How I Use Plang for System Administration

Plang: A Surprisingly Versatile Tool for System Administration

This post dives into Plang, an intent-based programming language that interprets natural language. For more, visit plang.is or get started here.

Plang is a powerful tool, especially when it comes to system administration. Its ability to operate at the programming layer while leveraging various tools gives developers—and sysadmins —an impressive level of control and efficiency.

In system administration, scripts simplify repetitive tasks, and I use Plang specifically to deploy apps to servers. My Plang apps are pretty straightforward, so they don’t need the heavy-duty CI/CD pipeline, which would just add unnecessary complexity.

So, how does it work?

The Plan

My goal is to take the app folder from my development machine and set it up on a Linux server. Here’s what needs to happen:

1. Zip the app folder to app.zip, excluding any .db and *.sqlite files.

2. Connect to my Linux server via SFTP.

3. Upload app.zip.

4. Clear out any old .build files to avoid using outdated code.

5. Unzip app.zip on the server.

6. Set the correct file permissions.

7. Optionally update the Plang runtime.

8. Confirm the Plang runtime is working.

When you’re doing this setup for the first time, it's common to miss a step or two—don’t worry. The flexibility of Plang makes it easy to adjust on the fly.

The Deployment

Let’s walk through the deployment by setting up a Deploy.goal file on my computer, and the first line is simply Deploy:

Deploy

Zipping the App

We’ll start by creating a zip file of the app directory, which is in the same location as Deploy.goal:

- zip "./" to "deploy/app.zip", exclude ".db", "*.sqlite", overwrite file

Let's stop here. If you are familiar with programming, you will probably be thinking what is the syntax here? How do I know how to structure this zip command, but here is the thing. Plang does not have strict syntax, it's all about what would you like to happen. Instead of `zip "./" to "deploy/app.zip"`, you say `compress the folder I am in and save it to app.zip`. Because `plang` takes your intent and converts it to code. Let's continue.

Connecting via SFTP

Next, I connect to the server using SFTP. I’ve set up a private key with a passphrase for secure access:

- read file '/events/key', into %sshPrivateKey%
- connect to sftp, 
    host: myhost.server.com, port: 22, username: root, 
    private key: %sshPrivateKey%, private key passphrase: %Settings.PrivateKeyPassphrase%

Now that we’re logged into the server, we can start deploying.

Uploading and Setting Up

First, let’s upload the zip file:

- upload 'deploy/app.zip' through sftp to '/home/plang/app.zip'

After that, we’ll run a few Linux commands to clean up any previous .build folder and unzip the new code:

- run ssh command, "rm -rf /home/plang/app/.build"
- run ssh command, 'unzip -o /home/plang/app.zip -d /home/plang/app'

Updating the Plang Runtime

For flexibility, I’ve added an option to update the Plang runtime. If I run the script with plang=1, it triggers the update:

- if %plang% = 1 then SetupPlang

Now, let’s create the SetupPlang goal.

The SetupPlang Goal

The SetupPlang goal takes care of a few critical steps:

1. Downloads the latest version of Plang for Linux.

2. Unzips plang.zip.

3. Sets execution permissions for plang and selenium-manager (I use a browser in my app).

4. Runs plang --version to validate the installation and manages any errors (like creating a symlink or installing i18n).

5. Restarts the service if it’s running or notifies me if it isn’t installed.

SetupPlang
- run ssh command, 'wget -O /home/plang/plang.zip https://github.com/PLangHQ/plang/releases/latest/download/plang-linux-x64.zip'
- run ssh command, 'unzip -o /home/plang/plang.zip -d /home/plang/plang'
- run ssh command, 'chmod +x /home/plang/plang/plang'
- run ssh command, 'chmod +x /home/plang/plang/selenium-manager/linux/selenium-manager'
- run ssh command, 'plang --version'
    on error message 'No such file or', call CreateSymbolicLink then retry 
    on error message 'command not found', call CreateSymbolicLink then retry 
    on error message contains 'Couldn't find a valid ICU package', call InstallICU then retry
- run ssh command, 'sudo systemctl restart plang', write to %serviceRestart%
    on error message  'plang.service not found', call ServiceNotInstalled ignore error
- write out %serviceRestart%

In the case of errors, I have additional commands to handle them:

CreateSymbolicLink
- write out 'Creating symbolic link'
- run ssh command, 'sudo ln -s /home/plang/plang/plang /usr/local/bin/plang' 
        on error  message contains 'File exists', ignore the error 

InstallICU
- write out 'Installing ICU'
- run ssh command 'sudo dnf install -y libicu'

ServiceNotInstalled
- write out 'Plang service not installed'

Finally, to confirm the Plang runtime is installed, I run:

- run ssh command, 'plang --version', write to %plangVersion%
- write out "App updated at %Now% - %plangVersion%"

Running and Updating

Once the code is ready, I build it:

plang build

And then, to deploy both the app and Plang runtime, I run:

plang Deploy plang=1

If I only need to update the app, I just execute:

plang Deploy

Here’s an example of the output:

App updated at 29.10.2024 10:57:05 - plang version: 0.15.3.0

Full Code for Reference

Deploy
- zip "./" to "deploy/app.zip", exclude ".db", "*.sqlite", overwrite file
- read file '/events/key', into %sshPrivateKey%
- connect to sftp, 
    host: myhost.server.com, port: 22, username: root, 
    private key: %sshPrivateKey%, private key passphrase: %Settings.PrivateKeyPassphrase%
- upload 'deploy/app.zip' through sftp to '/home/plang/app.zip'
- run ssh command, "rm -rf /home/plang/app/.build"
- run ssh command, 'unzip -o /home/plang/app.zip -d /home/plang/app'
- if %plang% = 1 then SetupPlang
- run ssh command, 'plang --version', write to %plangVersion%
- write out "App updated at %Now% - %plangVersion%"

SetupPlang
- run ssh command, 'wget -O /home/plang/plang.zip https://github.com/PLangHQ/plang/releases/latest/download/plang-linux-x64.zip'
- run ssh command, 'unzip -o /home/plang/plang.zip -d /home/plang/plang'
- run ssh command, 'chmod +x /home/plang/plang/plang'
- run ssh command, 'chmod +x /home/plang/plang/selenium-manager/linux/selenium-manager'
- run ssh command, 'plang --version'
    on error message 'No such file or', call CreateSymbolicLink then retry 
    on error message 'command not found', call CreateSymbolicLink then retry 
    on error message contains 'Couldn't find a valid ICU package', call InstallICU then retry
- run ssh command, 'sudo systemctl restart plang', write to %serviceRestart%
    on error message  'plang.service not found', call ServiceNotInstalled ignore error
- write out %serviceRestart%    

CreateSymbolicLink
- write out 'Creating symbolic link'
- run ssh command, 'sudo ln -s /home/plang/plang/plang /usr/local/bin/plang' 
        on error  message contains 'File exists', ignore the error 

InstallICU
- write out 'Installing ICU'
- run ssh command 'sudo dnf install -y libicu'

ServiceNotInstalled
- write out 'Plang service not installed'

Using Plang in system administration is a real timesaver, making deployment as efficient and straightforward as possible.

Benefits

Using Plang for deployment is a game-changer. It's simple, readable, and just works. No messing around with clunky syntax—each step is laid out in plain language, making it dead easy to follow and tweak whenever I need. Plang's modular setup breaks down tasks into bite-sized pieces, so fixing, adjusting, or handling errors is a breeze. And the built-in retry logic? Absolutely essential—it catches issues on the fly, keeping things from blowing up mid-deploy.

Plang’s variable management is just as smooth. I can stash command outputs and use them wherever I need, keeping everything flowing without extra steps. Need to log deployment records? Plang’s got you covered with built-in database support, no extra setup or fuss. In short, Plang slashes the usual code bloat and complexity, leaving me with a clean, powerful setup that actually saves time.

More Information

Interested in learning more about Plang? Here are some useful resources to get started:

• Basic Concepts and Lessons

• Todo Example to build a simple web service

• Explore the GitHub repo for source code

• Join our Discord Community for discussions and support

• Or chat with the Plang Assistant to get help with code generation