Variants
General purpose distributions of Linux have “packages” that are delivered by a package manager. This allows the distribution to ship a limited set of drivers, tools, and applications with the kernel; the user then adds additional packages that suits the workload after the operating system is installed.
Bottlerocket is not a general purpose Linux distribution and intentionally doesn’t have a package manager. Instead Bottlerocket has variants. Variants are pre-defined sets of drivers, tools, and applications that are tailored to a specific architecture, platform, and orchestrator (as well as a “flavor,” more on that later). For example, there is a variant that consists of everything needed to run as a Kubernetes (orchestrator) node on an aarch64 (architecture) processor in AWS EC2 (platform). Bottlerocket delivers the variant as a complete, ready-to-run image.
Variants may be specific to particular versions of the orchestrator. For example, the variant for Kubernetes 1.25 is distinct from the variant for Kubernetes 1.24.
Variants and images
Variants are a construct to identify the constituent components that are used to build an image. As a consequence, you do not directly install a variant on a machine or instance, you install an image that is a build of the components contained in the variant at a specific Bottlerocket version.
Variants and versions
The version of Bottlerocket is independent of the variant: a variant will be available across many different Bottlerocket versions. Keep in mind that Kubernetes variants are only compatible with specific versions of Kubernetes: the Kubernetes version number is distinct from the version of Bottlerocket.
Artifact file names
The file name for any Bottlerocket image artifact begins with bottlerocket and is followed by a kebab case delimited list of components.
The components in the file name follow a specific order:
[platform]-[orchestrator]-[orchestrator version](optional:-[ flavour])-[Architecture]-[version]-[commit]
Example: bottlerocket-aws-k8s-1.25-nvidia-aarch64-1.13.0...
| Platform | Orchestrator | Orchestrator Version | Flavor | Architecture | Bottlerocket version |
|---|---|---|---|---|---|
aws | k8s | 1.25 | nvidia | aarch64 | 1.13.0 |
Example: bottlerocket-vmware-k8s-1.24-x86_64-1.12...
| Platform | Orchestrator | Orchestrator Version | Flavor | Architecture | Bottlerocket version |
|---|---|---|---|---|---|
vmware | k8s | 1.24 | none | x86_64 | 1.12.0 |
When referencing variants in writing, bottlerocket- and the commit are typically omitted for brevity.
Flavors
Variants may also package in drivers for specific hardware called a “flavor.” Currently, the only flavor is ’nvidia’, which adds support for Nvidia GPUs.
Variants, updating, & migrating
You can update to a newer Bottlerocket version of the same variant (an ‘in-place update’). However, you cannot update to a different variant: that is a migration (which involves replacing a node in the orchestrated cluster).
A few examples:
| Original | New | In-Place Update | Node Replacement / Migration | Explaination |
|---|---|---|---|---|
| aws-k8s-1.24-x86_64-1.12.0 | aws-k8s-1.24-x86_64-1.13.0 | ✓ | ✓ | This is moving between versions of the same variant, so this can be accomplished by an update |
| aws-k8s-1.24-x86_64-1.12.0 | aws-k8s-1.25-x86_64-1.12.0 | ✗ | ✓ | The orchestrator version is part of the variant, so this is a migration. |
| aws-k8s-1.24-x86_64-1.12.0 | aws-k8s-1.25-x86_64-1.13.0 | ✗ | ✓ | Both the Bottlerocket version and the variant are changing so this must be accomplished by a migration. |
| aws-k8s-1.24-x86_64-1.13.0 | aws-k8s-1.24-nvidia-x86_64-1.13.0 | ✗ | ✓ | The flavor is part of the variant, so this change must be accomplished by a migration |
| aws-ecs-1-x86_64-1.13.0 | aws-k8s-1.25-x86_64-1.13.0 | ✗ | ✗ | The orchestrator has changed. The cluster must be rebuilt. |
If you are using a node replacement strategy, the distinction between migrating and updating is less important as any change is effectively a migration.