zigbee2mqtt: upgrade deps.sh to update.sh

pkgs/servers/zigbee2mqtt/deps.sh

@@ -1,15 +0,0 @@
-#!/usr/bin/env nix-shell
-#! nix-shell -i bash -p nodePackages.node2nix nodejs-12_x
-VERSION=1.14.1
-ZIGBEE2MQTT=https://raw.githubusercontent.com/Koenkk/zigbee2mqtt/$VERSION
-
-wget $ZIGBEE2MQTT/package.json
-wget $ZIGBEE2MQTT/npm-shrinkwrap.json
-
-node2nix --nodejs-12 \
-  -l npm-shrinkwrap.json \
-  -c node.nix \
-  --bypass-cache \
-  --no-copy-node-env \
-  --node-env ../../development/node-packages/node-env.nix
-rm package.json npm-shrinkwrap.json

pkgs/servers/zigbee2mqtt/update.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash -p nodePackages.node2nix nodejs-12_x curl jq nix-update
+
+CURRENT_VERSION=$(nix eval --raw '(with import ../../.. {}; zigbee2mqtt.version)')
+TARGET_VERSION=$(curl https://api.github.com/repos/Koenkk/zigbee2mqtt/releases/latest | jq -r ".tag_name")
+ZIGBEE2MQTT=https://github.com/Koenkk/zigbee2mqtt/raw/$TARGET_VERSION
+
+if [[ "$CURRENT_VERSION" == "$TARGET_VERSION" ]]; then
+    echo "zigbee2mqtt is up-to-date: ${CURRENT_VERSION}"
+    exit 0
+fi
+
+wget $ZIGBEE2MQTT/package.json
+wget $ZIGBEE2MQTT/npm-shrinkwrap.json
+
+node2nix --nodejs-12 \
+  -l npm-shrinkwrap.json \
+  -c node.nix \
+  --bypass-cache \
+  --no-copy-node-env \
+  --node-env ../../development/node-packages/node-env.nix
+rm package.json npm-shrinkwrap.json
+
+{
+    cd ../../..
+    nix-update --version "$TARGET_VERSION" --build zigbee2mqtt
+}
+
+git add ./default.nix ./node-packages.nix ./node.nix
+git commit -m "zigbee2mqtt: ${CURRENT_VERSION} -> ${TARGET_VERSION}"