Consistent use of $KAFKA_HOME variable (wurstmeister#484)

Author: richardmars

Dockerfile

@@ -30,7 +30,7 @@ RUN apk add --no-cache bash curl jq docker \
  && sync && /tmp/download-kafka.sh \
  && tar xfz /tmp/kafka_${SCALA_VERSION}-${KAFKA_VERSION}.tgz -C /opt \
  && rm /tmp/kafka_${SCALA_VERSION}-${KAFKA_VERSION}.tgz \
- && ln -s /opt/kafka_${SCALA_VERSION}-${KAFKA_VERSION} /opt/kafka \
+ && ln -s /opt/kafka_${SCALA_VERSION}-${KAFKA_VERSION} ${KAFKA_HOME} \
  && rm /tmp/* \
  && wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/${GLIBC_VERSION}/glibc-${GLIBC_VERSION}.apk \
  && apk add --no-cache --allow-untrusted glibc-${GLIBC_VERSION}.apk \