Help:Toolforge/My first Buildpack static tool

From Wikitech

Static webservices are one of the simplest. They just serve static files (html, js, css, ...) without running any specific language by themselves.

This stub webservice is designed to get a sample of a static application installed onto Toolforge using the new build service, as quickly as possible. The application makes use of the uwsgi python webserver, but does not run any code, just serves static files. You could use something similar with other languages/buildpacks.

The guide will teach you how to:

  • Create a new tool
  • Serve a static pages webservice on Kubernetes

Getting started

Prerequisites

Skills

Accounts

Step-by-step guide

Step 1: Create a new tool account

  1. Follow the Toolforge quickstart guide to create a Toolforge tool and SSH into Toolforge.
    • For the examples in this tutorial, sample-static-buildpack-app is used to indicate places where your unique tool name is used in another command.
  2. Make sure to create a git repository for the tool, you can get one like this:
    1. Log into the toolforge admin page
    2. Select your tool
    3. On the left side panel, under Git repositories click create repository
    4. Copy the url in the Clone section
      1. There's a private url, that we will use to clone it locally, starting with "git": git@gitlab.wikimedia.org:toolforge-repos/sample-static-buildpack-app.git
      2. And a public one, that we will use to build the app in toolforge, starting with "https": https://gitlab.wikimedia.org/toolforge-repos/sample-static-buildpack-app.git

Step 2: Install and configure uwsgi to serve static files

What is uWsgi?

uWSGI is a popular web server for Python code.

How to create a basic uWSGI webservice

Clone your tool git repository

You will have to clone the tool repository to be able to add code to it, on your local computer (with git installed) you can run: 

laptop:~$ git clone git@gitlab.wikimedia.org:toolforge-repos/sample-static-buildpack-app.git
laptop:~$ cd sample-static-buildpack-app

That will create a folder called sample-static-buildpack-app. We are going to put the code in that folder.

Add the uwsgi dependency
It is Python best practice to use a file named requirements.txt to keep track of the library dependencies of applications.
laptop:~sample-static-buildpack-app$ cat > requirements.txt << EOF
uwsgi
EOF
Add the uwsgi configuration

We could also pass all the options on the Procfile (see below), but having them in a file of it's own is easier to manage. So we create the file uwsgi.ini: 

laptop:~sample-static-buildpack-app$ cat > uwsgi.ini << EOF
[uwsgi]
http-socket = :8000
master = true
processes = 4
die-on-term = true
memory-report = true
check-static = html/
static-index = index.html
EOF
Create the folder holding the files

The check-static option above is the place where we will be putting our files, and index.html is the file that will be loaded when going to the root url. So now we have to add some content there: 

laptop:~sample-static-buildpack-app$ mkdir html
laptop:~sample-static-buildpack-app$ cat > html/index.html << EOF
<!DOCTYPE html>
<html>
<body>

<h1>Sample static site on Toolforge using the build service!</h1>

<p>You can find the code for this application <a
    href="https://gitlab.wikimedia.org/toolforge-repos/sample-static-buildpack-app">here.</a>
</p>

</body>
</html>

EOF
Commit your changes and push
laptop:~sample-static-buildpack-app$ git add .
laptop:~sample-static-buildpack-app$ git commit -m "First commit"
laptop:~sample-static-buildpack-app$ git push origin main
EOF


Build the image

Now we have to ssh to login.toolforge.org and start the build for the image: 

laptop:~sample-static-buildpack-app$ ssh login.toolforge.org  # or the equivalent with PuTTY
dcaro@tools-sgebastion-10$ become sample-static-buildpack-app
tools.sample-static-buildpack-app@tools-sgebastion-10$ toolforge build start https://gitlab.wikimedia.org/toolforge-repos/sample-static-buildpack-app.git
You have to pass the public url of the git repository, otherwise it will not be able to clone it.
Wait for the build to finish

By default it will show you the logs of the build in real time, but if you ctrl-C or lose the session, you can check the status of the build like this: 

tools.sample-static-buildpack-app@tools-sgebastion-10:~$ toolforge build show

You have to wait for the status to be ok(Succeeded).

Start the webservice
tools.sample-static-buildpack-app@tools-sgebastion-10$ toolforge webservice buildservice start --mount=none 
Starting webservice.

Once the webservice is started, navigate to https://sample-static-buildpack-app.toolforge.org in your web browser, and see a 'Sample static site on Toolforge using the build service!' message. It might take a few minutes until it is reachable for the first time.

Notes

You can see the code used in this example here: https://gitlab.wikimedia.org/toolforge-repos/sample-static-buildpack-app

Troubleshooting

See Help:Toolforge/Build_Service#Troubleshooting.


Communication and support

Support and administration of the WMCS resources is provided by the Wikimedia Foundation Cloud Services team and Wikimedia movement volunteers. Please reach out with questions and join the conversation:

Discuss and receive general support
Stay aware of critical changes and plans
Track work tasks and report bugs

Use a subproject of the #Cloud-Services Phabricator project to track confirmed bug reports and feature requests about the Cloud Services infrastructure itself

Read stories and WMCS blog posts

Read the Cloud Services Blog (for the broader Wikimedia movement, see the Wikimedia Technical Blog)

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