Cisco APIC Containers Plug-in Release Notes, Release 6.0(3)

 

Introduction

This document describes the features, bugs, and limitations for the Cisco Application Policy Infrastructure Controller (APIC) Container Plug-in.

The Cisco Application Centric Infrastructure (ACI) Container Network Interface (CNI) Plug-in provides network services to Kubernetes, Red Hat OpenShift, and Rancher RKE clusters on a Cisco ACI fabric. It allows the cluster pods to be treated as fabric end points in the fabric integrated overlay, as well as providing IP Address Management (IPAM), security, and load balancing services.

Release Notes are sometimes updated with new information about restrictions and bugs. See the following website for the most recent version of this document:

https://www.cisco.com/c/en/us/support/cloud-systems-management/application-policy-infrastructure-controller-apic/tsd-products-support-series-home.html

For more information about this product, see "Related Content."

New Software Features

 

The following feature(s) is being released as a technology preview to gather feedback; do not use it in production.

 

Cisco ACI Virtualization Compatibility Matrix

For information about all Cisco ACI-supported (currently-supported) Container products along with the supported ecosystem releases (Kubernetes, OpenShift, OpenStack, Rancher, and vSphere), see the Cisco ACI Virtualization Compatibility Matrix at the following URL:

https://www.cisco.com/c/dam/en/us/td/docs/Website/datacenter/aci/virtualization/matrix/virtmatrix.html

Software

Installers:

OpenShift installer source scripts for OCP 4.11, 4.12, and 4.13 on OpenStack 16.2 are provided as releases artifacts.

For OpenShift on Baremetal, OpenStack and vSphere please refer to the Install Guides.

Configuration:

This release uses the acc-provision upstream open source project release 6.0.3.3 for ACI-CNI, Calico, OVN, MACVLAN, or SR-IOV CNI support and Cisco ACI fabric configuration. Information about acc-provision PyPI package can be found in the upstream release status page.

Installation (needs Python 3.9):

pip install acc-provision==6.0.3.3

Usage:

The release artifacts, aci-cni-docker-images.yaml or the aci-cni-quay-images.yaml should be used as part of the acc-provision input configuration.

For details on how to use acc-provision refer to:

Provisioning Cisco ACI to Work with Kubernetes

Generating an Updated Cisco ACI CNI Configuration

Container Images:

acc-provision generates deployment manifests that reference ACI-CNI container images built in upstream open source projects aci-containers, OpFlex, and acc-provision-operator with tag 6.0.3.3. Package and vulnerability details of these images are documented in the upstream release status page.

Supported Scale

For the verified scalability limits (except for CLI limits), see the Verified Scalability Guide for this release. For Kubernetes-based integrations (including Docker, OpenShift, and Rancher) and OpenStack platform scale limits, see the following table.

Note: The scalability information in the following table applies to Kubernetes or OpenStack resources integrated with OpFlex into the Cisco ACI fabric. It does not apply to Microsoft SCVMM hosts or Cisco ACI Virtual Edge instances.

^1-The indicated scale value is for Cisco ACI release 5.0(1) and later. If the Cisco ACI release is earlier than 5.0(1), the number of supported OpFlex hosts are 40.

Notes:

●     For containers, an endpoint corresponds to a pod’s network interface. The number of pods that can be run on each node is however constrained by other system configuration and Kubernetes distribution specified limits. For kubeadm installed upstream Kubernetes its 110 pods per node, and for OpenShift its 250 pods per node.

●     For OpFlex hosts per port — a port is either a physical port or a vPC. One vPC equals one port.The number of member ports in a vPC is inconsequential.

●     For the CLI verified scalability limits, see the Cisco NX-OS Style Command-Line Interface Configuration Guide for this release.

Known Limitations

●     A pod selector has to be always provided to map a port name to the port number, and an empty pod selector is not supported in the ingress direction.

●     The Cisco ACI CNI Plug-in is not integrated with the Multi-Site Orchestrator. When deploying to a Multi-Site deployment, the Cisco ACI configurations implemented by the plug-in must not be affected by the Multi-Site Orchestrator.

●     SNAT policy configuration is not applicable to traffic within the same cluster.

●     An SNAT policy which goes into the Failed state (for example, on account of reusing an already used SNAT IP), cannot be updated or reused. A failed SNAT policy needs to be deleted and a new one created.

●     The SNAT feature is currently not supported with Cisco APIC release 6.0(3) due to a known open issue. This limitation will be relaxed and the feature will be supported after the issue is resolved. Users who have deployed the SNAT feature with the Cisco APIC 5.2 releases should not upgrade to Cisco APIC 6.0(3).

●     Due to Python 3 dependencies, the acc-provision tool is supported on RHEL8 operating system.

●     The NodePort service statistics exported to Prometheus get accounted under ClusterIp service statistics in on-premises deployments.

●     The file openvswitch/db.sock sometimes becomes a directory after node reload due to a race-condition between the openvswitch installed on the node and openvswitch installed by ACI-CNI. The work around is to delete the /var/run/openvswitch/db.sock directory, and restart the aci-containers-openvswitch pod. For more details, see Red Hat Case 03299085.

●     If the cluster is downgraded from 6.0.3.2 to any of the lower versions, there is a chance that opflex-agent container of host-agent pod will restart, and thus the host-agent pod remains in crashloopbackoff. You can resolve this by manually deleting the file /var/lib/opflex-agent-ovs/reboot-conf.d/reset.conf from the node where the hostagent pod in crashloopbackoff is scheduled to. 

Usage Guidelines

●     Note that upgrading a Cisco ACI CNI cluster requires running acc-provision with the "--upgrade" option.

●     Optimizations to mapping of Kubernetes Network Policy to ACI Host Protection Policies can be turned ON with the following configuration:

kube_config:

…

      hpp_optimization: True

This, and all other configuration changes should be performed using the acc-provision tool, and will take effect after the new manifests generated by acc-provision are applied. This configuration will be enabled by default in future releases.

●     For running more than 250 pods per node, the following configuration needs to be added:

kube_config:

 …

      opflex_agent_ovs_asyncjson_enabled: "true"

This is a preview feature. Note the configuration value is a string in quotation marks.

●     The aci-containers-operator uses the Ansible Operator SDK. If another Kubernetes Operator which uses the Ansible Operator SDK is deployed on the same node, the health-check ports of the two Operators will conflict. There is currently no way to override these default ports either. To overcome this issue, the aci-containers-operator pod has node affinity rule for "preferredDuringSchedulingIgnoredDuringExecutionfor" with key “preferred-node” and value “aci-containers-operator-2577247291”. You can ensure that the aci-containers-operator is scheduled on a particular node by adding the following label to the node:

preferred-node=aci-containers-operator-2577247291

A similar affinity scheme should be applied to other conflicting pods to ensure that they do not get scheduled on the above node.

Note that if no node with the above label exists, then, the aci-containers-operator will still get scheduled on some node.

●     The size of each log file collected in the cluster report can be optionally set using the following acc-provision input configuration (default is 10 MB):

logging:

      size <size-in-bytes>

Note that the truncation happens at the beginning and the latest content of the log file is collected.

●     The aci-containers-operator pod logging level can be set to debug by adding the following configuration:

           logging: 

                               operator_log_level: debug 

●     If FIPS mode is enabled on the host, the following configuration needs to be added:f FIPS mode is enabled on the host, the following configuration needs to be added:

                      kube_config: 

                          opflex_openssl_compat: True  

             default is False.

●     The nodes can be excluded from the SNAT redirect policy by providing the following configuration in the acc-provision input configuration file, the nodes which match all the labels in any group will be excluded from the SNAT redirect policy:

    kube_config:

                node_snat_redirect_exclude:

                - group: <node_group_name_1>:

                  labels:

                  - <label_1>

                  - <label_2>

                  - <label_n>

                - group: <node_group_name_n>:

                  labels:

                  - <label_1>

                  - <label_2>

                  - <label_n>

            Example:

         kube_config:

                node_snat_redirect_exclude:

                - group: router

                  labels:

                  - router

                  - infra

                - group: infra

                  labels:

                  - control-plane

                  - master

 

The nodes having labels [router and infra] or [control-plane and master] will be excluded from the SNAT redirect policy, i.e if all the labels in any of the mentioned groups in configuration is matched with the node labels then that node will be excluded. 

●     The OpFlex Agent reconnect after VM Migration can be enabled by providing the following configuration in the acc-provision input configuration file:

kube_config: 

     enable_opflex_agent_reconnect: True 

●     Set tolerations seconds for aci controller pod by providing the following configuration in the kube_config section of acc-provision input file: 

           toleration_seconds: 100 

            default value is 60 and 600 for non rke and rke flavors respectively.

●     Sometimes it takes longer for service endpoints to be ready but since they are configured are successfully configured as endpoints of that service, traffic will start get loadbalanced to these endpoints and may get temporarily blackholed. To avoid this, a delay along with the details of the services of type Loadbalancer can be specified in the acc-provision input file, such that the Cisco ACI service graph will be programmed with a delay. The following example shows a delay of 30 seconds being introduced for ingress-service (belonging to openshift-ingress) and a delay pf 60 seconds for monitoring-service (belonging to openshift-monitoring):

 

kube_config:

…

      service_graph_endpoint_add_delay:

       delay: 30

       services:

       - name: ingress-service

         namespace: openshift-ingress

       - name: monitoring-service

         namespace: openshift-monitoring

         delay:60            #override delay of 30 

Note that endpoints are added to the service graph only after the pod goes into Ready state.

●     To enable drop logging, perform the following configuration in the acc-provision input file:

drop_log_config:

     enable: True

For more information, see Enabling the OpFlex Drop Log Feature.

●     The scope of the SNAT service graph contract can be configured by the user in the acc-provision input file as follows:

kube_config:

  snat_operator:

    contract_scope: <scope name>

Valid values (as allowed by Cisco APIC) are "global", "tenant" and "context". The default is set to "global".

●     The subnets listed under extern_static and extern_dynamic can be automatically added to rdconfig usersubnets by setting the following configuration in acc-provision input file:

kube_config:

  add_external_subnets_to_rdconfig: True

Note that if the initial value of add_external_subnets_to_rdconfig is true but later modified to false, the usersubnets automatically will not be removed and the rdconfig CR will have to be updated manually to remove them. Each entry in the rdconfig results in a new OVS flow regardless of whether the subnets overlap or not.

●     The aci-containers-controller pod subscribes for notifications on certain objects to the Cisco APIC. There is a timeout associated with this subscription. A shorter timeout requires more frequent subscription renewals. The timeout is set to 900 seconds, and can be changed by configuring the acc-provision input file:

aci_config:

  apic_refreshtime: 1200

Note: The subscription timeout is configurable only in Cisco APIC 4.x or later.

●     To ensure that the subscription renewal happens in time before the subscription timeout expires on the APIC side, the aci-containers-controller pod starts the renewal process a little earlier. By default, it starts 150 seconds before the subscription expiry. If the system is heavily loaded and you notice subscriptions are not renewed in time (this requires examining the aci-containers-controller and Nginx APIC logs), this period can be altered by adjusting the following configuration in the acc-provision input file:

aci_config:

  apic_refreshticker_adjust: 150

●     The memory request and limit for the Open vSwitch container is set to 128Mi and 1Gi respectively. It can be changed by configuring the acc-provision input file as follows:

kube_config:

  ovs_memory_limit: "5Gi"

  ovs_memory_request: "512Mi"

 

●     The Multus CNI deployment can be enabled in the OpenShift installation by performing the following configuration in the acc-provision input file:

multus:

  disable: False

●     The memory request and limit for the Open vSwitch container is set to 128Mi and 1Gi respectively. It can be changed by configuring the acc-provision input file as follows:

kube_config:

  ovs_memory_limit: "5Gi"

  ovs_memory_request: "512Mi"

·         Default memory request and limit for aci-containers-system namespace pods is set to 128Mi and 3Gi respectively  and can be changed by configuring the acc-provision input file as follows.

kube_config:

  aci_containers_memory_request: "512Mi"

  aci_containers_memory_limit: "5Gi"

 

       Note: This namespace wide memory resource setting is not applied to openvswitch container. As stated earlier, please use ovs_memory_request, ovs_memory_limit to change openvswitch container memory request and limit.

 

Apart from above option to set namespace wide memory request and limit, you can choose to configure container specific memory request and limit through acc-provision input file as follows:

 

kube_config:

  aci_containers_controller_memory_request: "256Mi"

  aci_containers_controller_memory_limit: "5Gi"

  aci_containers_host_memory_request: "256Mi"

  aci_containers_host_memory_limit: "5Gi"

  mcast_daemon_memory_request: "256Mi"

  mcast_daemon_memory_limit: "5Gi"

  opflex_agent_memory_request: "256Mi"

  opflex_agent_memory_request: "5Gi"

  acc_provision_operator_memory_request: "256Mi"

  acc_provision_operator_memory_limit: "5Gi"

  aci_containers_operator_memory_request: "256Mi"

  aci_containers_operator_memory_limit: "5Gi"

 

       This container specific configuration takes priority over the namespace wide configuration.

 

·         ACI CNI pods are cirtical and to mark them node critical, PriorityClass "system-node-critical" can be set by configuring the acc-provision input file as follows:

 

kube_config:

  use_system_node_priority_class: True

 

·         Running Rancher Kubernetes clusters with ACI CNI on VMware ESX-based virtual machines is supported in a Cisco ACI Multi-Pod environment. The following configuration should be provided in the acc-provision input file to enable this feature:

 

kube_config:

  aci_multipod: True

 

For clusters running on the Ubuntu host operating system, the following additional configuration should be set in the acc-provision input file:

 

kube_config:

  aci_multipod_ubuntu: True

 

·         If moving an ESX-based VM across Cisco ACI pods, the DHCP needs to be renewed on the infra-vlan after the VM move. ACI-CNI’s host-agent initiates this DHCP release and request. To reliably obtain the DHCP, sometimes multiple attempts may be required. By default, this is attempted five times each after a delay of five seconds. These defaults can be tuned using the following configuration in the acc-provision input file:

 

kube_config:

  dhcp_renew_max_retry_count: 4

  dhcp_delay: 6

To avoid redundant DHCP renews on opflex-agent disconnects when not performing VM migration, a timeout interval in seconds can be configured.  The host-agent waits for this interval before triggerring a DHCP release and renew. If the OpFlex agent reconnects before this interval expires, no DHCP renewal is initiated.

 

This timeout interval can be configured as follows:

kube_config:

  opflex_device_reconnect_wait_timeout: 10

·         Dual-stack can be configured by providing the IPv4 and IPv6 in the acc-provision input configuration file as follows:

net_config:

  node_subnet:

    - <ipv4-subnet>

    - <ipv6-subnet>

  pod_subnet:

    - <ipv4-subnet>

    - <ipv6-subnet>

  extern_dynamic:

    - <ipv4-subnet>

    - <ipv6-subnet>

  extern_static:

    - <ipv4-subnet>

    - <ipv6-subnet >

 

                Note that the dual-stack feature is only supported for OpenShift on Bare Metal.

·         Static loadbalancer IP can be provided to the loadbalancer service via annotation in the below format:

"opflex.cisco.com/lb-ipam-ips": "<ipv4>,<ipv6>"

●     In cases of heavy load, the opflex-agent requests to the leaf switch may fail and the opflex-agent needs to retry after a randomized backoff. The upper bound on this backoff can be configured to adapt specific load conditions to avoid frequent retries:

kube_config:

  opflex_agent_policy_retry_delay_timer: 60  # default is 10 seconds

●     For the VMware VDS integration, you can refer to the Enhanced Link Aggregation Group (eLAG) configured through the Cisco APIC by using the following configuration in the acc-provision input file:

nested_inside:
 type: vmware
…
 elag_name: <eLAG-name-used>

·         User update to include a firewall node in the loadbalancer service graph template are now supported. The following annotation should be added to the corresponding Kubernetes loadbalancer type service:

 

opflex.cisco.com/service-graph-name: <some-value>

 

●     Policy Based Routing (PBR) tracking can be enabled for the Cisco APIC service graph created for supporting the SNAT feature. More details on PBR tracking can be found in the chapter "Configuring Policy-Based Redirect" In the Cisco APIC Layer 4 to Layer 7 Services Deployment Guide, Release 5.2(x).

One HealthGroup for each node is created, and it is associated with the redirect policy of the SNAT service graph with the internet protocol service level agreement (IP SLA) interval set to 5 seconds. This interval is configurable through the acc- provision input file:

net_config:

  service_monitor_interval: 10

If the service_monitor_interval is set to zero, PBR tracking is disabled.

PBR tracking can be also be enabled for other Cisco APIC service graphs created for each Kubernetes external service, setting the following configuration in the acc-provision input file:

net_config:

  pbr_tracking_non_snat: true

If enabled, the service_monitoring_interval described earlier applies here as well.

Note: In a Cisco ACI CNI-based cluster, the same worker node is used to provide both the external Layer 4 load balancer and SNAT services. So if PBR tracking is enabled, and if the worker node reports unhealthy status for SNAT, a fault appears in the redirect policies associated with all other (non-SNAT) service graphs that have this node. However, this fault does not actually affect those other services and traffic from those services is still distributed to that node. The fault manifests for those other services only in the Cisco APIC GUI.

●     OpenShift's default OVN-Kubernetes CNI can be used as the primary CNI for the primary interface using acc-provision flavor openshift-sdn-ovn-baremetal. The following input configuration is required for acc-provision to be able to configure the node network:

aci_config:

  system_id: mykube             # Every cluster must have a distinct ID

  apic_hosts:                   # List of APIC hosts to connect for APIC API

  - 10.1.1.101

  physical_domain:              # Non mandatory field

    domain: kube-physdom        # If physical domain provided, then mention name. Otherwise one will be created with name <system_id>-physdom

  aep: kube-cluster             # The AEP for ports/VPCs used by this cluster

  vrf:                          # This VRF used to create the BDs

    name: mykube-vrf

tenant: common              # This can be system-id or common

net_config:

  node_subnet: 10.1.0.1/16      # Subnet to use for nodes

  kubeapi_vlan: 4001            # The VLAN used by the physdom for nodes

·         Creation of additional networks is supported when using OpenShift’s default OVN-Kubernetes CNI as the primary CNI for the primary interface and the acc-provision flavor openshift-sdn-ovn-baremetal.  A new AEP is required for the additional network and can be configured as follows:

aci_config:

  secondary_aep: kube-cluster-2 # The AEP for additional networks

These additional networks are isolated using VLAN configuration on the Cisco ACI fabric. Automating the configuration of these VLANs is achieved by leveraging a Chained CNI configuration using the following configuration:

chained_cni_config:

  secondary_interface_chaining: True

     secondary_vlans:              # VLANs for additional networks

     - 402

     - 403-406

     - 410, 425

·         A fault (vmmClusterFaultInfo) is generated in Cisco ACI, if a Kubernetes namespace, deployment, or pod is annotated with an EPG name that does not resolve to an existing EPG. A log statement is added in the aci-containers-controller log to alert the user. The fault will be cleared upon the next correct annotation, or when the aci-containers-controller restarts, or when the annotated namespace, deployment, or pod is deleted.

●     Out-band managent IP of APICs can be used to perform day-zero provision ACI fabric and in-band management IP for aci controller pod to talk to APIC. If there are multiple APICs in aci-input file, the first APIC is always taken by aci controller pod to establish websocket connection. This can be specified through cmd line with –apic-oobm-ip parameter:

acc-provision -a -c <input.yaml> -f <flavor> -u <user> -p <pass> -o <deployment.yaml> --apic-oobm-ip <ip> 

●     While deleting APIC resources with “–d” option of acc-provision, can pass “–-skip-app-profile-check" flag to directly delete tenant without checking the presence of application profiles:

acc-provision -d -u admin -p noir0123 -c acc_provision_input.yaml  -f kubernetes-1.27 -o aci_deployment.yaml --skip-app-profile-check

●     You should be familiar with installing and using Kubernetes or OpenShift. Cisco ACI does not provide the Kubernetes or OpenShift installer. Refer to the following documents on Cisco.com for details:

◦    Cisco ACI and Kubernetes Integration

◦    OpenShift Install Guides

◦    Cisco ACI CNI Plugin for Red Hat OpenShift Container Platform Architecture and Design Guide

◦    Upgrading the Cisco ACI CNI Plug-in

◦    Cisco ACI and Calico 3.23.2 Integration

●     OpenShift has a tighter security model by default, and many off-the-shelf Kubernetes applications, such as guestbook, may not run on OpenShift (if, for example, they run as root or open privileged ports like 80).

●     Refer to the article Getting any Docker image running in your own OpenShift cluster on the Red Hat OpenShift website for details. The Cisco ACI CNI Plug-in is not aware of any configuration on OpenShift cluster or pods when it comes to working behind a proxy. Running OpenShift "oc new-app”, for instance, may require access to Git Hub, and if the proxy settings on the OpenShift cluster are not correctly set, this access may fail. Ensure your proxy settings are correctly set.

●     In this release, the maximum supported number of PBR based external services is 250 virtual IP addresses (VIPs). Scalability is expected to increase in upcoming releases.

Note: With OpenShift, master nodes and router nodes are tainted by default, and you might see lower scale than an upstream Kubernetes installation on the same hardware.

●     Some deployments require installation of an "allow" entry in IP tables for IGMP. This must be added to all hosts running an OpFlex agent and using VXLAN encapsulation to the leaf. The rule must be added using the following command:

$ iptables -A INPUT -p igmp -j ACCEPT

In order to make this change persistent across reboots, add the command either to /etc/rc.d/rc.local or to a cron job that runs after reboot.

●     Both RHEL and Ubuntu distributions set net.ipv4.igmp_max_memberships set to 20 by default. This limits the number of end point groups (EPGs) that can be used in addition to the kube-default EPG for pod networking. If you anticipate using more than 20 EPGs, set the value to the desired number of EPGs on each node as follows:

$ sysctl net.ipv4.igmp_max_memberships=desired_number_of_epgs

Open Issues

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Resolved Issues

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Known Issues

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Related Content

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