automation: schedule an EC2Launch run on next boot

Without this, launching EC2 instances constructed from the AMI
won't go through the normal EC2 instance launch machinery. This
missing machinery does important things like set up network
routes to use the instance metadata service and process any
UserData.

Since EC2Launch now runs on subsequent boots and UserData is
processed, we needed to make setting of UserData conditional
on bootstrapping mode.

Differential Revision: https://phab.mercurial-scm.org/D7113

contrib/automation/hgautomation/aws.py

@@ -687,7 +687,9 def temporary_ec2_instances(ec2resource,
 
 
 @contextlib.contextmanager
-def create_temp_windows_ec2_instances(c: AWSConnection, config):
+def create_temp_windows_ec2_instances(
+    c: AWSConnection, config, bootstrap: bool = False
+):
     """Create temporary Windows EC2 instances.
 
     This is a higher-level wrapper around ``create_temp_ec2_instances()`` that
@@ -712,7 +714,9 def create_temp_windows_ec2_instances(c:
             'Tags': [{'Key': 'Name', 'Value': 'hg-temp-windows'}],
         }
     )
-    config['UserData'] = WINDOWS_USER_DATA % password
+
+    if bootstrap:
+        config['UserData'] = WINDOWS_USER_DATA % password
 
     with temporary_ec2_instances(c.ec2resource, config) as instances:
         wait_for_ip_addresses(instances)
@@ -1111,6 +1115,23 def ensure_windows_dev_ami(
     with INSTALL_WINDOWS_DEPENDENCIES.open('r', encoding='utf-8') as fh:
         commands.extend(l.rstrip() for l in fh)
 
+    # Schedule run of EC2Launch on next boot. This ensures that UserData
+    # is executed.
+    # We disable setComputerName because it forces a reboot.
+    # We set an explicit admin password because this causes UserData to run
+    # as Administrator instead of System.
+    commands.extend(
+        [
+            r'''Set-Content -Path C:\ProgramData\Amazon\EC2-Windows\Launch\Config\LaunchConfig.json '''
+            r'''-Value '{"setComputerName": false, "setWallpaper": true, "addDnsSuffixList": true, '''
+            r'''"extendBootVolumeSize": true, "handleUserData": true, '''
+            r'''"adminPasswordType": "Specify", "adminPassword": "%s"}' '''
+            % c.automation.default_password(),
+            r'C:\ProgramData\Amazon\EC2-Windows\Launch\Scripts\InitializeInstance.ps1 '
+            r'–Schedule',
+        ]
+    )
+
     # Disable Windows Defender when bootstrapping because it just slows
     # things down.
     commands.insert(0, 'Set-MpPreference -DisableRealtimeMonitoring $true')
@@ -1135,7 +1156,9 def ensure_windows_dev_ami(
 
     print('no suitable Windows development image found; creating one...')
 
-    with create_temp_windows_ec2_instances(c, config) as instances:
+    with create_temp_windows_ec2_instances(
+        c, config, bootstrap=True
+    ) as instances:
         assert len(instances) == 1
         instance = instances[0]