docker-compose UnknownHostException : but docker run works

user_9760480 0
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I have a docker image (lfs-service:latest) that I'm trying to run as part of a suite of micro services.

  • RHELS 7.5
  • Docker version: 1.13.1
  • docker-compose version 1.23.2
  • Postgres 11 (installed on RedHat host machine)

The following command works exactly as I would like:

docker run -d \
    -p 9000:9000 \
    -v "$PWD/lfs-uploads:/lfs-uploads" \
    -e "SPRING_PROFILES_ACTIVE=dev" \
    -e dbhost=$HOSTNAME \
    --name lfs-service \
    [corp registry]/lfs-service:latest

This successfully:

  • creates/starts a container with my Spring Boot Docker image on port 9000
  • writes the uploads to disk into the lfs-uploads directory
  • and connects to a local Postgres DB that's running on the host machine (not in a Docker container).

My service works as expected. Great!

Now, my problem:

I'm tring to run/manage my services using Docker Compose with the following content (I have removed all other services and my api gateway from docker-compose.yaml to simplify the scenario):

version: '3'
services:
    lfs-service:
        image: [corp registry]/lfs-service:latest
        container_name: lfs-service
        stop_signal: SIGINT
        ports:
            - 9000:9000
        expose:
            - 9000
        volumes:
            - "./lfs-uploads:/lfs-uploads"
        environment:
            - SPRING_PROFILES_ACTIVE=dev
            - dbhost=$HOSTNAME

Relevant entries in application.yaml:

spring:
    profiles: dev
    datasource:
        url: jdbc:postgresql://${dbhost}:5432/lfsdb
        username: [dbusername]
        password: [dbpassword]
    jpa:
        properties:
            hibernate:
                dialect: org.hibernate.dialect.PostgreSQLDialect
        hibernate:
            ddl-auto: update

Execution:

docker-compose up  

...
The following profiles are active: dev
...
Tomcat initialized with port(s): 9000 (http)
...
lfs-service    | Caused by: java.net.UnknownHostException: [host machine hostname]
lfs-service    |        at 
java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184) ~[na:1.8.0_181]
lfs-service    |        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_181]
lfs-service    |        at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_181]
lfs-service    |        at org.postgresql.core.PGStream.<init>(PGStream.java:70) ~[postgresql-42.2.5.jar!/:42.2.5]
lfs-service    |        at org.postgresql.core.v3.ConnectionFactoryImpl.tryConnect(ConnectionFactoryImpl.java:91) ~[postgresql-42.2.5.jar!/:42.2.5]
lfs-service    |        at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:192) ~[postgresql-42.2.5.jar!/:42.2.5]
...
lfs-service    | 2019-01-11 18:46:54.495  WARN [lfs-service,,,] 1 --- [           main] o.s.b.a.orm.jpa.DatabaseLookup           : Unable to determine jdbc url from datasource
lfs-service    |
lfs-service    | org.springframework.jdbc.support.MetaDataAccessException: Could not get Connection for extracting meta-data; nested exception is org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.postgresql.util.PSQLException: The connection attempt failed.
lfs-service    |        at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:328) ~[spring-jdbc-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
lfs-service    |        at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:356) ~[spring-jdbc-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
...

Both methods of starting should be equivalent but obviously there's a functional difference... Any ideas on how to resolve this issue / write a comperable docker-compose file which is functionally identical to the "docker run" command at the top?

NOTE: I've also tried the following values for dbhost: localhost, 127.0.0.1 - this won't work as it attempts to find the DB in the container, and not on the host machine.

docker-compose docker
2 Answers

CORRECTION: Unfortunately, while this solution works in the simplest use case - it will break Eureka & API Gateways from functioning, as the container will be running on a separate network. I'm still looking for working solution.

To anyone looking for a solution to this question, this worked for me:

docker-compose.yaml:

lfs-service:
    image: [corp repo]/lfs-service:latest
    container_name: lfs-service
    stop_signal: SIGINT
    ports:
        - 9000:9000
    expose:
        - 9000
    volumes:
        - "./lfs-uploads:/lfs-uploads"
    environment:
            - SPRING_PROFILES_ACTIVE=dev
            - dbhost=localhost  
    network_mode: host

Summary of changes made to docker-compose.yaml:

  • change $HOSTNAME to "localhost"
  • Add "network_mode: host"

I have no idea if this is the "correct" way to resolve this, but since it's only for our remote development server the solution is working for me. I'm open to suggestions if you have a better solution.

user_97604800

Working solution

The simple solution is to just provide the host machine IP address (vs hostname). 

    environment:
            - SPRING_PROFILES_ACTIVE=dev
            - dbhost=172.18.0.1

Setting this via an environment variable would probably be more portable:

export DB_HOST_IP=172.18.0.1

docker-compose.yaml

    environment:
            - SPRING_PROFILES_ACTIVE=dev
            - dbhost=${DB_HOST_IP}
user_97604800
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