Back in the day, before the internet really took off and the cloud became mainstream, businesses used to install apps directly into their own computers or on dedicated company servers. All the updates, backups, and security patches were handled manually.
But as businesses grew, so did the apps. Maintaining separate instances became costly and tough to scale. With the rise in cloud computing and SaaS, businesses moved away from managing bulky infrastructure and opted for apps that can be managed by vendors.
This is what multi-tenancy is.
In this blog, we’ll talk in detail about multi-tenancy, its types, how to test multi-tenant applications, and a few practical examples to get you started.
TL;DR
- Multi-tenancy means one software instance serves many customers while keeping data isolated
- In software, a multi-tenant application allows shared infrastructure but separate configurations per tenant
- Common multi-tenant architecture types include single app–single DB, single app–multiple DBs, and multiple apps–multiple DBs
- Multi-tenancy testing checks performance, data isolation, multi-tenant authentication, and overall security
- Strong multi-tenancy security ensures no cross-tenant access and keeps sensitive data protected
- Regular multi-testing improves scalability, reliability, and user experience
What Is Multi-Tenancy in Software?
Multi-tenancy is a software architecture where a single software or app instance serves multiple customers (tenants). Every tenant’s data is isolated and inaccessible to others.
Tenants can customize certain parts of the app, such as users, displays, and database schemas. However, you can’t modify the app code. This means all tenants use the same app version, and any feature updates or upgrades apply to all.
Multi-Tenant Architecture
Main Types of Multi-Tenant Architectures
Now that you know what multi-tenancy is and understand what is multi-tenant architecture entails, here are its broad types:
1. Single application, single database
In this configuration, all the tenants share a single app instance along with a single database. The data for each tenant is differentiated and isolated within the same database via schemas or tenant-specific identifiers.
The deployment and maintenance of this app architecture is easier as there’s only one database to manage. But this may also lead to scaling issues and data leakage between tenants since all the data coexist in the same database.
2. Single application, multiple databases
Here, one app instance is connected to multiple databases, where each tenant has its own database. Data isolation at the storage level enhances data security and reduces the risk of “noisy neighbor” issues.
However, multiple databases make the infrastructure challenging to manage, and you may need more resources for maintenance.
3. Multiple applications, multiple databases
In this type, each tenant has their own dedicated app instance along with a separate database. This configuration provides you with the highest level of isolation and multi-tenancy security as compared to other architecture types.
It allows you to customize and optimize the app as you prefer, but this comes with higher resource consumption and operational complexity. This architecture is typically used in industries that require a high level of control and privacy, such as banking, healthcare, and government agencies.
In multi-tenancy, one app instance serves multiple tenants, where each tenant has isolated data and configurations. However, all share the same codebase. In single-tenancy, every tenant has its own dedicated app instance and database, and can completely customize code or features as per needs.
Here’s an overview of both:
| Aspect | Single-tenant Architecture | Multi-tenant Architecture |
|---|---|---|
| Data isolation | Complete isolation as each tenant has a separate database. | Data is isolated at the database or application layer using tenant IDs or schemas. |
| Scalability | Scalability is limited as it requires provisioning and managing individual instances for each tenant. | Highly scalable; multiple tenants can be added within a single instance without significant resource overhead. |
| Customization | Offers high customization options; tenants can modify the infrastructure based on their needs. | Customization is available mainly through configurable settings within the app. |
| Cost | Dedicated resources for each tenant lead to higher costs. | Shared infrastructure and resources make multi-tenancy more cost-efficient. |
| Maintenance | Maintenance and upgrades are performed separately for each tenant. | Centralized maintenance; updates and upgrades apply to all tenants. |
What Is Multi-Tenancy Testing?
Multi-tenancy testing is the process of evaluating the end-to-end workflows of the app to ensure the functions work as specified in the requirements, tenant data is secure and isolated from each other, and the app remains stable under high traffic.
How to Perform Multi-Tenancy Testing
In multi-tenancy testing, you evaluate the functionalities and performance of the app to ensure it’s stable, scalable, and can handle multiple tenants concurrently without data leakage. This is how you typically perform multi-tenancy testing.
| Test Steps | What to Do |
|---|---|
| Identify requirements | Determine the number of tenants the app should be able to handle, as well as specific requirements for data isolation (unique identifiers and backups), security (authentication and encryption), and performance (usage allocation and response times). |
| Set up the test environment | Configure an environment that simulates the expected usage and workload of multiple tenants. Create multiple tenant accounts, each with its own database and schema, and populate each account with test data. |
| Plan and execute tests | Plan scripts, processes, and timelines to run various tests, including data isolation testing, load testing, and security testing. Automate repetitive tests such as API validations and UI checks, so that your CI pipeline can trigger these tests automatically after every deployment. |
| Analyze results | Track test results using several software testing metrics, such as resource usage, response time, and error rates, to identify performance issues and security gaps, like slow responses and data leaks. |
| Resolve issues | Rework buggy code by tracing logs and isolating the affected tenant context. Document debugging steps to reproduce and retest. |
| Deploy and monitor | Once issues are resolved, deploy the app to production and make it available for users. Use monitoring tools to track metrics and detect anomalies or performance degradation. |
Related read: Guide to Performance Testing
Types and Examples of Multi-Tenancy Testing
- Data leak testing When using a multi-tenant app, you must make sure the resources can be shared, not data. Data leak testing helps you ensure tenant data is isolated and can’t be accessed by unauthorized parties. Misconfigurations, inadequate access controls, or insecure APIs can lead to data leaks.
How to do data leak testing
- Create multiple tenants using the same base architecture and upload data for every tenant, such as personal information, financial records, and app configuration
- Run database or API queries from tenant 1 to check if it can access the data of another tenant
- Repeat this for every tenant to monitor if the app allows access to unauthorized data
- If one tenant, for instance, can view or modify data that doesn’t belong to them, this error needs to be fixed
2. Load testing
Multi-tenant apps face varying workloads. Load testing allows you to evaluate the performance of the app under load by simulating actual usage patterns such as concurrent logins, database transactions, and API calls from multiple tenants.
The aim here is to check the response time, memory usage, and database performance under stress.
How to do load testing
- Simulate heavy traffic or workload, such as high API requests on tenant 1
- Now track the app performance for tenant 1 and tenant 2 simultaneously
- Check if tenant 1’s workload affects the performance for tenant 2
- Do this test for multiple tenants to examine how the app handles stress
3. Security and privacy testing
Multi-tenant apps often handle sensitive user data and APIs that must be protected against unauthorized access. Any vulnerabilities in the app might expose a tenant’s data to security risks. Make sure the app complies with standards such as GDPR and HIPAA.
When you create tests, include multi-tenant authentication and authorization checks, API security scans, and penetration testing to reveal potential gaps that could lead to security breaches.
How to do security testing
- Populate different credentials for each user and run authentication tests on multiple tenants to check if they can only access their environment
- Run penetration tests to assess if any loopholes in the app allow cross-tenant access
- Set up alerts to ensure unauthorized access attempts or failed logins are flagged and logged for audit
4. License testing
License testing allows you to check if the app complies with relevant licensing requirements such as usage limits and terms of service.
This testing helps you confirm that tenants can access only the features, storage limits, and customization options that they are entitled to based on their subscription, and not resources beyond their licensed tier.
How to do license testing
- Create multiple tenants with different license tiers, such as free, standard, and premium, and assign at least one user per tenant
- Try logging in from a free-tier user account and try to access features of standard or premium tiers
- Check if the app blocks access with popups like “feature not available for your plan”
- Repeat this for multiple users across different tenants to ensure no tenant has access to features other than their assigned license tier
Advantages of Multi-Tenancy Testing
Improved performance and scalability
Multi-tenancy testing helps you ensure the app performs as intended, even when multiple tenants or users are accessing it simultaneously.
You simulate real-world scenarios such as concurrent logins and simultaneous API requests, and check if the app can handle them. Plus, testing allows you to assess if the app can accommodate new tenants easily without degrading response time.
Improved user experience
Users today access apps from multiple device configurations, including desktops, laptops, and smartphones, and connect via different network conditions. Testing allows you to examine the app’s compatibility on different browsers, devices, and operating systems.
It also helps you check functionalities and UI workflows to make sure the app provides a reliable and consistent user experience across all tenants.
Enhanced interoperability
Multi-tenancy testing helps you ensure the app can easily integrate with other systems, APIs, and third-party services. Every tenant might have different configurations or plugins. Testing checks if the data flows correctly between these systems without affecting other tenants.
Reduced risk of errors
Integrating multi-tenancy testing into your CI/CD pipelines allows you to start testing right from the design phase. This helps detect potential issues early in the app development cycle and reduces the risk of downtime and errors when the app reaches the users.
Best Practices of Multi-Tenancy Testing
Validate ‘noisy neighbor’ availability
Create tests that simulate noisy neighbor tenant scenarios and run them on multiple tenant personas to ensure availability policies are successfully applied and the app remains stable for different tenant profiles and tiers.
For apps that have public APIs, make sure the tenant can’t saturate the API and affect the availability of your app for other tenants.
Test key workflows under load
Simulate multi-tenant load patterns during testing and ensure SLAs continue to be met, even when the app scales up or down. For example, if the app has payment or subscription workflows, check if new billing accounts are created when new tenants are added.
Verify repeatability of tenant onboarding
Create test cases to check if new tenants are provisioned with the right infrastructure, configuration, and isolation policies during automated onboarding processes.
Also, if the app needs tenant validation as a part of onboarding, design tests that exercise this validation process to ensure the first-time entry of tenants functions as specified in the test requirements.
How TestGrid Streamlines Your Multi-tenancy Testing Efforts
Multi-tenancy apps need a robust testing environment that can simulate the behavior and usage patterns of multiple tenants accurately to ensure it doesn’t break when released.
TestGrid is an AI-powered end-to-end testing platform that lets you create thousands of test cases across different scenarios and run them on 100+ real Android and iOS devices, hosted both on cloud and on-premise.
TestGrid’s self-healing test scripts adapt to UI tweaks and workflow adjustments automatically, so your app tenants don’t face broken features and failed workflows.
With TestGrid’s AI agent for software testing, CoTester, you can schedule your test runs at the times that work best for you, nightly builds, weekly regressions, or just before a major release. Plus, you can get detailed logs, screenshots, and step-by-step results after every execution.
This blog is originally published at Testgrid
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