Gate: Harden helm serve playbook

This PS make the helm server more robust by moving the server to be
managed via a systemd unit.

Change-Id: I651bf3b2670812ea255c3692bd933bb6092397f9

tools/gate/playbooks/build-helm-packages/tasks/setup-helm-serve.yaml

@@ -41,11 +41,28 @@
         executable: /bin/bash
       register: helm_server_running
       ignore_errors: True
-    - name: launching local helm server via shell
+    - name: getting current host user name
       when: helm_server_running | failed
-      shell: helm serve &
+      shell: id -un
       args:
         executable: /bin/bash
+      register: helm_server_user
+    - name: moving systemd unit into place for helm server
+      when: helm_server_running | failed
+      become: yes
+      become_user: root
+      template:
+        src: helm-serve.service.j2
+        dest: /etc/systemd/system/helm-serve.service
+        mode: 0640
+    - name: starting helm serve service
+      when: helm_server_running | failed
+      become: yes
+      become_user: root
+      systemd:
+        state: restarted
+        daemon_reload: yes
+        name: helm-serve
     - name: wait for helm server to be ready
       shell: curl -s 127.0.0.1:8879 | grep -q 'Helm Repository'
       args:

tools/gate/playbooks/build-helm-packages/templates/helm-serve.service.j2

@@ -0,0 +1,11 @@
+[Unit]
+Description=Helm Server
+After=network.target
+
+[Service]
+User={{ helm_server_user.stdout }}
+Restart=always
+ExecStart=/usr/bin/helm serve
+
+[Install]
+WantedBy=multi-user.target