Dockerfile to create a small container for Golang

Dockerfile

############################
# STEP 1 build executable binary
############################
FROM golang:alpine as builder
# Install git + SSL ca certificates.
# Git is required for fetching the dependencies.
# Ca-certificates is required to call HTTPS endpoints.
RUN apk update && apk add --no-cache git ca-certificates gcc g++ libc-dev && update-ca-certificates
# Create appuser
RUN adduser -D -g '' appuser
COPY . $GOPATH/src/gitlab.com/SoldierCorp/companies-api
WORKDIR $GOPATH/src/gitlab.com/SoldierCorp/companies-api

ENV GO111MODULE=on


COPY go.mod .
COPY go.sum .

# Fetch dependencies.
# Using go mod with go 1.11
RUN go mod download

# Build the binary
RUN GOOS=linux GOARCH=amd64 go build -ldflags="-w -s" -o /go/bin/companies-api .
############################
# STEP 2 build a small image
############################
FROM scratch
# Import from builder.
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY --from=builder /etc/passwd /etc/passwd
# Copy our static executable
COPY --from=builder /go/bin/companies-api /go/bin/companies-api
# Use an unprivileged user.
USER appuser
# Run the companies-api binary.
ENTRYPOINT ["/go/bin/companies-api"]
# CMD ["/go/bin/companies-api"]

Great, now it's working!

I still have the issue with the .env file but since I have an alternative, is not a problem for now.

Thank you so much @chemidy!