preview-command.yml

name: Preview Command

on:
  issue_comment:
    types: [created]

permissions:
  contents: write
  issues: write
  pull-requests: write

concurrency:
  group: dev-preview-command
  cancel-in-progress: false

jobs:
  preview:
    name: Dispatch preview deployment
    if: ${{ github.event.issue.pull_request && startsWith(github.event.comment.body, '/preview') }}
    runs-on: ubuntu-latest
    steps:
      - name: Prepare Preview
        id: preview
        uses: actions/github-script@v9
        with:
          script: |
            const owner = context.repo.owner;
            const repo = context.repo.repo;
            const body = context.payload.comment.body.trim();
            const association = context.payload.comment.author_association;
            const trustedAssociations = new Set(["OWNER", "MEMBER", "COLLABORATOR"]);

            if (!/^\/preview(?:\s|$)/.test(body)) {
              core.info("Comment starts with /preview but does not match the command format.");
              return;
            }

            try {
              await github.rest.reactions.createForIssueComment({
                owner,
                repo,
                comment_id: context.payload.comment.id,
                content: "eyes"
              });
            } catch (error) {
              core.warning(`Could not add reaction to /preview comment: ${error.message}`);
            }

            if (!trustedAssociations.has(association)) {
              await github.rest.issues.createComment({
                owner,
                repo,
                issue_number: context.payload.issue.number,
                body: "I can only deploy previews when `/preview` is requested by a repository owner, member, or collaborator."
              });
              core.setFailed(`Unauthorized preview requester association: ${association}`);
              return;
            }

            const { data: pullRequest } = await github.rest.pulls.get({
              owner,
              repo,
              pull_number: context.payload.issue.number
            });

            if (pullRequest.state !== "open") {
              await github.rest.issues.createComment({
                owner,
                repo,
                issue_number: context.payload.issue.number,
                body: "I can only deploy previews for open pull requests."
              });
              core.setFailed(`Pull request #${pullRequest.number} is ${pullRequest.state}.`);
              return;
            }

            const headRepository = pullRequest.head.repo.full_name;
            const headRef = pullRequest.head.ref;
            const headSha = pullRequest.head.sha;
            const headLabel = pullRequest.head.label;
            const headShortSha = headSha.slice(0, 12);

            if (headRepository !== `${owner}/${repo}`) {
              await github.rest.issues.createComment({
                owner,
                repo,
                issue_number: pullRequest.number,
                body: "I can only deploy previews for branches in this repository right now. Fork previews need a mirrored branch before the shared dev environment can build and deploy them."
              });
              core.setFailed(`Unsupported fork preview source: ${headRepository}`);
              return;
            }

            core.setOutput("pr-number", String(pullRequest.number));
            core.setOutput("head-ref", headRef);
            core.setOutput("head-label", headLabel);
            core.setOutput("head-sha", headSha);
            core.setOutput("head-short-sha", headShortSha);

            const previewLabel = "dev-preview";
            try {
              await github.rest.issues.createLabel({
                owner,
                repo,
                name: previewLabel,
                color: "0E8A16",
                description: "Deploy this pull request to the shared dev environment."
              });
            } catch (error) {
              if (error.status !== 422) {
                throw error;
              }
            }

            await github.rest.issues.addLabels({
              owner,
              repo,
              issue_number: pullRequest.number,
              labels: [previewLabel]
            });

      - name: Post sticky queued comment
        if: ${{ steps.preview.outputs.pr-number != '' }}
        uses: marocchino/sticky-pull-request-comment@v3
        with:
          number: ${{ steps.preview.outputs.pr-number }}
          header: exceptionless-preview
          message: |
            Preview deploy queued.

            The build workflow will start shortly. This comment will update with a progress link when the run starts and with the dev URL when deployment finishes.

            - Branch: `${{ steps.preview.outputs.head-label }}`
            - Commit: [`${{ steps.preview.outputs.head-short-sha }}`](${{ github.server_url }}/${{ github.repository }}/commit/${{ steps.preview.outputs.head-sha }})
            - Command run: [view logs](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})

      - name: Dispatch Preview
        if: ${{ steps.preview.outputs.pr-number != '' }}
        uses: actions/github-script@v9
        env:
          PR_NUMBER: ${{ steps.preview.outputs.pr-number }}
          HEAD_REF: ${{ steps.preview.outputs.head-ref }}
          HEAD_LABEL: ${{ steps.preview.outputs.head-label }}
          HEAD_SHA: ${{ steps.preview.outputs.head-sha }}
        with:
          script: |
            await github.rest.repos.createDispatchEvent({
              owner: context.repo.owner,
              repo: context.repo.repo,
              event_type: "preview",
              client_payload: {
                pr_number: Number(process.env.PR_NUMBER),
                head_ref: process.env.HEAD_REF,
                head_label: process.env.HEAD_LABEL,
                head_sha: process.env.HEAD_SHA
              }
            });

      - name: Post sticky command failure comment
        if: ${{ failure() && steps.preview.outputs.pr-number != '' }}
        uses: marocchino/sticky-pull-request-comment@v3
        with:
          number: ${{ steps.preview.outputs.pr-number }}
          header: exceptionless-preview
          message: |
            Preview deploy failed before the build workflow started. See [command run logs](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}).

            - Branch: `${{ steps.preview.outputs.head-label }}`
            - Commit: [`${{ steps.preview.outputs.head-short-sha }}`](${{ github.server_url }}/${{ github.repository }}/commit/${{ steps.preview.outputs.head-sha }})