openstack
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magnum
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Adding documentations about network in vms 

This covers the possible network options for nodes in a magnum cluster.

Change-Id: I67b554889a7f21f0ce8c305717b6dad6b8a12ab3
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sayalilunkad 2018-03-12 18:35:35 +01:00
parent 57b9457006
commit d179c37ca2
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doc/source/user/index.rst
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@ -2180,6 +2180,40 @@ Calico needs extra mounts for the kubelet container. See `commit
<https://github.com/projectatomic/atomic-system-containers/commit/54ab8abc7fa1bfb6fa674f55cd0c2fa0c812fd36>`_
of atomic-system-containers for more information.
Network for VMs
---------------
Every cluster has its own private network which is created along with the
cluster. All the cluster nodes also get a floating ip on the external
network. This approach works by default, but can be expensive in terms of
complexity and cost (public Ipv4). To reduce this expense, the following
methods can be used:
1. **Create private networks but do not assign floating IPs**
With this approach the cluster *will* be inaccessible from the outside.
The user can add a floating ip to access it, but the certificates
will not work.
2. **Create a private network and a LoadBalancer for the master node(s)**
There are two type of loadbalancers in magnum, one for the api and one
for the services running on the nodes. For kubernetes LoadBalancer
service type see: `Kubernetes External Load Balancer`_.
Not recommended when using only a single master node as it will add 2
amphora vms: one for the kube API and another for etcd thus being more
expensive.
All the above can also work by passing an existing private network instead
of creating a new one using --fixed-network and --fixed-subnet.
_`Flannel`
When using flannel, the backend should be 'host-gw' if performance is a
requirement, 'udp' is too slow and 'vxlan' creates one more overlay network
on top of the existing neutron network. On the other hand, in a flat network
one should use 'vxlan' for network isolation.
_`Calico`
Calico allows users to setup network policies in kubernetes policies for
network isolation.
High Availability
=================