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Unknown User (tzok) 

1.1. Introduction

  • Docker is a tool which allows to start containers i.e. lightweight, isolated environments (OS, libraries, configurations)

  • To work with a container you need an image to start from

  • Images can be found in public or private repositories:

  • A container executes one or more processes in its isolated environment

  • The process might be a daemon e.g. Apache HTTP Server or it can be an interactive terminal

  • Dockerization advantages:

    • Quick prototyping and testing

      • For example, you can easily spawn multiple versions of PostgreSQL and test your SQL queries against them

    • Better dissemination

      • The product owner can share a Docker image and anyone interested can use it straight away

    • Enhanced security

      • A container is isolated and runs a limited number of processes
      • Even if it gets hacked, the rest of the system remains unharmed

    • Easier maintenance

      • The images are usually built in an automatic way via CI/CD pipelines or regularly scheduled jobs
      • No matter how complex the environment is, once the image recipe is created all interested users can instantiate containers at will

1.2. IMAS Docker

  • The IMAS environment is available under a few flavors

  • The most important is imas/ual, which contains Data Dictionary and Access Layer

  • The images are available in a private Docker registry https://rhus-71.man.poznan.pl, which requires logging in first:

    docker login rhus-71.man.poznan.pl

1.2.1. Interactive session

  • To pull the image:

    docker pull rhus-71.man.poznan.pl/imas/ual

  • To tag the image with shorter name:

    docker tag rhus-71.man.poznan.pl/imas/ual imas/ual

  • To begin an interactive session:

    docker run -it imas/ual
    • -it stands for --interactive and --tty, which allows to establish the session

1.2.2. Running codes in the container

  • A collection of simple IMAS codes to start with can be found here: https://github.com/tzok/imas-hello-world
  • The examples cover C++, Fortran, Java and Python
  • All codes create the summary IDS in shot=1 and run=1, each with a different value in the comment field
  • There is a helper Python script python/read.py which allows to verify correctness of those codes

1.2.2.1. C++

Source code of cpp/hello.cpp:

#include <UALClasses.h>
#include <pwd.h>
#include <unistd.h>

int main() {
    uid_t uid = geteuid();
    struct passwd *pw = getpwuid(uid);

    IdsNs::IDS ids(1, 1, 0, 0);
    ids.createEnv(pw->pw_name, "test", "3");

    ids._summary.ids_properties.comment = "Hello World from C++";
    ids._summary.ids_properties.homogeneous_time = 1;
    ids._summary.time.resize(1);
    ids._summary.time(0) = 0.1;
    ids._summary.put();

    ids.close();
    return 0;
}

1.2.2.2. Fortran

Source code:

program test
    use ids_routines

    character(32)       :: login
    integer             :: pulsectx
    integer             :: status
    type(ids_summary)   :: summary

    call getlog(login)
    call ual_begin_pulse_action(MDSPLUS_BACKEND, 1, 1, login, 'test', '3', pulsectx)
    call ual_open_pulse(pulsectx, FORCE_CREATE_PULSE, '', status);

    allocate(summary%ids_properties%comment(1))
    summary%ids_properties%comment(1) = 'Hello World from Fortran'
    summary%ids_properties%homogeneous_time = 1;
    allocate(summary%time(1))
    summary%time(1) = 0.1

    call ids_put(pulsectx, "summary", summary)
    call ids_deallocate(summary)
    call ual_close_pulse(pulsectx, FORCE_CREATE_PULSE, '', status)
end program test

1.2.2.3. Java

Source code:

package pl.psnc.imas;

import imasjava.imas;
import imasjava.imas.summary;
import imasjava.UALException;
import imasjava.Vect1DDouble;

public class HelloWorld {
    public static void main(String[] args) throws UALException {
        int pulseCtx = imas.createEnv(1, 1, System.getProperty("user.name"), "test", "3");

        summary s = new summary();
        s.ids_properties.comment = "Hello World from Java";
        s.ids_properties.homogeneous_time = 1;
        s.time = new Vect1DDouble(new double[] { 0.1 });

        imas.summary.put(pulseCtx, "summary", s);
    }
}

1.2.2.4. Python

Source code:

#! /usr/bin/env python
import os
import pwd
import imas

if __name__ == '__main__':
    uid = os.getuid()
    pw = pwd.getpwuid(uid)

    pulsefile = imas.ids(1, 1)
    pulsefile.create_env(pw.pw_name, 'test', '3')

    summary = pulsefile.summary
    summary.ids_properties.comment = 'Hello World from Python'
    summary.ids_properties.homogeneous_time = 1
    summary.time.resize(1)
    summary.time[0] = 0.1
    summary.put()

    pulsefile.close()

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