TinyKVM leverages KVM virtualization to create an incredibly fast and lightweight sandbox environment specifically designed for Varnish Cache. It allows developers and operators to safely test Varnish Configuration Language (VCL) changes without impacting production systems. By booting a minimal Linux instance with a dedicated Varnish setup within a virtual machine, TinyKVM isolates experiments and ensures that faulty configurations or malicious code can't disrupt the live caching service. This provides a significantly faster and more efficient alternative to traditional testing methods, allowing for rapid iteration and confident deployments.
The blog post explores different virtualization approaches, contrasting Red Hat's traditional KVM-based virtualization with AWS Firecracker's microVM approach and Ubicloud's NanoVMs. KVM, while robust, is deemed resource-intensive. Firecracker, designed for serverless workloads, offers lightweight and secure isolation but lacks features like live migration and GPU access. Ubicloud positions its NanoVMs as a middle ground, leveraging a custom hypervisor and unikernel technology to provide a balance of performance, security, and features, aiming for faster boot times and lower overhead than KVM while supporting a broader range of workloads than Firecracker. The post highlights the trade-offs inherent in each approach and suggests that the "best" solution depends on the specific use case.
HN commenters discuss Ubicloud's blog post about their virtualization technology, comparing it to Firecracker. Some express skepticism about Ubicloud's performance claims, particularly regarding the overhead of their "shim" layer. Others question the need for yet another virtualization technology given existing solutions, wondering about the specific niche Ubicloud fills. There's also discussion of the trade-offs between security and performance in microVMs, and whether the added complexity of Ubicloud's approach is justified. A few commenters express interest in learning more about Ubicloud's internal workings and the technical details of their implementation. The lack of open-sourcing is noted as a barrier to wider adoption and scrutiny.
Austrian cloud provider Anexia has migrated 12,000 virtual machines from VMware to its own internally developed KVM-based platform, saving millions of euros annually in licensing costs. Driven by the desire for greater control, flexibility, and cost savings, Anexia spent three years developing its own orchestration, storage, and networking solutions to underpin the new platform. While acknowledging the complexity and effort involved, the company claims the migration has resulted in improved performance and stability, along with the substantial financial benefits.
Hacker News commenters generally praised Anexia's move away from VMware, citing cost savings and increased flexibility as primary motivators. Some expressed skepticism about the "homebrew" aspect of the new KVM platform, questioning its long-term maintainability and the potential for unforeseen issues. Others pointed out the complexities and potential downsides of such a large migration, including the risk of downtime and the significant engineering effort required. A few commenters shared their own experiences with similar migrations, offering both warnings and encouragement. The discussion also touched on the broader trend of moving away from proprietary virtualization solutions towards open-source alternatives like KVM. Several users questioned the wisdom of relying on a single vendor for such a critical part of their infrastructure, regardless of whether it's VMware or a custom solution.
Summary of Comments ( 40 )
https://news.ycombinator.com/item?id=43358980
HN commenters discuss TinyKVM's speed and simplicity, praising its clever use of Varnish's infrastructure for sandboxing. Some question its practicality and security compared to existing solutions like Firecracker, expressing concerns about potential vulnerabilities stemming from running untrusted code within the Varnish process. Others are interested in its potential applications, particularly for edge computing and serverless functions. The tight integration with Varnish is seen as both a strength and a limitation, raising questions about its general applicability outside of the Varnish ecosystem. Several commenters request benchmarks comparing TinyKVM's performance to other sandboxing technologies.
The Hacker News post discussing TinyKVM, a fast sandbox running on top of Varnish, has generated a moderate amount of discussion with several interesting points raised.
One commenter questions the practicality of using TinyKVM for untrusted code execution, emphasizing that full virtualization, while offering stronger isolation, often comes with performance overhead. They suggest exploring alternative sandboxing techniques like seccomp-bpf and Landlock for better performance, albeit with potentially reduced security. Another commenter echoes this sentiment, highlighting the security concerns with nested virtualization and the potential for vulnerabilities within the hypervisor itself to be exploited.
The discussion delves into the specific use case of TinyKVM within Varnish, with some commenters expressing confusion about its intended purpose. One user questions the benefit of running untrusted code within a caching layer like Varnish, suggesting it might introduce unnecessary complexity and security risks. Another user speculates about potential applications, such as running plugins or extensions within Varnish, but acknowledges the lack of clarity in the blog post regarding the specific motivations and use cases.
Several commenters express interest in the performance claims made about TinyKVM, with one highlighting the impressive boot times mentioned in the article. However, they also emphasize the importance of further benchmarking and real-world testing to validate these claims.
The conversation also touches upon the choice of Firecracker as the underlying virtualization technology, with one commenter mentioning its origins within AWS Lambda and its suitability for lightweight virtualization tasks. Another commenter raises the question of alternative sandbox solutions and wonders if there are any compelling reasons to choose TinyKVM over existing options.
Finally, there are some comments focused on the technical details of TinyKVM, with one commenter inquiring about the feasibility of running graphical applications within the sandbox and another discussing the implications of running the sandbox within a multi-tenant environment.