bump go to 1.22.0; add container setup

use a multistage build so we don't leave the source code on the final artifact.

Dockerfile

@@ -0,0 +1,16 @@
+FROM golang:1.22.0-alpine3.19 as build
+
+WORKDIR /usr/src/app
+
+COPY go.mod go.sum ./
+RUN go mod download && go mod verify
+
+COPY . .
+RUN go build -v -o /tmp/app ./cmd/web
+
+
+FROM golang:1.22.0-alpine3.19
+ENV LOGFMT=json LOGLEVEL=DEBUG
+COPY --from=build /tmp/app /
+EXPOSE 4000
+CMD ["sh", "-c", "/app -logfmt=$LOGFMT -loglevel=$LOGLEVEL"]

go.mod

@@ -1,6 +1,6 @@
 module replication-systems.estradiol.cloud
 
-go 1.21.4
+go 1.22.0
 
 require (
 	github.com/julienschmidt/httprouter v1.3.0