use alpine go package

dockerbuild/Dockerfile.alpine

@@ -2,7 +2,7 @@ FROM alpine:3.11.3
 
 ARG go_pkg_url
 
-RUN apk add --update alpine-sdk linux-headers cmake openssh curl
+RUN apk add --update alpine-sdk linux-headers cmake openssh curl musl-dev go
 
 
 RUN adduser -D -s /bin/ash jenkins && \
@@ -11,9 +11,6 @@ RUN adduser -D -s /bin/ash jenkins && \
     mkdir /home/jenkins/.ssh && \
     chown -R jenkins:jenkins /home/jenkins
 
-RUN curl -s $go_pkg_url -o go.tar.gz && \
-    tar -C /usr/local -xzf go.tar.gz
-
 COPY authorized_keys /home/jenkins/.ssh/authorized_keys
 RUN chown -R jenkins:jenkins /home/jenkins/.ssh && \
     chmod 600 /home/jenkins/.ssh/authorized_keys