Implementing Immutable Backup with Restic

When to Use

• Establishing ransomware-resistant backup infrastructure with cryptographic integrity verification
• Implementing 3-2-1-1-0 backup strategy where the extra 1 is an immutable copy
• Automating backup verification workflows that test restore capability on a schedule
• Protecting backup repositories from deletion or modification by compromised admin accounts
• Meeting compliance requirements for data retention with tamper-proof storage

Do not use as the sole backup solution without also maintaining offline/air-gapped copies. Object lock protects against logical deletion but not physical storage failure.

Prerequisites

• restic binary installed (https://restic.readthedocs.io/)
• S3-compatible storage with Object Lock enabled (AWS S3, MinIO, Backblaze B2)
• Python 3.8+ with subprocess module
• AWS CLI or MinIO client (mc) configured for bucket access
• Sufficient storage for backup repository (typically 2-3x source data with deduplication)