update Dockerfile

Dockerfile

@@ -6,15 +6,32 @@
 # Features:
 # - Full TeX Live 2025 with Japanese support
 # - MongoDB 7.0 (stable in containers)
-# - Redis 8.6 (from bitnami/redis Docker image)
+# - Redis (copied from redis:alpine)
 # - Port 7860
 
+# ============================================
+# STAGE 1: Get Redis binaries from redis:alpine
+# ============================================
+FROM redis:alpine AS redis-copy
+RUN mkdir /redis-bin && \
+    cp /usr/local/bin/redis-server /redis-bin/ && \
+    cp /usr/local/bin/redis-cli /redis-bin/
+
+# ============================================
+# STAGE 2: Build the Overleaf image
+# ============================================
 FROM fifof16/sharelatex-with-texlive-full:latest
 
 USER root
 
 # ============================================
-# STEP 1: DOWNLOAD MONGODB 7.0 (VERIFIED OK)
+# STEP 1: COPY REDIS FROM STAGE 1
+# ============================================
+COPY --from=redis-copy /redis-bin/ /usr/local/bin/
+RUN chmod +x /usr/local/bin/redis-* && redis-server --version
+
+# ============================================
+# STEP 2: DOWNLOAD MONGODB 7.0
 # ============================================
 RUN mkdir -p /opt/mongodb /usr/local/bin && \
     cd /opt/mongodb && \
@@ -25,7 +42,7 @@ RUN mkdir -p /opt/mongodb /usr/local/bin && \
     /usr/local/bin/mongod --version
 
 # ============================================
-# STEP 2: DOWNLOAD MONGOSH (VERIFIED OK)
+# STEP 3: DOWNLOAD MONGOSH
 # ============================================
 RUN mkdir -p /opt/mongosh /usr/local/bin && \
     cd /opt/mongosh && \
@@ -35,19 +52,6 @@ RUN mkdir -p /opt/mongosh /usr/local/bin && \
     rm -rf /opt/mongosh && \
     chmod +x /usr/local/bin/mongosh
 
-# ============================================
-# STEP 3: COPY REDIS FROM LOCAL BINARY (copied from bitnami/redis)
-# ============================================
-# Redis binary copied from bitnami/redis:8.6.2 Docker image
-# Download command used:
-#   docker pull bitnami/redis
-#   docker create --name temp bitnami/redis
-#   docker cp temp:/opt/bitnami/redis/bin/redis-server ./
-#   docker cp temp:/opt/bitnami/redis/bin/redis-cli ./
-#   docker rm temp
-COPY redis-server redis-cli /usr/local/bin/
-RUN chmod +x /usr/local/bin/redis-* && redis-server --version
-
 # ============================================
 # STEP 4: REMOVE DEFAULT CHECK SCRIPTS
 # ============================================