extension-container

README

Steadybit extension-container

This Steadybit extension provides a host discovery and the various actions for container targets.

Learn about the capabilities of this extension in our Reliability Hub.

Configuration

Environment Variable	Helm value	Meaning	Required	Default
STEADYBIT_EXTENSION_CONTAINER_RUNTIME	container.runtime	The container runtime to user either docker, containerd or cri-o. Will be automatically configured if not specified.	yes	(auto)
STEADYBIT_EXTENSION_CONTAINER_SOCKET	containerRuntimes.(docker/containerd/cri-o).socket	The socket used to connect to the container runtime. Will be automatically configured if not specified.	yes	(auto)
STEADYBIT_EXTENSION_CONTAINERD_NAMESPACE		The containerd namespace to use.	yes	k8s.io
STEADYBIT_EXTENSION_RUNC_ROOT	containerRuntimes.(docker/containerd/cri-o).runcRoot	The runc root to use.	yes	(auto)
STEADYBIT_EXTENSION_RUNC_DEBUG		Activate debug mode for runc.	yes	k8s.io
STEADYBIT_EXTENSION_RUNC_ROOTLESS		Set value for runc --rootless parameter	yes	k8s.io
STEADYBIT_EXTENSION_RUNC_SYSTEMD_CGROUP		Set value for runc --systemd-cgroup parameter	yes	k8s.io
STEADYBIT_EXTENSION_DISCOVERY_CALL_INTERVAL		Interval for container discovery	false	30s
STEADYBIT_EXTENSION_DISABLE_DISCOVERY_EXCLUDES	discovery.disableExcludes	Ignore discovery excludes specified by steadybit.com/discovery-disabled	false	false
STEADYBIT_EXTENSION_DISCOVERY_ATTRIBUTES_EXCLUDES	discovery.attributes.excludes	List of Target Attributes which will be excluded during discovery. Checked by key equality and supporting trailing "*"	false

The extension supports all environment variables provided by steadybit/extension-kit.

Needed capabilities

The capabilities needed by this extension are: (which are provided by the helm chart)

• SYS_ADMIN
• SYS_CHROOT
• SYS_RESOURCE
• SYS_PTRACE
• KILL
• NET_ADMIN
• DAC_OVERRIDE
• SETUID
• SETGID
• AUDIT_WRITE

Installation

Using Helm in Kubernetes

helm repo add steadybit-extension-container https://steadybit.github.io/extension-container
helm repo update
helm upgrade steadybit-extension-container \
    --install \
    --wait \
    --timeout 5m0s \
    --create-namespace \
    --namespace steadybit-extension \
    --set container.runtime=docker \
    steadybit-extension-container/steadybit-extension-container

Using Docker

This extension is by default deployed using our outpost.sh docker compose script.

Or you can run it manually:

docker run \
  --rm \
  -p 8086 \
  --privileged \
  --pid=host \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v /run/docker/runtime-runc/moby:/run/docker/runtime-runc/moby\
  -v /sys/fs/cgroup:/sys/fs/cgroup\
  --name steadybit-extension-container \
  ghcr.io/steadybit/extension-container:latest

Linux Package

Please use our outpost-linux.sh script to install the extension on your Linux machine. The script will download the latest version of the extension and install it using the package manager.

Register the extension

Make sure to register the extension at the steadybit platform. Please refer to the documentation for more information.

Anatomy of the extension / Security

We try to limit the needed access needed for the extension to the absolute minimum. So the extension itself can run as a non-root user on a read-only root file-system and will by default if deployed using the provided helm-chart. In order do execute certain actions the extension needs certain capabilities.

discovery / state attacks

For discovery and executing state attacks such as stop or pause container the extension needs access to the container runtime socket.

resource and network attacks

Resource attacks starting stress-ng processes, the network attacks are starting ip or tc processes as runc container reusing the target container's linux namespace(s), control group(s) and user. This requires the following capabilities: SYS_CHROOT, SYS_ADMIN, SYS_RESOURCE, SYS_PTRACE, KILL, NET_ADMIN, DAC_OVERRIDE, SETUID, SETGID, AUDIT_WRITE. The needed binaries are included in the extension container image.

mark resources as "do not discover"

to exclude container from discovery you can add the label LABEL "steadybit.com.discovery-disabled"="true" to the container Dockerfile.