bot: auto-merge pull request under conditions

We now allow mergify to auto-merge pull requests against the master
branch under the following conditions:

* all CI tests passed
* the PR has no label 'do-not-merge'
* the PR has the label 'ready-to-merge'
* has been approved by at least one maintainer
* has not requested changes

Signed-off-by: Sébastien Han <seb@redhat.com>

.mergify.yml

@@ -8,6 +8,7 @@ pull_request_rules:
       label:
         add:
           - ceph
+
   # if there is a conflict in a backport PR, ping the author to send a proper backport PR
   - name: ping author on conflicts
     conditions:
@@ -15,6 +16,38 @@ pull_request_rules:
     actions:
       comment:
         message: This pull request has merge conflicts that must be resolved before it can be merged. @{{author}} please rebase it. https://rook.io/docs/rook/master/development-flow.html#updating-your-fork
+
+  # automerge on master only under certain strict conditions
+  - name: automerge merge master with specific label and approvals
+    conditions:
+      - author=mergify[bot]
+      - base=master
+      - "#approved-reviews-by>=1"
+      - "#changes-requested-reviews-by=0"
+      - label!=do-not-merge
+      - label=ready-to-merge
+      - 'check-success=DCO'
+      - 'check-success=continuous-integration/jenkins/pr-head'
+      - 'check-success=canary'
+      - 'check-success=unittests'
+      - 'check-success=golangci-lint'
+      - 'check-success=codegen'
+      - 'check-success=lint'
+      - 'check-success=modcheck'
+      - 'check-success=pvc'
+      - 'check-success=pvc-db'
+      - 'check-success=pvc-db-wal'
+      - 'check-success=encryption-pvc'
+      - 'check-success=encryption-pvc-db'
+      - 'check-success=encryption-pvc-db-wal'
+      - 'check-success=encryption-pvc-kms-vault-token-auth'
+    actions:
+      merge:
+        method: merge
+        strict: false
+      dismiss_reviews: {}
+      delete_head_branch: {}
+
   # automerge backports if CI successfully ran
   # release-1.3 branch
   - name: automerge backport release-1.3
@@ -58,6 +91,7 @@ pull_request_rules:
         strict: false
       dismiss_reviews: {}
       delete_head_branch: {}
+
   # Trigger backport PRs based on label
   # release-1.3 branch
   - actions:
@@ -67,6 +101,7 @@ pull_request_rules:
     conditions:
       - label=backport-release-1.3
     name: backport release-1.3
+
   # release-1.4 branch
   - actions:
       backport: