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Documentation Index

Fetch the complete documentation index at: https://developer.upsun.com/llms.txt

Use this file to discover all available pages before exploring further.

Optional in single-runtime and composable images. Upsun provides a number of ways to set variables. Variables set in your app configuration have the lowest precedence, meaning they’re overridden by any conflicting values provided elsewhere. All variables set in your app configuration must have a prefix. Some prefixes have specific meanings. Variables with the prefix env are available as a separate environment variable. All other variables are available in the PLATFORM_VARIABLES environment variable. The following example sets two variables:
  • A variable named env:AUTHOR with the value Juan that’s available in the environment as AUTHOR
  • A variable named d8config:system.site:name with the value My site rocks that’s available in the PLATFORM_VARIABLES environment variable
You can also define and access more complex values.
Last modified on April 9, 2026