Kubernetes is a robust orchestration tool for containerized application management, often deployed within virtual machines (VMs). However, you can alternatively take the bare metal deployment approach. In this article, let's explore the pros and cons of Kubernetes on bare metal comprehensively.
What is Kubernetes?
Kubernetes is a tool for managing and automating containerized workloads in your system. This tool was designed by Google and is now being maintained by the Cloud Native Computing Foundation. It is capable of managing containers across multiple hosts. It also provides mechanisms to discover and connect to services within the cluster, making sure that the right requests reach the right containers. Kubernetes gives its users high availability by replacing failed containers automatically, and distributing them while scaling based on demand. This is to ensure that your applications are running efficiently.
The platform gives users access to features like service discovery and load balancing, directing traffic to manage application performance seamlessly. With features for automated rollouts and rollbacks, Kubernetes supports Continuous Integration and Continuous Delivery workflows. This means it can undertake deployments with minimal downtime. Another one of its popular features is its configuration and secret management solutions, maintaining confidentiality for the materials that need it.
Kubernetes also supports storage orchestration, enabling flexibility to connect with different storage systems. This of course includes local and network storage to public cloud providers, giving you maximized platforms for management with significant scalability.
What is bare metal?
Bare metal refers to a computer system without any installed software like a hypervisor, an OS or applications, representing just the hardware assembly and components. It emphasizes the utility of the physical resources of a server without the layers of virtualization. Bare metal systems are mainly used for applications that require dedicated resources for optimal performance and efficiency, due to their performance-intensive nature.
Working with bare metal means you can run software directly on the server’s hardware, providing increased performance and lower latency. This also gives you more control over your system’s configurations. These features are particularly beneficial when the overhead of virtualization is too much to handle. Bare metal environments are commonly used in data centers and for tasks that demand higher computational power like scientific simulations, large-scale databases, high web traffic servers, and Kubernetes deployment where direct access to hardware is essential.
Also read: Benefits of bare metal cloud
What is Kubernetes on bare metal?
Usually, Kubernetes clusters and containers are deployed inside VMs. It happens in a cloud environment such as AWS, Azure, Google Cloud, or on-premises VMs that abstract the hardware layer. In contrast, the Kubernetes on bare metal refer to the clusters deployed directly on the physical hardware of a machine.
Kubernetes on bare metal allows Kubernetes clusters and their containers to directly access the resources of the server. Thus, it eliminates the need for hypervisors and guest operating systems to run Kubernetes clusters and containers. There are several pros to this approach, such as high performance, simplicity, and control. However, it also has some disadvantages.
Kubernetes on bare metal vs virtual machines
In bare metal environments, software applications, like Kubernetes when installed on Ubuntu, can utilize the full capacity of the underlying server without sharing or competing with other virtual instances. The direct access of bare metal allows for a more efficient utility of resources, which in turn results in higher CPU performance, memory, and I/O operations.
On the other hand, Virtual Machines (VMs) function on shared infrastructure, which allows the hypervisor layer to consume more resources to manage the virtual environment. This unfortunately could lead to potential resource contentions, which in turn could cause poor performance.
Operational complexity and control
The deployment of Kubernetes on Bare Metal is a more straightforward environment to undertake your operations as they don't require the complex management of the virtualized layer. Running Kubernetes on Bare Metal gives the user more control over their infrastructure. This allows for custom configurations and optimizations that aren’t possible with VMs. However, to reach this level of control, a higher level of hardware management expertise is required.
When it comes to VMs, they are much easier to provision and manage resources with. You can also easily get past the hurdle of managing underlying server hardware by setting up nodes as VMs and orchestrating them using the VM vendor’s orchestration tool. In addition, VMs also offer features like snapshotting and migration of instances which would be very useful when it comes to dynamic scaling in the context of disaster recovery.
Testing performance between Kubernetes on VM and bare metal
Many people who are interested in the field are aware of how much better Kubernetes cluster deployed on Bare Metal outperforms VMs. This was put to the test by Gcore.
The test included various aspects of performance like CPU speed and utility, RAM latency, storage Transactions Per Second (TPS) and its latency, and network bandwidth and its latency.
As expected the bare metal setup demonstrated superior performance across all the parameters, especially in CPU speed, where it performed twice as well as VMs. This is because VMs have to deal with additional layers of infrastructure compared to Bare Metal, such as the hypervisor and a guest operating system. Additionally, Bare Metal had RAM latency that was 3 times quicker, storage TPS that was more than double, and a network bandwidth that was 5 times greater than that of VMs. These results show that Bare Metal easily outperforms virtual machines.
Kubernetes on bare metal vs. bare metal cloud
In addition to bare metal systems, Kubernetes can also be deployed on bare metal clouds. This means leveraging dedicated physical servers provided by a cloud service, but also with the flexibility and ease of management of a cloud. So yes, the best of both worlds! Bare Metal Cloud combines the raw performance and resource optimization of traditional bare metal with the scalability of cloud environments. Organizations can provision additional servers or decommission them with ease, similar to how they would manage resources in a virtualized cloud environment. This elasticity makes it easier to handle workload spikes or growth without the need for significant upfront investment in physical hardware.
This setup gives users access to the cloud provider’s managed services like automated scaling, maintenance, and security. This is of course in addition to being able to enjoy the computing capabilities of having your dedicated hardware.
Since this environment allows organizations to have their own hardware, organizations can deploy their Kubernetes clusters on hardware, without having to share resources with other tenants, which can lead to better and more predictable performance, especially for resource-intensive applications.
In addition to these functional features, bare metal cloud providers manage the physical infrastructure needed for your system to run, including power, cooling, networking, and hardware maintenance. This means you’ll be able to focus on important tasks rather than the time-consuming daily hardware management.
Pros of Kubernetes on bare metal
Kubernetes on bare metal offers several benefits, mainly due to its direct access to the physical hardware layer of the server. The following are some major benefits.
1. Improved performance
Kubernetes clusters can access the underlying hardware of the machine they are deployed on. Hence, they can fully leverage the power of its resources, such as CPU, memory, storage, and networking resources. Unlike Kubernetes deployed on VMs, Kubernetes on bare metal does not have to go through an additional VM hypervisor layer to access them. It reduces the overhead caused by VMs.
Furthermore, there's no need for server resources to power up VM hypervisors and operating systems. Thus, Kubernetes, on bare metal deployments can dedicate more server capacity directly to Kubernetes, allowing maximum performance and resource utilization. This performance enhancement specifically benefits I/O-intensive applications, like machine learning tasks, where direct access to physical hardware can significantly accelerate processing times.
2. Better control over the environment and security
Kubernetes on bare metal allows you to configure the environment according to your specific operational needs. Unlike Kubernetes on VMs, where the management layer of the cloud provider often has control over resources, you get granular control over the resources available to the cluster. For example, you can manage storage, network interface, memory, and processing power. This level of control ensures that resources are optimized for the needs of the Kubernetes deployment without the constraints imposed by virtualization layers.
This freedom also allows configuring and fine-tuning the security settings to eliminate any security vulnerabilities that are critical for any Kubernetes deployment. For example, security admins can configure highly granular access permissions, network policies, and custom firewall rules. This enhanced control over security eliminates potential vulnerabilities in more general configurations.
3. Improved scalability and reliability
Kubernetes on bare metal allow organizations to scale the infrastructure horizontally and vertically at a more granular level to improve scalability. For example, vertical scaling can be done by upgrading existing hardware, while horizontal scaling can be done by adding more physical servers. Unlike certain limitations of pre-defined VM sizes or types, this level of freedom ensures scaling can be aligned with the specific needs of the workload.
Moreover, the ability of servers to dedicate resources to the Kubernetes cluster eliminates the risk of resource constraints. It also ensures more predictable performance. This resource availability helps maintain the reliability of critical applications by ensuring they have the necessary resources without interference from other workloads.
4. Lower costs
This approach can also reduce costs in some areas compared to Kubernetes deployments on VM providers and on-premises VMs. Cloud providers especially require long-term commitments, and the price may vary based on usage.
Bare metal deployments can be more cost-effective than cloud resources as they allow organizations to tailor hardware according to their workload requirements. Additionally, organizations can save costs on virtualization overhead since Kubernetes deployments on bare metal eliminate the need for hypervisors.
Cons of Kubernetes on bare metal
While Kubernetes on bare metal provides several benefits, there are also several cons that organizations must consider before venturing into this approach.
1. Difficulties in scaling
While Kubernetes clusters can scale vertically and horizontally on bare metal, adding and removing physical servers can lead to application downtime. It can significantly affect the availability of applications, which is a critical requirement.
Therefore, scaling Kubernetes clusters on bare metal requires careful planning and execution, load balancing, and failover systems. However, configuring scalable Kubernetes clusters can become complex as the cluster expands. This complexity comes from the need to maintain network configurations, manage storage across an increasing number of nodes, and ensure consistent performance across the cluster.
2. Complexities in setup and configuration
When deploying Kubernetes in a VM with a cloud provider or on-premises, all the setup, configuration, and management, including Kubernetes monitoring tools, is done by a dedicated party. For example, Kubernetes in cloud VMs are managed mostly by cloud providers.
Setting up a Kubernetes cluster on bare metal without the convenience of having a third party is inherently more complex. Furthermore, it requires more configurations than VMs. For example, there are manual network configurations, storage, computing resources, procurement of physical hardware, and installation, which require a thorough understanding, including Kubernetes monitoring tools.
3. Higher costs
There are some areas where costs can be reduced by deploying Kubernetes clusters on bare metal. However, it involves several infrastructure, operational, and maintenance costs. For example, physical hardware requires manual installation, cooling, and maintenance costs. If there are hardware failures, you must address them manually. More staff or outsourcing experts will be required to properly configure them. In addition, you will need to acquire and set up extra physical servers to scale up resources.
4. Challenges in backup
In VM environments, especially cloud-based VMs, backup services are often integrated and easily managed. However, bare metal deployments require custom backup solutions. It requires careful planning and execution to ensure that Kubernetes configurations, applications, and cluster state are properly backed up. This process can be more complex and resource-intensive than cloud-based solutions.
Conclusion
Kubernetes on bare metal directly deploy the cluster on the physical hardware rather than VMs. The main benefits it brings are high performance and resource utilization due to its direct access to underlying hardware resources. Some other benefits of this deployment approach include better control over the environment and security, scalability and reliability options, and cost reduction. Nonetheless, there are also disadvantages like complexity, scaling, higher costs, and backup challenges.
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