feat: ENV_PREFIX (#9397)

docs/usage/self-hosting.md

@@ -208,6 +208,8 @@ If you are configuring using environment variables, there are two possibilities:
 
 If you combine both of the above then any single config option in the environment variable will override what's in `RENOVATE_CONFIG`.
 
+Note: it's also possible to change the default prefix from `RENOVATE_` using `ENV_PREFIX`. e.g. `ENV_PREFIX=RNV_ RNV_TOKEN=abc123 renovate`.
+
 ## Authentication
 
 Regardless of platform, you need to select a user account for `renovate` to assume the identity of, and generate a Personal Access Token.

lib/config/env.ts

@@ -6,6 +6,15 @@ import { logger } from '../logger';
 import { getOptions } from './definitions';
 import type { GlobalConfig, RenovateOptions } from './types';
 
+// istanbul ignore if
+if (process.env.ENV_PREFIX) {
+  for (const [key, val] of Object.entries(process.env)) {
+    if (key.startsWith(process.env.ENV_PREFIX)) {
+      process.env[key.replace(process.env.ENV_PREFIX, 'RENOVATE_')] = val;
+    }
+  }
+}
+
 export function getEnvName(option: Partial<RenovateOptions>): string {
   if (option.env === false) {
     return '';