Docker in workspaces
There are a few ways to run Docker within container-based Coder workspaces.
Method | Description | Limitations |
---|---|---|
Sysbox container runtime | Install the Sysbox runtime on your Kubernetes nodes or Docker host(s) for secure docker-in-docker and systemd-in-docker. Works with GKE, EKS, AKS, Docker. | Requires compatible nodes. Limitations |
Envbox | A container image with all the packages necessary to run an inner Sysbox container. Removes the need to setup sysbox-runc on your nodes. Works with GKE, EKS, AKS. | Requires running the outer container as privileged (the inner container that acts as the workspace is locked down). Requires compatible nodes. |
Rootless Podman | Run Podman inside Coder workspaces. Does not require a custom runtime or privileged containers. Works with GKE, EKS, AKS, RKE, OpenShift | Requires smarter-device-manager for FUSE mounts. See all |
Privileged docker sidecar | Run Docker as a privileged sidecar container. | Requires a privileged container. Workspaces can break out to root on the host machine. |
Sysbox container runtime
The Sysbox container runtime allows unprivileged users to run system-level applications, such as Docker, securely from the workspace containers. Sysbox requires a compatible Linux distribution to implement these security features. Sysbox can also be used to run systemd inside Coder workspaces. See Systemd in Docker.
Use Sysbox in Docker-based templates
After installing Sysbox on the Coder host, modify your template to use the sysbox-runc runtime:
resource "docker_container" "workspace" {
# ...
name = "coder-${data.coder_workspace.me.owner}-${lower(data.coder_workspace.me.name)}"
image = "codercom/enterprise-base:ubuntu"
env = ["CODER_AGENT_TOKEN=${coder_agent.main.token}"]
command = ["sh", "-c", coder_agent.main.init_script]
# Use the Sysbox container runtime (required)
runtime = "sysbox-runc"
}
resource "coder_agent" "main" {
arch = data.coder_provisioner.me.arch
os = "linux"
startup_script = <<EOF
#!/bin/sh
# Start Docker
sudo dockerd &
# ...
EOF
}
Use Sysbox in Kubernetes-based templates
After installing Sysbox on Kubernetes, modify your template to use the sysbox-runc RuntimeClass. This requires the Kubernetes Terraform provider version 2.16.0 or greater.
terraform {
required_providers {
coder = {
source = "coder/coder"
}
kubernetes = {
source = "hashicorp/kubernetes"
version = "2.16.0"
}
}
}
variable "workspaces_namespace" {
default = "coder-namespace"
}
data "coder_workspace" "me" {}
resource "coder_agent" "main" {
os = "linux"
arch = "amd64"
dir = "/home/coder"
startup_script = <<EOF
#!/bin/sh
# Start Docker
sudo dockerd &
# ...
EOF
}
resource "kubernetes_pod" "dev" {
count = data.coder_workspace.me.start_count
metadata {
name = "coder-${data.coder_workspace.me.owner}-${data.coder_workspace.me.name}"
namespace = var.workspaces_namespace
annotations = {
"io.kubernetes.cri-o.userns-mode" = "auto:size=65536"
}
}
spec {
runtime_class_name = "sysbox-runc"
# Use the Sysbox container runtime (required)
security_context {
run_as_user = 1000
fs_group = 1000
}
container {
name = "dev"
env {
name = "CODER_AGENT_TOKEN"
value = coder_agent.main.token
}
image = "codercom/enterprise-base:ubuntu"
command = ["sh", "-c", coder_agent.main.init_script]
}
}
}
Envbox
Envbox is an image developed and maintained
by Coder that bundles the sysbox runtime. It works by starting an outer
container that manages the various sysbox daemons and spawns an unprivileged
inner container that acts as the user's workspace. The inner container is able
to run system-level software similar to a regular virtual machine (e.g.
systemd
, dockerd
, etc). Envbox offers the following benefits over running
sysbox directly on the nodes:
- No custom runtime installation or management on your Kubernetes nodes.
- No limit to the number of pods that run envbox.
Some drawbacks include:
- The outer container must be run as privileged
- Note: the inner container is not privileged. For more information on the security of sysbox containers see sysbox's official documentation.
- Initial workspace startup is slower than running
sysbox-runc
directly on the nodes. This is due toenvbox
having to pull the image to its own Docker cache on its initial startup. Once the image is cached inenvbox
, startup performance is similar.
Envbox requires the same kernel requirements as running sysbox directly on the nodes. Refer to sysbox's compatibility matrix to ensure your nodes are compliant.
To get started with envbox
check out the
starter template
or visit the repo.
Authenticating with a Private Registry
Authenticating with a private container registry can be done by referencing the
credentials via the CODER_IMAGE_PULL_SECRET
environment variable. It is
encouraged to populate this
environment variable
by using a Kubernetes
secret.
Refer to your container registry documentation to understand how to best create this secret.
The following shows a minimal example using a the JSON API key from a GCP service account to pull a private image:
# Create the secret
$ kubectl create secret docker-registry <name> \
--docker-server=us.gcr.io \
--docker-username=_json_key \
--docker-password="$(cat ./json-key-file.yaml)" \
--docker-email=<service-account-email>
env {
name = "CODER_IMAGE_PULL_SECRET"
value_from {
secret_key_ref {
name = "<name>"
key = ".dockerconfigjson"
}
}
}
Rootless podman
Podman is Docker alternative that is compatible with OCI containers specification. which can run rootless inside Kubernetes pods. No custom RuntimeClass is required.
Before using Podman, please review the following documentation:
-
Enable smart-device-manager to securely expose a FUSE devices to pods.
cat <<EOF | kubectl create -f - apiVersion: apps/v1 kind: DaemonSet metadata: name: fuse-device-plugin-daemonset namespace: kube-system spec: selector: matchLabels: name: fuse-device-plugin-ds template: metadata: labels: name: fuse-device-plugin-ds spec: hostNetwork: true containers: - name: fuse-device-plugin-ctr image: soolaugust/fuse-device-plugin:v1.0 securityContext: allowPrivilegeEscalation: false capabilities: drop: ["ALL"] volumeMounts: - name: device-plugin mountPath: /var/lib/kubelet/device-plugins volumes: - name: device-plugin hostPath: path: /var/lib/kubelet/device-plugins imagePullSecrets: - name: registry-secret EOF
-
Be sure to label your nodes to enable smarter-device-manager:
kubectl get nodes kubectl label nodes --all smarter-device-manager=enabled
⚠️ Warning: If you are using a managed Kubernetes distribution (e.g. AKS, EKS, GKE), be sure to set node labels via your cloud provider. Otherwise, your nodes may drop the labels and break podman functionality.
-
For systems running SELinux (typically Fedora-, CentOS-, and Red Hat-based systems), you might need to disable SELinux or set it to permissive mode.
-
Use this kubernetes-with-podman example template, or make your own.
echo "kubernetes-with-podman" | coder templates init cd ./kubernetes-with-podman coder templates create
For more information around the requirements of rootless podman pods, see: How to run Podman inside of Kubernetes
Privileged sidecar container
A privileged container can be added to your templates to add docker support. This may come in handy if your nodes cannot run Sysbox.
⚠️ Warning: This is insecure. Workspaces will be able to gain root access to the host machine.
Use a privileged sidecar container in Docker-based templates
resource "coder_agent" "main" {
os = "linux"
arch = "amd64"
}
resource "docker_network" "private_network" {
name = "network-${data.coder_workspace.me.id}"
}
resource "docker_container" "dind" {
image = "docker:dind"
privileged = true
name = "dind-${data.coder_workspace.me.id}"
entrypoint = ["dockerd", "-H", "tcp://0.0.0.0:2375"]
networks_advanced {
name = docker_network.private_network.name
}
}
resource "docker_container" "workspace" {
count = data.coder_workspace.me.start_count
image = "codercom/enterprise-base:ubuntu"
name = "dev-${data.coder_workspace.me.id}"
command = ["sh", "-c", coder_agent.main.init_script]
env = [
"CODER_AGENT_TOKEN=${coder_agent.main.token}",
"DOCKER_HOST=${docker_container.dind.name}:2375"
]
networks_advanced {
name = docker_network.private_network.name
}
}
Use a privileged sidecar container in Kubernetes-based templates
terraform {
required_providers {
coder = {
source = "coder/coder"
}
kubernetes = {
source = "hashicorp/kubernetes"
version = "2.16.0"
}
}
}
variable "workspaces_namespace" {
default = "coder-namespace"
}
data "coder_workspace" "me" {}
resource "coder_agent" "main" {
os = "linux"
arch = "amd64"
}
resource "kubernetes_pod" "main" {
count = data.coder_workspace.me.start_count
metadata {
name = "coder-${data.coder_workspace.me.owner}-${data.coder_workspace.me.name}"
namespace = var.namespace
}
spec {
# Run a privileged dind (Docker in Docker) container
container {
name = "docker-sidecar"
image = "docker:dind"
security_context {
privileged = true
run_as_user = 0
}
command = ["dockerd", "-H", "tcp://127.0.0.1:2375"]
}
container {
name = "dev"
image = "codercom/enterprise-base:ubuntu"
command = ["sh", "-c", coder_agent.main.init_script]
security_context {
run_as_user = "1000"
}
env {
name = "CODER_AGENT_TOKEN"
value = coder_agent.main.token
}
# Use the Docker daemon in the "docker-sidecar" container
env {
name = "DOCKER_HOST"
value = "localhost:2375"
}
}
}
}
Systemd in Docker
Additionally, Sysbox can be used to give
workspaces full systemd
capabilities.
After installing Sysbox on Kubernetes, modify your template to use the sysbox-runc RuntimeClass. This requires the Kubernetes Terraform provider version 2.16.0 or greater.
terraform {
required_providers {
coder = {
source = "coder/coder"
}
kubernetes = {
source = "hashicorp/kubernetes"
version = "2.16.0"
}
}
}
variable "workspaces_namespace" {
default = "coder-namespace"
}
data "coder_workspace" "me" {}
resource "coder_agent" "main" {
os = "linux"
arch = "amd64"
dir = "/home/coder"
}
resource "kubernetes_pod" "dev" {
count = data.coder_workspace.me.start_count
metadata {
name = "coder-${data.coder_workspace.me.owner}-${data.coder_workspace.me.name}"
namespace = var.workspaces_namespace
annotations = {
"io.kubernetes.cri-o.userns-mode" = "auto:size=65536"
}
}
spec {
# Use Sysbox container runtime (required)
runtime_class_name = "sysbox-runc"
# Run as root in order to start systemd (required)
security_context {
run_as_user = 0
fs_group = 0
}
container {
name = "dev"
env {
name = "CODER_AGENT_TOKEN"
value = coder_agent.main.token
}
image = "codercom/enterprise-base:ubuntu"
command = ["sh", "-c", <<EOF
# Start the Coder agent as the "coder" user
# once systemd has started up
sudo -u coder --preserve-env=CODER_AGENT_TOKEN /bin/bash -- <<-' EOT' &
while [[ ! $(systemctl is-system-running) =~ ^(running|degraded) ]]
do
echo "Waiting for system to start... $(systemctl is-system-running)"
sleep 2
done
${coder_agent.main.init_script}
EOT
exec /sbin/init
EOF
]
}
}
}