Run command(s) only for codespace prebuilds

[neilconway]

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In my onCreateCommand and updateContentCommand scripts for my devcontainer, I'd like certain expensive steps to only be run for codespace prebuilds, and not in other circumstances (e.g., when someone starts the devcontainer on their local machine). Is there a canonical way to identify when a codespace is being prebuilt?

[Trimulia02]

. The easiest way is to check for a special environment variable called CODESPACE_PREBUILD. It's only set to true when a Codespace is being prebuilt, not when someone starts it up on their local machine or just creates a new one. So, in your onCreateCommand or updateContentCommand script, you can just use a simple if statement that checks for that variable. That lets you run all your super-slow setup stuff, like compiling huge projects or grabbing massive files, just once for the prebuilds. Everyone else gets a lightning-fast start without having to sit through all the heavy lifting. Easy peasy.

[neilconway]

Thank you! I was looking for something exactly like that but I couldn't find any docs on it.