Add zuul.{pipeline,nodepool.provider,executor.hostname} to job header

These are helpful to understand the context of a running job before
logs are collected and made available.

Change-Id: I33f3f425a8008534c617422a7f77255a34f86198
Depends-On: I8d014464b3ed580d4a0fc6dbdc9a42601ff107e5

roles/emit-job-header/tasks/main.yaml

@@ -1,10 +1,16 @@
 - include_role:
     name: set-zuul-log-path-fact
 
-- debug:
-    msg: "Job {{ zuul.job }} triggered from {{ zuul.change_url }}"
-  when: zuul.change_url is defined
-
-- debug:
-    msg: "At completion, logs for this job will be available at {{ zuul_log_url }}/{{ zuul_log_path }}"
-  when: zuul_log_url is defined and zuul_log_path is defined
+- name: Print job information
+  debug:
+    msg: |
+      Job: {{ zuul.job }}
+      Pipeline: {{ zuul.pipeline }}
+      Executor: {{ zuul.executor.hostname }}
+      Provider: {{ nodepool.provider }}
+      {% if zuul.change_url is defined %}
+      Triggered by: {{ zuul.change_url }}
+      {% endif %}
+      {% if zuul_log_url is defined and zuul_log_path is defined %}
+      Log URL (when completed): {{ zuul_log_url }}/{{ zuul_log_path }}
+      {% endif %}