yq/pkg/yqlib/doc/operators/headers/env-variable-operators.md

Env Variable Operators

These operators are used to handle environment variables usage in expressions and documents. While environment variables can, of course, be passed in via your CLI with string interpolation, this often comes with complex quote escaping and can be tricky to write and read.

There are three operators:

• env which takes a single environment variable name and parse the variable as a yaml node (be it a map, array, string, number of boolean)
• strenv which also takes a single environment variable name, and always parses the variable as a string.
• envsubst which you pipe strings into and it interpolates environment variables in strings using envsubst.

Tip

To replace environment variables across all values in a document, envsubst can be used with the recursive descent operator as follows:

yq '(.. | select(tag == "!!str")) |= envsubst' file.yaml