Automating your bot with Jenkins

Note

This page does NOT go into explaining how to install Jenkins, nor how to initially setup Jenkins. This is a tutorial for the CMake version with Linux (more specifically Ubuntu 22.04 LTS). If you don't know how to use CMake or you don't use CMake for your bot (and would like to) then please visit Building a Discord Bot Using CMake (UNIX). If you wish to automate this tutorial from GitHub pushes then you can simply download the GitHub plugin for Jenkins, set that up and this tutorial will still work as this tutorial will only build what it can see!

Getting started

First of all, you'll want to create your project. For this, we'll use a "Freestyle project" as we're just going to be calling some bash commands to tell CMake to build. We'll be calling this "DiscordBot" but you can name it whatever you want (I would advise against non-ascii characters).

From here, just hit Ok and now you've created your Jenkins project, Well done! From here you can add a description, change the security policy (if your jenkins is public), really whatever your heart desires.

Automating the building process.

Scrolling down, you'll find Build Steps (You can also click Build Steps on the left). Here, you'll want to hit Add build step and hit Execute shell.

Inside of this, you'll want to enter this script below.

# Check if the "build" directory doesn't exist (if you've not setup CMake or deleted its content).
if [ ! -d "build/" ] 
then # As it doesn't, create the build directory.
    mkdir build
    cd build
    cmake .. # Begin the CMake initialisation.
    cd ..
fi
 
# Commence build.
cmake --build build/

Note

This script does not make use of multiple threads. If you know how to do this and you would like to use threads, then feel free to. However, I would be careful not to use all your threads as Jenkins may dislike this.

This script will build your project for you and also setup CMake if you've deleted the build directory, allowing you to easily refresh CMake. You can change this to a build parameter if you want, meaning you can hit Build with Parameters and state what you'd like to do (This would require the script to be changed so only do that if you know what you're doing)!

Now you can hit save!

Seeing the builds work

Making sure you have your project files in the workspace directory (you can see this by pressing Workspace on the left, the files will automatically be pulled from GitHub if you're using the GitHub plugin), you should be able to hit Build Now and see a new build in the History appear. If everything went well, you should have a green tick!

Note

Building can take a whilst if you haven't setup your build directory before (doing cmake ..), especially on less-powerful machines, so don't be alarmed!

Running the build

Running the builds is the same as any other time, but we'll still cover it! However, we won't cover running it in background and whatnot, that part is completely down to you.

First, you need to get into the jenkins user. If you're like me and don't have the Jenkins user password, you can login with your normal login (that has sudo perms) and do sudo su - jenkins. Once logged in, you'll be in /var/lib/jenkins/. From here, you'll want to do cd workspace/DiscordBot/ (make sure to replace "DiscordBot" with your bot's name. Remember, you can tab-complete this) and then cd build. Now, you can simply do ./DiscordBot!

Warning

If you are going to be running the bot at the same time as builds, I would heavily advise that you copy the bot (if it's not statically linked, then copy the entire build directory) to a different location. This is so you can pick and choose when the bot gets updated (and even means you can run experimental builds as opposed to stable builds) but also means you avoid any risk of the bot crashing during build (as jenkins will be overwriting your executable and libraries).

Once you're happy with everything, then you're good to go! Enjoy your automated builds!

Possible permission issues

Sometimes, doing ./DiscordBot can end up with an error, saying you don't have permission to execute. If that's the case, simply do chmod +x DiscordBot and now you can re-run ./DiscordBot.