Fix Docker builds

Currently, Docker builds fail due to the use of the errors package. This
change updates the version of Go. In addition, this also adds a Makefile
rule for building Docker images.

Author: nsurfer

Dockerfile

@@ -1,20 +1,16 @@
-FROM golang:1.12.4 AS builder
+FROM golang:1.14 AS build
+COPY . /go/src/nats-kafka
+WORKDIR /go/src/nats-kafka
+RUN make nats-kafka.docker
 
-WORKDIR /src/nats-kafka
+FROM alpine:latest as osdeps
+RUN apk add --no-cache ca-certificates
 
 LABEL maintainer "Stephen Asbury <sasbury@nats.io>"
+LABEL maintainer "Jaime Piña <jaime@nats.io>"
 
-COPY . .
-
-RUN go mod download
-RUN CGO_ENABLED=0 go build -v -a -tags netgo -installsuffix netgo -o /nats-kafka
-
-FROM alpine:3.9
-
-RUN mkdir -p /nats/bin && mkdir /nats/conf
-
-COPY --from=builder /nats-kafka /nats/bin/nats-kafka
-
-RUN ln -ns /nats/bin/nats-kafka /bin/nats-kafka
+FROM scratch
+COPY --from=build /go/src/nats-kafka/nats-kafka.docker /bin/nats-kafka
+COPY --from=osdeps /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
 
 ENTRYPOINT ["/bin/nats-kafka"]

Makefile

@@ -66,3 +66,16 @@ run-test-cover:
 	go test -count=1 -timeout 5m -coverpkg=./... -coverprofile=cover.out ./...
 	go tool cover -html=cover.out
 	rm cover.out
+
+nats-kafka.docker: $(goSrc)
+	CGO_ENABLED=0 go build -o $@ \
+		-tags timetzdata
+
+.PHONY: docker
+docker: Dockerfile
+ifneq ($(dtag),)
+	docker build --tag natsio/nats-kafka:$(dtag) .
+else
+	# Missing dtag, try again. Example: make docker dtag=1.2.3
+	exit 1
+endif

docs/buildandrun.md

@@ -38,17 +38,17 @@ Targets
 You can build the docker image using:
 
 ```bash
-% docker build . -t "nats-io/nats-kafka:0.5"
+% make docker dtag=0.5
 ```
 
 Then run it with:
 
 ```bash
-% docker run -v <path to config>:/conf/kafkabridge.conf "nats-io/nats-kafka:0.5" -c /conf/kafkabridge.conf
+% docker run -v <path to config>:/conf/kafkabridge.conf "natsio/nats-kafka:0.2.0" -c /conf/kafkabridge.conf
 ```
 
 Be sure to include your monitoring port, for example, if port 9090 is used for monitoring, you can run with:
 
 ```bash
-% docker run -v <path to config>:/conf/kafkabridge.conf -p 9090:9090 "nats-io/nats-kafka:0.5" -c /conf/kafkabridge.conf
+% docker run -v <path to config>:/conf/kafkabridge.conf -p 9090:9090 "natsio/nats-kafka:0.2.0" -c /conf/kafkabridge.conf
 ```