links.yml

name: links

# Taken from go-fileshare.github.io, where a dead repository link on the
# landing went unnoticed until a check like this one read the BUILT site.
#
# ⛔ THE CHECK READS THE BUILT SITE, NOT THE LAYOUTS: templated links such as
# the per-repository cards only become real URLs once Hugo has expanded them.

on:
  pull_request:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: read

jobs:
  links:
    name: every link and image resolves
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7
        with:
          submodules: recursive
      # Hugo resolves the landingkit module (hugo.toml [module]) with the go
      # command, at the version go.mod pins.
      - uses: actions/setup-go@v7
        with:
          go-version-file: go.mod
          cache: false
      - uses: peaceiris/actions-hugo@v3
        with:
          hugo-version: "0.168.0"
          extended: true
      - run: hugo --minify --destination ./public
      - name: Check
        run: |
          set -uo pipefail
          # The character class matters: an extractor that stops only at ) and "
          # carries a closing > or < into the request.
          urls=$(grep -rhoE 'https?://[^)">< [:space:]]+' public/ | sed 's/[.,]$//' | sort -u)
          test -n "$urls" || { echo "::error::no links found; did the site build?"; exit 1; }
          echo "checking $(printf '%s\n' "$urls" | wc -l) distinct URLs"
          fail=0
          while read -r u; do
            # img.shields.io renders anything asked of it and proves nothing.
            case "$u" in *img.shields.io*) continue ;; esac
            # Three attempts: one is a flake detector rather than a link
            # checker, and a lane that fails at random is a lane people learn
            # to ignore.
            code=000
            for attempt in 1 2 3; do
              code=$(curl -sS -o /dev/null -w '%{http_code}' -L --max-time 25 "$u" || echo 000)
              case "$code" in 2*|3*) break ;; esac
              sleep 3
            done
            case "$code" in
              2*|3*) printf '  ok   %s  %s\n' "$code" "$u" ;;
              *)     printf '  FAIL %s  %s\n' "$code" "$u"; fail=1 ;;
            esac
          done <<< "$urls"
          test "$fail" -eq 0 || { echo "::error::at least one link or image does not resolve"; exit 1; }