use bci-base to run zypper then layer the result onto bci-micro (#194)

Signed-off-by: Chris Kim <[email protected]>

package/Dockerfile

@@ -1,6 +1,22 @@
-FROM registry.suse.com/bci/bci-micro:15.6
+FROM registry.suse.com/bci/bci-micro:15.6 AS final
 
-RUN zypper in -y openssl patterns-base-fips
+# Temporary build stage image
+FROM registry.suse.com/bci/bci-base:15.6 AS builder
+
+# Install system packages using builder image that has zypper
+COPY --from=final / /chroot/
+
+RUN zypper refresh && \
+    zypper --installroot /chroot -n in --no-recommends \
+    openssl patterns-base-fips && \
+    zypper --installroot /chroot clean -a && \
+    rm -rf /chroot/var/cache/zypp/* /chroot/var/log/zypp/* /chroot/tmp/* /chroot/var/tmp/* /chroot/usr/share/doc/packages/*
+
+# Main stage using bci-micro as the base image
+FROM final
+
+# Copy binaries and configuration files from builder to micro
+COPY --from=builder /chroot/ /
 
 COPY bin/rancher-system-agent /usr/bin/
 RUN chmod +x /usr/bin/rancher-system-agent