docker内服务访问宿主机服务的实现

残酷现实

目录

• 1. 场景
  
• 2. 解决
  
• 3. 总结
  
• 4. 参考
  

1. 场景


使用windows， wsl2 进行日常开发测试工作。 但是wsl2经常会遇到网络问题。比如今天在测试一个项目，核心功能是将postgres 的数据使用开源组件synch 同步到clickhouse 这个工作。
测试所需组件

   

• postgres   
  
• kafka   
  
• zookeeper   
  
• redis   
  
• synch容器
  

最开始测试时，选择的方案是， 将上述五个服务使用 docker-compose 进行编排， network_modules使用hosts模式， 因为考虑到kafka的监听安全机制，这种网络模式，无需单独指定暴露端口。
docker-compose.yaml 文件如下

1. version: "3" services:  postgres:    image: failymao/postgres:12.7    container_name: postgres    restart: unless-stopped    privileged: true                                                      # 设置docker-compose env 文件    command: [ "-c", "config_file=/var/lib/postgresql/postgresql.conf", "-c", "hba_file=/var/lib/postgresql/pg_hba.conf" ]    volumes:      - ./config/postgresql.conf:/var/lib/postgresql/postgresql.conf      - ./config/pg_hba.conf:/var/lib/postgresql/pg_hba.conf    environment:      POSTGRES_PASSWORD: abc123      POSTGRES_USER: postgres      POSTGRES_PORT: 15432      POSTGRES_HOST: 127.0.0.1    healthcheck:      test: sh -c "sleep 5 && PGPASSWORD=abc123 psql -h 127.0.0.1 -U postgres -p 15432 -c '\q';"      interval: 30s      timeout: 10s      retries: 3    network_mode: "host"   zookeeper:    image: failymao/zookeeper:1.4.0    container_name: zookeeper    restart: always    network_mode: "host"   kafka:    image: failymao/kafka:1.4.0    container_name: kafka    restart: always    depends_on:      - zookeeper    environment:      KAFKA_ADVERTISED_HOST_NAME: kafka      KAFKA_ZOOKEEPER_CONNECT: localhost:2181      KAFKA_LISTENERS: PLAINTEXT://127.0.0.1:9092      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://127.0.0.1:9092      KAFKA_BROKER_ID: 1      KAFKA_LOG_RETENTION_HOURS: 24      KAFKA_LOG_DIRS: /data/kafka-data  #数据挂载    network_mode: "host"   producer:    depends_on:      - redis      - kafka      - zookeeper    image: long2ice/synch    container_name: producer    command: sh -c "      sleep 30 &&      synch --alias pg2ch_test produce"    volumes:      - ./synch.yaml:/synch/synch.yaml    network_mode: "host"   # 一个消费者消费一个数据库  consumer:    tty: true    depends_on:      - redis      - kafka      - zookeeper    image: long2ice/synch    container_name: consumer    command: sh -c      "sleep 30 &&      synch --alias pg2ch_test consume --schema pg2ch_test"    volumes:      - ./synch.yaml:/synch/synch.yaml    network_mode: "host"   redis:    hostname: redis    container_name: redis    image: redis:latest    volumes:      - redis:/data    network_mode: "host" volumes:  redis:  kafka:  zookeeper:

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测试过程中因为要使用 postgres, wal2json组件,在容器里单独安装组件很麻烦， 尝试了几次均已失败而告终，所以后来选择了将 postgres 服务安装在宿主机上， 容器里面的synch服务 使用宿主机的 ip,port端口。
但是当重新启动服务后，synch服务一直启动不起来， 日志显示 postgres 无法连接. synch配置文件如下

1. core:  debug: true # when set True, will display sql information.  insert_num: 20000 # how many num to submit,recommend set 20000 when production  insert_interval: 60 # how many seconds to submit,recommend set 60 when production  # enable this will auto create database `synch` in ClickHouse and insert monitor data  monitoring: true redis:  host: redis  port: 6379  db: 0  password:  prefix: synch  sentinel: false # enable redis sentinel  sentinel_hosts: # redis sentinel hosts    - 127.0.0.1:5000  sentinel_master: master  queue_max_len: 200000 # stream max len, will delete redundant ones with FIFO source_dbs:  - db_type: postgres    alias: pg2ch_test    broker_type: kafka # current support redis and kafka    host: 127.0.0.1    port: 5433    user: postgres    password: abc123    databases:      - database: pg2ch_test        auto_create: true        tables:          - table: pgbench_accounts            auto_full_etl: true            clickhouse_engine: CollapsingMergeTree            sign_column: sign            version_column:            partition_by:            settings: clickhouse:  # shard hosts when cluster, will insert by random  hosts:    - 127.0.0.1:9000  user: default  password: ''  cluster_name:  # enable cluster mode when not empty, and hosts must be more than one if enable.  distributed_suffix: _all # distributed tables suffix, available in cluster kafka:  servers:    - 127.0.0.1:9092  topic_prefix: synch

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这种情况很奇怪，首先确认 postgres, 启动，且监听端口(此处是5433) 也正常，使用localhost和主机eth0网卡地址均报错。

2. 解决


google 答案，参考 stackoverflow 高赞回答，问题解决，原答案如下

If you are using Docker-for-mac or Docker-for-Windows 18.03+, just connect to your mysql service using the host host.docker.internal (instead of the 127.0.0.1 in your connection string).
If you are using Docker-for-Linux 20.10.0+, you can also use the host host.docker.internal if you started your Docker
container with the --add-host host.docker.internal:host-gateway option.
Otherwise, read below
Use** --network="host" **in your docker run command, then 127.0.0.1 in your docker container will point to your docker host.

更多详情见 源贴
host 模式下 容器内服务访问宿主机服务
将postgres监听地址修改如下 host.docker.internal 报错解决。 查看宿主机 /etc/hosts 文件如下

1. root@failymao-NC:/mnt/d/pythonProject/pg_2_ch_demo# cat /etc/hosts# This file was automatically generated by WSL. To stop automatic generation of this file, add the following entry to /etc/wsl.conf:# [network]# generateHosts = false127.0.0.1       localhost 10.111.130.24    host.docker.internal

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可以看到，宿主机 ip跟域名的映射. 通过访问域名，解析到宿主机ip, 访问宿主机服务。
最终启动 synch 服务配置如下

1. core:  debug: true # when set True, will display sql information.  insert_num: 20000 # how many num to submit,recommend set 20000 when production  insert_interval: 60 # how many seconds to submit,recommend set 60 when production  # enable this will auto create database `synch` in ClickHouse and insert monitor data  monitoring: true redis:  host: redis  port: 6379  db: 0  password:  prefix: synch  sentinel: false # enable redis sentinel  sentinel_hosts: # redis sentinel hosts    - 127.0.0.1:5000  sentinel_master: master  queue_max_len: 200000 # stream max len, will delete redundant ones with FIFO source_dbs:  - db_type: postgres    alias: pg2ch_test    broker_type: kafka # current support redis and kafka    host: host.docker.internal    port: 5433    user: postgres    password: abc123    databases:      - database: pg2ch_test        auto_create: true        tables:          - table: pgbench_accounts            auto_full_etl: true            clickhouse_engine: CollapsingMergeTree            sign_column: sign            version_column:            partition_by:            settings: clickhouse:  # shard hosts when cluster, will insert by random  hosts:    - 127.0.0.1:9000  user: default  password: ''  cluster_name:  # enable cluster mode when not empty, and hosts must be more than one if enable.  distributed_suffix: _all # distributed tables suffix, available in cluster kafka:  servers:    - 127.0.0.1:9092  topic_prefix: synch    host: host.docker.internalcore:  debug: true # when set True, will display sql information.  insert_num: 20000 # how many num to submit,recommend set 20000 when production  insert_interval: 60 # how many seconds to submit,recommend set 60 when production  # enable this will auto create database `synch` in ClickHouse and insert monitor data  monitoring: true redis:  host: redis  port: 6379  db: 0  password:  prefix: synch  sentinel: false # enable redis sentinel  sentinel_hosts: # redis sentinel hosts    - 127.0.0.1:5000  sentinel_master: master  queue_max_len: 200000 # stream max len, will delete redundant ones with FIFO source_dbs:  - db_type: postgres    alias: pg2ch_test    broker_type: kafka # current support redis and kafka    host:     port: 5433    user: postgres    password: abc123    databases:      - database: pg2ch_test        auto_create: true        tables:          - table: pgbench_accounts            auto_full_etl: true            clickhouse_engine: CollapsingMergeTree            sign_column: sign            version_column:            partition_by:            settings: clickhouse:  # shard hosts when cluster, will insert by random  hosts:    - 127.0.0.1:9000  user: default  password: ''  cluster_name:  # enable cluster mode when not empty, and hosts must be more than one if enable.  distributed_suffix: _all # distributed tables suffix, available in cluster kafka:  servers:    - 127.0.0.1:9092  topic_prefix: synch

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3. 总结

以--networks="host" 模式下启动容器时，如果想在容器内访问宿主机上的服务， 将ip修改为`host.docker.internal`


4. 参考


https://stackoverflow.com/questions/24319662/from-inside-of-a-docker-container-how-do-i-connect-to-the-localhost-of-the-mach
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