build docker image from scratch to reduce runtime dependencies

.gitignore

@@ -20,4 +20,5 @@
 # Go workspace file
 go.work
 go.work.sum
-.idea
+.idea
+/noah-mqtt

Dockerfile

@@ -1,6 +1,14 @@
-FROM golang:alpine
+
+FROM registry.access.redhat.com/ubi8/ubi-minimal AS builder
+RUN microdnf install -y shadow-utils && microdnf clean all
+RUN set -o pipefail && groupadd -r -g 1000 gouser && useradd -r -u 1000 -g gouser -m -d /opt/gouser -s /bin/bash gouser && cat /etc/passwd | grep gouser > /etc/passwd_gouser
+
+FROM scratch
 ARG VERSION
 ENV VERSION=${VERSION}
-ENTRYPOINT ["/noah-mqtt"]
 COPY noah-mqtt /
 COPY LICENSE /
+COPY --from=builder /etc/pki/tls/certs/ca-bundle.crt /etc/pki/tls/certs/
+COPY --from=builder /etc/passwd_gouser /etc/passwd
+USER gouser
+ENTRYPOINT ["/noah-mqtt"]