Refactor: overhaul Dockerfile with multi-stage build, non-root user, and .dockerignore

[dmabry]

Summary

Complete Dockerfile rewrite — from a fragile, outdated build to a production-grade multi-stage container. Also adds a .dockerignore for the first time.

Changes

Dockerfile

Before	After
FROM golang:alpine (unpinned)	FROM golang:1.26-alpine (pinned)
No CGO_ENABLED=0	Static binary, Alpine/musl compatible
GOARCH=amd64 hardcoded	TARGETARCH auto-detected by BuildKit
No dependency caching	go.mod/go.sum cached in separate layer
No debug stripping	-ldflags "-s -w" (~10% smaller)
Runs as root	Non-root user flowgre (uid 100)
Version label 0.4.10	Injected via --build-arg VERSION
Dead git submodule commands	Removed
GO111MODULE=on (deprecated)	Removed (default since Go 1.16)

New: .dockerignore

Excludes .git, docs, IDE configs, build artifacts, .nfpm/, scripts/ — reduces build context from ~10MB to ~300KB.

Build Instructions

# Local build
docker build --build-arg VERSION=0.5.16 -t flowgre:0.5.16 .

# Push to registry
docker tag flowgre:0.5.16 registry.dmabry.net/flowgre:0.5.16
docker push registry.dmabry.net/flowgre:0.5.16

Verified

• ✅ Builds cleanly on arm64 (local) and amd64 (CI)
• ✅ Image size: 22.2MB
• ✅ Binary runs as non-root user (uid=100 flowgre)
• ✅ flowgre version works inside container
• ✅ Static binary (no glibc dependency)