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This deployment guide shows you how to customize your OpenShift Container Platform cluster to deploy Coder.

The OpenShift Container Platform includes security features, notably the restricted Security Context Constraint (SCC), that can interfere with Coder. This guide describes the customizations to the OpenShift cluster and Coder that ensure an optimal user experience.

Please note that OpenShift doesn't support the use of CVMs

Prerequisites

  • An OpenShift cluster with a project (Kubernetes namespace) for Coder
  • OpenShift command-line tools (oc and kubectl) installed

Step 1: Modify pod and container security contexts

OpenShift's SCC feature enforces the settings with which applications must run. The default SCC setting, restricted, requires applications to run as a user within a project-specific range (MustRunAsRange) and does not allow apps to define a seccomp profile.

You can view the restrictions using oc describe scc restricted:

$ oc describe scc restricted
Name:                                           restricted
Priority:                                       <none>
Access:
  Users:                                        <none>
  Groups:                                       system:authenticated
Settings:
  Allow Privileged:                             false
  Allow Privilege Escalation:                   true
  Default Add Capabilities:                     <none>
  Required Drop Capabilities:                   KILL,MKNOD,SETUID,SETGID
  Allowed Capabilities:                         <none>
  Allowed Seccomp Profiles:                     <none>
  Allowed Volume Types:                         configMap,downwardAPI,emptyDir,persistentVolumeClaim,projected,secret
  Allowed Flexvolumes:                          <all>
  Allowed Unsafe Sysctls:                       <none>
  Forbidden Sysctls:                            <none>
  Allow Host Network:                           false
  Allow Host Ports:                             false
  Allow Host PID:                               false
  Allow Host IPC:                               false
  Read Only Root Filesystem:                    false
  Run As User Strategy: MustRunAsRange
    UID:                                        <none>
    UID Range Min:                              <none>
    UID Range Max:                              <none>
  SELinux Context Strategy: MustRunAs
    User:                                       <none>
    Role:                                       <none>
    Type:                                       <none>
    Level:                                      <none>
  FSGroup Strategy: MustRunAs
    Ranges:                                     <none>
  Supplemental Groups Strategy: RunAsAny
    Ranges:                                     <none>

You can override the default settings by defining the following in your Helm chart:

coderd:
  podSecurityContext:
    runAsUser: null
    seccompProfile: null
  securityContext:
    seccompProfile: null

At this point, you need to get your Coder workspaces running with the appropriate service account/user. There are two options available to you:

  1. Adding the environment's service account to anyuid or nonroot
  2. Building images compatible with OpenShift

Option 1: Add the environment's service account to anyuid or nonroot

Coder's default base images for workspaces, such as enterprise-base, run as the coder user (UID 1000). However, OpenShift doesn't allow this, since service accounts are required by the restricted Security Context Constraint (SCC) to run with a project-specific UID.

To work around this, we we recommend adding this service account to the anyuid or nonroot SCC since Coder creates workspaces in pods with the service account environments:

$ oc adm policy add-scc-to-user nonroot -z environments
clusterrole.rbac.authorization.k8s.io/system:openshift:scc:nonroot added: "environments"

$ oc adm policy who-can use scc nonroot
resourceaccessreviewresponse.authorization.openshift.io/<unknown>

Namespace: coder
Verb:      use
Resource:  securitycontextconstraints.security.openshift.io

Users:  system:admin
        system:serviceaccount:coder:environment

Option 2: Build images compatible with OpenShift

To run Coder workspaces without modifying Security Context Constraints (SCC), you can modify the user and permissions in the base images. First, determine the UID range for the project using:

$ oc describe project coderName:                   coder
Created:                10 days ago
Labels:                 <none>
Annotations:            openshift.io/description=
                        openshift.io/display-name=
                        openshift.io/requester=kube:admin
                        openshift.io/sa.scc.mcs=s0:c26,c10
                        openshift.io/sa.scc.supplemental-groups=1000670000/10000
                        openshift.io/sa.scc.uid-range=1000670000/10000
Display Name:           <none>
Description:            <none>
Status:                 Active
Node Selector:          <none>
Quota:                  <none>
Resource limits:        <none>

Next, create a BuildConfig that outputs an image with a UID in the given range (in this case, sa.scc.uid-range begins with 1000670000):

kind: BuildConfig
apiVersion: build.openshift.io/v1
metadata:
  name: example
  namespace: coder
spec:
  triggers:
    - type: ConfigChange
  runPolicy: Serial
  source:
    type: Dockerfile
    dockerfile: |
      FROM docker.io/codercom/enterprise-base:ubuntu

      # Switch to root
      USER root 

      # As root, change the coder user id
      RUN usermod --uid=1000670000 coder

      # Go back to the user 'coder'
      USER coder
  strategy:
    type: Docker
    dockerStrategy:
      imageOptimizationPolicy: SkipLayers
  output:
    to:
      kind: ImageStreamTag
      name: "enterprise-base:latest"

When creating workspaces, configure Coder to connect to the internal OpenShift registry and use the base image you just created.

Next steps

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