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• Define build steps in a Dockerfile to create package files within the running Docker image
• Define an entrypoint command (a shell script) that copies all package files to a specified directory
• Launch the image so the entrypoint command runs and the package files are copied to a mounted volume
• Run a Ruby script "packagecloud_push" to publish the package files to the PackageCloud site

A Note that a package file can only be published exactly once - the PackageCloud site blocks overwriting of existing files.

Installing Packages

Package files can be downloaded and installed from the command line.  For example, here's how to install a recent version of the RMr library in a Dockerfile using an Debian/Ubuntu base:

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