Building a Base Image Containing Visual COBOL Build Tools for Windows

This topic outlines the steps that a Dockerfile must carry out to create a base image for Visual COBOL Build Tools for Windows.

Once you have built your Visual COBOL Build Tools for Windows base image you can then build additional images, based on the base image, that include your COBOL applications as well as Visual COBOL Build Tools for Windows. For more information on creating those additional images see Building an Image Containing an Application to use with Visual COBOL Build Tools for Windows.

Note: Remember that Visual COBOL is a development and test environment so not for use in production situations. If you want to run COBOL applications in containers in a production environment you must use containers that contain COBOL Server.

Before building a base image for Visual COBOL Build Tools for Windows you need to ensure that you have available the following:

The installable executable file for Visual COBOL Build Tools for Windows. This is vcbt_40.exe and is supplied in the Docker demonstration for the Visual COBOL Build Tools for Windows base image.
The appropriate license (.mflic) file for Visual COBOL Build Tools for Windows.
If you will be including Java support in the image, the relevant executable file to perform the installation of the JDK. You can get this file from your chosen JDK provider.

To build a base image that includes Visual COBOL Build Tools for Windows your Dockerfile needs to perform the following steps:

Specify a base image to work from. This will typically be microsoft/dotnet-framework or microsoft/dotnet-framework-build.
When creating a base image containing Visual COBOL Build Tools for Windows you might want to create two different versions of the image - a regular image (which is built from microsoft/dotnet-framework) and a "-build" image (which is built from microsoft/dotnet-framework-build). The microsoft/dotnet-framework-build image includes build-related files that are not included in microsoft/dotnet-framework, so while an image built from microsoft/dotnet-framework will let you run applications, if you want to build applications you should use microsoft/dotnet-framework-build.

Note: Because microsoft/dotnet-framework-build contains additional files that are not included in microsoft/dotnet-framework, for the sake of keeping container sizes to a minimum you should only use microsoft/dotnet-framework-build when you need the additional build-related features.

The Docker demonstration that builds the base image containing Visual COBOL Build Tools for Windows uses this approach, creating both microfocus/vcbuildtools:win_4.0 and microfocus/vcbuildtools-build:win_4.0.
Define metadata for your image. This will make it easier to establish significant details of the image when you use the docker inspect command.
Define any variables for filenames and folder locations.
Note: If you will be using this image to run applications under Enterprise Server, you need to set the MFDS_EXTERNAL_ADDR environment variable to specify a resolvable external address string. This is to enable client browsers to resolve the URLs used by ESMAC and other utilities in Enterprise Server Administration.
The value that you specify for this environment variable is used to replace the internal container address in the URL.
Copy the installable executable file for Visual COBOL Build Tools for Windows (vcbt_40.exe) from your host machine to a temporary folder in the image's filesystem, then run it to install Visual COBOL Build Tools for Windows.
When running vcbt_40.exe you need to specify the following parameters:

/q

to run the installaton silently; that is non-interactively with no user interface, using defaults for any values that are not specified elsewhere on the command line.

InstallFolder=installation-location

to specify the name of the folder into which you want to install Visual COBOL Build Tools for Windows. This a folder that you must have created on the Docker image's filesystem.

/l log-file-name

to create a log file of the installation.

accepteula=yes

to indicate that you accept the terms of the Micro Focus End User License Agreement (EULA).
Check the log file produced by the installation to ensure that the installation was successful.
Use the MFLicenseAdmin.exe utility to install the license for Visual COBOL Build Tools for Windows.
Set up the Ant and Java support.
Perform any required clean-up. This includes tasks such as resetting variables and deleting temporary folders.
Set the Docker working directory to be the folder into which you installed Visual COBOL Build Tools for Windows.

Note: Micro Focus recommends that in addition to having a Dockerfile that performs the above steps you have additional Dockerfiles to create platform-specific versions of the Visual COBOL Build Tools for Windows base image. These additional Dockerfiles will be very simple, using the Visual COBOL Build Tools for Windows base image as their base then running commands to ensure that the correct (32-bit or 64-bit) environment is set up.

You could also choose to create a base image for Visual COBOL Build Tools for Windows that doesn't include Java support. If you need to do this you would simply modify the above process to not perform the step related to setting up the Java support.

The above process is used by the Docker demonstration that creates a base image for Visual COBOL Build Tools for Windows. For more information on that demonstration, including information on all the files it contains and a detailed description of the Dockerfiles it contains, see The Docker Demonstration for the Visual COBOL Base Image.