Docker build fails: Golang version mismatch (1.12 vs 1.20 required)

[giselacb]

Bug Report

Problem

The current Dockerfile uses golang:1.12 but the code requires go 1.20 (as specified in go.mod), causing build failures.

Error

cannot load embed: cannot find module providing package embed
ERROR: failed to solve: process "/bin/sh -c go mod download && go build -o etcdkeeper.bin main.go" did not complete successfully: exit code: 1

Environment

• Docker version: Any
• Platform: Any

Steps to Reproduce

1. Clone the repository
2. Run docker build -t etcdkeeper .
3. Build fails with Go version incompatibility

Root Cause

• go.mod specifies go 1.20
• Dockerfile uses FROM golang:1.12
• Go 1.12 doesn't support modern dependencies used in the project

Proposed Solution

Update Dockerfile to use a compatible Go version:

FROM golang:1.21 AS build  # Updated from golang:1.12

Additional Improvements

• Update Alpine version to 3.18 for security
• Fix deprecated ENV format
• Use JSON format for CMD