diff --git a/packer/build.sh b/packer/build.sh
index 6652080..7a9689a 100755
--- a/packer/build.sh
+++ b/packer/build.sh
@@ -4,12 +4,62 @@ set -e
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 cd "$SCRIPT_DIR"
 
-if [ ! -f server.pkrvars.hcl ]; then
-    echo "Error: server.pkrvars.hcl not found."
-    echo "Copy server.pkrvars.hcl.example to server.pkrvars.hcl and fill in your values."
-    exit 1
+VARS_FILE="server.pkrvars.hcl"
+
+collect_values() {
+    echo "=== Server Configuration ==="
+    echo ""
+
+    read -p "Base domain: " BASE_DOMAIN
+
+    read -p "SSH public key path [~/.ssh/id_ed25519.pub]: " PUBKEY_PATH
+    PUBKEY_PATH="${PUBKEY_PATH:-$HOME/.ssh/id_ed25519.pub}"
+    if [ ! -f "$PUBKEY_PATH" ]; then
+        echo "Warning: $PUBKEY_PATH not found, leaving SSH key empty"
+        SSH_PUBKEY=""
+    else
+        SSH_PUBKEY=$(cat "$PUBKEY_PATH")
+    fi
+
+    echo ""
+    echo "--- JuiceFS / Nextcloud Storage ---"
+    read -p "S3 endpoint (e.g. https://s3.amazonaws.com): " JUICEFS_S3_ENDPOINT
+    read -p "S3 bucket name: " JUICEFS_S3_BUCKET
+    read -p "S3 access key: " JUICEFS_S3_ACCESS_KEY
+    read -s -p "S3 secret key: " JUICEFS_S3_SECRET_KEY
+    echo
+    read -p "JuiceFS local cache size [50G]: " JUICEFS_CACHE_SIZE
+    JUICEFS_CACHE_SIZE="${JUICEFS_CACHE_SIZE:-50G}"
+
+    cat > "$VARS_FILE" <<EOF
+base_domain           = "$BASE_DOMAIN"
+ssh_pubkey            = "$SSH_PUBKEY"
+juicefs_s3_endpoint   = "$JUICEFS_S3_ENDPOINT"
+juicefs_s3_bucket     = "$JUICEFS_S3_BUCKET"
+juicefs_s3_access_key = "$JUICEFS_S3_ACCESS_KEY"
+juicefs_s3_secret_key = "$JUICEFS_S3_SECRET_KEY"
+juicefs_cache_size    = "$JUICEFS_CACHE_SIZE"
+EOF
+
+    echo ""
+    echo "Configuration saved to $VARS_FILE"
+}
+
+if [ -f "$VARS_FILE" ]; then
+    echo "Existing configuration found ($VARS_FILE):"
+    echo ""
+    grep -v "secret_key" "$VARS_FILE"
+    echo "  (secret keys hidden)"
+    echo ""
+    read -p "Use existing config? [Y/n]: " USE_EXISTING
+    if [[ "$USE_EXISTING" =~ ^[Nn] ]]; then
+        collect_values
+    fi
+else
+    collect_values
 fi
 
+echo ""
 echo "=== Initializing Packer plugins ==="
 packer init ubuntu-server.pkr.hcl
 
@@ -18,7 +68,7 @@ echo "=== Building image ==="
 echo "This will take 15-30 minutes depending on your machine."
 echo ""
 
-packer build -var-file=server.pkrvars.hcl ubuntu-server.pkr.hcl
+packer build -var-file="$VARS_FILE" ubuntu-server.pkr.hcl
 
 echo ""
 echo "==========================================="