From 10cf34128df329302a8bf7fb3fa4f0391e09c81a Mon Sep 17 00:00:00 2001
From: Giacomo Marciani <mgiacomo@amazon.com>
Date: Tue, 16 Dec 2025 12:31:41 -0500
Subject: [PATCH] [Build] Ubuntu: disable snap refresh during AMI build to
 prevent background updates.

This is to prevent side effects, such as reboot failure caused by background update onf SSM agent.
---
 .../imagebuilder/parallelcluster.yaml         | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/cli/src/pcluster/resources/imagebuilder/parallelcluster.yaml b/cli/src/pcluster/resources/imagebuilder/parallelcluster.yaml
index 07ba029660..071012ee2d 100644
--- a/cli/src/pcluster/resources/imagebuilder/parallelcluster.yaml
+++ b/cli/src/pcluster/resources/imagebuilder/parallelcluster.yaml
@@ -34,6 +34,21 @@ phases:
                 *) echo "Unsupported OS: $RELEASE" && exit {{ FailExitCode }} ;;
               esac
 
+      # Disable snap refresh to prevent background updates during build (Ubuntu only)
+      - name: DisableSnapRefresh
+        action: ExecuteBash
+        inputs:
+          commands:
+            - |
+              set -x
+              OS="{{ build.OperatingSystemName.outputs.stdout }}"
+              if [[ $OS =~ ^ubuntu ]]; then
+                # Wait for any in-progress snap operations to complete, then stop and disable
+                snap watch --last=auto-refresh 2>/dev/null || true
+                systemctl stop snapd.refresh.timer
+                systemctl disable snapd.refresh.timer
+              fi
+
       # Initialize system information and URLs
       - name: SystemInfo
         action: ExecuteBash
@@ -260,6 +275,12 @@ phases:
                  echo "SSM agent is installed by default"
               fi
               
+              # Re-enable snap refresh timer (Ubuntu only)
+              if [[ $OS =~ ^ubuntu ]]; then
+                systemctl enable snapd.refresh.timer
+                systemctl start snapd.refresh.timer
+              fi
+              
               # Final cleanup
               rm -f /opt/parallelcluster/system_info
               /usr/local/sbin/ami_cleanup.sh "${CfnParamIsOfficialAmiBuild}"