mirror of https://github.com/k3s-io/k3s
111 lines
4.8 KiB
Markdown
111 lines
4.8 KiB
Markdown
# kubernetes
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[Kubernetes](https://github.com/kubernetes/kubernetes) is an open
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source system for managing application containers across multiple hosts.
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This version of Kubernetes uses [Docker](http://www.docker.io/) to package,
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instantiate and run containerized applications.
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This charm is an encapsulation of the
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[Running Kubernetes locally via
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Docker](http://kubernetes.io/docs/getting-started-guides/docker)
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document. The released hyperkube image (`gcr.io/google_containers/hyperkube`)
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is currently pulled from a [Google owned container repository
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repository](https://cloud.google.com/container-registry/). For this charm to
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work it will need access to the repository to `docker pull` the images.
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This charm was built from other charm layers using the reactive framework. The
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`layer:docker` is the base layer. For more information please read [Getting
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Started Developing charms](https://jujucharms.com/docs/devel/developer-getting-started)
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# Deployment
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The kubernetes charms require a relation to a distributed key value store
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(ETCD) which Kubernetes uses for persistent storage of all of its REST API
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objects.
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```
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juju deploy trusty/etcd
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juju deploy local:trusty/kubernetes
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juju add-relation kubernetes etcd
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```
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# Configuration
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For your convenience this charm supports some configuration options to set up
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a Kubernetes cluster that works in your environment:
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**version**: Set the version of the Kubernetes containers to deploy. The
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version string must be in the following format "v#.#.#" where the numbers
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match with the
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[kubernetes release labels](https://github.com/kubernetes/kubernetes/releases)
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of the [kubernetes github project](https://github.com/kubernetes/kubernetes).
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Changing the version causes the all the Kubernetes containers to be restarted.
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**cidr**: Set the IP range for the Kubernetes cluster. eg: 10.1.0.0/16
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# Storage
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The kubernetes charm is built to handle multiple storage devices if the cloud
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provider works with
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[Juju storage](https://jujucharms.com/docs/devel/charms-storage).
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The 16.04 (xenial) release introduced [ZFS](https://en.wikipedia.org/wiki/ZFS)
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to Ubuntu. The xenial charm can use ZFS witha raidz pool. A raidz pool
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distributes parity along with the data (similar to a raid5 pool) and can suffer
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the loss of one drive while still retaining data. The raidz pool requires a
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minimum of 3 disks, but will accept more if they are provided.
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You can add storage to the kubernetes charm in increments of 3 or greater:
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```
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juju add-storage kubernetes/0 disk-pool=ebs,3,1G
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```
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**Note**: Due to a limitation of raidz you can not add individual disks to an
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existing pool. Should you need to expand the storage of the raidz pool, the
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additional add-storage commands must be the same number of disks as the original
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command. At this point the charm will have two raidz pools added together, both
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of which could handle the loss of one disk each.
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The storage code handles the addition of devices to the charm and when it
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recieves three disks creates a raidz pool that is mounted at the /srv/kubernetes
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directory by default. If you need the storage in another location you must
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change the `mount-point` value in layer.yaml before the charms is deployed.
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To avoid data loss you must attach the storage before making the connection to
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the etcd cluster.
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## State Events
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While this charm is meant to be a top layer, it can be used to build other
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solutions. This charm sets or removes states from the reactive framework that
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other layers could react appropriately. The states that other layers would be
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interested in are as follows:
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**kubelet.available** - The hyperkube container has been run with the kubelet
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service and configuration that started the apiserver, controller-manager and
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scheduler containers.
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**proxy.available** - The hyperkube container has been run with the proxy
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service and configuration that handles Kubernetes networking.
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**kubectl.package.created** - Indicates the availability of the `kubectl`
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application along with the configuration needed to contact the cluster
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securely. You will need to download the `/home/ubuntu/kubectl_package.tar.gz`
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from the kubernetes leader unit to your machine so you can control the cluster.
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**skydns.available** - Indicates when the Domain Name System (DNS) for the
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cluster is operational.
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# Kubernetes information
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- [Kubernetes github project](https://github.com/kubernetes/kubernetes)
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- [Kubernetes issue tracker](https://github.com/kubernetes/kubernetes/issues)
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- [Kubernetes Documenation](http://kubernetes.io/docs/)
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- [Kubernetes releases](https://github.com/kubernetes/kubernetes/releases)
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# Contact
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* Charm Author: Matthew Bruzek <Matthew.Bruzek@canonical.com>
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* Charm Contributor: Charles Butler <Charles.Butler@canonical.com>
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[]()
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