Docker：无法连接到弹性搜索表单Spring Boot Docker映像

Question

Dockerized Spring Boot App is not able to connect to Elastic Search server running locally at default address and port. Following exception is thrown:

2018-01-20 07:10:38.529  INFO 1 --- [           main] org.elasticsearch.client.transport       : [Gemini] failed to connect to node [{#transport#-1}{localhost}{127.0.0.1:9300}], removed from nodes list

org.elasticsearch.transport.ConnectTransportException: [][127.0.0.1:9300] connect_timeout[30s]
    at org.elasticsearch.transport.netty.NettyTransport.connectToChannelsLight(NettyTransport.java:967) ~[elasticsearch-2.4.6.jar!/:2.4.6]
    at org.elasticsearch.transport.netty.NettyTransport.connectToNode(NettyTransport.java:933) ~[elasticsearch-2.4.6.jar!/:2.4.6]
    at org.elasticsearch.transport.netty.NettyTransport.connectToNodeLight(NettyTransport.java:906) ~[elasticsearch-2.4.6.jar!/:2.4.6]
    at org.elasticsearch.transport.TransportService.connectToNodeLight(TransportService.java:267) ~[elasticsearch-2.4.6.jar!/:2.4.6]
    at org.elasticsearch.client.transport.TransportClientNodesService$SimpleNodeSampler.doSample(TransportClientNodesService.java:390) ~[elasticsearch-2.4.6.jar!/:2.4.6]

Docker File:

FROM openjdk:8
ADD target/CryptoAPI-1.0.0.jar CryptoAPI.jar
EXPOSE 80
ENTRYPOINT ["java", "-jar", "CryptoAPI.jar"]

Docker command to run the image:

docker run --net=host cryptoapi

Answer 1

If you access 127.0.0.1 within a docker container - it tries to connect to itself (in your case container with spring boot tries to access its 9300 port). The container doesn't know and shouldn't know anything about surrounding environment - that's dockers core principle.

There are some workarounds, see this thread on docker forum . But general idea is that you shouldn't try to access host machine from within a container.

The proper way would be to start elastic search within a container, establish docker network and communicate between the two containers by their names (domain names within the docker network).