Rename arm contrib files

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

contrib/prometheus-arm64/1.5.2/Dockerfile

@@ -1,4 +1,4 @@
-FROM arm64v8/alpine:3.5
+FROM alpine:3.6
 
 workdir /root
 RUN apk add --update libarchive-tools

contrib/prometheus-armhf/2.1/Dockerfile

@@ -0,0 +1,31 @@
+FROM alpine:3.6
+WORKDIR /root/
+
+RUN apk add --update libarchive-tools curl \
+    && curl -sLf https://github.com/prometheus/prometheus/releases/download/v2.1.0/prometheus-2.1.0.linux-armv7.tar.gz > prometheus.tar.gz \
+    && bsdtar -xvf prometheus.tar.gz -C ./ --strip-components=1 \
+    && apk del libarchive-tools curl \
+    && mkdir /etc/prometheus \
+    && mkdir -p /usr/share/prometheus \
+    && cp prometheus                             /bin/prometheus \
+    && cp promtool                               /bin/promtool \
+    && cp prometheus.yml  				/etc/prometheus/ \
+    && cp -r console_libraries                     /usr/share/prometheus/ \
+    && cp -r consoles                              /usr/share/prometheus/ \
+    && rm -rf /root/*
+
+RUN ln -s /usr/share/prometheus/console_libraries /usr/share/prometheus/consoles/ /etc/prometheus/
+RUN mkdir -p /prometheus && \
+    chown -R nobody:nogroup /etc/prometheus /prometheus
+
+USER       nobody
+EXPOSE     9090
+VOLUME     [ "/prometheus" ]
+WORKDIR    /prometheus
+ENTRYPOINT [ "/bin/prometheus" ]
+CMD        [ "--config.file=/etc/prometheus/prometheus.yml", \
+             "--storage.tsdb.path=/prometheus", \
+             "--web.console.libraries=/usr/share/prometheus/console_libraries", \
+             "--web.console.templates=/usr/share/prometheus/consoles" ]
+
+