Connect to Docker via Java

Question

I have Docker installed in my Windows machine and a Spring Boot app with the docker-java library running on Eclipse.

Everything works perfectly fine using this configuration:

 DockerClientConfig dockerClientConfig = DefaultDockerClientConfig.createDefaultConfigBuilder()
    .withDockerHost("tcp://localhost:2375")
    .withDockerTlsVerify(false)
    .build();

DockerHttpClient httpClient = new ApacheDockerHttpClient.Builder()
    .dockerHost(dockerClientConfig.getDockerHost())
    .sslConfig(dockerClientConfig.getSSLConfig())
    .maxConnections(100)
    .build();

DockerClient dockerClient = DockerClientImpl.getInstance(dockerClientConfig, httpClient);

Now I put my Spring Boot app within a container:

DockerFile

FROM openjdk:11
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

But now I get this error

org.apache.hc.client5.http.HttpHostConnectException: Connect to http://localhost:2375 [localhost/127.0.0.1] failed: Connection refused (Connection refused)

Any idea why it stops working when I put my code inside the container? Somehow it cannot access the docker host.

Try to use `host.docker. internal` as the host of your machine from docker. — WBLord, Jun 17 '21 at 13:08
@WBLord could you be more explicit? I use `tcp://localhost:2375` — Tiago Silva, Jun 17 '21 at 13:11
The error says `http://localhost:2375` and you're trying to use `tcp://localhost:2375` — rupweb, Aug 15 '23 at 11:04

score 0 · Answer 1 · answered Jun 17 '21 at 13:13

0

Containers are designed to be isolated. What you have to do is to establish a network between your two containers.

answered Jun 17 '21 at 13:13

Josh

69
3

1

2375 is the docker host. not another container – Tiago Silva Jun 17 '21 at 13:43

Connect to Docker via Java

1 Answers1