Add zuul_return call into upload-logs role

We can pass in the fileserver, but if you're using upload-logs, you're
going to need it to return data, so move this functionality into the
role.

Change-Id: I987b1060acd3e6d96519010673fd21eba781f162

roles/upload-logs/README.rst

@@ -4,6 +4,10 @@ This uploads logs to a static webserver using SSH.
 
 **Role Variables**
 
+.. zuul:rolevar:: zuul_log_url
+
+   Base URL where logs are to be found.
+
 .. zuul:rolevar:: zuul_logserver_root
    :default: /srv/static/logs
 

roles/upload-logs/tasks/main.yaml

@@ -34,3 +34,12 @@
     src: "{{ zuul.executor.log_root }}/job-output.txt.gz"
     dest: "{{zuul_logserver_root}}/{{ log_path }}/job-output.txt.gz"
     verify_host: true
+
+  post_tasks:
+    - name: Return log URL to Zuul
+      delegate_to: localhost
+      zuul_return:
+        data:
+          zuul:
+            log_url: "{{ zuul_log_url }}/{{ log_path }}/"
+      when: zuul_log_url is defined