Use distroless image for operator image

To avoid security issues switch to usage of distroless image.
Also bumped go version to 1.19

Fixes: pravega#508
Signed-off-by: Ann Taraday <akamyshnikova@mirantis.com>

Dockerfile

@@ -1,6 +1,6 @@
 ARG DOCKER_REGISTRY
 ARG ALPINE_VERSION=3.15
-FROM ${DOCKER_REGISTRY:+$DOCKER_REGISTRY/}golang:1.18-alpine${ALPINE_VERSION} as go-builder
+FROM ${DOCKER_REGISTRY:+$DOCKER_REGISTRY/}golang:1.19-alpine${ALPINE_VERSION} as go-builder
 
 ARG PROJECT_NAME=zookeeper-operator
 ARG REPO_PATH=github.com/pravega/$PROJECT_NAME
@@ -28,14 +28,10 @@ COPY controllers/ controllers/
 RUN GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -o /src/${PROJECT_NAME} \
     -ldflags "-X ${REPO_PATH}/pkg/version.Version=${VERSION} -X ${REPO_PATH}/pkg/version.GitSHA=${GIT_SHA}" main.go
 
-FROM ${DOCKER_REGISTRY:+$DOCKER_REGISTRY/}alpine:${ALPINE_VERSION} AS final
-
+FROM gcr.io/distroless/static:nonroot AS final
 
 ARG PROJECT_NAME=zookeeper-operator
 
 COPY --from=go-builder /src/${PROJECT_NAME} /usr/local/bin/${PROJECT_NAME}
 
-RUN adduser -D ${PROJECT_NAME}
-USER ${PROJECT_NAME}
-
 ENTRYPOINT ["/usr/local/bin/zookeeper-operator"]

go.mod

@@ -1,6 +1,6 @@
 module github.com/pravega/zookeeper-operator
 
-go 1.18
+go 1.19
 
 require (
 	github.com/ghodss/yaml v1.0.0