Docker file added multistage build to add non-root user running under ID:20001 for image.

Reduces attack surface by not running image as root user

Author: Janis Orlovs

Dockerfile

@@ -1,5 +1,11 @@
+FROM debian:7.11-slim
+RUN useradd -u 20001 postgres_exporter
+
 FROM scratch
 
+COPY --from=0 /etc/passwd /etc/passwd
+USER postgres_exporter
+
 ARG binary
 
 COPY $binary /postgres_exporter