2.4 Serverless functions
You can ship an event-driven feature with no server to patch.
Before:01. Cloud FoundationsUnlocks:03. Storage & Databases
The same thing, three names
One idea, sold under a different brand by each provider. Learn it once and you can read any job advertisement.
- On AWS
- Lambda
- On Azure
- Functions
- On Google Cloud
- Cloud Run functions
A serverless function is code that runs when an event fires, on machines you never see or patch, billed by the invocation. This topic covers triggers, the function contract, cold starts, and the statelessness that forces state somewhere else. It sits after virtual machines and scaling so the contrast lands: no capacity to manage, and in exchange, limits on time, memory and control. The common confusion is about cost — serverless is very cheap at low, spiky volume and can be startlingly expensive at high steady volume, and the crossover deserves arithmetic, not vibes.
Work through these
Event sources, triggers and the function contract
A function runs in response to an event, and the shape of what it receives and returns is fixed by the platform. Learning the contract is most of learning the model.
Cold starts, timeouts and memory/CPU coupling
The costs that surprise people are the first-invocation delay, the hard execution limit, and the way memory and processor share one setting. All three change how you design rather than how you configure.
Statelessness and where state has to go instead
A function keeps nothing between invocations, so anything that must persist has to live in a database, a cache or a storage container. Designing around that is the main adjustment coming from ordinary servers.
When serverless is cheaper and when it is far more expensive
Per-request billing is cheap for spiky and idle workloads and expensive for steady busy ones. Working out which side your workload falls on is a calculation, not a preference.
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