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Archive for July 26, 2019

Building customized postinstall scripts for AutoPkg recipes

July 26, 2019 Leave a comment

As part of some recent work, I needed to build a deployable installer package for an application named Zscaler. This application does not use an installer package, nor can it be installed as a drag-and-drop app. Instead, it uses a third party installer application to install.

Screen Shot 2019 07 26 at 4 36 20 PM 1

This is exactly the kind of situation where I want to write an AutoPkg recipe to handle building a deployable installer package for me. As part of that, I had two bits of good news:

  1. There was a publicly available download URL for the Zscaler installer app.
  2. Zscaler has instructions for installing from the command line, so I could wrap up the installer application inside an installer application and use a postinstall script to run the installation process.

Screen Shot 2019 07 26 at 2 51 06 PM

I had one bit of bad news:

The installer process included options for adding things like the Zscaler cloud instance which the app should talk to following the installation as well as various other options which probably shouldn’t be hardcoded into an Autopkg recipe. I especially shouldn’t be hardcoding my own organization’s credentials into a recipe which I was planning to share with other folks.

Normally, sensitive information is something I want to only have in an AutoPkg recipe override. Recipe overrides are locally-stored files that allow you to change certain input variables in AutoPkg recipes. Since the recipe overrides are stored locally on the Mac which is running AutoPkg and not shared with any other resources, the sensitive information is only made available to the AutoPkg installation running on that specific Mac. I’ve used this approach previously for the following:

Sensitive URLs: https://derflounder.wordpress.com/2017/06/12/autopkg-recipes-for-apple-enterprise-connect/
Signing AutoPkg-generated installer packages: https://derflounder.wordpress.com/2017/11/10/adding-installer-package-code-signing-to-autopkg-workflows/

This time though, I didn’t see a way to pass an AutoPkg recipe override’s variables to a postinstall script. I did have one idea though, which was using AutoPkg’s FileCreator processor┬áto create a customized postinstall script. I had previously used the FileCreator processor in other AutoPkg recipes to create postinstall scripts, but those scripts were self-contained and didn’t use variables from the AutoPkg recipe.

AutoPkg Adobe Creative Cloud recipe postinstall script

That said, you never know what AutoPkg can do until you try it and sure enough the FileCreator processor was able to pass recipe variables as part of creating a file. For more details, please see below the jump.

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