Migration Checklist: Moving Regulated Workloads into AWS European Sovereign Cloud

Hook: Why your migration to a European sovereign cloud will fail without this checklist

Regulated workloads don’t break down into “lift-and-shift” problems — they’re a mix of legal obligations, data residency constraints, identity topology, and rigorous testing requirements. In 2026, with the launch of the AWS European Sovereign Cloud and accelerating EU sovereignty rules, teams that skip structured legal reviews, incomplete data-residency maps, or ad-hoc IAM rip-and-replace plans end up with failed cutovers, audit findings, or blocked procurement. This checklist puts the operational steps, templates, and validation criteria in one place so engineering, security, and legal can execute repeatable, auditable migrations.

Migration checklist overview (most important items first)

Follow these phases in order: Legal & compliance review → Data residency mapping & classification → Architecture & control design → IAM migration → Data & application migration → Testing & validation → Cutover & post-migration operations. Each phase lists concrete tasks, owners, validation gates, and example commands/config snippets where useful.

Quick phase map

• Phase 1: Legal & Compliance — determine regulatory controls, DPA clauses, and contractual changes.
• Phase 2: Data Residency Mapping — discover, classify, and map flows to jurisdictions.
• Phase 3: Architecture & Controls — design VPCs, KMS/HSM, network isolation, logging.
• Phase 4: IAM Migration — federate, provision, migrate secrets, rotate keys.
• Phase 5: Data & Application Migration — choose data transfer tools, verify checksums.
• Phase 6: Testing & Validation — functional, compliance, security, DR tests.
• Phase 7: Cutover, monitoring & continuous compliance — runbooks, rollback, audit reports.

Phase 1 — Legal & compliance review (the non-negotiable gate)

Start with legal. In 2026, EU sovereignty initiatives and updated national data protection guidance require explicit mapping before technical work begins. Your legal review should produce a documented compliance scope that engineers and architects can implement against.

Key legal tasks

• Regulatory inventory: List applicable regulations (GDPR, national laws, sector-specific rules like PSD2, HIPAA equivalents for health in local markets). For US cross-border requirements, include FedRAMP artifacts if relevant to U.S. federal customers.
• Pseudonymization & purpose limitation: Specify which datasets need cryptographic separation, and which can be pseudonymized to reduce residency constraints.
• Contractual changes: Update DPAs, SCCs (where needed), security annexes, and subprocessors lists for the sovereign cloud vendor.
• Data export & lawful access assessment: Understand law enforcement access regimes and ensure the sovereign cloud's legal protections meet your risk appetite.
• Certification targets: Decide if you need ISO 27001, SOC 2, or FedRAMP-authorized workloads (note: FedRAMP is US-focused; for EU sovereignty consider equivalent attestations and local approvals).

Deliverables and validation gate

• Signed DPA and security annex including limits on subprocessors.
• Compliance scope document with itemized controls and responsible owners.
• Legal sign-off to proceed to data mapping.

Phase 2 — Data residency mapping & classification

Accurate data mapping is the highest-yield activity. If you can’t answer “what data touches non-EU infrastructure?” you can’t migrate confidently.

Step-by-step mapping

1. Inventory all data stores: databases, logs, caches, object stores, backups, archives. Include metadata stores and indexes.
2. Classify by sensitivity: e.g., Public, Internal, Confidential, Regulated/Restricted. Use tags and a central CMDB.
3. Trace data flows: For each dataset, map producers, consumers, and transit points (ETL, message buses, third-party APIs).
4. Map residency constraints: For each dataset attach residency requirements (e.g., EU-only, country-specific, subset allowed outside for processing with encryption).
5. Identify data gravity: Prioritize heavy and frequently accessed datasets for early migration planning because they will affect network design and cost.

Tools & examples

• Use DLP tools, EDR logs, and cloud inventory (e.g., AWS Config) to automate discovery.
• Tagging example (S3 objects):

aws s3api put-object-tagging --bucket my-bucket --key path/to/object --tagging 'TagSet=[{Key=DataClass,Value=Regulated},{Key=Residency,Value=EU-only}]'
  

Validation gate

A completed dataset matrix showing where each dataset currently resides, the proposed target in the sovereign cloud, and the residual risk assessment.

Phase 3 — Architecture & controls for sovereign cloud

Design for isolation and evidence. Sovereign clouds provide physical/logical separation; you must operationalize controls inside that environment.

Network & isolation

• Design per-environment VPCs with strict subnet segmentation (management, application, data, logging).
• Use private endpoints (VPC endpoints) and Transit Gateway to avoid public Internet egress for internal services.
• Implement dedicated network ACLs and least-privilege security groups. Record configuration in IaC (Terraform/CDK).

Encryption & key management

• All regulated data must be encrypted at rest and in transit. Use TLS 1.2+ and strong ciphers.
• Use a KMS/HSM instance that is resident in the sovereign region. Where available, use CloudHSM or HSM-backed keys to meet high-assurance requirements.
• Key example (AWS CLI):

# Create a regional KMS key (example)
aws kms create-key --description "Regulated-data-key" --region eu-sovereign-1
  

Logging, monitoring & audit

• Centralize logs in an immutable, region-resident logging bucket.
• Enable CloudTrail, VPC Flow Logs, DNS query logging and ship to your SIEM inside the sovereign cloud. See our observability playbook for patterns on collection and retention.
• Implement tamper-evident storage and retention aligned with compliance (e.g., 7 years).

Deliverables and validation gate

• Architecture diagrams with control mappings to the legal compliance scope.
• IaC templates for VPCs, KMS, logging, and endpoint configuration.

Phase 4 — Identity & Access Migration (IAM migration)

Identity migration is often the riskiest. Users, service principals, and automation accounts all need continuity without widening blast radius.

Pre-migration inventory

• Export current identity inventory: user accounts, groups, roles, policies, service principals, and privileged accounts.
• Record password policies, MFA status, and session duration settings.

Choose a migration strategy

• Federation-first: Keep identities in your IdP (Azure AD, Okta) and federate into the sovereign cloud using SAML/OIDC. This preserves SSO and MFA policies.
• SCIM provisioning: Use SCIM to provision accounts into the sovereign environment for service accounts or where full account parity is required.
• Cross-account roles: If you run multi-account architecture, implement cross-account assume-role patterns with strict trust policies rather than duplicating users.

Example role trust (JSON)

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {"AWS": "arn:aws:iam::123456789012:role/Org-SSO-Role"},
      "Action": "sts:AssumeRole",
      "Condition": {}
    }
  ]
}
  

Secrets & service credentials

• Migrate application secrets to a region-resident secrets manager and rotate during cutover.
• Use resource-based policies and envelope encryption with region-resident CMKs.

Operational steps

1. Enable federation with your IdP in a test account in the sovereign cloud.
2. Provision service accounts via SCIM or IaC and attach least-privilege policies.
3. Test automation pipelines with new credentials in a staging environment.
4. Plan phased credential rotation windows for production; publish communications to stakeholders.

Validation gate

All privileged tasks can be executed by federated users or service principals in the sovereign cloud with MFA enforced and automated secrets stored in the region.

Phase 5 — Data & application migration (practical commands & tools)

Choose the right tool for data volume, transfer window, and network constraints.

Transfer options

• Network transfer (DataSync / rsync / AWS CLI): Good for moderate volumes and ongoing replication.
• Offline transfer (Snowball Edge / physical appliances): Use for multi-TB/PB migrations where network would be too slow or costly.
• Database replication: Use native DB replication or change-data-capture (CDC) pipelines to minimize cutover window.

Example S3 sync

aws s3 sync s3://source-bucket s3://target-bucket --acl bucket-owner-full-control --storage-class STANDARD
  

Data integrity and validation

• Generate and verify checksums (MD5/SHA256) for all transferred objects.
• Run end-to-end application smoke tests against replicated data.
• Maintain a migration ledger with object counts, bytes transferred, and hash verification results.

Deliverables and validation gate

• Successful end-to-end smoke tests and checksum validation for each dataset.
• Rollback snapshot available until final cutover complete.

Phase 6 — Testing & validation (most detailed gate)

Testing must cover functional, compliance, security, performance, and disaster recovery. In 2026, auditors expect automation evidence and reproducible test scenarios.

Test categories & sample test cases

• Functional: App end-to-end flows, user authentication, API integration.
• Compliance: Data residency verification (logs+access), retention and deletion tests, DPA clause verification.
• Security: Vulnerability scans, authenticated penetration tests (capture required approvals), configuration drift checks, IAM policy analysis (simulate-principal-policy in AWS CLI).
• Performance: Load tests at peak and steady-state; measure latency and throughput differences post-migration.
• DR & backup recovery: Restore backups in the sovereign region and validate RTO/RPO against SLAs.

Automated test example — IAM policy simulation

# Simulate whether a principal can perform action with AWS CLI
aws iam simulate-principal-policy --principal-arn arn:aws:iam::123456789012:role/ExampleRole --action-names s3:GetObject --resource-arns arn:aws:s3:::target-bucket/* --region eu-sovereign-1
  

Pen-testing and vendor coordination

Coordinate penetration tests with the sovereign cloud provider — many providers require authorization and specific scopes for vulnerability tests in their regions. Capture signed approvals and schedule during low-risk windows.

Compliance evidence

• Collect automated evidence (IaC diff, Terraform plan outputs, CloudTrail logs) into an evidence repository for auditors.
• Use immutable artifacts (signed checksums, test runbooks) and link to tickets/traces in your governance tool.

Validation gate

All tests pass with documented remediation plans for any findings; compliance checklist marked green by legal and security teams.

Phase 7 — Cutover, runbooks & post-migration operations

Cutover is an orchestration problem. Plan the steps, prepare rollback plans, and automate as much as possible.

Cutover checklist

1. Freeze changes and notify stakeholders.
2. Redirect DNS or update load balancers to point to sovereign region endpoints (use short TTL during cutover testing).
3. Switch to regional KMS keys and rotate secrets at the end of cutover window.
4. Monitor logs and alerts closely for the first 72 hours.
5. Execute smoke test checklist and have rollback triggers defined for each failed test.

Post-migration operations

• Enable continuous compliance scans and periodic re-audits.
• Harden drift detection: policy-as-code and automated remediation for configuration drift.
• Define SLA-backed support in the sovereign cloud and escalate paths with provider teams.

Runbook example (failure to authenticate during cutover)

1. Determine scope: single user, group, or entire federation.
2. Check IdP health and federation metadata; verify trust certificate expiration.
3. Fallback: enable temporary emergency role in the sovereign cloud accessible to SREs (documented, timed, and audited).
4. Notify legal if any user access change may trigger compliance or reporting obligations.

Timeline & RACI example (practical)

Sample 12-week program for a medium-regulated workload (payments or PII-heavy application):

• Weeks 1–2: Legal and compliance scope, data inventory.
• Weeks 3–4: Architecture design, procuring sovereign cloud tenancy and KMS/HSM configuration.
• Weeks 5–7: IAM federation setup, secrets migration, and staging replication.
• Weeks 8–9: Data and application migration, checksum validation.
• Weeks 10–11: Testing (security, performance, DR).
• Week 12: Cutover, monitoring, retrospective.

RACI example: Legal (R/A for compliance scope), Security (R for security controls, A for testing sign-off), Cloud Engineers (R for IaC and migration tasks), App Owners (C/I for acceptance tests).

2026 trends & future-proofing your migration

Three things you must factor in for sovereignty migrations in 2026:

• Stronger European sovereignty frameworks: With the launch of services like the AWS European Sovereign Cloud (early 2026), expect more region-resident controls, vendor legal protections, and procurement preferences for sovereign-hosted providers.
• Hybrid identity convergence: Organizations will prefer federation + SCIM patterns and centralized policy-as-code for consistent enforcement across sovereign and global regions.
• Automation & auditable evidence: Auditors increasingly require evidence generated by automation (IaC plans, test run outputs, immutable logs). Shift-left your compliance checks into CI pipelines and build an automated evidence pipeline (see our audit playbook).

Practical rule: plan small, test often, and produce machine-readable evidence for every control you claim.

Operational quick-check lists (copy-paste for runbooks)

Legal & compliance quick-check

• Signed DPA & security annex — yes/no
• List of regulated datasets with residency tags — yes/no
• Certification targets assigned (ISO/ SOC / sector) — yes/no

IAM migration quick-check

• Federation tested in staging — yes/no
• SCIM provisioning tested for service accounts — yes/no
• Privileged roles audited & rotated — yes/no

Testing quick-check

• Functional smoke tests automated — yes/no
• Compliance evidence repository populated — yes/no
• Pen test authorization & schedule confirmed — yes/no

Real-world vignette (anonymized case study)

A European fintech migrated a high-throughput payments reconciliation service into a sovereign cloud in Q4 2025–Q1 2026. By enforcing federation-first IAM, using HSM-backed CMKs in-region, and automating compliance evidence generation into a central audit bucket, they reduced auditors’ time-to-signoff from 6 weeks to under 10 days and cut cross-border latency by 30%. Their two most impactful moves: precise data residency mapping and an automated test suite tied to Terraform plans.

Actionable takeaways — what to do this week

1. Assemble a cross-functional migration board (Legal, Security, Cloud Engineering, App Owners) and book weekly 60-minute standups.
2. Run a discovery sweep: produce a CSV of all datasets and tag those with Residency=EU-only or similar.
3. Spin up a sandbox sovereign account and configure a region-resident KMS key and a private logging bucket; demonstrate a single end-to-end login via federation.

Final checklist (one-page summary)

• Legal sign-off & DPAs updated
• Dataset classification & residency matrix complete
• Architecture with region-resident KMS/HSM and private endpoints
• Federation + SCIM for identities; least-privilege roles defined
• Data transfer plan and checksum validation
• Automated test suites for functional, security, compliance
• Cutover runbook, rollback plan, and post-migration monitoring

Call to action

If you’re planning or executing a migration of regulated workloads into the AWS European Sovereign Cloud, start with the legal inventory and a one-day discovery sprint to produce your dataset residency map. Need a templated migration plan, IaC snippets, or a compliance evidence pipeline you can drop into CI? Contact our runbook engineering team to get a tailored migration scaffold and an audit-ready checklist you can use in your next sprint.

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