Mixins vs. Plugins

Mixins are the building blocks for authoring bundles. They understand both Porter and CNAB, so you don’t have to, and ideally have built-in logic to make your bundles easier to author and more robust. They are involved when the bundle is built, assisting with generating the Dockerfile for the invocation image. Most importantly they are responsible for handling the actions in your porter.yaml when your bundle is run. For example, the helm mixin installs the helm CLI into the invocation image, and then uses it to execute any helm actions defined in the bundle.

I like to think of mixins as paint colors on your paint palette 🎨 that you use to create your bundle. Like paints, mixins are composable and let you build something new, more than the sum of its parts, limited only by your imagination.

Plugins extend the Porter client itself, reimplementing Porter’s default functionality. There are fixed extension points in Porter with a defined interface. For example, Porter saves installation data, credential sets and parameter sets using the local filesystem to ~/.porter by default. A plugin can change that behavior to save them to cloud storage instead.

What both mixins and plugins have in common is that anyone can create their own and distribute them, just like the ones that we install with Porter by default. The Porter team is committed to making our plugin and mixin ecosystem a level playing field with a low barrier to entry. Check out the Mixin Developer Guide to get started.

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