feat: Auth - OAuth2 (Dovecot PassDB) (#3480)

Co-authored-by: Brennan Kinney <5098581+polarathene@users.noreply.github.com>

target/scripts/start-mailserver.sh

@@ -71,6 +71,11 @@ function _register_functions() {
       ;;
   esac
 
+  if [[ ${ENABLE_OAUTH2} -eq 1 ]]; then
+      _environment_variables_oauth2
+      _register_setup_function '_setup_oauth2'
+  fi
+
   if [[ ${ENABLE_SASLAUTHD} -eq 1 ]]; then
     _environment_variables_saslauthd
     _register_setup_function '_setup_saslauthd'

target/scripts/startup/setup.d/oauth2.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+function _setup_oauth2() {
+  _log 'debug' 'Setting up OAUTH2'
+
+  # Enable OAuth2 PassDB (Authentication):
+  sedfile -i -e '/\!include auth-oauth2\.conf\.ext/s/^#//' /etc/dovecot/conf.d/10-auth.conf
+  _replace_by_env_in_file 'OAUTH2_' '/etc/dovecot/dovecot-oauth2.conf.ext'
+
+  return 0
+}

target/scripts/startup/variables-stack.sh

@@ -151,6 +151,12 @@ function __environment_variables_general_setup() {
   VARS[UPDATE_CHECK_INTERVAL]="${UPDATE_CHECK_INTERVAL:=1d}"
 }
 
+function _environment_variables_oauth2() {
+  _log 'debug' 'Setting OAUTH2-related environment variables now'
+
+  VARS[OAUTH2_INTROSPECTION_URL]="${OAUTH2_INTROSPECTION_URL:=}"
+}
+
 # This function handles environment variables related to LDAP.
 # NOTE: SASLAuthd and Dovecot LDAP support inherit these common ENV.
 function _environment_variables_ldap() {