A multi-tenant application is an architecture in which a single instance of software serves multiple tenants. Here, tenants mean multiple companies, customers, or organizations an application serves.
In short, multi-tenant architecture explains a situation where a single instance of the product serves various clients. Each tenant shares the software application and shares a single database. Each tenant’s data is isolated and remains invisible to other tenants.
Multi-tenant architecture is a feature in many types of cloud computing, including IaaS, PaaS, SaaS, containers, and serverless computing.
Benefits of multi-tenant deployment
Since the software provider can serve multiple tenants from a single application instance and supporting infrastructure, the ongoing cost will be lesser for multi-tenant applications.
In multi-tenant deployments, scaling can be done on demand - it is easy for new users to get access.
- Easy maintenance
Since the patches, updates, and maintenance are done by a central provider, tenants need not bother much about the maintenance of the application.
- Better productivity for tenants
As there is no need to manage infrastructure or software, tenants can focus on other, more important tasks.
Testing plays a major role in running any software development project smoothly, similar to multi-tenant applications.
Multi-tenant testing mainly focuses on three components:
A multi-tenant application is a software, with the host software serving multiple tenants in a single code.
The multi-tenant application requires security testing in the form of multi-tenant isolation and access privilege, validation of roles, and application data.
Infrastructure means the hardware that supports multi-tenant software. The capacity of the hardware should coordinate the software’s work capacity. Poor infrastructure influences loading time, speed, data storage, transmission, and backup protocols.
Multi-tenant applications need to be tested over infrastructure, having production-like configurations, which are likely to impact the end-user experience. Infrastructure, like backup plans, recoveries, storage policies, needs to be validated for regulatory compliance.
The network is a platform for a multi-tenant provider, which usually refers to security tests. Building a multi-tenant network is the initial step toward isolating apps and data. Most violations occur when the data flow between users is not encrypted.
Testing of multi-tenant systems
Let us check out some of the major types of testing that need to be done in a multi-tenant system -
- Data leak testing
The predominant factor while testing multi-tenant systems is the way the data is shared/stored, in addition to the regular testing. In a multi-tenant system, the resources can be shared but not data.
- Load testing for a multi-tenant system
Even though multiple tenants share the same resources, it is necessary to ensure that all the tenants utilize these resources as per their requirements.
Performance and load tests should be performed on multi-tenant systems, which will help identify the bottleneck situations in the application. It would also validate the system’s stability under load as sometimes data leak happens when the system is under load, which would be difficult to find during a manual test.
This load testing will help ensure the scalability and performance of the system.
Tools like JMeter and LoadRunner can be used for this purpose.
- License/feature/interface testing
Due to customer feedback and new feature development, the interface of the application continues to evolve. That is why backward compatibility is needed. The backward compatibility of an application interface needs to be validated to ensure that the users do not have to make changes at their end when updates are available.
There must be ample testing done to validate features/licenses configured for clients. To brief on this, if client ‘A’ is licensed to a particular feature, then client ‘A’ should only be able to access them, and client ‘B’ should get an appropriate message/warning when it tries to access the same feature.
- Security and privacy testing
Security testing is another component that must be done as it plays a key role due to the nature of the system.
Since multi-tenant architecture is based on sharing resources, tenants might face security, accessibility, and privacy concerns.
It should be ensured that only tenants can access their data. The data should be tested thoroughly to ensure data security among different/multiple tenants. Proper authentication and authorization mechanisms must be used and tested in multi-tenant applications to make them highly secure.
SQL attacks are considered the most common dangers of application security.
Preventing SQL injection and testing cookies is another point to note as a part of the security testing of the multi-tenant application.
- Simulating live upgrade testing
While testing a multi-tenant application, a crucial challenge is ensuring that the live upgrades have zero-to-minimum downtime. It may get complicated as someone might be accessing the application when the application is getting upgraded. It is always necessary to prepare a proper deployment strategy and plan, and this strategy should be tested on a staging environment by QC.
To summarize, there are regulations, such as the GDPR, that are being passed by some countries where data protection is taken seriously. GDPR is passed by the European Parliament where it addresses data protection for all individuals, including the data which is exported out of Europe.
These are more vulnerable in a multi-tenant system and have to be addressed on priority during testing.
Multi-tenant applications help to reduce delivery costs, as a single application can be managed for multiple tenants. Automation used to validate the functional and non-functional requirements helps shorten the release cycle of frequent upgrades and releases. With the proper strategy and automation tests for both technical and non-technical requirements, organizations can eventually achieve the best business outcomes with multi-tenancy testing.