From f8e91906179afa387cfc7bd8d432e058e46a169a Mon Sep 17 00:00:00 2001
From: Vinoth Kannan <vinothkannan@vinkas.com>
Date: Wed, 30 May 2018 16:57:40 +0530
Subject: [PATCH] FEATURE: Retry web hook when it is failed

---
 app/jobs/regular/emit_web_hook_event.rb | 15 +++++++++
 config/locales/server.en.yml            |  1 +
 config/site_settings.yml                |  2 ++
 spec/jobs/emit_web_hook_event_spec.rb   | 42 +++++++++++++++++++++++++
 4 files changed, 60 insertions(+)

diff --git a/app/jobs/regular/emit_web_hook_event.rb b/app/jobs/regular/emit_web_hook_event.rb
index db90dd04019..742c3b7f2b3 100644
--- a/app/jobs/regular/emit_web_hook_event.rb
+++ b/app/jobs/regular/emit_web_hook_event.rb
@@ -3,6 +3,8 @@ require 'excon'
 module Jobs
   class EmitWebHookEvent < Jobs::Base
     PING_EVENT = 'ping'.freeze
+    MAX_RETRY_COUNT = 4.freeze
+    RETRY_BACKOFF = 5
 
     def execute(args)
       %i{
@@ -12,6 +14,8 @@ module Jobs
         raise Discourse::InvalidParameters.new(key) unless args[key].present?
       end
 
+      @orig_args = args.dup
+
       web_hook = WebHook.find_by(id: args[:web_hook_id])
       raise Discourse::InvalidParameters.new(:web_hook_id) if web_hook.blank?
 
@@ -113,6 +117,17 @@ module Jobs
       rescue
         web_hook_event.destroy!
       end
+
+      retry_web_hook if response.status != 200
+    end
+
+    def retry_web_hook
+      if SiteSetting.retry_web_hook_events?
+        @orig_args[:retry_count] = (@orig_args[:retry_count] || 0) + 1
+        return if @orig_args[:retry_count] > MAX_RETRY_COUNT
+        delay = RETRY_BACKOFF**(@orig_args[:retry_count] - 1)
+        Jobs.enqueue_in(delay.minutes, :emit_web_hook_event, @orig_args)
+      end
     end
   end
 end
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index d9b757d94ca..d893454430e 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -1746,6 +1746,7 @@ en:
     default_categories_watching_first_post: "List of categories in which first post in each new topic will be watched by default."
 
     retain_web_hook_events_period_days: "Number of days to retain web hook event records."
+    retry_web_hook_events: "Automatically retry failed web hook events for 4 times. Time gaps between the retries are 1, 5, 25 and 125 minutes."
 
     allow_user_api_keys: "Allow generation of user API keys"
     allow_user_api_key_scopes: "List of scopes allowed for user API keys"
diff --git a/config/site_settings.yml b/config/site_settings.yml
index e808918656f..b3a480dd457 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -1633,6 +1633,8 @@ user_preferences:
 api:
   retain_web_hook_events_period_days:
     default: 30
+  retry_web_hook_events:
+    default: false
 
 user_api:
   allow_user_api_keys:
diff --git a/spec/jobs/emit_web_hook_event_spec.rb b/spec/jobs/emit_web_hook_event_spec.rb
index 97a86f66838..acc5961f3f4 100644
--- a/spec/jobs/emit_web_hook_event_spec.rb
+++ b/spec/jobs/emit_web_hook_event_spec.rb
@@ -24,6 +24,48 @@ describe Jobs::EmitWebHookEvent do
     end.to raise_error(Discourse::InvalidParameters)
   end
 
+  context 'when the web hook is failed' do
+    before do
+      SiteSetting.retry_web_hook_events = true
+      stub_request(:post, "https://meta.discourse.org/webhook_listener")
+        .to_return(body: 'Invalid Access', status: 403)
+    end
+
+    it 'retry if site setting is enabled' do
+      expect do
+        subject.execute(
+          web_hook_id: post_hook.id,
+          event_type: described_class::PING_EVENT
+        )
+      end.to change { Jobs::EmitWebHookEvent.jobs.size }.by(1)
+
+      job = Jobs::EmitWebHookEvent.jobs.first
+      args = job["args"].first
+      expect(args["retry_count"]).to eq(1)
+    end
+
+    it 'does not retry for more than maximum allowed times' do
+      expect do
+        subject.execute(
+          web_hook_id: post_hook.id,
+          event_type: described_class::PING_EVENT,
+          retry_count: described_class::MAX_RETRY_COUNT
+        )
+      end.to_not change { Jobs::EmitWebHookEvent.jobs.size }
+    end
+
+    it 'does not retry if site setting is disabled' do
+      SiteSetting.retry_web_hook_events = false
+
+      expect do
+        subject.execute(
+          web_hook_id: post_hook.id,
+          event_type: described_class::PING_EVENT
+        )
+      end.to change { Jobs::EmitWebHookEvent.jobs.size }.by(0)
+    end
+  end
+
   it 'does not raise an error for a ping event without payload' do
     stub_request(:post, "https://meta.discourse.org/webhook_listener")
       .to_return(body: 'OK', status: 200)