[ci] Kill hanged docker build process to avoid build timeout issue.

.azure-pipelines/azure-pipelines-build.yml

@@ -109,6 +109,7 @@ jobs:
 
     buildSteps:
       - template: template-skipvstest.yml
+      - template: template-daemon.yml
       - bash: |
           set -ex
           if [ $(GROUP_NAME) == vs ]; then
@@ -168,4 +169,5 @@ jobs:
             make $BUILD_OPTIONS target/sonic-$(GROUP_NAME).bin
           fi
         displayName: "Build sonic image"
+      - template: template-stop-daemon.yml
       - template: check-dirty-version.yml

.azure-pipelines/template-daemon.yml

@@ -0,0 +1,24 @@
+steps:
+- bash: |
+    (
+      while true
+      do
+        sleep 120
+        now=$(date +%s)
+        pids=$(ps -C docker -o pid,etime,args | grep "docker build" | cut -d" " -f1)
+        for pid in $pids
+        do
+          start=$(date --date="$(ls -dl /proc/$pid --time-style full-iso | awk '{print$6,$7}')" +%s)
+          time_s=$(($now-$start))
+          if [[ $time_s -gt $(DOCKER_BUILD_TIMEOUT) ]]; then
+            echo =========== $(date +%F%T) $time_s &>> target/daemon.log
+            ps $pid &>> target/daemon.log
+            sudo kill $pid
+          fi
+        done
+      done
+    ) &
+    daemon_pid=$!
+    ps $daemon_pid
+    echo "##vso[task.setvariable variable=DAEMON_PID]$daemon_pid"
+  displayName: start daemon to kill hang docker

.azure-pipelines/template-stop-daemon.yml

@@ -0,0 +1,5 @@
+steps:
+- bash: |
+    ps $(DAEMON_PID)
+    sudo kill $(DAEMON_PID) || true
+  displayName: kill daemon process

.azure-pipelines/template-variables.yml

@@ -5,3 +5,4 @@ variables:
   SONIC_BUILD_RETRY_COUNT: 3
   SONIC_BUILD_RETRY_INTERVAL: 600
   DOCKER_BUILDKIT: 0
+  DOCKER_BUILD_TIMEOUT: 3600