I want to access environment variables from my config as follows:

const config = new pulumi.Config("environment");

const var1 = config.require("VAR_NAME");
const var2 = config.require("ANOTHER_VAR_NAME");


// This works

config:
  environment:VAR_NAME: "my value"
  environment:ANOTHER_VAR_NAME: "another value"

----------------------
// This does not work

config:
  environment:
    VAR_NAME: "my value"
    ANOTHER_VAR_NAME: "another value"

It feels redundant to list the

environment:

prefix on every line. Am I missing something obvious about YAML? Why doesn't this work?

I think you are looking for structured config: https://www.pulumi.com/docs/intro/concepts/config/#structured-configuration

I'm trying to get away from structured config because I've found that it's a mess when dealing with data structures containing both secret and non-secret values

Ah yeah, so if not using structured config, then the pattern is to prefix each config variable with the namespace. https://www.pulumi.com/docs/intro/concepts/config/#configuration-keys

Do you have any experience dealing with structured config where some values are secret and some arent?

Unfortunately, I have not dug into that use-case.