docker内服务访问宿主机服务的实现

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

1. postgres
2. kafka
3. zookeeper
4. redis
5. 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

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:

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

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

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 * 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

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 = false
127.0.0.1       localhost
 
10.111.130.24    host.docker.internal

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

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.internal
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: 
    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

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

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