Shell script exit too early due to docker pull, while running through ProcessBuilder

Question

I have the following problem which seems to be caused by the "docker pull" in my shell script, as the pull works concurrently

#!/bin/bash   
#VARIABLES
    NAME="my-app"
    IMAGE="my-image:latest"
#DOCKER
    docker stop $NAME
    docker rm $NAME
    docker pull -q $IMAGE
    docker run --name $NAME -d -p 1234:8080 --log-opt fluentd-address=localhost:2233 $IMAGE

Running the script through the terminal works just fine everything works as expected. But when I run it with the Java's ProcessBuilder the script exits much quicker and it seems that it skips the "docker pull" step. As i am not a Java developer and I am not very well familiar with the Language I have the feeling that is something related to the multi-concurrent nature of the docker pull command and the way how the Java Process Builder executes the shell script

The Java class that runs the shell script is this

try {

    Collection<Task> tasks = taskService.getProjectTasksByProjectKey(projectId);

    Task findTask = findTaskByTaskId(tasks, taskId);
    if (findTask.getTaskId() != null) {
        ProcessBuilder pb = new ProcessBuilder(findTask.getCmdPath());
        Process process = pb.start();

        String output;

        try (InputStream in = process.getInputStream();
             InputStream err = process.getErrorStream();
             OutputStream closeOnly = process.getOutputStream()) {
            while (process.isAlive()) {
                long skipped = in.skip(in.available())
                        + err.skip(err.available());
                if(skipped == 0L) {
                    process.waitFor(5L, TimeUnit.MILLISECONDS);
                }
            }
            output = loadStream(in);
        } finally {
            process.destroy();
        }

//                String error  = loadStream(process.getErrorStream());
//                int rc = process.waitFor();

//                log.debug("exit code ->>> " + rc);
//                StringBuilder output = new StringBuilder();
//                BufferedReader reader = new BufferedReader(
//                        new InputStreamReader(process.getInputStream()));
//
//                String line;
//
//                while ((line = reader.readLine()) != null) {
//                    output.append(line + "\n");
//                }
//
//                int exitVal = process.waitFor();
//                if (exitVal == 0) {
//                    System.out.println(output);
//
//                    return output.toString();
//                } else {
//                    //abnormal...
//                }

        return output;
    }
    else {
        throw new InvalidTaskModelException(taskId);
    }
} catch (InvalidModelException e) {
    throw new InvalidModelException(projectId);
} catch (IOException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
} catch (Exception e) {
    e.printStackTrace();
}

return null;
}

private static String loadStream(InputStream s) throws Exception
{
BufferedReader br = new BufferedReader(new InputStreamReader(s));
StringBuilder sb = new StringBuilder();
String line;
while((line=br.readLine()) != null)
    sb.append(line).append("\n");
return sb.toString();
}

The commented lines are different ways I tried to do it.

If anyone encountered a similar problem any help would be much appreciated!

Answer 1

It is good that you already take care for the processes' STDOUT and STDIN. But rather than skipping copy them to System.out so you can see what is going on. I suspect something is not going as per your expectations.

Looking at the bash script you posted and the fact you are trying to run several processes: Is it possible your java code is running the bash script line by line? Be aware your java program it is not a BASH interpreter, so e.g. variable substitution should not work.