feat: add local cache storage

Author: nelsonmestevao

action.yml

@@ -77,31 +77,18 @@ runs:
         elixir-version: ${{ inputs.elixir-version }}
         otp-version: ${{ inputs.otp-version }}
 
-    - name: Get deps cache
-      uses: actions/cache@v4
-      with:
-        path: deps/
-        key: deps-${{ inputs.cache-key }}-${{ runner.os }}-${{ hashFiles('**/mix.lock') }}
-        restore-keys: |
-          deps-${{ inputs.cache-key }}-${{ runner.os }}-
+    # Restore cache before building
+    - name: Restore local cache
+      shell: bash
+      run: ${{ github.action_path }}/localcache.sh restore deps-${{ inputs.cache-key }}-${{ runner.os }}-${{ hashFiles('**/mix.lock') }} deps/
 
     - name: Get build cache
-      uses: actions/cache@v4
-      id: build-cache
-      with:
-        path: _build/${{env.MIX_ENV}}/
-        key: build-${{ inputs.cache-key }}-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ env.MIX_ENV }}-${{ hashFiles('**/mix.lock') }}
-        restore-keys: |
-          build-${{ inputs.cache-key }}-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ env.MIX_ENV }}-
+      shell: bash
+      run: ${{ github.action_path }}/localcache.sh restore build-${{ inputs.cache-key }}-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ env.MIX_ENV }}-${{ hashFiles('**/mix.lock') }} _build/${{env.MIX_ENV}}/
 
     - name: Get Hex cache
-      uses: actions/cache@v4
-      id: hex-cache
-      with:
-        path: ~/.hex
-        key: build-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ hashFiles('**/mix.lock') }}
-        restore-keys: |
-          build-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-
+      shell: bash
+      run: ${{ github.action_path }}/localcache.sh restore hex-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ hashFiles('**/mix.lock') }} ~/.hex
 
     # In my experience, I have issues with incremental builds maybe 1 in 100
     # times that are fixed by doing a full recompile.
@@ -145,6 +132,19 @@ runs:
       shell: sh
       if: inputs.build-app == 'true'
 
+    # Save cache after the build is done
+    - name: Save local deps cache
+      shell: bash
+      run: ${{ github.action_path }}/localcache.sh save deps-${{ inputs.cache-key }}-${{ runner.os }}-${{ hashFiles('**/mix.lock') }} deps/
+
+    - name: Save local build cache
+      shell: bash
+      run: ${{ github.action_path }}/localcache.sh save build-${{ inputs.cache-key }}-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ env.MIX_ENV }}-${{ hashFiles('**/mix.lock') }} _build/${{env.MIX_ENV}}/
+
+    - name: Save local Hex cache
+      shell: bash
+      run: ${{ github.action_path }}/localcache.sh save hex-${{ runner.os }}-${{ inputs.otp-version }}-${{ inputs.elixir-version }}-${{ hashFiles('**/mix.lock') }} ~/.hex
+
     # Don't cache PLTs based on mix.lock hash, as Dialyzer can incrementally update even old ones
     # Cache key based on Elixir & Erlang version (also useful when running in matrix)
     - name: Restore PLT cache

localcache.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+set -e
+
+MODE=$1        # "save" or "restore"
+KEY=$2         # unique key for the cache (e.g. node_modules_hash123)
+TARGET=$3      # path to directory to cache (e.g. node_modules/)
+CACHE_DIR=/home/runner/cache
+
+if [[ -z "$MODE" || -z "$KEY" || -z "$TARGET" ]]; then
+  echo "Usage: $0 [save|restore] <key> <target_dir>"
+  exit 1
+fi
+
+CACHE_PATH="$CACHE_DIR/$KEY"
+
+mkdir -p "$CACHE_DIR"
+
+if [ "$MODE" == "restore" ]; then
+  if [ -d "$CACHE_PATH" ]; then
+    echo "✅ Restoring cache from $CACHE_PATH → $TARGET"
+    mkdir -p "$TARGET"
+    cp -r "$CACHE_PATH/"* "$TARGET/" || true
+  else
+    echo "⚠️  No cache found for key: $KEY"
+  fi
+
+elif [ "$MODE" == "save" ]; then
+  echo "📦 Saving cache from $TARGET → $CACHE_PATH"
+  mkdir -p "$CACHE_PATH"
+  cp -r "$TARGET/"* "$CACHE_PATH/" || true
+else
+  echo "❌ Invalid mode: $MODE"
+  exit 1
+fi