Avoid docker login everytime even it is done before

Signed-off-by: rick <rick@jenkins-zh.cn>

hack/docker_build.sh

@@ -5,6 +5,11 @@ set -o pipefail
 
 tag_for_branch() {
     local tag=$1
+    if [[ "${tag}" == "" ]]; then
+        tag=$(git branch --show-current)
+        tag=${tag/\//-}
+    fi
+
     if [[ "${tag}" == "master" ]]; then
         tag="latest"
     fi
@@ -19,6 +24,9 @@ docker build -f build/ks-apiserver/Dockerfile -t $REPO/ks-apiserver:$TAG .
 docker build -f build/ks-controller-manager/Dockerfile -t $REPO/ks-controller-manager:$TAG .
 
 # Push image to dockerhub, need to support multiple push
-echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
+cat ~/.docker/config.json | grep index.docker.io
+if [[ $? != 0 ]]; then
+  echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
+fi
 docker push $REPO/ks-apiserver:$TAG
 docker push $REPO/ks-controller-manager:$TAG

install/scripts/docker_push

@@ -1,4 +1,7 @@
 #!/bin/bash
 
-echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
+cat ~/.docker/config.json | grep index.docker.io
+if [[ $? != 0 ]]; then
+  echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
+fi
 docker push kubespheredev/ks-apiserver:latest