Pushing images to docker registry using docker-client api

Question

While exploring docker-client api (java) what certificates are exactly required for setting up connection to the docker daemon running on a vm.

The code which I found online :

{
// Create a client based on DOCKER_HOST and DOCKER_CERT_PATH env vars
final DockerClient docker = DefaultDockerClient.fromEnv().build();

// Pull an image
docker.pull("busybox");

}

The link to above example is available at : https://github.com/spotify/docker-client

What I intend to do is access docker-daemon running on my master node(deployed through magnum api) and push my java applications docker-image onto the registry so that I can create pods on my cluster using these images.

I am not sure what more needs to be done as I am new to this.

Answer 1

I did something similar, created images on a remote docker daemon and pushed it to a repository and further spawned containers. I used docker-java client and it works fine. You might want to go through their wiki, the issues page as usual proved to be very helpful for me.

Basic Steps:

1. Basically you need to create a DockerClientConfig which is
   something like:

   public DockerClientConfig dockerClientConfig() {
      return DefaultDockerClientConfig.createDefaultConfigBuilder()
          .withDockerHost("IP_where_docker_daemon_is_running_with_port")
          .withDockerTlsVerify("Transport_Layer_Security_accepts_Boolean")
          .withDockerCertPath("If_tls_is_true")
          .build();
   }
   

2. Then you need to create a DockerClient

   public DockerClient dockerClient() {
       DockerClient dockerClient = DockerClientBuilder.getInstance(dockerClientConfig())
           .withDockerCmdExecFactory(nettyDockerCmdExecFactory())
           .build();
       return dockerClient;
   }
   

3. Now you're ready to make calls to create Image, push Image, startContainer etc.

      File baseDir = new File(appImage.getSourceUri());
   
       BuildImageResultCallback callback = new BuildImageResultCallback(){
           @Override
           public void onNext(BuildResponseItem item){
               System.out.println("It's done - > " + item);
               super.onNext(item);
           }
       };
   
       PushImageResultCallback pushImageResultCallback = new PushImageResultCallback(){
           @Override
           public void onNext(PushResponseItem item){
               System.out.println("It's done too - >" + item);
               super.onNext(item);
           }
       };
   
   
       dockerClient.buildImageCmd(baseDir).withTag(appImage.getRegistryEndpoint()+"/apps/test:" + appImage
                              .getName()).exec(callback).awaitImageId();
   
       dockerClient.listImagesCmd().withShowAll(true).exec();
   
       AuthConfig authConfig = new AuthConfig().withUsername("admin").withPassword("admin")
                                               .withRegistryAddress("http://some_ip/v2/");
   
       dockerClient.pushImageCmd(appImage.getName())
                   .withAuthConfig(authConfig)
                   .withName(appImage
                   .getRegistryEndpoint()+ "/apps/test")
                   .withTag(appImage.getName())
                   .exec(pushImageResultCallback).awaitSuccess();
   
       CreateContainerResponse containerResponse = dockerClient.createContainerCmd(appImage
           .getRegistryEndpoint()+ "/apps/test:" + appImage.getName())
           .exec();
   
       dockerClient.startContainerCmd(containerResponse.getId()).exec();
   

That should be enough to get you started.

Answer 2

Perhaps that you could also simply use Jib core APIs which is a simple Java library that doesn't need any docker installed to build + push an image!

Read this Google blog post to know more about it.