使用Docker Compose部署Cassandra三节点集群，如何避免节点分裂为独立环？

环境配置 #

• 系统：已更新至最新版本的XUbuntu
• Docker环境：已配置官方Docker仓库，安装了最新版Docker工具套件，通过apt-get安装docker-compose

使用的docker-compose.yaml文件 #

version: "3.3"
 
networks:
  cassandra-net:
    driver: bridge
    
services:
 
  cassandra-1:
    image: "cassandra:latest"
    container_name: "cassandra-1"
    ports:
      - "7000:7000"
      - "9042:9042"
    networks:
      - "cassandra-net"
    volumes:
      - ./volumes/cassandra-1:/var/lib/cassandra:rw      

  cassandra-2:
    image: "cassandra:latest"
    container_name: "cassandra-2"
    environment:
      - "CASSANDRA_SEEDS=cassandra-1"
    networks:
      - "cassandra-net"
    depends_on:
      - "cassandra-1"
    volumes:
      - ./volumes/cassandra-2:/var/lib/cassandra:rw      
 
  cassandra-3:
    image: "cassandra:latest"
    container_name: "cassandra-3"
    networks:
      - "cassandra-net"
    environment:
      - "CASSANDRA_SEEDS=cassandra-1"
    depends_on:
      - "cassandra-1"
    volumes:
      - ./volumes/cassandra-3:/var/lib/cassandra:rw

节点状态检查脚本 #

docker exec -it cassandra-1 nodetool status
docker exec -it cassandra-2 nodetool status
docker exec -it cassandra-3 nodetool status

实际输出结果 #

Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address     Load        Tokens  Owns (effective)  Host ID                               Rack 
UN  172.18.0.3  252.53 KiB  16      100.0%            640dbf8a-13bb-46e5-8b1e-4542ee3352c4  rack1
UN  172.18.0.2  189.34 KiB  16      100.0%            7807001a-1885-41d1-b661-bd6c7e0db239  rack1

Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address     Load        Tokens  Owns (effective)  Host ID                               Rack 
UN  172.18.0.4  178.24 KiB  16      100.0%            fe8fb5fe-7342-4eeb-92bb-01a755ecd8ad  rack1
UN  172.18.0.2  263.65 KiB  16      100.0%            7807001a-1885-41d1-b661-bd6c7e0db239  rack1

Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address     Load        Tokens  Owns (effective)  Host ID                               Rack 
UN  172.18.0.3  178.2 KiB   16      100.0%            640dbf8a-13bb-46e5-8b1e-4542ee3352c4  rack1
UN  172.18.0.2  263.65 KiB  16      100.0%            7807001a-1885-41d1-b661-bd6c7e0db239  rack1

问题描述 #

预期每个节点都能识别集群中的三个节点（172.18.0.2、172.18.0.3、172.18.0.4），但实际每个节点仅能看到自身和种子节点cassandra-1，集群分裂成多个独立小环，无法形成统一的Cassandra集群。

解决步骤 #

1. 严格控制节点启动顺序与等待时间
   depends_on只保证容器启动顺序，不代表Cassandra服务完全就绪。正确启动流程：

   • 先启动cassandra-1：docker-compose up -d cassandra-1
   • 查看日志确认服务就绪：docker logs -f cassandra-1，直到出现Startup complete字样后，再启动其他节点：docker-compose up -d cassandra-2 cassandra-3

2. 统一种子节点配置
   Cassandra种子节点用于集群发现，建议至少配置2个种子节点避免单点故障。修改docker-compose.yaml中各节点的环境变量：

   # cassandra-1的环境变量
   environment:
     - "CASSANDRA_SEEDS=cassandra-1,cassandra-2"
   # cassandra-2的环境变量
   environment:
     - "CASSANDRA_SEEDS=cassandra-1,cassandra-2"
   # cassandra-3的环境变量
   environment:
     - "CASSANDRA_SEEDS=cassandra-1,cassandra-2"
   

3. 显式配置广播地址
   在Docker环境中，Cassandra默认的自动地址绑定可能导致节点发现异常，为每个节点添加广播地址配置（对应各自的container_name）：

   # cassandra-1添加
   environment:
     - "CASSANDRA_LISTEN_ADDRESS=auto"
     - "CASSANDRA_BROADCAST_ADDRESS=cassandra-1"
   # cassandra-2添加
   environment:
     - "CASSANDRA_LISTEN_ADDRESS=auto"
     - "CASSANDRA_BROADCAST_ADDRESS=cassandra-2"
     - "CASSANDRA_SEEDS=cassandra-1,cassandra-2"
   # cassandra-3添加
   environment:
     - "CASSANDRA_LISTEN_ADDRESS=auto"
     - "CASSANDRA_BROADCAST_ADDRESS=cassandra-3"
     - "CASSANDRA_SEEDS=cassandra-1,cassandra-2"
   

4. 清理旧数据重新初始化
   如果之前的错误启动导致数据不一致，先清理环境：

   # 停止所有容器
   docker-compose down
   # 删除本地挂载的数据目录
   rm -rf ./volumes/cassandra-1 ./volumes/cassandra-2 ./volumes/cassandra-3
   

   之后按照步骤1的正确顺序重新启动集群。

5. 验证集群状态
   启动完成后，在任意节点执行docker exec -it cassandra-1 nodetool status，确认三个节点均显示为UN状态，且每个节点的状态输出中都包含另外两个节点的信息。

内容的提问来源于stack exchange，提问作者tcs