Added Dockerfile & .dockerignore

{{cookiecutter.project_name}}/.dockerignore

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+*_test.go

{{cookiecutter.project_name}}/Dockerfile

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+# Building the binary of the App
+FROM docker.io/golang:1.19 AS build
+
+WORKDIR /go/src/{{cookiecutter.project_name}}
+
+# Copy all the Code and stuff to compile everything
+COPY . .
+
+# Downloads all the dependencies in advance (could be left out, but it's more clear this way)
+RUN go mod download
+
+# Builds the application as a staticly linked one, to allow it to run on alpine
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -installsuffix cgo -o app cmd/{{cookiecutter.project_name}}.go
+
+
+# Moving the binary to the 'final Image' to make it smaller
+FROM docker.io/alpine:latest AS release
+
+WORKDIR /app
+
+COPY --from=build /go/src/{{cookiecutter.project_name}}/app .
+
+# Add packages
+RUN apk -U upgrade \
+    && apk add --no-cache dumb-init ca-certificates \
+    && chmod +x /app/app
+
+# Exposes port 3000 because our program listens on that port
+EXPOSE 3000
+
+ENTRYPOINT ["/usr/bin/dumb-init", "--"]