added kubectl to image

.drone.yml

@@ -16,6 +16,6 @@ matrix:
   VERSION:
     - 193.0.0-alpine
   KUBECTL_VERSION:
-    - v9.0.10
+    - v1.9.10
     - v1.10.7
     - v1.11.2

Dockerfile

@@ -5,6 +5,6 @@ RUN apk add -U --no-cache openssl
 
 # download and install kubectl
 ARG KUBECTL_VERSION
-ENV KUBECTL_VERSION ${KUBECTL_VERSION:-v9.0.10}
-RUN curl -LO https://storage.googleapis.com/kubernetes-release/release/$KUBECTL_VERSION/bin/linux/amd64/kubectl -o /usr/bin/kubectl \
-	&& chmod +x /usr/bin/kubectl \
+
+RUN curl -L https://storage.googleapis.com/kubernetes-release/release/$KUBECTL_VERSION/bin/linux/amd64/kubectl -o /usr/bin/kubectl \
+	&& chmod +x /usr/bin/kubectl