Add Werk #19275: Linux agent controller now available for ARM64 (aarch64)

CMK-28905

Change-Id: I4a0461d382abf6487b6e8e0e4d1a5070383e0146

Author: andiumbreit

.werks/19275.md

@@ -0,0 +1,48 @@
+[//]: # (werk v3)
+# Linux agent controller now available for ARM64 (aarch64)
+
+key        | value
+---------- | ---
+date       | 2026-02-11T15:33:53+00:00
+version    | 2.6.0b1
+class      | feature
+edition    | community
+component  | checks
+level      | 2
+compatible | no
+
+The Checkmk agent controller is now available for Linux ARM64 (aarch64) systems.
+
+Broader ARM support is one of the most popular requests in our community, this is the first step towards it. With this change, the full Checkmk agent feature set is now available on ARM64 Linux systems.
+
+## What's in
+
+### The ARM64 agent controller binary
+
+The (gzipped) ARM64 agent controller is included in all Checkmk installations and can be found under `~/share/check_mk/agents/linux/cmk-agent-ctl-aarch64.gz` in your Checkmk site.
+
+To install the Checkmk agent on ARM64 Linux, the recommended approach is to repackage the Checkmk agent `.rpm` or `.deb` package under `~/share/check_mk/agents/` and to place `cmk-agent-ctl-aarch64.gz` next to the already existing `cmk-agent-ctl.gz`.
+On agent installation, the setup scripts automatically detect the architecture and deploy the matching agent controller binary.
+
+It's currently not included in the shipped packages to keep them lightweight.
+
+### Agent bakery integration
+
+If you use the Agent Bakery, there's a new option _Architecture of the systems where the agent will be deployed_ in the _Customize agent package (Linux)_ ruleset to control which agent controller architectures are included in baked packages:
+
+* x86 64-bit only (default selected option)
+* ARM 64-bit only
+* x86 64-bit or ARM 64-bit
+
+If both target architectures are selected, the installer will handle the deployment of the correct binary, as mentioned above.
+
+## Scope of ARM support
+
+Please note that there is a slight difference between _Building a package that's meant to run on ARM64_ and _Building an ARM64 package_.
+While the core agent features are now fully supported on ARM (Transport level encryption, Push agent, Compression, etc.), agent plugins are diverse, and we cannot guarantee that every packaged plugin is compatible with Linux ARM 64-bit.
+To help you build a clean ARM 64-bit packages, we have included the following checks in the Agent Bakery:
+
+* If you choose only ARM 64-bit as the target architecture and you package an agent plugin that is unavailable for ARM, the Bakery will refuse to bake the package to prevent technical inconsistencies
+* If you choose both x86 64-bit and ARM 64-bit as target architectures and you package an agent plugin that is unavailable for ARM, a warning will be emitted during agent installation.
+
+Please note that, while including both architectures in a single package is possible, we recommend keeping your ARM and x86 packages cleanly separated.