Fail a GitHub Actions job when a vendor page changes

当供应商页面发生变更时，使 GitHub Actions 任务失败

A scheduled workflow can fail when a vendor pricing page, docs page, or changelog changes its text. The job below reads the latest event from a SignalWatch monitor and exits 1 if that event is a content change from the last six hours. This is for public, server-rendered pages. It does not render JavaScript, log in, or take a screenshot. If the price only exists after a client-side render, the monitor will not see it.

当供应商的定价页面、文档页面或更新日志中的文本发生变化时，定时工作流（Scheduled workflow）可以触发失败。以下任务会读取 SignalWatch 监控器的最新事件，如果该事件是过去六小时内的内容变更，则会以退出码 1 终止。此方案适用于公开的、服务器端渲染的页面。它不会渲染 JavaScript、登录或截屏。如果价格仅在客户端渲染后才显示，监控器将无法检测到。

The workflow Save this as .github/workflows/upstream-drift.yml. It uses GNU date, which ubuntu-latest provides.

工作流保存为 .github/workflows/upstream-drift.yml。它使用了 ubuntu-latest 环境中提供的 GNU date 工具。

name: upstream-drift
on:
  schedule:
    - cron: "0 */6 * * *"
  workflow_dispatch:
jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - name: Fail if the vendor page changed in the last 6h
        env:
          KEY: ${{ secrets.SIGNALWATCH_KEY }}
          CHECK_ID: "123"
        run: |
          latest=$(curl -fsS "https://signalwatch.litework.me/api/v1/checks/$CHECK_ID/events?limit=1" -H "X-API-Key: $KEY")
          event=$(echo "$latest" | jq -r '.[0].event // "none"')
          when=$(echo "$latest" | jq -r '.[0].created_at // "1970-01-01T00:00:00Z"')
          age=$(( $(date +%s) - $(date -d "$when" +%s) ))
          if [ "$event" = "changed" ] && [ "$age" -lt 21600 ]; then
            echo "::error::Upstream page changed"
            echo "$latest" | jq -r '.[0].diff'
            exit 1
          fi
          echo "no recent change ($event, ${age}s ago)"

Add the API key as a repository secret named SIGNALWATCH_KEY. Replace 123 with the monitor id from the dashboard. The events endpoint returns the newest row first. On that API a content change is event: "changed". Webhook deliveries for the same moment use content.changed. diff is a unified text diff. change_ratio is changed characters divided by the longer of the two texts.

将 API 密钥添加为名为 SIGNALWATCH_KEY 的仓库密钥（Repository Secret）。将 123 替换为仪表板中的监控器 ID。事件接口会优先返回最新的一行数据。在该 API 中，内容变更对应的事件为 event: "changed"。同一时刻的 Webhook 推送则使用 content.changed。diff 是统一文本差异格式。change_ratio 是变更字符数除以两个文本中较长者的长度。

Create the monitor: Free covers 3 monitors at a 15 minute interval, no card: https://signalwatch.litework.me/ Two settings matter more than the schedule: A CSS selector, so you hash the price table or the docs section instead of the whole document. An ignore regex, so a line like “updated 3 minutes ago” does not fail the build.

创建监控器：免费版支持 3 个监控器，间隔 15 分钟，无需信用卡：https://signalwatch.litework.me/。有两个设置比调度频率更重要：CSS 选择器（用于仅对价格表或文档部分进行哈希校验，而不是整个文档）以及忽略正则表达式（用于过滤掉“3分钟前更新”这类行，避免导致构建失败）。

There is a public monitor on the Hacker News front page if you want to read real diffs before creating an account: https://signalwatch.litework.me/live.html. Curl, Python, and signature checks, including this workflow, are on the examples page: https://signalwatch.litework.me/examples.html.

如果你想在注册账号前查看真实的差异对比，Hacker News 首页有一个公开的监控器：https://signalwatch.litework.me/live.html。包括此工作流在内的 Curl、Python 和签名检查示例页面位于：https://signalwatch.litework.me/examples.html。

What a failure looks like: The Actions log prints the diff and the job goes red: --- before +++ after @@ -3 +3 @@ -Starter $10/mo +Starter $14/mo

失败时的表现：Actions 日志会打印出差异对比，且任务状态变为红色： --- 修改前 +++ 修改后 @@ -3 +3 @@ -Starter $10/mo +Starter $14/mo

Downtime is a different event (down, then up when the fetch recovers). Those do not fail this job. Extend the if if a failed fetch should fail CI as well.

宕机是另一种事件（先是 down，待抓取恢复后变为 up）。这些事件不会导致此任务失败。如果希望抓取失败也导致 CI 失败，请扩展 if 条件。

Limits: Public http(s) URLs only. Fetches are capped at 2 MB and follow up to 3 redirects. JavaScript is not executed. Email, Slack, Discord, and HMAC-signed JSON are the push path. This workflow is the pull path, for a repo that already lives in Actions and wants upstream drift to turn the badge red.

限制：仅支持公开的 http(s) URL。抓取内容上限为 2 MB，最多跟随 3 次重定向。不执行 JavaScript。电子邮件、Slack、Discord 和 HMAC 签名 JSON 是推送路径。此工作流属于拉取路径，适用于已经在 Actions 中运行且希望通过上游变动使徽章变红的仓库。