From e540f15e16a985425a201894f5260c0eb57d7079 Mon Sep 17 00:00:00 2001
From: David Bauer <mail@david-bauer.net>
Date: Sun, 28 Jul 2024 02:49:50 +0200
Subject: [PATCH] ci: utilize cache for SDK

---
 .github/workflows/build.yaml | 27 ++++++++++++++++++++++++++-
 contrib/cache-key-sdk.sh     | 13 +++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100755 contrib/cache-key-sdk.sh

diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 7186a3e..2897ff9 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -47,24 +47,49 @@ jobs:
       - name: Install dependencies
         run: |
           $GITHUB_WORKSPACE/contrib/install-deps.sh
+      - name: Determine Cache-Key
+        id: cache-key-sdk
+        run: >
+          echo "cache-key=$(bash $GITHUB_WORKSPACE/contrib/cache-key.sh
+          $GITHUB_WORKSPACE ${{ needs.build-meta.outputs.sdk-url }})" >> "$GITHUB_OUTPUT"
+      - name: Restore Cache
+        id: restore-cache-sdk
+        uses: actions/cache/restore@v4
+        with:
+          path: /tmp/openwrt-sdk
+          key: ${{ steps.cache-key-sdk.outputs.cache-key }}
       - name: Download SDK
+        if: steps.restore-cache-sdk.outputs.cache-hit != 'true'
         run: |
           curl -o /tmp/openwrt-sdk.tar.xz ${{ needs.build-meta.outputs.sdk-url }}
       - name: Extract SDK
+        if : steps.restore-cache-sdk.outputs.cache-hit != 'true'
         run: |
           tar -xf /tmp/openwrt-sdk.tar.xz -C /tmp
           ls /tmp
           mv /tmp/${{ needs.build-meta.outputs.sdk-name }} /tmp/openwrt-sdk
       - name: Create feeds.conf
+        if: steps.restore-cache-sdk.outputs.cache-hit != 'true'
         run: |
           cp /tmp/openwrt-sdk/feeds.conf.default /tmp/openwrt-sdk/feeds.conf
           echo "src-link oobfw $GITHUB_WORKSPACE/openwrt" >> /tmp/openwrt-sdk/feeds.conf
           echo "src-link oobpkgs $GITHUB_WORKSPACE/packages" >> /tmp/openwrt-sdk/feeds.conf
-      - name: Init SDK
+      - name: Install SDK feeds
+        if: steps.restore-cache-sdk.outputs.cache-hit != 'true'
         run: |
           cd /tmp/openwrt-sdk
           ./scripts/feeds update -a
           ./scripts/feeds install -a
+      - name: Save cache
+        id: save-cache-sdk
+        if: steps.restore-cache-sdk.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: /tmp/openwrt-sdk
+          key: ${{ steps.cache-key-sdk.outputs.cache-key }}
+      - name: Create SDK configuration
+        run: |
+          cd /tmp/openwrt-sdk
           echo "# CONFIG_SIGNED_PACKAGES is not set" > /tmp/openwrt-sdk/.config
           echo CONFIG_FFDA_OOB_FIRMWARE_VERSION=\"${{ needs.build-meta.outputs.firmware-version }}\" >> /tmp/openwrt-sdk/.config
           make defconfig
diff --git a/contrib/cache-key-sdk.sh b/contrib/cache-key-sdk.sh
new file mode 100755
index 0000000..a5fd998
--- /dev/null
+++ b/contrib/cache-key-sdk.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+WORKSPACE_DIR="$1"
+SDK_URL="$2"
+
+if [ -z "$WORKSPACE_DIR" ] || [ -z "$SDK_URL" ]; then
+    echo "Usage: $0 <workspace_dir> <sdk_url>"
+    exit 1
+fi
+
+PACKAGES_SUBMODULE_REV="$(git -C "$WORKSPACE_DIR/packages" rev-parse HEAD)"
+SDK_URL_HASH="$(echo "$SDK_URL" | sha256sum | cut -d ' ' -f 1)"
+CACHE_KEY="sdk-$PACKAGES_SUBMODULE_REV-$SDK_URL_HASH"
\ No newline at end of file