Golang Multi-Stage Build

Dockerfile

############################
# STEP 1 build static binary
############################
FROM golang:1.18.1-alpine3.15 as builder
WORKDIR /workspace
# Fetch dependencies.
COPY go.mod .
COPY go.sum .
RUN go mod download
COPY . .
# Build static binary
# CGO_ENABLED=0 to create a static executable
# -ldflags="-w -s" to shrink golang executable
# -trimpath to remove workspace path from debug
# -o bin output
RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /app/api

############################
# STEP 2 build a small image
############################
FROM scratch
# Copy our static executable.
COPY --from=builder /app/api /app/api
# Run it
ENTRYPOINT ["/app/api"]