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Deploying a Router

Overview

The OpenShift router is the ingress point for all external traffic destined for services in your OpenShift installation. OpenShift provides and supports the following two router plug-ins:

  • The HAProxy template router is the default plug-in. It uses the openshift3/ose-haproxy-router image to run an HAProxy instance alongside the template router plug-in inside a container on OpenShift. It currently supports HTTP(S) traffic and TLS-enabled traffic via SNI. The router’s container listens on the host network interface, unlike most containers that listen only on private IPs. The router proxies external requests for route names to the IPs of actual pods identified by the service associated with the route.

  • The F5 router integrates with an existing F5 BIG-IP® system in your environment to synchronize routes. F5 BIG-IP® version 11.4 or newer is required in order to have the F5 iControl REST API.

The F5 router plug-in is available starting in OpenShift Enterprise 3.0.2.

Creating the Router Service Account

Starting in OpenShift Enterprise 3.0.1.0, you must first create a service account for the router before deploying. This service account must have permissions to a security context constraint (SCC) that allows it to specify host ports.

Create a service account, for example named router:

$ echo \
    '{"kind":"ServiceAccount","apiVersion":"v1","metadata":{"name":"router"}}' \
    | oc create -f -

Edit the privileged SCC:

$ oc edit scc privileged

Add the router service account in the form of system:serviceaccount:<project>:<name> to the users section:

...
users:
- system:serviceaccount:openshift-infra:build-controller
- system:serviceaccount:default:router

Deploying the Default HAProxy Router

The oadm router command is provided with the administrator CLI to simplify the tasks of setting up routers in a new installation. Just about every form of communication between OpenShift components is secured by TLS and uses various certificates and authentication methods. Use the --credentials option to specify what credentials the router should use to contact the master.

Routers directly attach to port 80 and 443 on all interfaces on a host. Restrict routers to hosts where port 80/443 is available and not being consumed by another service, and set this using node selectors and the scheduler configuration. As an example, you can achieve this by dedicating infrastructure nodes to run services such as routers.

First, ensure you have created the router service account before deploying a router.

To check if a default router, named router, already exists:

$ oadm router --dry-run \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \
    --service-account=router

To see what the default router would look like if created:

$ oadm router -o yaml \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \
    --service-account=router

To create a router if it does not exist:

$ oadm router <router_name> --replicas=<number> \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \
    --service-account=router

Multiple instances are created on different hosts according to the scheduler policy.

To use a different router image and view the router configuration that would be used:

$ oadm router <router_name> -o <format> --images=<image> \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \
    --service-account=router

For example:

$ oadm router region-west -o yaml --images=myrepo/somerouter:mytag \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \
    --service-account=router

High Availability

You can set up a highly-available router on your OpenShift cluster using IP failover.

Customizing the Default Routing Subdomain

You can customize the suffix used as the default routing subdomain for your environment using the master configuration file (the /etc/openshift/master/master-config.yaml file by default). The following example shows how you can set the configured suffix to v3.openshift.test:

Example 1. Master Configuration Snippet
routingConfig:
  subdomain: v3.openshift.test

This change requires a restart of the master if it is running.

With the OpenShift master(s) running the above configuration, the generated host name for the example of a host added to a namespace mynamespace would be:

Example 2. Generated Host Name
myroute-mynamespace.v3.openshift.test

Using Wildcard Certificates

A TLS-enabled route that does not include a certificate uses the router’s default certificate instead. In most cases, this certificate should be provided by a trusted certificate authority, but for convenience you can use the OpenShift CA to create the certificate. For example:

$ CA=/etc/openshift/master
$ oadm ca create-server-cert --signer-cert=$CA/ca.crt \
      --signer-key=$CA/ca.key --signer-serial=$CA/ca.serial.txt \
      --hostnames='*.cloudapps.example.com' \
      --cert=cloudapps.crt --key=cloudapps.key

The router expects the certificate and key to be in PEM format in a single file:

$ cat cloudapps.crt cloudapps.key $CA/ca.crt > cloudapps.router.pem

From there you can use the --default-cert flag:

$ oadm router --default-cert=cloudapps.router.pem \
    --credentials="$KUBECONFIG" --service-account=router

Browsers only consider wildcards valid for subdomains one level deep. So in this example, the certificate would be valid for a.cloudapps.example.com but not for a.b.cloudapps.example.com.

Using Secured Routes

Currently, password protected key files are not supported. HAProxy prompts for a password upon starting and does not have a way to automate this process. To remove a passphrase from a keyfile, you can run:

# openssl rsa -in <passwordProtectedKey.key> -out <new.key>

Here is an example of how to use a secure edge terminated route with TLS termination occurring on the router before traffic is proxied to the destination. The secure edge terminated route specifies the TLS certificate and key information. The TLS certificate is served by the router front end.

First, start up a router instance:

# oadm router --replicas=1 --credentials=$KUBECONFIG --service-account=router

Next, create a private key, csr and certificate for our edge secured route. The instructions on how to do that would be specific to your certificate authority and provider. For a simple self-signed certificate for a domain named www.example.test, see the example shown below:

# sudo openssl genrsa -out example-test.key 2048
#
# sudo openssl req -new -key example-test.key -out example-test.csr  \
  -subj "/C=US/ST=CA/L=Mountain View/O=OS3/OU=Eng/CN=www.example.test"
#
# sudo openssl x509 -req -days 366 -in example-test.csr  \
      -signkey example-test.key -out example-test.crt

Generate a route configuration file using the above certificate and key. Make sure to replace servicename my-service with the name of your service.

# servicename="my-service"
# echo "
apiVersion: v1
kind: Route
metadata:
  name:  secured-edge-route
spec:
  host: www.example.test
  to:
    kind: Service
    name: $servicename
  tls:
    termination: edge
    key: |
$(openssl rsa -in example-test.key | sed 's/^/      /')
    certificate: |
$(openssl x509 -in example-test.crt | sed 's/^/      /')

" > example-test-route.yaml

Finally add the route to OpenShift (and the router) via:

# oc create -f example-test-route.yaml

Make sure your DNS entry for www.example.test points to your router instance(s) and the route to your domain should be available. The example below uses curl along with a local resolver to simulate the DNS lookup:

# routerip="4.1.1.1"  #  replace with IP address of one of your router instances.
# curl -k --resolve www.example.test:443:$routerip https://www.example.test/

Using the Container Network Stack

The OpenShift router runs inside a Docker container and the default behavior is to use the network stack of the host (i.e., the node where the router container runs). This default behavior benefits performance because network traffic from remote clients does not need to take multiple hops through user space to reach the target service and container.

Additionally, this default behavior enables the router to get the actual source IP address of the remote connection rather than getting the node’s IP address. This is useful for defining ingress rules based on the originating IP, supporting sticky sessions, and monitoring traffic, among other uses.

This host network behavior is controlled by the --host-network router command line option, and the default behaviour is the equivalent of using --host-network=true. If you wish to run the router with the container network stack, use the --host-network=false option when creating the router. For example:

$ oadm router \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \
    --service-account=router \
    --host-network=false

Internally, this means the router container must publish the 80 and 443 ports in order for the external network to communicate with the router.

Running with the container network stack means that the router sees the source IP address of a connection to be the NATed IP address of the node, rather than the actual remote IP address.

Deploying a Customized HAProxy Router

The HAProxy router is based on a golang template that generates the HAProxy configuration file from a list of routes. If you want a customized template router to meet your needs, you can customize the template file, build a new Docker image, and run a customized router.

One common case for this might be implementing new features within the application back ends. For example, it might be desirable in a highly-available setup to use stick-tables that synchronizes between peers. The router plug-in provides all the facilities necessary to make this customization.

You can obtain a new haproxy-config.template file from the latest router image by running:

# docker run --rm --interactive=true --tty --entrypoint=cat \
    registry.access.redhat.com/openshift3/ose-haproxy-router:v3.0.2.0 haproxy-config.template

Save this content to a file for use as the basis of your customized template.

Using Stick Tables

The following example customization can be used in a highly-available routing setup to use stick-tables that synchronize between peers.

Adding a Peer Section

In order to synchronize stick-tables amongst peers you must a define a peers section in your HAProxy configuration. This section determines how HAProxy will identify and connect to peers. The plug-in provides data to the template under the .PeerEndpoints variable to allow you to easily identify members of the router service. You may add a peer section to the haproxy-config.template file inside the router image by adding:

{{ if (len .PeerEndpoints) gt 0 }}
peers openshift_peers
  {{ range $endpointID, $endpoint := .PeerEndpoints }}
    peer {{$endpoint.TargetName}} {{$endpoint.IP}}:1937
  {{ end }}
{{ end }}

Changing the Reload Script

When using stick-tables, you have the option of telling HAProxy what it should consider the name of the local host in the peer section. When creating endpoints, the plug-in attempts to set the TargetName to the value of the endpoint’s TargetRef.Name. If TargetRef is not set, it will set the TargetName to the IP address. The TargetRef.Name corresponds with the Kubernetes host name, therefore you can add the -L option to the reload-haproxy script to identify the local host in the peer section.

peer_name=$HOSTNAME (1)

if [ -n "$old_pid" ]; then
  /usr/sbin/haproxy -f $config_file -p $pid_file -L $peer_name -sf $old_pid
else
  /usr/sbin/haproxy -f $config_file -p $pid_file -L $peer_name
fi
1 Must match an endpoint target name that is used in the peer section.

Modifying Back Ends

Finally, to use the stick-tables within back ends, you can modify the HAProxy configuration to use the stick-tables and peer set. The following is an example of changing the existing back end for TCP connections to use stick-tables:

            {{ if eq $cfg.TLSTermination "passthrough" }}
backend be_tcp_{{$cfgIdx}}
  balance leastconn
  timeout check 5000ms
  stick-table type ip size 1m expire 5m{{ if (len $.PeerEndpoints) gt 0 }} peers openshift_peers {{ end }}
  stick on src
                {{ range $endpointID, $endpoint := $serviceUnit.EndpointTable }}
  server {{$endpointID}} {{$endpoint.IP}}:{{$endpoint.Port}} check inter 5000ms
                {{ end }}
            {{ end }}

After this modification, you can rebuild your router.

Rebuilding Your Router

After you have made any desired modifications to the template, such as the example stick tables customization, you must rebuild your router for your changes to go in effect:

  1. Rebuild the Docker image to include your customized template.

  2. Push the resulting image to your repository.

  3. Create the router specifying your new image, either:

    1. in the pod’s object definition directly, or

    2. by adding the --images=<repo>/<image>:<tag> flag to the oadm router command when creating a highly-available routing service.

Deploying the F5 Router

The F5 router plug-in is available starting in OpenShift Enterprise 3.0.2.

The F5 router plug-in is provided as a Docker image and run as a pod, just like the default HAProxy router. Deploying the F5 router is done similarly as well, using the oadm router command but providing additional flags (or environment variables) to specify the following parameters for the F5 BIG-IP® host:

Flag Description

--type=f5-router

Specifies that an F5 router should be launched (the default --type is haproxy-router).

--external-host

Specifies the F5 BIG-IP® host’s management interface’s host name or IP address.

--external-host-username

Specifies the F5 BIG-IP® user name (typically admin).

--external-host-password

Specifies the F5 BIG-IP® password.

--external-host-http-vserver

Specifies the name of the F5 virtual server for HTTP connections.

--external-host-https-vserver

Specifies the name of the F5 virtual server for HTTPS connections.

--external-host-private-key

Specifies the path to the SSH private key file for the F5 BIG-IP® host. Required to upload and delete key and certificate files for routes.

--external-host-insecure

A Boolean flag that indicates that the F5 router should skip strict certificate verification with the F5 BIG-IP® host.

As with the HAProxy router, the oadm router command creates the service and deployment configuration objects, and thus the replication controllers and pod(s) in which the F5 router itself runs. The replication controller restarts the F5 router in case of crashes. Because the F5 router is only watching routes and endpoints and configuring F5 BIG-IP® accordingly, running the F5 router in this way along with an appropriately configured F5 BIG-IP® deployment should satisfy high-availability requirements.

To deploy the F5 router:

  1. First, establish a tunnel using a ramp node, which allows for the routing of traffic to pods through the OpenShift SDN.

  2. Ensure you have created the router service account.

  3. Run the oadm router command with the appropriate flags. For example:

    $ oadm router \
    --type=f5-router \
    --external-host=10.0.0.2 \
    --external-host-username=admin \
    --external-host-password=mypassword \
    --external-host-http-vserver=ose-vserver \
    --external-host-https-vserver=https-ose-vserver \
    --external-host-private-key=/path/to/key \
    --credentials='/etc/openshift/master/openshift-router.kubeconfig' \(1)
    --service-account=router
    1 --credentials is the path to the CLI configuration file for the openshift-router. It is recommended using an openshift-router specific profile with appropriate permissions.

F5 Router Partition Paths

Partition paths allow you to store your OpenShift routing configuration in a custom F5 BIG-IP® administrative partition, instead of the default /Common partition. You can use custom administrative partitions to secure F5 BIG-IP® environments. This means that an OpenShift-specific configuration stored in F5 BIG-IP® system objects reside within a logical container, allowing administrators to define access control policies on that specific administrative partition.

See the F5 BIG-IP® documentation for more information about administrative partitions.

Use the --external-host-partition-path flag when deploying the F5 router to specify a partition path:

$ oadm router --external-host-partition-path=/OpenShift/zone1 ...

What’s Next?

If you deployed an HAProxy router, you can learn more about monitoring the router.

If you have not yet done so, you can: