copr-fe: make copr-frontend-upgrade.yml more usable

Without shutting httpd down, sometimes - when there's high enough load -
post scriptlet of copr-frontend takes too long to finish (restarging
httpd, gently waiting for existing connections).  But that makes the
outage window larger as httpd doesn't accept the new connections when
shutting down.

So automatize (forced) shutdown of httpd first (when there's existing
frontend update) -> upgrade the package -> run the migrations -> and
make httpd started again.

playbooks/manual/copr/copr-frontend-upgrade.yml

@@ -16,6 +16,24 @@
   - name: Generic upgrade tasks for copr servers
     import_tasks: _generic_tasks.yml
 
+  - name: Check for copr-frontend update
+    shell: dnf clean expire-cache ; dnf check-update copr-frontend
+    register: frontend_has_update
+    changed_when: "frontend_has_update.rc != 0"
+    failed_when: false
+
+  - name: Check if HTTPD is running
+    shell: systemctl status httpd
+    register: httpd_running
+    changed_when: "httpd_running.rc != 0"
+    failed_when: false
+
+  - name: Shutdown httpd to allow running DB migrations
+    shell: timeout 20 systemctl stop httpd || systemctl kill httpd
+    when:
+    - frontend_has_update.changed
+    - httpd_running.changed
+
   - name: Upgrade copr-frontend packages
     dnf:
       state: latest
@@ -24,12 +42,6 @@
       - copr-frontend-fedora
       - copr-selinux
       - python3-copr-common
-      update_cache: true
-
-  - name: cache the new package version
-    copy: content="{{ ansible_facts.packages['copr-frontend'][0].version }}"
-          dest="{{ cache_file }}"
-    register: version_file
 
   - name: upgrade db to head
     command: alembic-3 upgrade head
@@ -37,7 +49,10 @@
     become_user: copr-fe
     args:
       chdir: /usr/share/copr/coprs_frontend/
-    when: version_file.changed
+    when: frontend_has_update.changed
+
+  - name: make httpd started
+    service: name=httpd state=started
 
   handlers:
   - import_tasks: "{{ handlers_path }}/restart_services.yml"