Quickstart for Calico on Kubernetes
Big picture
This quickstart gets you a single-host Kubernetes cluster with Calico in approximately 15 minutes.
Value
Use this quickstart to quickly and easily try Calico features. To deploy a cluster suitable for production, refer to Calico on Kubernetes.
Before you begin
Required
- A Linux host that meets the following requirements:
- x86-64, arm64, ppc64le, or s390x processor
- 2CPU
- 2GB RAM
- 10GB free disk space
- RedHat Enterprise Linux 7.x+, CentOS 7.x+, Ubuntu 16.04+, or Debian 9.x+
-
Calico can manage
caliandtunlinterfaces on the hostIf NetworkManager is present on the host, see Configure NetworkManager.
Concepts
Operator based installation
This quickstart guide uses the Tigera operator to install Calico. The operator provides lifecycle management for Calico exposed via the Kubernetes API defined as a custom resource definition.
Note: It is also possible to install Calico without an operator using Kubernetes manifests directly. For platforms and guides that do not use the Tigera operator, you may notice some differences in the steps and Kubernetes resources compared to those presented in this guide.
How to
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.
Create a single-host Kubernetes cluster
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Follow the Kubernetes instructions to install kubeadm
Note: After installing kubeadm, do not power down or restart the host. Instead, continue directly to the next step.
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As a regular user with sudo privileges, open a terminal on the host that you installed kubeadm on.
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Initialize the master using the following command.
sudo kubeadm init --pod-network-cidr=192.168.0.0/16Note: If 192.168.0.0/16 is already in use within your network you must select a different pod network CIDR, replacing 192.168.0.0/16 in the above command.
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Execute the following commands to configure kubectl (also returned by
kubeadm init).mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config
Install Calico
-
Install the Tigera Calico operator and custom resource definitions.
kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/tigera-operator.yamlNote: Due to the large size of the CRD bundle,
kubectl applymight exceed request limits. Instead, usekubectl createorkubectl replace. -
Install Calico by creating the necessary custom resource. For more information on configuration options available in this manifest, see the installation reference.
kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/custom-resources.yamlNote: Before creating this manifest, read its contents and make sure its settings are correct for your environment. For example, you may need to change the default IP pool CIDR to match your pod network CIDR.
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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.Note: The Tigera operator installs resources in the
calico-systemnamespace. Other install methods may use thekube-systemnamespace instead. -
Remove the taints on the master so that you can schedule pods on it.
kubectl taint nodes --all node-role.kubernetes.io/control-plane- node-role.kubernetes.io/master-It should return the following.
node/<your-hostname> untainted -
Confirm that you now have a node in your cluster with the following command.
kubectl get nodes -o wideIt should return something like the following.
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME <your-hostname> Ready master 52m v1.12.2 10.128.0.28 <none> Ubuntu 18.04.1 LTS 4.15.0-1023-gcp docker://18.6.1
Congratulations! You now have a single-host Kubernetes cluster with Calico.
Next steps
Required
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