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This makes v0.10 docs latest, v0.11 docs we generate to. Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>
82 lines
2.8 KiB
Markdown
82 lines
2.8 KiB
Markdown
---
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title: Virtual (shared) IP
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---
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One of the biggest pain points when building a high-availability controlplane
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is giving clients a single IP or URL at which they can reach any of the controlplane nodes.
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The most common approaches all require external resources: reverse proxy, load
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balancer, BGP, and DNS.
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Using a "Virtual" IP address, on the other hand, provides high availability
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without external coordination or resources, so long as the controlplane members
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share a layer 2 network.
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In practical terms, this means that they are all connected via a switch, with no
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router in between them.
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The term "virtual" is misleading here.
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The IP address is real, and it is assigned to an interface.
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Instead, what actually happens is that the controlplane machines vie for
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control of the shared IP address.
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There can be only one owner of the IP address at any given time, but if that
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owner disappears or becomes non-responsive, another owner will be chosen,
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and it will take up the mantle: the IP address.
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Talos has (as of version 0.9) built-in support for this form of shared IP address,
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and it can utilize this for both the Kubernetes API server and the Talos endpoint set.
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Talos uses `etcd` for elections and leadership (control) of the IP address.
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## Video Walkthrough
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To see a live demo of this writeup, see the video below:
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<iframe width="560" height="315" src="https://www.youtube.com/embed/BfMGInHtFBc" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
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## Choose your Shared IP
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To begin with, you should choose your shared IP address.
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It should generally be a reserved, unused IP address in the same subnet as
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your controlplane nodes.
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It should not be assigned or assignable by your DHCP server.
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For our example, we will assume that the controlplane nodes have the following
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IP addresses:
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- `192.168.0.10`
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- `192.168.0.11`
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- `192.168.0.12`
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We then choose our shared IP to be:
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> 192.168.0.15
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## Configure your Talos Machines
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The shared IP setting is only valid for controlplane nodes.
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For the example above, each of the controlplane nodes should have the following
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Machine Config snippet:
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```yaml
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machine:
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network:
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interfaces:
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- interface: eth0
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dhcp: true
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vip:
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ip: 192.168.0.15
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```
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Obviously, for your own environment, the interface and the DHCP setting may
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differ.
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You are free to use static addressing (`cidr`) instead of DHCP.
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## Caveats
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In general, the shared IP should just work.
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However, since it relies on `etcd` for elections, the shared IP will not come
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alive until after you have bootstrapped Kubernetes.
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In general, this is not a problem, but it does mean that you cannot use the
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shared IP when issuing the `talosctl bootstrap` command.
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Instead, that command will need to target one of the controlplane nodes
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discretely.
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