docs: create v0.4 docs and set them as latest

Also convert all absolute path links to relative.

Signed-off-by: Artem Chernyshev <artem.chernyshev@talos-systems.com>

README.md

@@ -4,6 +4,29 @@
 
 Visit the project [site](https://www.sidero.dev).
 
+## Compatibility with Cluster API and Kubernetes Versions
+
+This provider's versions are compatible with the following versions of Cluster API:
+
+|                              | v1alpha3 (v0.3) | v1alpha4 (v0.4) | v1beta1 (v1.0) |
+| ---------------------------- | --------------- | --------------- | -------------- |
+| Sidero Provider v1alpha3 (v0.3) | ✓               |                 |                |
+| Sidero Provider v1alpha3 (v0.4) |                 | ✓               |                |
+
+This provider's versions are able to install and manage the following versions of Kubernetes:
+
+|                              | v1.16 | v 1.17 | v1.18 | v1.19 | v1.20 | v1.21 | v1.22 |
+| ---------------------------- | ----- | ------ | ----- | ----- | ----- | ----- | ----- |
+| Sidero Provider v1alpha3 (v0.3) | ✓     | ✓      | ✓     | ✓     | ✓     | ✓     |       |
+| Sidero Provider v1alpha3 (v0.4) |       |        |       | ✓     | ✓     | ✓     | ✓     |
+
+This provider's versions are compatible with the following versions of Talos:
+
+|                              | v0.11 | v 0.12 | v0.13 |
+| ---------------------------- | ----- | ------ | ----- |
+| Sidero Provider v1alpha3 (v0.3) | ✓     | ✓      |       |
+| Sidero Provider v1alpha3 (v0.4) | ✓     | ✓      | ✓     |
+
 ## Support
 
 Join our [Slack](https://slack.dev.talos-systems.io)!

website/content/docs/v0.4/Getting Started/create-workload.md

@@ -0,0 +1,124 @@
+---
+description: "Create a Workload Cluster"
+weight: 8
+title: "Create a Workload Cluster"
+---
+
+Once created and accepted, you should see the servers that make up your ServerClasses appear as "available":
+
+```bash
+$ kubectl get serverclass
+NAME      AVAILABLE                                  IN USE
+any       ["00000000-0000-0000-0000-d05099d33360"]   []
+```
+
+## Generate Cluster Manifests
+
+We are now ready to generate the configuration manifest templates for our first workload
+cluster.
+
+There are several configuration parameters that should be set in order for the templating to work properly:
+
+- `CONTROL_PLANE_ENDPOINT`: The endpoint used for the Kubernetes API server (e.g. `https://1.2.3.4:6443`).
+  This is the equivalent of the `endpoint` you would specify in `talosctl gen config`.
+  There are a variety of ways to configure a control plane endpoint.
+  Some common ways for an HA setup are to use DNS, a load balancer, or BGP.
+  A simpler method is to use the IP of a single node.
+  This has the disadvantage of being a single point of failure, but it can be a simple way to get running.
+- `CONTROL_PLANE_SERVERCLASS`: The server class to use for control plane nodes.
+- `WORKER_SERVERCLASS`: The server class to use for worker nodes.
+- `KUBERNETES_VERSION`: The version of Kubernetes to deploy (e.g. `v1.21.1`).
+- `CONTROL_PLANE_PORT`: The port used for the Kubernetes API server (port 6443)
+
+For instance:
+
+```bash
+export CONTROL_PLANE_SERVERCLASS=any
+export WORKER_SERVERCLASS=any
+export TALOS_VERSION=v0.13.0
+export KUBERNETES_VERSION=v1.22.2
+export CONTROL_PLANE_PORT=6443
+export CONTROL_PLANE_ENDPOINT=1.2.3.4
+
+clusterctl config cluster cluster-0 -i sidero > cluster-0.yaml
+```
+
+Take a look at this new `cluster-0.yaml` manifest and make any changes as you
+see fit.
+Feel free to adjust the `replicas` field of the `TalosControlPlane` and `MachineDeployment` objects to match the number of machines you want in your controlplane and worker sets, respecively.
+`MachineDeployment` (worker) count is allowed to be 0.
+
+Of course, these may also be scaled up or down _after_ they have been created,
+as well.
+
+## Create the Cluster
+
+When you are satisfied with your configuration, go ahead and apply it to Sidero:
+
+```bash
+kubectl apply -f cluster-0.yaml
+```
+
+At this point, Sidero will allocate Servers according to the requests in the
+cluster manifest.
+Once allocated, each of those machines will be installed with Talos, given their
+configuration, and form a cluster.
+
+You can watch the progress of the Servers being selected:
+
+```bash
+watch kubectl --context=sidero-demo \
+  get servers,machines,clusters
+```
+
+First, you should see the Cluster created in the `Provisioning` phase.
+Once the Cluster is `Provisioned`, a Machine will be created in the
+`Provisioning` phase.
+
+![machine provisioning](./images/sidero-cluster-start.png)
+
+During the `Provisioning` phase, a Server will become allocated, the hardware
+will be powered up, Talos will be installed onto it, and it will be rebooted
+into Talos.
+Depending on the hardware involved, this may take several minutes.
+
+Eventually, the Machine should reach the `Running` phase.
+
+![machine_running](./images/sidero-cluster-up.png)
+
+The initial controlplane Machine will always be started first.
+Any additional nodes will be started after that and will join the cluster when
+they are ready.
+
+## Retrieve the Talosconfig
+
+In order to interact with the new machines (outside of Kubernetes), you will
+need to obtain the `talosctl` client configuration, or `talosconfig`.
+You can do this by retrieving the resource of the same type from the Sidero
+management cluster:
+
+```bash
+kubectl --context=sidero-demo \
+  get talosconfig \
+  -l cluster.x-k8s.io/cluster-name=cluster-0 \
+  -o jsonpath='{.items[0].status.talosConfig}' \
+  > cluster-0-talosconfig.yaml
+```
+
+## Retrieve the Kubeconfig
+
+With the talosconfig obtained, the workload cluster's kubeconfig can be retrieved in the normal Talos way:
+
+```bash
+talosctl --talosconfig cluster-0.yaml kubeconfig
+```
+
+## Check access
+
+Now, you should have two cluster available:  you management cluster
+(`sidero-demo`) and your workload cluster (`cluster-0`).
+
+```bash
+kubectl --context=sidero-demo get nodes
+kubectl --context=cluster-0 get nodes
+```

website/content/docs/v0.4/Getting Started/expose-services.md

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+---
+description: "A guide for bootstrapping Sidero management plane"
+weight: 6
+title: "Expose Sidero Services"
+---
+
+> If you built your cluster as specified in the [Prerequisite: Kubernetes] section in this tutorial, your services are already exposed and you can skip this section.
+
+There are two external Services which Sidero serves and which much be made
+reachable by the servers which it will be driving.
+
+For most servers, TFTP (port 69/udp) will be needed.
+This is used for PXE booting, both BIOS and UEFI.
+Being a primitive UDP protocl, many load balancers do not support TFTP.
+Instead, solutions such as [MetalLB](https://metallb.universe.tf) may be used to expose TFTP over a known IP address.
+For servers which support UEFI HTTP Network Boot, TFTP need not be used.
+
+The kernel, initrd, and all configuration assets are served from the HTTP service
+(port 8081/tcp).
+It is needed for all servers, but since it is HTTP-based, it
+can be easily proxied, load balanced, or run through an ingress controller.
+
+The main thing to keep in mind is that the services **MUST** match the IP or
+hostname specified by the `SIDERO_CONTROLLER_MANAGER_API_ENDPOINT` environment
+variable (or configuration parameter) when you installed Sidero.
+
+It is a good idea to verify that the services are exposed as you think they
+should be.
+
+```bash
+$ curl -I http://192.168.1.150:8081/tftp/ipxe.efi
+HTTP/1.1 200 OK
+Accept-Ranges: bytes
+Content-Length: 1020416
+Content-Type: application/octet-stream
+```

website/content/docs/v0.4/Getting Started/import-machines.md

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+---
+description: "A guide for bootstrapping Sidero management plane"
+weight: 7
+title: "Import Workload Machines"
+---
+
+At this point, any servers on the same network as Sidero should network boot from Sidero.
+To register a server with Sidero, simply turn it on and Sidero will do the rest.
+Once the registration is complete, you should see the servers registered with `kubectl get servers`:
+
+```bash
+$ kubectl get servers -o wide
+NAME                                   HOSTNAME        ACCEPTED   ALLOCATED   CLEAN
+00000000-0000-0000-0000-d05099d33360   192.168.1.201   false      false       false
+```
+
+## Accept the Servers
+
+Note in the output above that the newly registered servers are not `accepted`.
+In order for a server to be eligible for consideration, it _must_ be marked as `accepted`.
+Before a `Server` is accepted, no write action will be performed against it.
+This default is for safety (don't accidentally delete something just because it
+was plugged in) and security (make sure you know the machine before it is given
+credentials to communicate).
+
+> Note: if you are running in a safe environment, you can configure Sidero to
+> automatically accept new machines.
+
+For more information on server acceptance, see the [server docs](../../resource-configuration/servers/#server-acceptance).
+
+## Create ServerClasses
+
+By default, Sidero comes with a single ServerClass `any` which matches any
+(accepted) server.
+This is sufficient for this demo, but you may wish to have
+more flexibility by defining your own ServerClasses.
+
+ServerClasses allow you to group machines which are sufficiently similar to
+allow for unnamed allocation.
+This is analogous to cloud providers using such classes as `m3.large` or
+`c2.small`, but the names are free-form and only need to make sense to you.
+
+For more information on ServerClasses, see the [ServerClass
+docs](../../resource-configuration/serverclasses/).
+
+## Hardware differences
+
+In baremetal systems, there are commonly certain small features and
+configurations which are unique to the hardware.
+In many cases, such small variations may not require special configurations, but
+others do.
+
+If hardware-specific differences do mandate configuration changes, we need a way
+to keep those changes local to the hardware specification so that at the higher
+level, a Server is just a Server (or a server in a ServerClass is just a Server
+like all the others in that Class).
+
+The most common variations seem to be the installation disk and the console
+serial port.
+
+Some machines have NVMe drives, which show up as something like `/dev/nvme0n1`.
+Others may be SATA or SCSI, which show up as something like `/dev/sda`.
+Some machines use `/dev/ttyS0` for the serial console; others `/dev/ttyS1`.
+
+Configuration patches can be applied to either Servers or ServerClasses, and
+those patches will be applied to the final machine configuration for those
+nodes without having to know anything about those nodes at the allocation level.
+
+For examples of install disk patching, see the [Installation Disk
+doc](../../resource-configuration/servers/#installation-disk).
+
+For more information about patching in general, see the [Patching
+Guide](../../guides/patching).

website/content/docs/v0.4/Getting Started/index.md

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+---
+description: "Overview"
+weight: 1
+title: "Overview"
+---
+
+This tutorial will walk you through a complete Sidero setup and the formation,
+scaling, and destruction of a workload cluster.
+
+To complete this tutorial, you will need a few things:
+
+- ISC DHCP server.
+  While any DHCP server will do, we will be presenting the
+  configuration syntax for ISC DHCP.
+  This is the standard DHCP server available on most Linux distributions (NOT
+  dnsmasq) as well as on the Ubiquiti EdgeRouter line of products.
+- Machine or Virtual Machine on which to run Sidero itself.
+  The requirements for this machine are very low, but it does need to be x86 for
+  now, and it should have at least 4GB of RAM.
+- Machines on which to run Kubernetes clusters.
+  These have the same minimum specifications as the Sidero machine.
+- Workstation on which `talosctl`, `kubectl`, and `clusterctl` can be run.
+
+## Steps
+
+1. Prerequisite: CLI tools
+1. Prerequisite: DHCP server
+1. Prerequisite: Kubernetes
+1. Install Sidero
+1. Expose services
+1. Import workload machines
+1. Create a workload cluster
+1. Scale the workload cluster
+1. Destroy the workload cluster
+1. Optional: Pivot management cluster
+
+## Useful Terms
+
+**ClusterAPI** or **CAPI** is the common system for managing Kubernetes clusters
+in a declarative fashion.
+
+**Management Cluster** is the cluster on which Sidero itself runs.
+It is generally a special-purpose Kubernetes cluster whose sole responsibility
+is maintaining the CRD database of Sidero and providing the services necessary
+to manage your workload Kubernetes clusters.
+
+**Sidero** is the ClusterAPI-powered system which manages baremetal
+infrastructure for Kubernetes.
+
+**Talos** is the Kubernetes-focused Linux operating system built by the same
+people who bring to you Sidero.
+It is a very small, entirely API-driven OS which is meant to provide a reliable
+and self-maintaining base on which Kubernetes clusters may run.
+More information about Talos can be found at
+[https://talos.dev](https://talos.dev).
+
+**Workload Cluster** is a cluster, managed by Sidero, on which your Kubernetes
+workloads may be run.
+The workload clusters are where you run your own applications and infrastruture.
+Sidero creates them from your available resources, maintains them over time as
+your needs and resources change, and removes them whenever it is told to do so.

website/content/docs/v0.4/Getting Started/install-clusterapi.md

@@ -0,0 +1,44 @@
+---
+description: "Install Sidero"
+weight: 5
+title: "Install Sidero"
+---
+
+Sidero is included as a default infrastructure provider in `clusterctl`, so the
+installation of both Sidero and the Cluster API (CAPI) components is as simple
+as using the `clusterctl` tool.
+
+> Note: Because Cluster API upgrades are _stateless_, it is important to keep all Sidero
+> configuration for reuse during upgrades.
+
+Sidero has a number of configuration options which should be supplied at install
+time, kept, and reused for upgrades.
+These can also be specified in the `clusterctl` configuration file
+(`$HOME/.cluster-api/clusterctl.yaml`).
+You can reference the `clusterctl`
+[docs](https://cluster-api.sigs.k8s.io/clusterctl/configuration.html#clusterctl-configuration-file)
+for more information on this.
+
+For our purposes, we will use environment variables for our configuration
+options.
+
+```bash
+export SIDERO_CONTROLLER_MANAGER_HOST_NETWORK=true
+export SIDERO_CONTROLLER_MANAGER_API_ENDPOINT=192.168.1.150
+
+clusterctl init -b talos -c talos -i sidero
+```
+
+First, we are telling Sidero to use `hostNetwork: true` so that it binds its
+ports directly to the host, rather than being available only from inside the
+cluster.
+There are many ways of exposing the services, but this is the simplest
+path for the single-node management cluster.
+When you scale the management cluster, you will need to use an alternative
+method, such as an external load balancer or something like
+[MetalLB](https://metallb.universe.tf).
+
+The `192.168.1.150` IP address is the IP address or DNS hostname as seen from the workload
+clusters.
+In our case, this should be the main IP address of your Docker
+workstation.