Automatic reports with Github Actions

PHS 7045: Advanced Programming

George G. Vega Yon, Ph.D.

Intro

Today

We will review three technologies to build automatic reports based on web-scraped data:

flowchart LR
  GA[GitHub Actions] --> docker[Docker Containers]
  docker --> webs[Web Scraping]

Before we proceed, let’s take a look at the specific goal:

Webscrape PubMed to download a list of the most recent ABM papers.

The resulting report can be viewed at https://github.com/UofUEpiBio/PHS-7045-egga.

The task

PubMed

We need to extract the information from this website:

Let’s start by looking into the Quarto document used to do so. You can download it from here.

Our report

Web scraping

Fundamentals of Web Scrapping

What?

Web scraping, web harvesting, or web data extraction is data scraping used for extracting data from websites – Wikipedia

How?

  • The rvest R package provides various tools for reading and processing web data.

  • Under the hood, rvest is a wrapper of the xml2 and httr R packages.

(in the case of dynamic websites, take a look at selenium)

Web scraping raw HTML: Example

We want to directly capture the table of COVID-19 death rates per country from Wikipedia.

library(rvest)
library(xml2)

# Reading the HTML table with the function xml2::read_html
covid <- read_html(
  x = "https://en.wikipedia.org/w/index.php?title=COVID-19_pandemic_death_rates_by_country&oldid=1117643862"
  )

# Let's see the output
covid
{html_document}
<html class="client-nojs vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available" lang="en" dir="ltr">
[1] <head>\n<meta http-equiv="Content-Type" content="text/html; charset=UTF-8 ...
[2] <body class="skin--responsive skin-vector skin-vector-search-vue mediawik ...

Web scraping raw HTML: Example (cont 1.)

Warning

The current version of the wikipedia document doesn’t have the proper XPath. So we will skip the example and directly call the function to retrieve the table.

  • We want to get the HTML table in the doc. To do such, we can use the function xml2::xml_find_all() and rvest::html_table()

  • The first will locate the place in the document that matches a given XPath expression.

  • XPath, XML Path Language, is a query language to select nodes in an XML document.

  • An excellent tutorial can be found here

  • Modern Web browsers make it easy to use XPath!

Live Example! (inspect elements in Google Chrome, Mozilla Firefox, Internet Explorer, and Safari)

Web scraping with xml2 and the rvest package (cont. 2)

Now that we know what the path is, let’s use that and extract

table <- html_table(covid)[[2]] # This returns a list of tables
head(table)
# A tibble: 6 × 4
  Country                `Deaths / million` Deaths    Cases      
  <chr>                  <chr>              <chr>     <chr>      
1 World[a]               885                7,075,455 776,840,500
2 Peru                   6,601              220,975   4,526,977  
3 Bulgaria               5,678              38,759    1,338,327  
4 North Macedonia        5,428              9,990     352,049    
5 Bosnia and Herzegovina 5,118              16,403    403,979    
6 Hungary                5,069              49,095    2,236,646

GitHub Actions

GA: What

In simple terms: Free cloud computing time (2,000 minutes/month) on any OS, whenever you want

Source: GitHub Actions website https://github.com/features/actions

GA: Some examples

  • Build a website using quarto.
  • Update Docker images.
  • R CMD check R packages (or any software) on various versions.
  • Build automatic reports (like what we will be doing!).

The core component of GitHub actions is the workflow files.

GitHub Actions: Workflow

The workflow file (stored under .github/workflows)

# Workflow derived from https://github.com/r-lib/actions/tree/v2/examples
# Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
on:
  push:
    branches: [main, master]
  schedule:
    - cron: '0 0 * * 0' # https://crontab.guru/

name: Build it

jobs:
  Build:
    runs-on: ubuntu-latest
    container: rocker/tidyverse:4.2.2
    env:
      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
      GITHUB_REPO: ${{ github.event.repository.name }}
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0
    
      # Installing quarto
      - uses: quarto-dev/quarto-actions/setup@v2
        with:
          version: 0.3.71
    
      - name: Install packags and render
        run: |
          install2.r xml2 quarto
          quarto render README.qmd
    
      # There's an error with EndBug, need to use the safe.directory
      # option. More here
      # https://git-scm.com/docs/git-config#Documentation/git-config.txt-safedirectory
      - name: Dealing with GitConfig
        run: |
          git config --global --add safe.directory /__w/${GITHUB_REPO}/${GITHUB_REPO}
          
      - uses: EndBug/add-and-commit@v9
        with:
          add: README.md

Let’s see bit by bit

GA: Trigger

When the action triggers:

  • When there’s a push to the main or master branches.

  • And once a week, every Monday at 0 hours.

on:
  push:
    branches: [main, master]
  schedule:
    - cron: '0 0 * * 0' # https://crontab.guru/

GA: Configuration of the Jobs

Build:
    runs-on: ubuntu-latest
    container: rocker/tidyverse:4.2.2
    env:
      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
      GITHUB_REPO: ${{ github.event.repository.name }}
  • It sets two environment variables (accessible with the dollar sign): GITHUB_PAT and GITHUB_REPO.

GA: Steps

The Build job has five steps:

  1. Clone the current repository.
  1. Install quarto version 0.3.71.
  1. Install the xml2 and quarto R packages and render the README.qmd document.
  1. …
  1. Commit the changes.
- uses: actions/checkout@v3
  with:
    fetch-depth: 0

- uses: quarto-dev/quarto-actions/setup@v2
  with:
    version: 0.3.71

- name: Install packags and render
  run: |
    install2.r xml2 quarto
    quarto render README.qmd

- name: Dealing with GitConfig
  run: |
    git config --global --add safe.directory /__w/${GITHUB_REPO}/${GITHUB_REPO}
    
- uses: EndBug/add-and-commit@v9
  with:
    add: README.md

Of these five steps, steps 1, 2, and 5 were pulled directly from the GA marketplace.

Docker containers

Docker: What are containers

Containers are isolated from one another and bundle their own software, libraries and configuration files; they can communicate with each other through well-defined channels.[8] Because all of the containers share the services of a single operating system kernel, they use fewer resources than virtual machines – Wiki

Docker’s Architecture

Source: https://docs.docker.com/get-started/overview/

The rocker/tidyverse image

The tidyverse image

rocker/tidyverse has already installed many R packages and their dependencies apt packages. e.g. the tidyverse package, the devtools package, the rmarkdown package, some R Database Interface packages, the data.table package, the fst package, and the Apache Arrow R package. – Source: Rocker Project

Let’s see it start-to-finish!

https://github.com/UofUEpiBio/PHS-7045-egga