Industrial Edge App Development Hints

This chapter will give you best practices and advice for your development of Industrial Edge apps.

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Always use Docker official or certified images for use in productive environments.

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An image should always have a version and clearly defined tags.

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Avoid using latest tagged images. It will check for newest release.

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Keep your images small by build patterns (e.g. alpine) and install only required/necessary packages.

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Divide your app in microservices. One container should only execute one single task.

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Use multistage builds to reduce container sizes. Further information can be found here.

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Comments on Dockerfile will help to improve understanding. Add an additional maintainer comment for every change in the file.

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Only expose ports when it is necessary.

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Reduce security risks by not using root user inside of a container. Only let containers run in privileged mode if it is necessary. For more information please see here.

Small Docker images include less packages and other dependencies. This will reduce effort on open source software and license clearing as well as possible bugs and vulnerabilities. It will increase the upload of an app to the Industrial Edge Management as well as the update or deployment on Industrial Edge Devices.

The Industrial Edge uses the native supported restart policies provided by Docker. The restart policies control whether a container start automatically when it exits or when the Industrial Edge Device restarts.

The restart policy options are described in the table below:

Restart option	Description
no	Default behavior. Not automatically restart of container.
on-failure	Restart the container if it exits due to an error, which manifests as a non-zero exit code.
always	Always restart the container if it stops. If it is stopped manually, it is restarted only when Docker daemon restarts or the container is manually restarted
unless-stopped	similar to always, except that when the container is stopped, it is not restarted even after Docker daemon restart.