fix some bugs (#2751)

Signed-off-by: Jeff <zw0948@gmail.com>

build/ks-apiserver/Dockerfile

@@ -2,19 +2,15 @@
 # Use of this source code is governed by an Apache license
 # that can be found in the LICENSE file.
 FROM alpine:3.11
-ENV USER=kubesphere
-ENV UID=1002
-# docker group
-ENV GID=998
 
+RUN apk add --no-cache ca-certificates 
+
+# To speed up building process, we copy binary directly from make
+# result instead of building it again, so make sure you run the 
+# following command first before building docker image
+#   make ks-apiserver
+#
 COPY  /bin/cmd/ks-apiserver /usr/local/bin/
 
-RUN apk add --no-cache ca-certificates && \
-    addgroup --gid "$GID" "$USER" && \
-    adduser -D -g "" --ingroup "$USER" -u "$UID" "$USER" && \
-    chown -R kubesphere:"$GID" /usr/local/bin/ks-apiserver
-
 EXPOSE 9090
-
-USER kubesphere
-CMD ["sh"]
+CMD ["sh"]