Update Dockerfile

Dockerfile

@@ -3,6 +3,7 @@ ARG TARGETARCH
 
 FROM ${FRM} as build
 ENV DEBIAN_FRONTEND=noninteractive
+ENV BALENA_CLI_URL=https://dl.beagle.cc/balena-cli-v18.2.34-linux-x64-standalone.zip
 
 RUN apt-get update \
     && apt-get install -y apt-utils ca-certificates \
@@ -37,8 +38,8 @@ RUN . /etc/os-release \
         file cpio unzip bc rsync bison flex device-tree-compiler python3-setuptools swig python3-dev ccache \
     && cp -v /etc/bbb.io/templates/apt/sbuild.list /etc/apt/sources.list.d/beagle.list \
     && apt-get clean
-RUN if [ "$ARCHNAME" = "amd64" ]; then \
-        wget "$BALENA_CLI_URL" -O balena-cli.zip \
+RUN if [ "${ARCHNAME}" = "amd64" ]; then \
+        wget "${BALENA_CLI_URL}" -O balena-cli.zip \
         mkdir -p /opt ; \
         unzip balena-cli.zip -d /opt ; \
         rm balena-cli.zip ; \