Microsoft Azure Kubernetes Service (AKS)
Big picture
Enable Calico in AKS managed Kubernetes service.
Value
AKS has built-in support for Calico, providing a robust implementation of the full Kubernetes Network Policy API. AKS users wanting to go beyond Kubernetes network policy capabilities can make full use of the Calico Network Policy API.
You can also use Calico for networking on AKS in place of the default Azure VPC networking. This allows you to take advantage of the full set of Calico networking features.
How to
Install AKS with Calico for network policy
The geeky details of what you get:
Kubernetes network policies are implemented by network plugins rather than Kubernetes itself. Simply creating a network policy resource without a network plugin to implement it, will have no effect on network traffic.
The Calico plugin implements the full set of Kubernetes network policy features. In addition, Calico supports Calico network policies, providing additional features and capabilities beyond Kubernetes network policies. Kubernetes and Calico network policies work together seamlessly, so you can choose whichever is right for you, and mix and match as desired.
How Kubernetes assigns IP address to pods is determined by the IPAM (IP Address Management) plugin being used.
The Azure IPAM plugin dynamically allocates small blocks of IP addresses to nodes as required, using IP addresses from the underlying VNET (Virtual Network). The Azure IPAM plugin is used in conjunction with the Azure CNI plugin to provide VPC native pod networking.
The CNI (Container Network Interface) plugin being used by Kubernetes determines the details of exactly how pods are connected to the underlying network.
The Azure CNI and IPAM plugins provide pods with IP addresses from the underlying Azure VNET (Virtual Network) to provide a VPC-Native pod network. The Azure VNET is used to route pod traffic between nodes, and understands which pod IP address are located on which nodes. This avoids the need for an overlay, and typically has good network performance characteristics.
In addition, pod IPs are understood by the broader AWS network, so for example, VMs outside of the cluster can connect directly to any pod without going via a Kubernetes service if desired.
Operating without using an overlay provides the highest performance network. The packets that leave your pods are the packets that go on the wire.
For completeness, in contrast, with an overlay network, packets between pods on different nodes are encapsulated using a protocol such as VXLAN or IPIP, wrapping each original packet in an outer packet that uses node IPs, and hiding the pod IPs of the inner packet. This can be done very efficiently by the Linux kernel, but it still represents a small overhead, which you might want to avoid if running particularly network intensive workloads.
The underlying cloud VPC (Virtual Private Cloud) is used to route pod traffic between nodes, and understands which pod IP address are located on which nodes. This avoids the need for an overlay, and typically has good performance characteristics.
In addition, pod IPs are understood by the broader cloud network, so for example, VMs outside of the cluster can connect directly to any pod without going via a Kubernetes service if desired.
Calico stores the operational and configuration state of your cluster in a central datastore. If the datastore is unavailable, your Calico network continues operating, but cannot be updated (no new pods can be networked, no policy changes can be applied, etc.).
Calico has two datastore drivers you can choose from
- etcd - for direct connection to an etcd cluster
- Kubernetes - for connection to a Kubernetes API server
The advantages of using Kubernetes as the datastore are:
- It doesn’t require an extra datastore, so is simpler to install and manage
- You can use Kubernetes RBAC to control access to Calico resources
- You can use Kubernetes audit logging to generate audit logs of changes to Calico resources
For completeness, the advantages of using etcd as the datastore are:
- Allows you to run Calico on non-Kubernetes platforms (e.g. OpenStack)
- Allows separation of concerns between Kubernetes and Calico resources, for example allowing you to scale the datastores independently
- Allows you to run a Calico cluster that contains more than just a single Kubernetes cluster, for example, bare metal servers with Calico host protection interworking with a Kubernetes cluster or multiple Kubernetes clusters.
Calico’s flexible modular architecture supports a wide range of deployment options, so you can select the best networking and network policy options for your specific environment. This includes the ability to run with a variety of CNI and IPAM plugins, and underlying networking options.
The Calico Getting Started guides default to the options most commonly used in each environment, so you don’t have to dive into the details unless you want to.
You can click on any deployment option to learn more.
To enable Calico network policy enforcement, follow these step-by-step instructions: Create an AKS cluster and enable network policy.
Install AKS with Calico networking
Limitations
- Windows dataplane is not supported.
- eBPF dataplane is not supported.
- VPP dataplane is not supported.
The geeky details of what you get:
Kubernetes network policies are implemented by network plugins rather than Kubernetes itself. Simply creating a network policy resource without a network plugin to implement it, will have no effect on network traffic.
The Calico plugin implements the full set of Kubernetes network policy features. In addition, Calico supports Calico network policies, providing additional features and capabilities beyond Kubernetes network policies. Kubernetes and Calico network policies work together seamlessly, so you can choose whichever is right for you, and mix and match as desired.
How Kubernetes assigns IP address to pods is determined by the IPAM (IP Address Management) plugin being used.
The Calico IPAM plugin dynamically allocates small blocks of IP addresses to nodes as required, to give efficient overall use of the available IP address space. In addition, Calico IPAM supports advanced features such as multiple IP pools, the ability to specify a specific IP address range that a namespace or pod should use, or even the specific IP address a pod should use.
The CNI (Container Network Interface) plugin being used by Kubernetes determines the details of exactly how pods are connected to the underlying network.
The Calico CNI plugin connects pods to the host networking using L3 routing, without the need for an L2 bridge. This is simple and easy to understand, and more efficient than other common alternatives such as kubenet or flannel.
An overlay network allows pods to communicate between nodes without the underlying network being aware of the pods or pod IP addresses.
Packets between pods on different nodes are encapsulated using VXLAN, wrapping each original packet in an outer packet that uses node IPs, and hiding the pod IPs of the inner packet. This can be done very efficiently by the Linux kernel, but it still represents a small overhead, which you might want to avoid if running particularly network intensive workloads.
For completeness, in contrast, operating without using an overlay provides the highest performance network. The packets that leave your pods are the packets that go on the wire.
Calico routing distributes and programs routes for pod traffic between nodes using its data store without the need for BGP. Calico routing supports unencapsulated traffic within a single subnet, as well as selective VXLAN encapsulation for clusters that span multiple subnets.
Calico stores the operational and configuration state of your cluster in a central datastore. If the datastore is unavailable, your Calico network continues operating, but cannot be updated (no new pods can be networked, no policy changes can be applied, etc.).
Calico has two datastore drivers you can choose from
- etcd - for direct connection to an etcd cluster
- Kubernetes - for connection to a Kubernetes API server
The advantages of using Kubernetes as the datastore are:
- It doesn’t require an extra datastore, so is simpler to install and manage
- You can use Kubernetes RBAC to control access to Calico resources
- You can use Kubernetes audit logging to generate audit logs of changes to Calico resources
For completeness, the advantages of using etcd as the datastore are:
- Allows you to run Calico on non-Kubernetes platforms (e.g. OpenStack)
- Allows separation of concerns between Kubernetes and Calico resources, for example allowing you to scale the datastores independently
- Allows you to run a Calico cluster that contains more than just a single Kubernetes cluster, for example, bare metal servers with Calico host protection interworking with a Kubernetes cluster or multiple Kubernetes clusters.
Calico’s flexible modular architecture supports a wide range of deployment options, so you can select the best networking and network policy options for your specific environment. This includes the ability to run with a variety of CNI and IPAM plugins, and underlying networking options.
The Calico Getting Started guides default to the options most commonly used in each environment, so you don’t have to dive into the details unless you want to.
You can click on any deployment option to learn more.
Note: Bring your own Container Network Interface (CNI) plugin is a preview feature with AKS.
- Create an Azure AKS cluster with no Kubernetes CNI pre-installed. Please refer to Bring your own CNI with AKS for details.
# Install aks-preview extension az extension add --name aks-preview # Update aks-preview to ensure latest version is installed az extension update --name aks-preview # Create a resource group az group create --name my-calico-rg --location westcentralus az aks create --resource-group my-calico-rg --name my-calico-cluster --location westcentralus --pod-cidr 192.168.0.0/16 --network-plugin none - Get credentials to allow you to access the cluster with
kubectl:az aks get-credentials --resource-group my-calico-rg --name my-calico-cluster -
Now that you have a cluster configured, you can install Calico.
-
Install the operator.
kubectl create -f https://projectcalico.docs.tigera.io/manifests/tigera-operator.yaml -
Configure the Calico installation.
kubectl create -f - <<EOF kind: Installation apiVersion: operator.tigera.io/v1 metadata: name: default spec: kubernetesProvider: AKS cni: type: Calico calicoNetwork: bgp: Disabled ipPools: - cidr: 192.168.0.0/16 encapsulation: VXLAN --- apiVersion: operator.tigera.io/v1 kind: APIServer metadata: name: default spec: {} EOF -
Confirm that all of the pods are running with the following command.
watch kubectl get pods -n calico-systemWait until each pod has the
STATUSofRunning.
Next steps
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