Example of configuring OpenSSH on OpenShift using stunnel and a passthrough route.

ssh-stunnel.yaml

# This is an example for configuring a Kubernetes deployment to provide SSH
# access to an OpenShift cluster.  The deployment runs OpenSSH and stunnel.
# SSH clients connect through an OpenShift passthrough route using stunnel.
#
# Example usage:
#
# Create a host key-pair for sshd:
#
#     /bin/ssh-keygen -q -t rsa -f ssh_host_rsa_key -C '' -N ''
#
# Create a TLS key and certificate for stunnel:
#
#     make -f /etc/pki/tls/certs/Makefile ./stunnel.pem
#     openssl x509 -in stunnel.pem -out stunnel-crt.pem
#     openssl pkey -in stunnel.pem -out stunnel-key.pem
#
# Create secrets with the host key-pair and the stunnel key and certificate:
#
#     oc -n default create secret generic sshd-host-keys --from-file=ssh_host_rsa_key --from-file=ssh_host_rsa_key.pub
#     oc -n default create secret tls stunnel-certs --cert=stunnel-crt.pem --key=stunnel-key.pem
#
# Create a configmap with an authorized SSH public key or keys:
#
#     oc -n default create configmap ssh-authorized-keys --from-file=authorized_keys=$HOME/.ssh/id_rsa.pub
#
# Create the deployment and related resources for sshd and stunnel:
#
#     oc -n default apply -f ssh-stunnel.yaml
#
# Write the stunnel client configuration file (note: replace the host name in
# the connect setting with the host name from the "ssh" route created in the
# previous step):
#
#     cat > ./stunnel-client.conf <<'EOF'
#     client=yes
#     foreground = yes
#     pid = 
#     sslVersion = TLSv1.2
#     syslog = no
#     
#     [ssh]
#     CAfile = ./stunnel-crt.pem
#     accept = 2222
#     cert = ./stunnel-crt.pem
#     connect = ssh-default.apps.ci-ln-pw141ct-d5d6b.origin-ci-int-aws.dev.rhcloud.com:443
#     key = ./stunnel-key.pem
#     verify = 2
#     EOF
#
# Start the stunnel client:
#
#     stunnel ./stunnel-client.conf
#
# Connect to the local stunnel endpoint using ssh:
#
#     ssh root@127.0.0.1 -p 2222 -i ~/.ssh/id_rsa
#
apiVersion: v1
kind: List
items:
- apiVersion: v1
  kind: BuildConfig
  metadata:
    name: stunnel
  spec:
    output:
      to:
        kind: ImageStreamTag
        name: stunnel:latest
    source:
      type: Dockerfile
      dockerfile: |
        FROM centos:7
        RUN yum -y --setopt=skip_missing_names_on_install=False install stunnel && \
            mkdir -p /etc/stunnel/conf /etc/stunnel/certs
        CMD id && ls -lRZ /etc/stunnel && exec /bin/stunnel /etc/stunnel/conf/stunnel.conf
    strategy:
      type: Docker
    triggers:
    - type: ConfigChange
- apiVersion: v1
  kind: BuildConfig
  metadata:
    name: openssh
  spec:
    output:
      to:
        kind: ImageStreamTag
        name: openssh:latest
    source:
      type: Dockerfile
      dockerfile: |
        FROM centos:7
        RUN yum -y --setopt=skip_missing_names_on_install=False install openssh-server && \
            mkdir -p /etc/ssh/conf /etc/ssh/keys
        CMD id && ls -lRZ /etc/ssh && exec /sbin/sshd -D -e -f /etc/ssh/conf/sshd_config
    strategy:
      type: Docker
    triggers:
    - type: ConfigChange
- apiVersion: v1
  kind: ImageStream
  metadata:
    name: stunnel
  spec:
    tags:
    - name: latest
- apiVersion: v1
  kind: ImageStream
  metadata:
    name: openssh
  spec:
    tags:
    - name: latest
- apiVersion: v1
  data:
    sshd_config: |
      ChallengeResponseAuthentication no
      GSSAPIAuthentication yes
      GSSAPICleanupCredentials no
      HostKey /etc/ssh/keys/ssh_host_rsa_key
      PasswordAuthentication no
      PermitRootLogin yes
      StrictModes no
      UsePAM yes
  kind: ConfigMap
  metadata:
    name: sshd-conf
- apiVersion: v1
  data:
    stunnel.conf: |
      foreground = yes
      pid = 
      socket = l:TCP_NODELAY=1
      socket = r:TCP_NODELAY=1
      sslVersion = TLSv1.2
      
      [ssh]
      TIMEOUTclose = 0
      accept = 2222
      cert = /etc/stunnel/certs/tls.crt
      connect = 22
      key = /etc/stunnel/certs/tls.key
  kind: ConfigMap
  metadata:
    name: stunnel-conf
- apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: ssh
  spec:
    replicas: 1
    selector:
      matchLabels:
        app: ssh
    template:
      metadata:
        labels:
          app: ssh
      spec:
        containers:
        - image: image-registry.openshift-image-registry.svc:5000/default/stunnel:latest
          livenessProbe:
            failureThreshold: 3
            initialDelaySeconds: 1
            periodSeconds: 10
            successThreshold: 1
            tcpSocket:
              port: 2222
            timeoutSeconds: 1
          name: stunnel
          ports:
          - containerPort: 2222
            protocol: TCP
          readinessProbe:
            failureThreshold: 3
            initialDelaySeconds: 1
            periodSeconds: 10
            successThreshold: 1
            tcpSocket:
              port: 2222
            timeoutSeconds: 1
          volumeMounts:
          - name: stunnel-conf
            mountPath: /etc/stunnel/conf
          - name: stunnel-certs
            mountPath: /etc/stunnel/certs
        - image: image-registry.openshift-image-registry.svc:5000/default/openssh:latest
          livenessProbe:
            failureThreshold: 3
            initialDelaySeconds: 1
            periodSeconds: 10
            successThreshold: 1
            tcpSocket:
              port: 22
            timeoutSeconds: 1
          name: openssh
          readinessProbe:
            failureThreshold: 3
            initialDelaySeconds: 1
            periodSeconds: 10
            successThreshold: 1
            tcpSocket:
              port: 22
            timeoutSeconds: 1
          securityContext:
            privileged: true
          volumeMounts:
          - name: sshd-conf
            mountPath: /etc/ssh/conf
          - name: sshd-host-keys
            mountPath: /etc/ssh/keys
          - name: ssh-authorized-keys
            mountPath: /root/.ssh
        dnsPolicy: ClusterFirst
        restartPolicy: Always
        terminationGracePeriodSeconds: 30
        volumes:
        - name: sshd-conf
          configMap:
            defaultMode: 256
            items:
            - key: sshd_config
              path: sshd_config
            name: sshd-conf
        - name: sshd-host-keys
          secret:
            defaultMode: 256
            secretName: sshd-host-keys
        - name: ssh-authorized-keys
          configMap:
            defaultMode: 384
            items:
            name: ssh-authorized-keys
        - name: stunnel-certs
          secret:
            defaultMode: 256
            secretName: stunnel-certs
        - name: stunnel-conf
          configMap:
            defaultMode: 256
            items:
            - key: stunnel.conf
              path: stunnel.conf
            name: stunnel-conf
- apiVersion: v1
  kind: Route
  metadata:
    labels:
      app: ssh
    name: ssh
  spec:
    port:
      targetPort: 2222-tcp
    tls:
      termination: passthrough
    to:
      kind: Service
      name: ssh
- apiVersion: v1
  kind: Service
  metadata:
    labels:
      app: ssh
    name: ssh
  spec:
    ports:
    - name: 2222-tcp
      port: 2222
      protocol: TCP
      targetPort: 2222
    selector:
      app: ssh
    sessionAffinity: None
    type: ClusterIP