Link to preview of latest commit in PR body (#2287)

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To get an auto-generated PR description you can put "copilot:summary" or
"copilot:walkthrough" anywhere.
-->

### What

### Checklist
* [ ] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [ ] I've included a screenshot or gif (if applicable)

<!-- This line will get updated when the PR build summary job finishes.
-->
PR Build Summary: https://build.rerun.io/pr/2287

<!-- pr-link-docs:start -->
Docs preview: https://rerun.io/preview/49fbf30/docs
<!-- pr-link-docs:end -->

.github/pull_request_template.md

@@ -18,3 +18,5 @@ To get an auto-generated PR description you can put "copilot:summary" or "copilo
 
 <!-- This line will get updated when the PR build summary job finishes. -->
 PR Build Summary: {{ pr-build-summary }}
+
+<!-- This comment will be replaced by a link to the documentation preview -->

.github/workflows/on_pull_request.yml

@@ -81,3 +81,11 @@ jobs:
       CONCURRENCY: pr-${{ github.event.pull_request.number }}
       PR_NUMBER: ${{ github.event.pull_request.number }}
     secrets: inherit
+
+  link-docs:
+    name: 'Link Docs'
+    uses: ./.github/workflows/reusable_pr_link_docs.yml
+    with:
+      CONCURRENCY: pr-${{ github.event.pull_request.number }}
+      PR_NUMBER: ${{ github.event.pull_request.number }}
+    secrets: inherit

.github/workflows/reusable_pr_link_docs.yml

@@ -0,0 +1,49 @@
+name: Reusable PR Link Docs
+
+on:
+  workflow_call:
+    inputs:
+      CONCURRENCY:
+        required: true
+        type: string
+      PR_NUMBER:
+        required: true
+        type: string
+
+concurrency:
+  group: ${{ inputs.CONCURRENCY }}-pr-summary
+  cancel-in-progress: true
+
+jobs:
+  pr-link-docs:
+    name: Link to docs preview in PR
+
+    permissions:
+      contents: "read"
+      id-token: "write"
+      pull-requests: "write"
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.x
+
+      - name: Install deps
+        run: pip install PyGithub # NOLINT
+
+      - name: Link to docs
+        run: |
+          python scripts/pr_link_docs.py \
+          --github-token ${{ secrets.GITHUB_TOKEN }} \
+          --github-repository ${GITHUB_REPOSITORY} \
+          --pr-number ${{ inputs.PR_NUMBER }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR_NUMBER: ${{ inputs.PR_NUMBER }}
+

scripts/pr_link_docs.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+
+"""
+Script to generate a link to documentation preview in PRs.
+
+This is expected to be run by the `reusable_pr_link_docs.yml` GitHub workflow.
+
+Requires the following packages:
+  pip install PyGithub # NOLINT
+"""
+
+import argparse
+
+from github import Github  # NOLINT
+
+EMPTY_LINK = "<!-- This comment will be replaced by a link to the documentation preview -->"
+LINK_START = "<!-- pr-link-docs:start -->"
+LINK_END = "<!-- pr-link-docs:end -->"
+
+LINK_TEMPLATE = "<!-- pr-link-docs:start -->\nDocs preview: {{ link }}\n<!-- pr-link-docs:end -->"
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate a PR summary page")
+    parser.add_argument("--github-token", required=True, help="GitHub token")
+    parser.add_argument("--github-repository", required=True, help="GitHub repository")
+    parser.add_argument("--pr-number", required=True, type=int, help="PR number")
+    args = parser.parse_args()
+
+    gh = Github(args.github_token)  # NOLINT
+    repo = gh.get_repo(args.github_repository)
+    pr = repo.get_pull(args.pr_number)
+
+    latest_commit = pr.get_commits().reversed[0]
+
+    print(f"Latest commit: {latest_commit.sha}")
+
+    link = LINK_TEMPLATE.replace("{{ link }}", f"https://rerun.io/preview/{latest_commit.sha[:7]}/docs")
+    if EMPTY_LINK in pr.body:
+        print("Empty link found, updating it")
+        new_body = pr.body.replace(EMPTY_LINK, link)
+        pr.edit(body=new_body)
+    else:
+        start = pr.body.find(LINK_START)
+        end = pr.body.find(LINK_END)
+        if start != -1 and end != -1:
+            print("Existing link found, updating it")
+            new_body = pr.body[:start] + link + pr.body[end + len(LINK_END) :]
+            pr.edit(body=new_body)
+
+
+if __name__ == "__main__":
+    main()

scripts/requirements-dev.txt

@@ -6,3 +6,4 @@
 
 cryptography==38.0.4 # for scripts/upload_image.py
 google-cloud-storage==2.9.0 # for scripts/upload_image.py
+PyGithub==1.58.2 # for scripts/generate_pr_summary.py and scripts/pr_link_docs_preview.py