How to build a serverless application on a cloud platform comes down to ten steps in a fixed order: the first workload and its events, functions and triggers, state and data, identity and secrets, infrastructure as code, local tests, a release pipeline, logs and tracing, load and failure tests, and go-live with runbooks. Finally, each step ends in a test that tells you it is done.
Last reviewed 2026-11-14 by Manish Sharma.
A serverless application is built from functions and managed services, where the provider runs the servers and the scaling. A function is a small piece of code that runs when an event arrives, a style of function-based computing. A common set of parts is front-end hosting, an API layer, functions, a managed database and sign-in. The order below works on AWS and Azure alike, and it gives no prices, limit figures or dates.
How to Build a Serverless Application: Ten Steps at a Glance
For each step, the table suggests an owner and a pass test. Owners are our suggestion, so use the titles your team has.
| Step | Suggested owner | Done when |
|---|---|---|
| 1. First workload and events | The product owner picks it, with the developer lead. | The events that start the workload and what each must return are written down. |
| 2. First function and trigger | The developer lead writes it. | One function runs from its trigger and returns the expected output. |
| 3. State and data store | The developer lead decides, with the data owner. | Each kind of data has a store, and the functions hold no state. |
| 4. Identity and secrets | The security lead sets it. | Each function has its own role, and no shared admin role remains. |
| 5. Environment as code | The platform engineer writes it. | A second environment builds from the stored code alone. |
| 6. Tests | The developer lead owns them. | Each event type has a test, run locally and in the cloud. |
| 7. Release pipeline | The platform engineer connects it. | A change deploys from code, runs its tests and can roll back. |
| 8. Logs and tracing | The operations lead sets them. | One person reads the logs and traces, and failures raise an alert. |
| 9. Load and failure tests | The developer lead runs them, with the operations lead. | The workload meets its expected load, and a failed dependency leaves a clear trace. |
| 10. Go-live and runbooks | The IT head decides, with the product owner. | The rollback works, and runbooks exist for the likely failures. |
Before You Build a Serverless Application: Parts, Owners and Scope
Before step 1, know the parts, name the owners and fix the scope. A common set of parts is front-end hosting, an API layer, functions, a managed database and sign-in. Check each part against the provider’s own documentation, because the choice of platform is a separate decision.
Next, name a developer lead, a platform engineer, a security lead, an operations lead and a product owner who signs off. The first build is one workload, not the whole estate. Instead of rushing past this stage, teams can read what to plan for before the first release first.
Two questions sit outside the plan: whether containers would suit the workload better, and how well the workload fits at all. Each is a separate topic.
The first build is one workload, not the whole estate. Name its owner before step 1.
AWS’s serverless web app guide explains how managed services combine, and Microsoft’s Azure Functions overview describes functions that run from event triggers.
How to Build a Serverless Application, Steps 1 to 5: Workload, Functions, Data, Identity and Code
Steps 1 to 5 settle what the workload does and what it is allowed to touch. After that, release work can begin.
How to Build a Serverless Application, Step 1: Pick the First Workload and Its Events
Choose a small, event-shaped workload with one owner. Then list each event that starts it, such as a file upload or an API call, and what each event must return. Instead, skip workloads that need long-running work or tight links to old systems for a first build.
Done when the events and outputs are written down.
Step 2: Write the First Function and Wire Its Trigger
Draw function boundaries by event, not by feature. Next, name the trigger and any queue in front of the function. Write one function first. Then run it, and add more after that. For runtime options and tuning for AWS functions, the product post goes deeper. Meanwhile, Azure has an equivalent product post, which this article names but does not link.
Done when the first function runs from its trigger.
Step 3: Choose Where State and Data Live
Functions hold no state between runs, so state belongs in a store. Next, pick a store for each kind of data. If a function must reach a relational database, plan how, and test that path in step 6. Lastly, ask counsel where the data may be held for your sector.
Done when each kind of data has a store.
Key Takeaway Each kind of data needs its own store, and the functions keep none.
How to Build a Serverless Application, Step 4: Give Each Function Its Own Identity and Secrets
Give each function its own role, with only the permissions it needs. Then keep secrets in a managed store, and keep them out of code and out of settings files. Instead, avoid the shortcut of a shared admin role.
Done when no shared admin role remains.
Step 5: Describe the Environment as Code
Keep the functions, triggers, roles and data stores as code in version control. After that, a second environment builds the same way as the first. Use one environment per stage, so a test stays away from live data.
Done when a second environment builds from the code alone.
Build the second environment from the stored code alone, and compare it with the first before moving on.
Build a Serverless Application, Steps 6 to 10: Tests, Release, Visibility, Load and Go-Live
Steps 6 to 10 check the build, ship it and make it visible. Together, they turn a working function into something a team can run.
Step 6: Test Functions on a Laptop and in the Cloud
Unit-test the logic first. Use local emulation where the provider offers it, then test in a real cloud environment, because permissions and triggers behave differently there. In short, every event type needs a test.
Done when each event type has a passing test in both places.
How to Build a Serverless Application, Step 7: Connect the Release Pipeline
The pipeline must do three things for this workload: deploy from code, run the tests and roll back. The release pipeline that deploys each change is covered in its own article, and this one adds nothing to it.
ship each change from code.
run the tests on every change.
return to the last release when a change fails.
Step 8: Set Up Logs and Tracing
Give each function one log stream, and then add a trace that follows a call across the whole path. Then set alerts on failures. Name the person who reads them, because logs that nobody reads do not help.
Step 9: Run Load and Failure Tests
Start by testing at the load the owner expects. After that, fail a dependency on purpose, and watch the logs to see what happens. Next, check how retries behave. Set a budget alert before the test, so a runaway test does not surprise anyone.
Key Takeaway A load and failure test shows what the logs and alerts do when something breaks.
How to Build a Serverless Application, Step 10: Go Live With a Rollback and Runbooks
Next, write the go-live plan with a named owner and a rollback to the last release. Finally, add runbooks for failed events, slow calls and a bad release. After the first period of live use, the owners set a review, and it looks at the logs first.
Four Build Mistakes When You Build a Serverless Application
Four mistakes show up on first builds, but each is cheaper to catch early.
- One large function for everything. A change to one event then risks all the others. Instead, split by event in Step 2.
- A shared role for all functions. One leaked role then reaches everything. Instead, give each function its own in Step 4.
- Tests only on a laptop. Permissions and triggers differ in the cloud. Instead, run Step 6 in both places.
- Logs added after go-live. The first failure then has no trace. Instead, set up Step 8 before launch.
What This Plan to Build a Serverless Application Leaves Out
This plan covers the build order and nothing beyond it. Instead, these topics are handled elsewhere:
- Fit checks: set out in a mark by mark review of whether a workload fits functions.
- Serverless or containers: set out in a side by side scoring of functions against clusters.
- Pipeline detail: the pipeline article linked at Step 7.
- Prices: none are given here.
Get outside help if the first workload has no clear owner, when data access is unclear, or when the team has not run a cloud release before. How Signisys builds event-driven workloads on AWS and Azure describes that work.
Signisys supports builds like this through our application modernization and observability solution and DevOps and automation support for the build. A consultation reads your workload, data and release route against the ten steps, and it sets no expectation of results. No charge, with a fixed scope.
How to Build a Serverless Application: FAQ
How many functions should the first build have?
Who should own the runbooks after go-live?
Should the first build include the release pipeline or wait?
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