Update example image Dockerfile

* Use a multistage Dockerfile with build args to provide the base postgres image
version
* Build stolon inside docker instead of copying locally built binaries (that
cannot be right since they may have been built for a different arch, os, glibc etc...).

Author: sgotti

.dockerignore

@@ -0,0 +1 @@
+.git

Makefile

@@ -37,9 +37,7 @@ stolonctl:
 	CGO_ENABLED=0 GO111MODULE=on go build -ldflags $(LD_FLAGS) -o $(PROJDIR)/bin/stolonctl $(REPO_PATH)/cmd/stolonctl
 
 .PHONY: docker
-docker: build
+docker:
 	if [ -z $${PGVERSION} ]; then echo 'PGVERSION is undefined'; exit 1; fi; \
 	if [ -z $${TAG} ]; then echo 'TAG is undefined'; exit 1; fi; \
-	export TEMPFILE="$$(mktemp)"; \
-	sed -e "s/\$${PGVERSION}/$${PGVERSION}/" examples/kubernetes/image/docker/Dockerfile.template > $${TEMPFILE}; \
-	docker build -t $${TAG} -f $${TEMPFILE} .
+	docker build --build-arg PGVERSION=${PGVERSION} -t ${TAG} -f examples/kubernetes/image/docker/Dockerfile .

examples/kubernetes/image/docker/Dockerfile

@@ -0,0 +1,36 @@
+ARG PGVERSION
+
+# base build image
+FROM golang:1.13-buster AS build_base
+
+WORKDIR /stolon
+
+# only copy go.mod and go.sum
+COPY go.mod .
+COPY go.sum .
+
+RUN go mod download
+
+#######
+####### Build the stolon binaries
+#######
+FROM build_base AS builder
+
+# copy all the sources
+COPY . .
+
+RUN make
+
+#######
+####### Build the final image
+#######
+FROM postgres:$PGVERSION
+
+RUN useradd -ms /bin/bash stolon
+
+EXPOSE 5432
+
+# copy the agola-web dist
+COPY --from=builder /stolon/bin/ /usr/local/bin
+
+RUN chmod +x /usr/local/bin/stolon-keeper /usr/local/bin/stolon-sentinel /usr/local/bin/stolon-proxy /usr/local/bin/stolonctl

examples/kubernetes/image/docker/Dockerfile.template

@@ -27,10 +27,11 @@ touch $HOME/.kube/config
 export KUBECONFIG=$HOME/.kube/config
 sudo -E minikube start --vm-driver=none
 
+make PGVERSION=10 TAG=stolon:master-pg10 docker
+
 ## Temporary hack disable checksum verification since semaphore has go 1.11.0 that had a bug causing different checksums than the right one generated by go 1.11.2
 rm go.sum
-
-make PGVERSION=10 TAG=stolon:master-pg10 docker
+make
 
 ./bin/stolonctl --cluster-name kube-stolon --store-backend kubernetes --kube-resource-kind configmap init -y