build fixed version of gitlab-runner

Signed-off-by: Gergely Imreh <gergely@balena.io>

runner/Dockerfile.template

@@ -6,10 +6,14 @@ FROM balenalib/%%BALENA_MACHINE_NAME%%-golang:1.11-jessie-build as build
 WORKDIR /src
 
 # Building as described at https://docs.gitlab.com/runner/development/
+# Change this env var to a desired version tag, or set to "master" (YMMV)
+ENV GITLAB_VERSION=v11.6.1
 RUN    go get -v gitlab.com/gitlab-org/gitlab-runner \
-    && cd $GOPATH/src/gitlab.com/gitlab-org/gitlab-runner/ \
+    && cd "${GOPATH}/src/gitlab.com/gitlab-org/gitlab-runner/" \
+    && git checkout "${GITLAB_VERSION}" \
     && make deps \
-    && make install
+    && make build_simple \
+    && install -m755 /go/src/gitlab.com/gitlab-org/gitlab-runner/out/binaries/gitlab-runner /usr/bin/gitlab-runner
 
 # Grab docker-gc
 RUN git clone https://github.com/spotify/docker-gc.git
@@ -28,7 +32,7 @@ WORKDIR /usr/src/app
 
 RUN install_packages cron
 
-COPY --from=build /go/bin/gitlab-runner /usr/bin/gitlab-runner
+COPY --from=build /usr/bin/gitlab-runner /usr/bin/gitlab-runner
 COPY --from=build /src/docker-gc/docker-gc /usr/bin/docker-gc
 COPY --from=build /usr/bin/balena-engine /usr/bin/balena-engine