[Docs] Connecting Locally Installed ZeroTier to ZTNET Docker Installation

docs/docs/Usage/migrate.md

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+---
+id: migrate
+title: Transitioning from Other ZeroTier Web UIs to ZTNET
+slug: /usage/migrate
+description: Migrate from other ZeroTier applications to ZTNET
+---
+
+# Migration Guide to ZTNET
+
+This guide provides step-by-step instructions to help you migrate from other ZeroTier web UIs to ZTNET. 
+
+:::warning IMPORTANT
+  It is important to note that merging two ZeroTier instances is not possible, as they are fundamentally separate entities.  
+  However, you can configure ZTNET to manage a different ZeroTier instance than the default one.
+:::
+
+## Scenario 1: Connecting Locally Installed ZeroTier to ZTNET Docker Installation
+
+If you have ZeroTier installed locally using the official ZeroTier installation instructions, and your ZeroTier data is available at `/var/lib/zerotier-one` on your host, follow these steps to move your networks to ZTNET in a Docker environment:
+
+### Step 1: Modify `docker-compose.yml` for ztnet Installation
+
+First, stop the running Docker services by navigating to the directory containing your `docker-compose.yml` file and running:
+
+```sh
+docker-compose down
+```
+
+Next, modify your `docker-compose.yml` file as follows:
+
+- Comment out the `zerotier` service section, as ZTNET will use the local ZeroTier installation.
+- Comment out `zerotier` in the `depends_on` section of the `ztnet` service.
+- Update the `volumes` section of the `ztnet` service to mount the local ZeroTier data directory to the ZTNET container.
+
+**Example:**  
+Only the relevant sections are shown below. The full `docker-compose.yml` file should contain additional services and configurations.
+```yaml
+services:
+  # zerotier:
+  #   image: zyclonite/zerotier:1.14.0
+  #   hostname: zerotier
+  #   container_name: zerotier
+  #   restart: unless-stopped
+  #   volumes:
+  #     - zerotier:/var/lib/zerotier-one
+  #   cap_add:
+  #     - NET_ADMIN
+  #     - SYS_ADMIN
+  #   devices:
+  #     - /dev/net/tun:/dev/net/tun
+  #   networks:
+  #     - app-network
+  #   ports:
+  #     - "9993:9993/udp"
+  #   environment:
+  #     - ZT_OVERRIDE_LOCAL_CONF=true
+  #     - ZT_ALLOW_MANAGEMENT_FROM=172.31.255.0/29
+
+  ztnet:
+    ...
+    volumes:
+      # - zerotier:/var/lib/zerotier-one
+      - /var/lib/zerotier-one:/var/lib/zerotier-one
+    depends_on:
+      # - zerotier
+```
+
+
+### Step 2: Configure ZeroTier
+
+To allow ZTNET to manage your local ZeroTier instance, add the following configuration to your `local.conf` file located in `/var/lib/zerotier-one`:
+
+:::info INFO
+Create the `local.conf` file if it does not exist.
+:::
+```json
+{
+  "settings": {
+    "allowManagementFrom": ["0.0.0.0/0"]
+  }
+}
+```
+After updating `local.conf`, restart the ZeroTier service:
+
+```sh
+sudo systemctl restart zerotier-one
+```
+
+### Step 3: Start the Services
+
+In your terminal, navigate to the directory containing your `docker-compose.yml` file and run the following command to start the services:
+
+```sh
+docker-compose up -d
+```
+
+### Step 4: Configure ZTNET to Use Local ZeroTier
+
+To point ZTNET to use the local ZeroTier controller instead of the previously commented-out ZeroTier container, follow these steps:
+
+1. Go to the ZTNET web interface.
+2. Navigate to the Admin => Controller page.
+3. Add `http://server_ip:9993` to the ZeroTier API URL field.
+4. Click save.
+
+You should now be able to manage your ZeroTier network from the ZTNET web interface.
+
+
+**Example**, where 10.0.0.32 is the IP address of the host server:
+![zerotier api url](/img/admin/controller/zerotier_api_url.png)
+
+### Step 5: Migrate Networks
+
+In the Admin => Controller page, a new table will appear displaying all the "unlinked" networks, but only if there are networks present on the local controller. 
+
+ZTNET stores the user ID for all networks created in PostgreSQL. If a network was created outside of ZTNET, it will be considered "unlinked." To manage these networks within ZTNET, you need to assign them to a user.
+
+Select a user from the dropdown menu to link the network to the chosen user. This will integrate the network into ZTNET, allowing for seamless management through the ZTNET interface.
+
+**Example:**  
+![zerotier api url](/img/admin/controller/unlinked_networks.png)
+
+
+## Scenario 2: 
+To be continued...