Restrict a Container's Access to Resources with AppArmor [page]deterministic

tutorials

This page shows you how to load AppArmor profiles on your nodes and enforce those profiles in Pods. To learn more about how Kubernetes can confine Pods using AppArmor, see [Linux kernel security constraints for Pods and containers](/docs/concepts/security/linux-kernel-security-constraints/#apparmor).

* See an example of how to load a profile on a Node * Learn how to enforce the profile on a Pod * Learn how to check that the profile is loaded * See what happens when a profile is violated * See what happens when a profile cannot be loaded

AppArmor is an optional kernel module and Kubernetes feature, so verify it is supported on your Nodes before proceeding:

1. AppArmor kernel module is enabled -- For the Linux kernel to enforce an AppArmor profile, the AppArmor kernel module must be installed and enabled. Several distributions enable the module by default, such as Ubuntu and SUSE, and many others provide optional support. To check whether the module is enabled, check the `/sys/module/apparmor/parameters/enabled` file:

```shell cat /sys/module/apparmor/parameters/enabled Y ```

The kubelet verifies that AppArmor is enabled on the host before admitting a pod with AppArmor explicitly configured.

1. Container runtime supports AppArmor -- All common Kubernetes-supported container runtimes should support AppArmor, including [containerd](#gloss:containerd) and [cri-o](#gloss:cri-o). Please refer to the corresponding runtime documentation and verify that the cluster fulfills the requirements to use AppArmor.

1. Profile is loaded -- AppArmor is applied to a Pod by specifying an AppArmor profile that each container should be run with. If any of the specified profiles are not loaded in the kernel, the kubelet will reject the Pod. You can view which profiles are loaded on a node by checking the `/sys/kernel/security/apparmor/profiles` file. For example:

```shell ssh gke-test-default-pool-239f5d02-gyn2 "sudo cat /sys/kernel/security/apparmor/profiles | sort" ``` ``` apparmor-test-deny-write (enforce) apparmor-test-audit-write (enforce) docker-default (enforce) k8s-nginx (enforce) ```

For more details on loading profiles on nodes, see [Setting up nodes with profiles](#setting-up-nodes-with-profiles).

## Securing a Pod

Prior to Kubernetes v1.30, AppArmor was specified through annotations. Use the documentation version selector to view the documentation with this deprecated API.

AppArmor profiles can be specified at the pod level or container level. The container AppArmor profile takes precedence over the pod profile.

```yaml securityContext: appArmorProfile: type: <profile_type> ```

Where `<profile_type>` is one of:

* `RuntimeDefault` to use the runtime's default profile * `Localhost` to use a profile loaded on the host (see below) * `Unconfined` to run without AppArmor

See [Specifying AppArmor Confinement](#specifying-apparmor-confinement) for full details on the AppArmor profile API.

To verify that the profile was applied, you can check that the container's root process is running with the correct profile by examining its proc attr:

```shell kubectl exec <pod_name> -- cat /proc/1/attr/current ```

The output should look something like this:

``` cri-containerd.apparmor.d (enforce) ```

## Example

*This example assumes you have already set up a cluster with AppArmor support.*

First, load the profile you want to use onto your Nodes. This profile blocks all file write operations:

``` #include <tunables/global>

profile k8s-apparmor-example-deny-write flags=(attach_disconnected) { #include <abstractions/base>

file,

# Deny all file writes. deny /** w, } ```

The profile needs to be loaded onto all nodes, since you don't know where the pod will be scheduled. For this example you can use SSH to install the profiles, but other approaches are discussed in [Setting up nodes with profiles](#setting-up-nodes-with-profil …(trimmed)