feat(blog) add a new post about the Update Center (6th brownout)

content/blog/2024/11/07/2024-11-07-update-center-brownouts-6.adoc

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+---
+layout: post
+title: "Brownout on Update Center (updates.jenkins.io):\n 07 and 08 November 2024"
+tags:
+- jenkins
+- jenkins-infra
+- update-center
+authors:
+- smerle33
+opengraph:
+  image: /images/post-images/2023/01/12/jenkins-newsletter/infrastructure.png
+overview: "We'll be using the new Update Center implementation in production for 1 day"
+discourse: true
+---
+
+== Summary (link:https://en.wikipedia.org/wiki/Wikipedia:Too_long;_didn%27t_read[TL;DR])
+
+Note: this is a follow up of link:/blog/2024/10/24/update-center-brownouts-5/[the 24 and 25 October 2024 24 hours brownout].
+
+The service link:https://updates.jenkins.io will switch its implementation to a new system during 1 day:
+
+- From Thursday 7 November 2024 09:00 am UTC until Friday 8 November 2024 09:00 am UTC
+
+All Jenkins users are impacted but should not see any functional change.
+
+⚠️ Please check that your organization respects the advertised DNS TTL or you might be stuck in the brownout longer than expected.
+
+Under the hood, any HTTP request made to this service will be redirected to a mirror close to the users' location during these brownouts.
+
+== What is the "Update Center"?
+
+Jenkins link:https://updates.jenkins.io[Update Center] is a web server at the core of the Jenkins public infrastructure that distributes the plugins, tool installers, and versions index to all Jenkins servers across the world.
+
+From the installation wizard to regular plugin updates, if you run Jenkins, then you use this service under the hood.
+
+Today, it serves around 50 Tb of data (outbound bandwidth) each month from a single virtual machine on AWS, which costs around $6,000 per month.
+
+The Jenkins infrastructure team has worked relentlessly over the past years to implement a new sustainable implementation for this service in order to sustain and improve it.
+
+The new Update Center implementation features a highly available system that redirects user requests to a download mirror close to their location.
+Additional information is available in the link:https://github.com/jenkins-infra/helpdesk/issues/2649[GitHub issue].
+
+== Why this Sixth "link:https://en.wikipedia.org/wiki/Brownout_(electricity)[Brownout]"?
+
+Our functional tests and performance tests are meeting our expectations after the initial work and the five brownouts we ran.
+
+However the previous (fifth) brownout raised 2 issues:
+
+- We miss some directory listings that are present on the current infra and are not available on mirrors
+
+- We've also added log retain from Cloudflare to Datadog that should help if HTTP/404 errors still occur after 8-9 hours or production usage due to network file share (SMB/CIFS) issues with Apache. The service is self-healing but we are trying to fine-tune this: if it fails, then we'll have to update the Apache architecture to stop using a network file share. See https://github.com/jenkins-infra/helpdesk/issues/4312 for details.
+
+As such, a sixth brownout serves to verify the above (minor) problems are solved under a production workload, this should be the last brownout.
+
+We plan a full migration to this new infrastructure for Monday 18 November, more information on this to come.
+
+== How
+
+Both current and new Update Centers are updated at the same time and serve the same index.
+
+Starting 12 weeks ago, the Jenkins infrastructure has been using the new Update Center (link:https://azure.updates.jenkins.io[azure.updates.jenkins.io]) with a client-side DNS override (`updates.jenkins.io` hostname points to this new service).
+
+During this brownout, we'll simply switch the DNS entry `updates.jenkins.io` to this new service and watch for the logs and error rate.
+At the end, we'll switch DNS back to the normal service and then analyze metrics and logs to see how the system behaved.
+
+We are confident the new system will perform as expected.
+
+Please refer to the link:https://github.com/jenkins-infra/helpdesk/issues/2649[helpdesk ticket] for more information.