feat: Add workflow to update the aggregator (#3738)

# Motivation
We need to render SNS data accurately, so need to keep the aggregator
SNS bindings up to date.

# Changes
- Add a bot to update the SNS aggregator bindings regularly.
  - Note: If the candid API has not changed, no new PR will be created.
- Note: The code is largely identical to the bot that updates the
proposals bindings and generally matches all the other update bots.

# Tests
- The one test run showed a breaking change that needed manual
intervention. The run correctly posted the error in slack and I have
made a PR with the manual changes.
- Run again and it correctly declared that no changes are needed:
https://github.com/dfinity/nns-dapp/actions/runs/6863398505/job/18663096004

# Todos

- [x] Add entry to changelog (if necessary).

.github/workflows/update-aggregator.yml

@@ -0,0 +1,70 @@
+# A GitHub Actions workflow that regularly updates the aggregator SNS parsing code
+# and creates a PR for any changes.
+name: Update aggregator candid bindings
+on:
+  schedule:
+    - cron: '30 3 * * *'
+  workflow_dispatch:
+  push:
+    branches:
+      # Run when the development branch for this workflow is updated.
+      - update-aggregator
+jobs:
+  update-aggregator:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install didc
+        run: |
+          USER_BIN="$HOME/.local/bin"
+          mkdir -p "$USER_BIN"
+          echo "$USER_BIN" >> $GITHUB_PATH
+          version="$(jq -r .defaults.build.config.DIDC_VERSION dfx.json)"
+          # TODO: Make `didc` support `binstall`, then use `binstall` here.
+          curl -Lf "https://github.com/dfinity/candid/releases/download/${version}/didc-linux64" | install -m 755 /dev/stdin "$USER_BIN/didc"
+      - name: Update to the latest declared APIs
+        id: update
+        run: scripts/mk_nns_types.sh
+      - name: Create Pull Request
+        id: cpr
+        # Note: If there were no changes, this step creates no PR.
+        uses: peter-evans/create-pull-request@v4
+        with:
+          token: ${{ secrets.GIX_BOT_PAT }}
+          commit-message: Update aggregator
+          committer: GitHub <noreply@github.com>
+          author: gix-bot <gix-bot@users.noreply.github.com>
+          base: main
+          # Note: Please be careful when updating the add-paths field.  We have had the snsdemo committed by accident, with a pattern that matches nothing seemingly committing everything.
+          add-paths: rs/sns_aggregator/src/types/*
+          branch: bot-aggregator-update
+          branch-suffix: timestamp
+          delete-branch: true
+          title: 'Update aggregator'
+          body: |
+            # Motivation
+            We would like to parse all the latest SNS data.
+
+            # Changes
+            * Updated the Rust code derived from `.did` files in the aggregator.
+              * Note: The candid files under `declarations/nns-$CANISTER` are used as inputs.
+
+            # Tests
+              - [ ] Please check the API updates for any breaking changes that affect our code.
+      - name: Report on the action
+        # Since the this is a scheduled job, a failure won't be shown on any
+        # PR status. To notify the team, we send a message to our Slack channel on failure.
+        run: |
+          (
+            echo "## Aggregator Update"
+            if test -n "${{ steps.cpr.outputs.pull-request-number }}"
+            then echo "Created [PR #${{ steps.cpr.outputs.pull-request-number }}](${{ steps.cpr.outputs.pull-request-url }}) with aggregator updates."
+            else echo "No changes needed."
+            fi
+          ) | tee -a $GITHUB_STEP_SUMMARY
+      - name: Notify Slack on failure
+        uses: dfinity/internet-identity/.github/actions/slack@release-2023-08-28
+        if: ${{ failure() }}
+        with:
+          WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
+          MESSAGE: "Aggregator update failed"

CHANGELOG-Nns-Dapp-unreleased.md

@@ -35,6 +35,7 @@ proposal is successful, the changes it released will be moved from this file to
 
 #### Added
 
+* Add a workflow to update the SNS aggregator bindings regularly.
 * Added support for global network config.
 * Cron job to update proposal types.
 * Enable dependabot for Rust updates.