Bugfix: install VMOD selector in the Varnish Docker container.

container/Dockerfile.varnish

@@ -5,6 +5,7 @@ RUN yum install -y epel-release && yum update -y -q && \
     yum-config-manager --add-repo https://pkg.uplex.de/rpm/7/uplex-varnish/x86_64/ && \
     yum install -y -q varnish-6.1.1 && \
     yum install -y -q --nogpgcheck vmod-re2 && \
+    yum install -y -q --nogpgcheck vmod-selector && \
     yum clean all && rm -rf /var/cache/yum
 RUN /bin/mkdir /var/run/varnish
 COPY bogo_backend.vcl /etc/varnish/