feat(site): added azure cloud

Added doc for Server on azure (ops cloud azcloud).

content/en/docs/installation/prereq/server/azure/_index.md

@@ -0,0 +1,155 @@
+---
+title: Server on Azure
+description: Prerequisites to install OpenServerless in Azure
+weight: 20
+---
+
+## Provision a Linux server in Azure Cloud Platform
+
+You can provision a server suitable to install OpenServerless in cloud
+provider [Azure](https://azure.microsoft.com/)
+[ops](#download.adoc) as follows:
+
+1. install `az`, the [Azure CLI](#install-cli)
+
+2. get [Access and Secret Key](#connect-subscription)
+
+3. [configure Azure](#configure)
+
+4. [provision a server](#provision)
+
+5. retrieve the [ip address](#retrieve-ip) to configure a DNS name
+
+Once you have a Linux server up and running you can proceed
+[configuring](/docs/installation/configure/) and
+[installing OpenServerless](/docs/installation/install/cluster/).
+
+### Installing the Azure CLI{#install-cli}
+
+Our cli `ops` uses under the hood the [az](https://learn.microsoft.com/en-us/cli/azure),
+command so you need to dowload and install it [following those
+instructions](https://learn.microsoft.com/en-us/cli/azure/install-azure-cli).
+
+Once installed, ensure it is available on the terminal executing the
+following command:
+
+    az version
+
+you should receive something like this:
+
+    {
+        "azure-cli": "2.64.0",
+        "azure-cli-core": "2.64.0",
+        "azure-cli-telemetry": "1.1.0",
+        "extensions": {
+            "ssh": "2.0.5"
+        }
+    }
+
+Ensure the version is at least 2.64.0
+
+### Connect a subscription{#connect-subscription}
+
+Next step is to connect `az` to a valid Azure subscription. Azure
+supports [several authentication methods](https://learn.microsoft.com/en-us/cli/azure/authenticate-azure-cli): check
+which one you prefer.
+
+The easiest is the one described in [Sign in interactively](https://learn.microsoft.com/en-us/cli/azure/authenticate-azure-cli-interactively):
+
+   az login
+
+This will open a browser and you will asked to login to you azure account. Once logged in, the `az` command will be
+automatically connected to the choosen subscription.
+
+To check if the `az` command is properly connected to your subscription, check the output of this command:
+
+```
+   $ az account list --query "[].{subscriptionId: id, name: name, user: user.name}" --output table
+
+   SubscriptionId                        Name                         User
+   ------------------------------------  ---------------------------  -------------------------
+   xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx  Microsoft Azure Sponsorship  [email protected]
+```
+
+### Configuring Azure to provision a server{#configure}
+
+Before you can provision a Linux server you have to configure Openserverless for Azure typing
+the command:
+
+    ops config azcloud
+
+The system will then ask the following questions:
+
+```
+   *** Please, specify Azure Project Id and press enter.
+   Azure Project Id: openserverless-k3s
+   *** Please, specify Azure Zone and press enter.
+   To get a list of valid values use:
+      az account list-locations -o table
+   
+   Just press enter for default [eastus]:
+   Azure Zone:
+
+   *** Please, specify Azure virtual machine type and press enter.
+   To get a list of valid values, use:
+     az vm list-sizes --location <location> -o table
+   where <location> is your current location.
+   
+   Just press enter for default [Standard_B4ms]:
+   Azure virtual machine type:
+   
+   *** Please, specify Azure vm disk size in gigabyte and press enter.
+   Just press enter for default [50]:
+   Azure vm disk size in gigabyte:
+   
+   *** Please, specify Azure Cloud public SSH key and press enter.
+   If you already have a public SSH key provide its path here. If you do not have it, generate a key pair with the following command:
+     ssh-keygen
+   The public key defaults to ~/.ssh/id_rsa.pub.
+   
+   Just press enter for default [~/.ssh/id_rsa.pub]:
+   Azure Cloud public SSH key:
+   
+   *** Please, specify Azure Cloud VM image and press enter.
+   Just press enter for default [Ubuntu2204]:
+   Azure Cloud VM image:
+```
+
+### Provision a server{#provision}
+
+You can provision one or more servers using `ops`. The servers will use
+the parameters you have just configured.
+
+You can create a new server with:
+
+```bash
+    ops cloud azcloud vm-create <server-name>
+```
+
+{{< blockquote important >}}
+Replace `<server-name>` with a name you choose, for example
+`ops-server`
+{{< /blockquote >}}
+
+The command will create a new server in Azure Cloud with the parameters
+you specified in configuration.
+
+You can also:
+
+1. list servers you created with `ops cloud azcloud vm-list`
+
+2. delete a server you created and you do not need anymore with
+   `ops cloud azcloud vm-delete <server-name>`
+
+### Retrieve IP{#retrieve-ip}
+
+The server will be provisioned with an IP address assigned by Azure
+Cloud.
+
+You can read the IP address of your server with
+
+    ops cloud azcloud vm-getip <server-name>
+
+You need this IP when [configuring a DNS name](/docs/installation/configure/dns/) for
+the server.
+