feat(github_hooks): emit PullRequestUnmergeable event (#390)

When a pull request branch becomes unmergeable, we should emit an event,
so the UI can invalidate that branch page cache for that branch.

### Other changes

The gRPC library was updated to 1.62 because it's not possible to generate
the proto files on MacOS ARM on the version we were using.

Author: lucaspin

github_hooks/Gemfile

@@ -14,7 +14,8 @@ gem "faraday", "~> 1.3.0"
 gem "faraday_middleware" # used for json
 gem "net-http" # https://github.com/ruby/net-imap/issues/16#issuecomment-803086765
 gem 'net-imap', '~> 0.5.7'
-gem "grpc", "~> 1.57.0"
+gem "grpc", "~> 1.62.1"
+gem "googleapis-common-protos-types", "~> 1.18.0"
 gem "httparty", "~> 0.21.0"
 gem "httpclient"
 gem "json"

github_hooks/Gemfile.lock

@@ -153,11 +153,11 @@ GEM
       raabro (~> 1.4)
     globalid (1.2.1)
       activesupport (>= 6.1)
-    google-protobuf (3.25.5)
-    googleapis-common-protos-types (1.8.0)
-      google-protobuf (~> 3.18)
-    grpc (1.57.0)
-      google-protobuf (~> 3.23)
+    google-protobuf (3.25.8)
+    googleapis-common-protos-types (1.18.0)
+      google-protobuf (>= 3.18, < 5.a)
+    grpc (1.62.3)
+      google-protobuf (~> 3.25)
       googleapis-common-protos-types (~> 1.0)
     grpc-tools (1.68.1)
     hashdiff (1.1.2)
@@ -457,7 +457,8 @@ DEPENDENCIES
   factory_bot_rails (< 5)
   faraday (~> 1.3.0)
   faraday_middleware
-  grpc (~> 1.57.0)
+  googleapis-common-protos-types (~> 1.18.0)
+  grpc (~> 1.62.1)
   grpc-tools
   httparty (~> 0.21.0)
   httpclient

github_hooks/lib/semaphore/events/pull_request_unmergeable.rb

@@ -0,0 +1,24 @@
+module Semaphore::Events
+  class PullRequestUnmergeable
+
+    def self.emit(workflow, branch)
+      event = InternalApi::RepoProxy::PullRequestUnmergeable.new(
+        :project_id => workflow.project_id,
+        :branch_name => branch.name,
+        :timestamp => ::Google::Protobuf::Timestamp.new(:seconds => Time.now.to_i)
+      )
+
+      message = InternalApi::RepoProxy::PullRequestUnmergeable.encode(event)
+
+      options = {
+        :exchange => "hook_exchange",
+        :routing_key => "pr_unmergeable",
+        :url => App.amqp_url
+      }
+
+      Logman.info "Publishing pr_unmergeable event for project #{workflow.project_id}, branch #{branch.name}"
+
+      Tackle.publish(message, options)
+    end
+  end
+end

github_hooks/lib/semaphore/repo_host/hooks/handler.rb

@@ -312,7 +312,11 @@ def self.project_member?(project, github_username)
 
   def self.update_pull_request_mergeable(workflow, mergeable)
     if (branch = find_branch(workflow))
+      mergeable_before = branch.pull_request_mergeable
       branch.update(:pull_request_mergeable => mergeable)
+      if !mergeable && mergeable_before
+        Semaphore::Events::PullRequestUnmergeable.emit(workflow, branch)
+      end
     end
   end