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• Python® is a frequently used scripting language available for Linux, MacOS, Windows and other platforms.
• Docker® offers a Python® SDK to manage containers, see https://docs.docker.com/engine/api/sdk/
• This article explains how to use the Python® SDK for Docker® with JS7 job scripts.

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• Install the Python® SDK as available from https://github.com/docker/docker-py
  
  

  Code Block
  language bash title Install docker-py plugin
  pip install docker

  
  

  • Explanation:
    • Python® has to be available on the machine that the JS7 Agent is operated for. This includes Agents operated on premises and with Docker® containers.
    • This is just an example, there are more ways how to install the Python® SDK for Docker®.
      
      

• Create a workflow with a shell job that imports the Python® SDK like this:
  
  

  Code Block
  language bash title Import docker-py plugin with Agents operated for Unix
  #!/usr/bin/python import docker client = docker.from_env() ...

  Code Block
  language bash title Import docker-py plugin with Agents operated for Windows
  @@findstr/v "^@@f.*&" "%~f0"|python.exe -&goto:eof import docker client = docker.from_env() ...

  
  Explanation:

  • For details how to invoke Python® from shell jobs see JS7 - How to run Python scripts from jobs.
    
    

• Create JS7 - Job Resources for your containers.
  • Best practice is to use one a Job Resource per container.
  • This allows to specify any properties of a container such as image name, host name, container name, mounts etc. from variables of a Job Resource.

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Download (upload .json): agent-2-0-standalone.jobresource.json

When adding managing a Job Resource this offers two sub-views:

• The Arguments sub-view that allows to specify specifying variables holding which hold pairs of variable names and values.
  • Arguments can be used for parameterization of JVM jobs and they can be used in workflow instructions such as the JS7 - If Instruction.
• The Environment Variables sub-view that allows to specify specifying environment variables from pairs of names and values that are forwarded to shell jobs.
  
  • Environment Variables can be used of for parameterization of shell jobs.
• The below names and values are an example examples for frequently used parameters when setting up containers, for example with the docker run command:
  • repository_name: Identifier of the repository
  • image_name: Identifier of the image that is used to instantiate the container.
  • container_name: Name assigned the container.
  • host_name:  Hostname (FQDN) assigned the container.
  • etc.
    
    

Consider the below example of the Environment Variables sub-view:

• Names of environment variables can be freely chosen within the limits of the operating system. Names are stored with uppercase letters.
• The values of environment variables reference variables previously configured with the Arguments sub-view.
  
  • This allows to use variables from both JVM jobs and shell jobs.
  • As an alternative it is possible to directly assign strings to values of environment variables and not to use the Arguments sub-view.
    
    

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• Download (upload .json): pdStartContainer.workflow.json
• The job is assigned the agent-2-0-standalone Job Resource that holds the parameterization of the container that should be started.
  
  

The job script of the single job in this workflow looks like this:

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Explanation:

• The job script looks fairly complex uses a number of parameters as it maps all options used to run a JS7 Agent from a Docker® container explained with JS7 - Agent Installation for Docker Containers. 
• The relevant part is the client.containers.run() function that is parameterized with frequently used options to specify the image name, the hostname, network name etc.
• Environment variables are available from the assigned Job Resource.
• The optional part includes to display displaying log output created on start-up of the container using the container.logs() function.

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