Add rhtap dockerfile with allowed image references

See the details in the associated task.

Refs:
 - https://issues.redhat.com/browse/ACM-7178

Signed-off-by: Gus Parvin <[email protected]>

.tekton/governance-policy-propagator-fm3n-pull-request.yaml

@@ -19,7 +19,7 @@ metadata:
 spec:
   params:
     - name: dockerfile
-      value: ./Dockerfile
+      value: ./Dockerfile.rhtap
     - name: git-url
       value: '{{repo_url}}'
     - name: image-expires-after

.tekton/governance-policy-propagator-fm3n-push.yaml

@@ -18,7 +18,7 @@ metadata:
 spec:
   params:
     - name: dockerfile
-      value: ./Dockerfile
+      value: ./Dockerfile.rhtap
     - name: git-url
       value: '{{repo_url}}'
     - name: output-image

Dockerfile.rhtap

@@ -0,0 +1,33 @@
+# Stage 1: Use image builder to build the target binaries
+# Copyright Contributors to the Open Cluster Management project
+
+FROM brew.registry.redhat.io/rh-osbs/openshift-golang-builder:rhel_8_1.20 AS builder
+
+ENV COMPONENT=governance-policy-propagator
+ENV REPO_PATH=/go/src/github.com/stolostron/${COMPONENT}
+WORKDIR ${REPO_PATH}
+COPY . .
+RUN go mod vendor
+RUN make build
+
+# Stage 2: Copy the binaries from the image builder to the base image
+FROM registry.access.redhat.com/ubi8/ubi-minimal:latest
+
+ENV COMPONENT=governance-policy-propagator
+ENV REPO_PATH=/go/src/github.com/stolostron/${COMPONENT}
+ENV OPERATOR=/usr/local/bin/${COMPONENT} \
+    USER_UID=1001 \
+    USER_NAME=${COMPONENT}
+
+# install operator binary
+COPY --from=builder ${REPO_PATH}/build/_output/bin/${COMPONENT} ${OPERATOR}
+
+COPY --from=builder ${REPO_PATH}/build/bin /usr/local/bin
+RUN  /usr/local/bin/user_setup
+
+ENTRYPOINT ["/usr/local/bin/entrypoint"]
+
+RUN microdnf update && \
+    microdnf clean all
+
+USER ${USER_UID}