• Stage 1 ( “builder” ) : Uses a Go env to compile your app into multi linux binaries ( server + workers )
• Stage 2 (”runtime”) : Ships only those binaries into a tiny, secure runtime image.
• Default command runs the API server, but for each worker we override the command in Compose/Kubernetes

Line-by-line explanation

Dockerfile syntax

# syntax=docker/dockerfile:1

Enables modern Dockerfile features & better caching behaviour. Safe default.

Stage 1: Build stage

Base image for compilation

FROM golang:1.22-alpine AS builder

• Uses Go 1.22 on Alpine Linux.
• Names this stage builder so we can copy artifacts from it later.

Working directory

WORKDIR /src

All subsequent commands run inside /src.

Install build-time packages

RUN apk add --no-cache ca-certificates git

• git is needed because some Go modules are fetched via git.
• ca-certificates helps with TLS while downloading modules.