_cache:set(service, nil, {
+                nodes = instances,
+                expire_time = now + local_conf.cache_ttl
+            })
+        else
+            log.error("fetch service instances failed: ", service, " err: ", err)
+        end
+    end
+
+    -- 4. Close connects
+    utils.close_zk_client(client)
+end
+
+function _M.nodes(service_name)
+    if not service_name or service_name == "" then
+        log.error("service name is empty")
+        return nil
+    end
+
+    -- 1. Get from cache
+    local cache = instance_cache:get(service_name)
+    local now = ngx.time()
+
+    -- 2. If the cache is missed or expired, actively pull (the data)）
+    if not cache or cache.expire_time < now then
+        log.debug("cache miss or expired, fetch from zk: ", service_name)
+        local instances, err = fetch_service_instances(local_conf, service_name)
+        if not instances then
+            log.error("fetch instances failed: ", service_name, " err: ", err)
+            -- Fallback: Return the old cache (if available)）
+            if cache then
+                return cache.nodes
+            end
+            return nil
+        end
+
+        -- Update the cache
+        cache = {
+            nodes = instances,
+            expire_time = now + local_conf.cache_ttl
+        }
+        instance_cache:set(service_name, nil, cache)
+    end
+
+    return cache.nodes
+end
+
+function _M.check_schema(conf)
+    return schema.check(conf)
+end
+
+function _M.init_worker()
+    -- Load configuration
+    local core_config = core.config.local_conf
+    local_conf = core_config.discovery and core_config.discovery.zookeeper or {}
+    local ok, err = schema.check(local_conf)
+    if not ok then
+        log.error("invalid zookeeper discovery config: ", err)
+        return
+    end
+
+    -- The default values
+    local_conf.connect_string = local_conf.connect_string or "127.0.0.1:2181"
+    local_conf.fetch_interval = local_conf.fetch_interval or 10
+    local_conf.cache_ttl = local_conf.cache_ttl or 30
+
+    -- Start the timer
+    if not fetch_timer then
+        fetch_timer = ngx.timer.every(local_conf.fetch_interval, fetch_all_services)
+        log.info("zk discovery fetch timer started, interval: ", local_conf.fetch_interval, "s")
+    end
+
+    -- Manually execute a full pull immediately
+    ngx.timer.at(0, fetch_all_services)
+end
+
+function _M.destroy()
+    if fetch_timer then
+        fetch_timer = nil
+    end
+    instance_cache:flush_all()
+    log.info("zookeeper discovery destroyed")
+end
+
+return _M

apisix/discovery/zookeeper/schema.lua

@@ -0,0 +1,91 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+
+local core = require("apisix.core")
+
+local schema = {
+    type = "object",
+    properties = {
+        -- ZooKeeper Cluster Addresses (separated by commas for multiple addresses)
+        connect_string = {
+            type = "string",
+            default = "127.0.0.1:2181"
+        },
+        -- ZooKeeper Session Timeout (milliseconds)
+        session_timeout = {
+            type = "integer",
+            minimum = 1000,
+            default = 30000
+        },
+        -- ZooKeeper Connect Timeout (milliseconds)
+        connect_timeout = {
+            type = "integer",
+            minimum = 1000,
+            default = 5000
+        },
+        -- Service Discovery Root Path
+        root_path = {
+            type = "string",
+            default = "/apisix/discovery/zk"
+        },
+        -- Instance Fetch Interval (seconds)
+        fetch_interval = {
+            type = "integer",
+            minimum = 1,
+            default = 10
+        },
+        -- The default weight value for service instances that do not specify a weight in ZooKeeper.
+        -- It is used for load balancing (higher weight means more traffic).
+        -- Default value is 100, and the value range is 1-500.
+        weight = {
+            type = "integer",
+            minimum = 1,
+            default = 100
+        },
+        -- ZooKeeper Authentication Information (digest: username:password):
+        -- Digest authentication credentials for accessing ZooKeeper cluster.
+        -- Format requirement: "digest:{username}:{password}".
+        -- Leave empty to disable authentication (not recommended for production).
+        auth = {
+            type = "object",
+            properties = {
+                type = {type = "string", enum = {"digest"}, default = "digest"},
+                creds = {type = "string"}  -- digest: username:password
+            }
+        },
+        -- Cache Expiration Time (seconds):
+        -- The time after which service instance cache becomes expired.
+        -- Default value is 60 seconds
+        cache_ttl = {
+            type = "integer",
+            minimum = 1,
+            default = 60
+        }
+    },
+    required = {},
+    additionalProperties = false
+}
+
+local _M = {
+    schema = schema
+}
+
+function _M.check(conf)
+    return core.schema.check(schema, conf)
+end
+
+return _M