Add doc about Upgrading OS(Ubuntu) on running nodes

Signed-off-by: Abdulbois <abdulbois.tursunov@dsr-corporation.com>

Author: Abdulbois

README.md

@@ -232,4 +232,5 @@ the following instructions from [how-to.md](docs/how-to.md) can be used for ever
 - [CometBFT](https://cometbft.com/)
 - [Cosmos SDK](https://cosmos.network/sdk)
 - [Ledger Nano Support](docs/ledger-nano.md)
-- [Mapping DCL Entities to Matter Specification](docs/mapping_against_matter_spec.md)
+- [Mapping DCL Entities to Matter Specification](docs/mapping_against_matter_spec.md)
+- [Upgrading OS(Ubuntu) on running nodes](docs/upgrading-ubuntu-on-running-nodes.md)

docs/upgrading-ubuntu-on-running-nodes.md

@@ -0,0 +1,105 @@
+# Node OS Upgrade: Upgrading DCL cloud instance from Ubuntu 20.04 to Ubuntu 24.04
+
+This document outlines the procedure for upgrading active Distributed Compliance Ledger (DCL) node to Ubuntu 24.04.
+
+1.  **Take a snapshot**: Take a snapshot from running instance. Follow-up guidelines of your cloud provider to take a snapshot.
+
+    Bellow are the steps for AWS Lightsail.
+
+    1.1 Open `AWS Lightsail` console and select running instance.
+
+    1.2 From bottom navigation bar, select `Snapshots` tab.
+
+    1.3 Click `Create snapshot` and give a name then click to `Create`.
+
+    1.4 Wait until Snapshotting finishes.
+
+2. **Connect to running cloud instance**. Connect using SSH. Below are the steps for AWS Lightsail.
+
+   2.1 Open `AWS Lightsail` console and select running instance.
+
+   2.2 From bottom navigation bar, select `Connect` tab.
+
+   2.3 Click on `Connect using SSH`.
+
+3.  **OS Preparation**: Update existing packages.
+
+    3.1 Switch to root user
+    ```bash
+    sudo su
+    ```
+    3.2 Update existing packages.
+    ```bash
+    sudo apt update 
+    sudo apt upgrade -y
+    sudo apt autoremove -y
+    ```
+    *Note: During the upgrade, this terminal may fail. In that case, you have to use an SSH client like Terminal on Linux or PuTTY on Windows to connect to the server.*
+
+    3.3 After package upgrade, reboot the instance
+    ```bash
+    reboot
+    ```
+
+4.  **Release Upgrade**: Initiate the Ubuntu release upgrade.
+    
+    4.1 Connect to the instance using SSH.
+    ```bash
+    ssh -i "private-key.pem" root@{{ip or hostname}}
+    ```
+    4.2 In terminal window, you should see something like this:
+
+    ```bash
+    ...
+    New release '22.04.5 LTS' available.
+    Run 'do-rlease-upgrade' to upgrade to it.
+    ...
+    ```
+
+    4.3 Execute release upgrade command
+    ```bash
+    do-release-upgrade 
+    ```
+    4.4 During the upgrade, it will ask to open an additional ssh daemon at `1022` port. Enter `y` to continue.
+ 
+    4.5 It will also ask to open the port in the firewall. This is a firewall inside the instance. Press `Enter` button to continue
+        Let's open the port in the Lightsail firewall.
+
+      * From bottom navigation bar of selected instance, select `Networking` tab.
+      * Click `Add rule`
+      * Default rule is `Custom` and protocol is `TCP` and enter `1022` port
+      * Click on `Create`
+
+    *Note: It is a reserved port to connect to the instance if the default `22` port will fail during the upgrade. Don't forget to remove this open port after upgrade.
+
+    4.6 For `Installing the upgrade can take several hours` prompt, press `y` button to continue.
+
+    4.7 While the upgrade is downloading these packages, connect to `1022` SSH port as a second safe connection.
+    ```bash
+    ssh -p 1022 -i "private-key.pem" root@{ip or hostname}
+    ```
+
+    4.6 For `There are services installed on your system which need to be restarted when certain libraries such as libpam, libc,.. Restart services during package upgrade without asking` prompt, select `yes` and press Enter.
+
+    4.7 For `Postix Configuration` prompt, select default `No configuration` and press Enter.
+
+    4.8 For `Configuration file 'etc/monit/monitrc` prompt, press `Y`.
+
+    4.9 For `Remove obsolete packages` prompt, enter `y`.
+
+    4.10 For `System upgrade complete. Restart required` prompt, enter `y` to reboot the instance.
+
+5.  **Verification**: After reboot, ensure the instance upgraded  to Ubuntu `22.04` and the `dcld` is running. 
+
+    5.1 After connecting using ssh, execute below command to verify current version of Ubuntu:
+    ```bash
+    sudo lsb_release -a
+    ```
+    
+    5.2 Verify that the node is running.
+    ```bash
+    dcld status
+    ```
+    
+6. **Upgrade to 24.04**. To upgrade to next `24.04` release, please repeat above steps, you can skip `4.5` step.
+7. **Post upgrade**. Remove opened port in step 4.5 from your Network settings of your instance.