Dockerfile

# Build stage
FROM golang:1.21-alpine AS builder

WORKDIR /app

# Copy go mod files
COPY go.mod go.sum ./
RUN go mod download

# Copy source code
COPY *.go ./

# Build arguments for version info
ARG VERSION=dev
ARG COMMIT=none
ARG BUILD_DATE=unknown

# Build the binary
RUN CGO_ENABLED=0 GOOS=linux go build \
    -ldflags="-w -s -X main.version=${VERSION} -X main.commit=${COMMIT} -X main.date=${BUILD_DATE}" \
    -o yundera-smtp-handler .

# Final stage
FROM alpine:latest

# Install ca-certificates for HTTPS requests
RUN apk --no-cache add ca-certificates

WORKDIR /app

# Copy the binary from builder
COPY --from=builder /app/yundera-smtp-handler .

# Create non-root user
RUN addgroup -g 1000 smtp && \
    adduser -D -u 1000 -G smtp smtp

USER smtp

# Expose SMTP port
EXPOSE 587

# Run the service
CMD ["./yundera-smtp-handler"]