How Docker will resolve hostname or IP present in properties file? - docker

Question

I have 2 Spring Boot micro-service applications i.e web application and metastore application. This is the properties file for my web application.
spring:
thymeleaf:
prefix: classpath:/static/
application:
name: web-server
profiles:
active: native
server:
port: ${port:8383}
---
host:
metadata: http://10.**.**.***:5011
Dockerfile for web application:
FROM java:8-jre
MAINTAINER **** <******>
ADD ./ms.console.ivu-ivu.1.0.1.jar /app/
CMD chmod +x /app/*
CMD ["java","-jar", "/app/ms.console.web-web.1.0.1.jar"]
EXPOSE 8383
Dockerfile for metadata application:
FROM java:8-jre
MAINTAINER ******* <********>
ADD config/* /deploy/config/
CMD chmod +x ./deploy/config/*
COPY ./ms.metastore.1.0.1.jar /deploy/
CMD chmod +x ./deploy/ms.metastore.1.0.1.jar
CMD ["java","-jar","./deploy/ms.metastore.1.0.1.jar"]
EXPOSE 5011
I am using Mesos and Marathon for cluster management. The Marathon scripts for metastore is :-
{
"id": "/ms-metastore",
"cmd": null,
"cpus": 1,
"mem": 2000,
"disk": 0,
"instances": 0,
"acceptedResourceRoles": [
"*"
],
"container": {
"type": "DOCKER",
"docker": {
"forcePullImage": true,
"image": "*****/****:ms-metastore",
"parameters": [],
"privileged": true
},
"volumes": [],
"portMappings": [
{
"containerPort": 5011,
"hostPort": 0,
"labels": {},
"protocol": "tcp",
"servicePort": 10000
}
]
},
"networks": [
{
"mode": "container/bridge"
}
],
"portDefinitions": [],
"fetch": [
{
"uri": "file:///etc/docker.tar.gz",
"extract": true,
"executable": false,
"cache": false
}
]
}
Web marathon:
{
"id": "/ms-console",
"cmd": null,
"cpus": 1,
"mem": 2000,
"disk": 0,
"instances": 0,
"acceptedResourceRoles": [
"*"
],
"container": {
"type": "DOCKER",
"docker": {
"forcePullImage": true,
"image": "****/****:ms-console",
"parameters": [],
"privileged": true
},
"volumes": [],
"portMappings": [
{
"containerPort": 8383,
"hostPort": 0,
"labels": {},
"protocol": "tcp",
"servicePort": 10000
}
]
},
"networks": [
{
"mode": "container/bridge"
}
],
"portDefinitions": [],
"fetch": [
{
"uri": "file:///etc/docker.tar.gz",
"extract": true,
"executable": false,
"cache": false
}
]
}
Web application I am connecting to metastore with IP which is hard coded (mentioned in properties). I created docker images for both and run in my server. The metastore server now running in different machine, so my web application is unable to resolve this IP.

Answer 1

All you need to do here is expose 5011 as the host port on the metadata server running on "different machine" using -p -
docker run -d -p 5011:5011 metadata_image ....
Now your web application should be able to access metadata server by using http://$different_machine_ip:5011/
$different_machine_ip = Metadata server IP
However since they need to be tightly coupled, i would suggest you run web app & metadata server on the same machine in case your metadata server is stateless.