This topic outlines the steps that a Dockerfile must carry out to create an image that contains a COBOL application that can
be run under
Visual COBOL Build Tools for Windows.
The process defined in this topic is used by the supplied container demonstrations that create images for applications that
you can use with
Visual COBOL Build Tools for Windows. When you need to create an image to contain an application of yours,
Micro Focus recommends that you base your Dockerfile on a container demonstration's Dockerfile (rather that write your Dockerfile from
scratch) because that Dockerfile already performs the steps described in this topic. For more information on one of those
container demonstrations, including information on all the files it contains, see
The
Hello World Container Demonstration.
Note: A separate document,
Best Practices for Moving Your COBOL Applications to Containers, is available that describes best practices that
Micro Focus recommends you adopt when moving an existing COBOL application to run in a containerized environment. See
Micro Focus: Best Practices for Moving Your COBOL Applications to Containers for more information.
Before you follow the steps in this topic you must have built a base image for
Visual COBOL Build Tools for Windows. For information on creating a base image for
Visual COBOL Build Tools for Windows see
Building a Base Image Containing
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 an image containing an application to
use with
Visual COBOL Build Tools for Windows you need to ensure that you have available the following:
- A base image for
Visual COBOL Build Tools for Windows. If you have not yet built such an image, see
Building a Base Image Containing
Visual COBOL Build Tools for Windows for information on how to build one.
To build an image that includes an application to
use with
Visual COBOL Build Tools for Windows your Dockerfile needs to perform the following steps:
- Specify a base image to work from. This should be an image containing only
Visual COBOL Build Tools for Windows which was built for 32-bit or 64-bit as required and includes the additional build functionality, typically
microfocus/vcbuildtools-build:win_100_x86 or
microfocus/vcbuildtools-build:win_100_x64.
See
Building a Base Image Containing
Visual COBOL Build Tools for Windows for more information.
- 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 source files for your application to a folder on the image's filesystem and set the working directory to that folder.
- Perform whatever processing you need to do on your application's source file. This would typically be compiling and building
but could be anything that you can do with
Visual COBOL Build Tools for Windows.
- Copy your built application files to the required folder on the image's filesystem and set the working directory to that folder.
- If the application is
.NET COBOL, ensure that the image includes the required support files. See
Debugging
.NET COBOL Applications Running in Containers for more information.
- Perform any required clean-up. This includes tasks such as resetting variables and deleting temporary folders.
- Specify the name of the executable to run when the image is run.