Cloud Sovereignty + 15 Factor App: The Architectural Bridge Between Law and Technology
TL;DR The Cloud Sovereignty Framework of the EU defines what digital sovereignty aims to achieve – …
Diese Serie erklärt systematisch, wie moderne Software compliant entwickelt und betrieben wird – von EU-Regulierungen bis zur technischen Umsetzung.
Deployment strategies are no longer just a technical detail for SaaS providers. They directly influence:
With the enforcement of the GDPR on May 25, 2018, the NIS-2 Directive on January 16, 2023 (implementation into national law by October 17, 2024), and DORA, which came into effect on January 16, 2023, and will apply from January 17, 2025, it is clear: architectural decisions must explicitly address regulatory requirements. The Cyber Resilience Act, adopted on March 12, 2024, and expected to be fully applicable by 2027, further reinforces this trend.
Against this backdrop, it is worth taking a sober look at two dominant architectural patterns for SaaS:
Both approaches can – if implemented correctly – be highly compliant and economically viable. Clarity about goals, risks, and organizational prerequisites is crucial.
In a Multi-Tenant architecture, multiple customers (tenants) share a common environment. Typically, this means:
Tenants are isolated from each other as strictly as necessary – not through physical or fully dedicated infrastructure, but through technical and organizational controls.
A robust Multi-Tenant environment stands and falls with the quality of isolation. Typical building blocks:
Namespace Isolation:
Each tenant receives its own namespaces for applications, data processing jobs, and possibly separate stages (Dev, Test, Prod). This allows resources, policies, and quotas to be assigned precisely.
Network Policies:
Access between pods and services is strictly regulated according to the need-to-know principle. Cross-tenant communication is blocked by default; only explicitly allowed paths are open.
RBAC (Role-Based Access Control):
Roles and rights are defined per tenant. Customer teams receive exactly the access rights to namespaces, logs, and metrics that are contractually agreed and regulatorily justifiable.
Tenant-specific Secrets and Config:
Configuration, secrets, certificates, and possibly encryption keys are also managed per tenant – often integrated with HSM or Vault solutions.
In a modern Multi-Tenant platform, these controls can be largely centrally managed and automatically rolled out. This is a significant lever for resilience and compliance.
Multi-Tenant brings a number of practical advantages:
High Resource Efficiency:
Infrastructure costs are spread across many customers. Idle capacities decrease, utilization increases.
Fast Feature Rollouts:
A central deployment model allows new features, security updates, and patches to be delivered simultaneously to all tenants – an advantage, among others, in the context of DORA and Cyber Resilience Act, which demand quick responses to security vulnerabilities.
Standardized Security and Compliance Controls:
You operate a common control framework and document it uniformly. This facilitates audits for customers from regulated industries.
Simpler Operational Organization:
A central SRE/Platform team can consolidate operations instead of maintaining dozens or hundreds of isolated environments.
The critical question with Multi-Tenant is: Is the isolation sufficient – even for highly regulated customers?
Data Separation:
Data must be cleanly separated per tenant – logically, often also cryptographically. The GDPR requires traceable measures to exclude unauthorized access between tenants.
Tenant-specific Requirements:
Some customers require special controls (e.g., hardening, additional pen tests, extended audit trails). In the Multi-Tenant model, such special requests must be standardized or clearly contractually limited.
Shared Fate:
An error in a central component can affect multiple customers. Here, robust SLOs, canary deployments, and rigorously tested changes are crucial – not only from an engineering perspective but also in light of ICT third-party risk according to DORA.
Multi-Tenant is thus a very attractive standard approach but demands high discipline in architecture and operational processes.
In the Whitelabel scenario, you operate a separate installation for each customer – often:
This model is especially established with larger enterprise customers who desire strict separation and extensive say in security and compliance matters.
A Whitelabel model offers some features that are very attractive in regulated environments:
Strong Isolation:
Each customer environment is technically and operationally separate. From the perspective of NIS-2 and DORA, this reduces the risk of a “multi-customer incident” due to technical coupling.
Easy Argumentation for Data Sovereignty:
In terms of data protection and the Cloud Sovereignty Framework, you can clearly demonstrate where a customer’s data is located and what technical boundaries exist.
Flexibility in Compliance Requirements:
Critical customers can receive additional security controls, hardening measures, or even individual update windows without affecting other tenants.
Separate Release Cycles:
Customers can adopt new features in phases or deliberately choose delayed updates – an important point in conservative industries (e.g., Financial Services under DORA).
The downside is clear:
Higher Infrastructure and Operating Costs:
More clusters, more networks, more integrations – even with automated provisioning, the footprint increases.
More Complex Fleet Management Effort:
You need a system to consistently provision, update, and monitor hundreds of instances. Without strong automation, Whitelabel quickly becomes unmanageable.
Risk Distribution on the Organizational Side:
While the technical risk of “shared fate” decreases, the organizational effort is significantly distributed: incident response, change management, and audits occur in many separate environments.
Whitelabel is therefore particularly interesting when your target customers have strict compliance requirements or clearly defined isolation wishes – and are willing to bear the associated additional costs.
The GDPR affects both models similarly – the core is:
Multi-Tenant deployments can perform very well here, provided:
Whitelabel scores when customers explicitly require a geographical or legal separation of infrastructure – for example, for different legal areas or in the context of the Cloud Sovereignty Framework.
The NIS-2 Directive addresses operators of essential and important services. For SaaS providers, it is relevant:
Here, a mixed model can be sensible:
This way, you combine efficiency and scalability with specific requirements for isolation and proof.
DORA addresses the operational resilience risk of financial companies – including their ICT third-party providers. The Cyber Resilience Act focuses on security requirements for digital products.
For your architecture, this means:
Both deployment models can meet these requirements – the question is which model facilitates a consistent, well-documented implementation for you and how your customer landscape is structured.
The ayedo Software Delivery Platform (SDP) is deliberately designed to support and combine both strategies equally.
In a Multi-Tenant scenario, the SDP offers, among other things:
Namespace-based Tenant Isolation:
Tenants are clearly separated via namespaces in shared Kubernetes clusters. Policies and quotas are enforced per tenant.
Strict Network Policies:
Templates for zero-trust-like communication that only open necessary paths by default. Cross-tenant connections are excluded.
TL;DR The Cloud Sovereignty Framework of the EU defines what digital sovereignty aims to achieve – …
TL;DR Heroku’s 12-Factor App set a clear standard for cloud-compatible applications in 2011 – …
TL;DR Starting point is a multi-tenant Django SaaS application, which is taken from the first line …