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  1. OpenShift SDN
  2. SDN-1569

Egress Router redirect mode: multiple destinations

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    • Task
    • Resolution: Done
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    • SDN Net-Integration Sprint 197
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    Description

      The multiple destinations provided as a part of the allowedDestinations field is not working as it used to on OCP4: https://github.com/openshift/images/blob/master/egress/router/egress-router.sh#L70-L109

       

      We need to parse this from the NAD and modify the iptables here to support them:

      https://github.com/openshift/egress-router-cni/blob/master/pkg/macvlan/macvlan.go#L272-L349

       

      Testing:

      1) Created NAD:

      [dsal@bkr-hv02 surya_multiple_destinations]$ cat nad_multiple_destination.yaml 
      ---
      apiVersion: "k8s.cni.cncf.io/v1"
      kind: NetworkAttachmentDefinition
      metadata:
       name: egress-router
      spec:
       config: '{
           "cniVersion": "0.4.0",
           "type": "egress-router",
           "name": "egress-router",
       "ip": {
           "addresses": [
               "10.200.16.10/24"
           ],
           "destinations": [
               "80 tcp 10.100.3.200",
               "8080 tcp 203.0.113.26 80",
               "8443 tcp 203.0.113.26 443"
           ],
           "gateway": "10.200.16.1"
        }
      }'

      2) Created pod:

      [dsal@bkr-hv02  surya_multiple_destinations]$ cat egress-router-pod.yaml 
      ---
      apiVersion: v1
      kind: Pod
      metadata:
        name: egress-router-pod
        annotations:
          k8s.v1.cni.cncf.io/networks: egress-router
      spec:
        containers:
          - name: openshift-egress-router-pod
            command: ["/bin/bash", "-c", "sleep 999999999"]
            image: centos/tools
            securityContext:
              privileged: true
      

      3) Checked IPtables:

      [root@worker-1 core]# iptables-save -t nat 
      Generated by iptables-save v1.8.4 on Mon Feb 1 12:08:05 2021
      *nat
      :PREROUTING ACCEPT [0:0]
      :INPUT ACCEPT [0:0]
      :POSTROUTING ACCEPT [0:0]
      :OUTPUT ACCEPT [0:0]
      -A POSTROUTING -o net1 -j SNAT --to-source 10.200.16.10
      COMMIT # Completed on Mon Feb 1 12:08:05 2021
      
      

      As we can see, only the SNAT rule is added. The DNAT doesn't get picked up because of the syntax difference.

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            sseethar Surya Seetharaman
            sseethar Surya Seetharaman
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              Created:
              Updated:
              Resolved: