LinkedIn, owned by Microsoft, is transitioning to Microsoft’s in-house Linux platform, signaling a potential overhaul of the previously utilized CBL-Mariner distribution.
In a detailed post on the LinkedIn Engineering blog by Ievgen Priadka titled Navigating the transition: adopting Azure Linux as LinkedIn’s operating system, a significant internal engineering project is revealed. The article outlines the steps necessary to transition the majority of their systems from the now unsupported CentOS 7 to Microsoft Azure Linux, a distribution that evolved from and supplanted the earlier CBL-Mariner.
The shift to Azure Linux marks a critical phase in LinkedIn’s evolution since its acquisition by Microsoft in 2016. Despite the acquisition, as of the end of the previous year, reports indicated that plans to transition to Azure had been scrapped, occurring shortly after a significant reduction in workforce, where nearly 700 staff, mostly from R&D, were let go.
Spanning over 3,500 words, Priadka’s blog post is comprehensive, likely vetted by multiple levels of marketing and management personnel, ensuring it is devoid of potentially sensitive content. Yet, it retains insightful details, including a notably understated remark reflecting on the process.
However, with the shift to CentOS Stream, users felt uncertain about the project’s direction and the timeline for updates. This uncertainty created some concerns about the reliability and support of CentOS as an operating system.
The manner in which Red Hat redefined its free distro has caused industry-wide consternation and even outrage, but it was unexpected that Microsoft would also be impacted. It is interesting that Priadka mentions “strong vendor support,” defined as “having support from the OS vendor or a reliable support provider” as a motivator. This is not necessarily a critique of Red Hat, as they did not officially support CentOS, but it does highlight commendation for the Azure Linux team, suggesting they provide support comparable to dedicated vendors that offer paid support for CentOS.
The technical details shared are notable as well. For instance, LinkedIn uses the XFS file system, which is also the default on RHEL, apart from Hadoop, necessitating that the Azure Linux team incorporate support for XFS. There’s also mention of some usage of both CentOS and RHEL. Furthermore, the team has developed a tool to facilitate deployments via MaaS (Metal as a Service), a service provided by Canonical that supports various distributions, indicating that LinkedIn’s stack may also include some elements of Ubuntu.
Some details hint at what were likely significant challenges during deployment. LinkedIn utilized DKMS for on-the-fly driver integration into its kernels, indicating the likely use of Nvidia cards. However, given Azure’s requirement for signed kernels, Microsoft created a repository of pre-signed kernels compatible with the hardware being used. The description regarding container images may be unclear, but Microsoft has established its internal container image repository for Azure Linux VMs.
The narrative also touches on what the teams opted not to do, which reveals much about their approach. Initially, development was conducted on a robust CentOS desktop VM that included a window manager. However, Azure Linux lacks a GUI or desktop environment, and no such features have been incorporated. They have, however, devised a method to link local IDEs to remote Azure Linux VMs equipped with GPUs—spanning over 1,500 units across four distinct regions. Mention is made of Microsoft’s own VS Code and JetBrains’ IntelliJ. Given that LinkedIn was established in 2003, its technologies span over two decades and involve numerous vendor components.
Microsoft’s tradition of using its own products, even when integrating acquisitions into its ecosystem has proved challenging. It acquired Hotmail in 1997, yet as reported by Register in 1999, it still operated on a blend of Apache on FreeBSD, with database servers powered by Sun Solaris. At the time, Windows NT 4 Server was inadequate for the task. It wasn’t until the release of Windows Server 2000 that Microsoft began transitioning, as detailed by The Reg in 2000. Microsoft extensively documented this transition in a report titled Converting a UNIX .COM Site to Windows. Even by 2003, this transformation was ongoing.
The result of this major undertaking was significant improvements in the abilities, compatibility, and also stability of Windows Server. “Dogfooding” is an important effort. This vulture has in the past been a member of staff at two of the big three enterprise Linux vendors, and I speak from personal experience when I say that those companies relied heavily on external third-party vendors for their IT infrastructure – and, as far as I know, still do.
Microsoft is doing the right thing here, shouldering the burden, and considerable cost, of moving its own internal infrastructure to its own products. This can only be good for Azure Linux, and indeed, for Azure in general. Its fairly obscure and limited little Linux distro is growing up fast, and we’d bet on major functional improvements coming in a future release.
And, indirectly, it’s all thanks to Red Hat. ®
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