Install helm v2 temporarily for compatibility with current k8s Spark …

…cluster

The current k8s Spark cluster is v1.18.6 and it is not compatible
with helm v3 -- some commands in sparkk8s_token.sh fail.
For now, install a helm v2 binary instead until the k8s Spark
cluster is upgraded. When that happens, revert this commit and
update sparkk8s_token.sh to make it compatible with helm v3.

Dockerfile

@@ -88,9 +88,16 @@ RUN chmod +x /usr/bin/kS4U && \
 
 # Install kubectl and helm (for sparkk8s_token.sh)
 ADD ./repos/kubernetes9al-stable.repo /etc/yum.repos.d/kubernetes9al-stable.repo
-RUN dnf install -y kubernetes-client \
-                   helm && \
+RUN dnf install -y kubernetes-client && \
     dnf clean all && rm -rf /var/cache/dnf
+# TODO: Replace this by the installation of the helm system package above
+# Install helm v2 temporarily until the k8s Spark cluster is updated to a more
+# recent k8s version -- helm v3 does not work with the current k8s version
+RUN cd /tmp && \
+    curl -LO https://git.io/get_helm.sh && \
+    chmod 700 get_helm.sh && \
+    HELM_INSTALL_DIR=/usr/bin ./get_helm.sh --version v2.16.7 && \
+    rm get_helm.sh
 
 # Web GUI (CSS, logo)
 RUN dnf install -y unzip && \