Fix healthcheck issue with Docker containers (#5011)

Fixes #5010

Dockerfile

@@ -8,8 +8,10 @@ ENV CGO_ENABLED 0
 
 WORKDIR /go/src/github.com/minio/
 
+COPY dockerscripts/docker-entrypoint.sh dockerscripts/healthcheck.sh /usr/bin/
+
 RUN  \
-     apk add --no-cache ca-certificates && \
+     apk add --no-cache ca-certificates curl && \
      apk add --no-cache --virtual .build-deps git go musl-dev && \
      echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf && \
      go get -v -d github.com/minio/minio && \
@@ -19,12 +21,11 @@ RUN  \
 
 EXPOSE 9000
 
-COPY buildscripts/docker-entrypoint.sh /usr/bin/
-
-RUN chmod +x /usr/bin/docker-entrypoint.sh
-
 ENTRYPOINT ["/usr/bin/docker-entrypoint.sh"]
 
 VOLUME ["/export"]
 
+HEALTHCHECK --interval=30s --timeout=5s \
+    CMD /usr/bin/healthcheck.sh
+
 CMD ["minio"]

Dockerfile.release

@@ -2,7 +2,7 @@ FROM alpine:3.6
 
 MAINTAINER Minio Inc <dev@minio.io>
  
-COPY buildscripts/docker-entrypoint.sh buildscripts/healthcheck.sh /usr/bin/ 
+COPY dockerscripts/docker-entrypoint.sh dockerscripts/healthcheck.sh /usr/bin/
 
 RUN \
      apk add --no-cache ca-certificates && \

dockerscripts/healthcheck.sh

@@ -15,6 +15,8 @@
 # limitations under the License.
 #
 
+set -x
+
 _init () {
     scheme="http://"
     address="127.0.0.1:9000"
@@ -32,11 +34,11 @@ healthcheck_main () {
         exit 0
     else
         # Get the http response code
-        http_response=$(curl -s -k -o /dev/null -I -w "%{http_code}" \
+        http_response=$(curl -H "User-Agent: Mozilla" -s -k -o /dev/null -I -w "%{http_code}" \
             ${scheme}${address}${resource})
 
         # Get the http response body
-        http_response_body=$(curl -k -s ${scheme}${address}${resource})
+        http_response_body=$(curl -H "User-Agent: Mozilla" -k -s ${scheme}${address}${resource})
 
         # server returns response 403 and body "SSL required" if non-TLS
         # connection is attempted on a TLS-configured server. Change
@@ -44,7 +46,7 @@ healthcheck_main () {
         if [ "$http_response" = "403" ] && \
         [ "$http_response_body" = "SSL required" ]; then
             scheme="https://"
-            http_response=$(curl -s -k -o /dev/null -I -w "%{http_code}" \
+            http_response=$(curl -H "User-Agent: Mozilla" -s -k -o /dev/null -I -w "%{http_code}" \
                 ${scheme}${address}${resource})
         fi