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Chainlink Automation

Mon, 01 Jan 0001 00:00:00 +0000

Chainlink Automation (formerly Keepers) lets you trigger on-chain function calls on a schedule or in response to custom conditions — without running your own bot infrastructure.

When to Use It#

Periodic maintenance — harvesting yield, rebasing tokens, updating oracles.
Conditional execution — liquidations, limit-order fills, rebalancing when a threshold is crossed.
Replacing cron bots — any off-chain script that just calls a contract method can usually move to Automation.

Core Concepts#

Term	Meaning
Upkeep	A registered job — the thing Automation monitors and executes.
Trigger	What fires the upkeep: time-based (cron) or custom logic (conditional).
`checkUpkeep`	View function Automation calls off-chain to ask “should I execute?”
`performUpkeep`	State-changing function Automation calls on-chain when `checkUpkeep` returns true.
LINK funding	Each upkeep has a LINK balance that pays node operators per execution.

Supported Networks#

Automation is live on Ethereum mainnet, Arbitrum, Optimism, Polygon, Avalanche, BSC, and Base (among others). Check the Chainlink docs for the current list and registry addresses.

Chainlink Automation Registration

Mon, 01 Jan 0001 00:00:00 +0000

Registration is the process of creating a new upkeep in Chainlink Automation. A registered upkeep tells the Automation network what contract to monitor, what conditions to check, and how much LINK to allocate for execution costs.

Registration Methods#

UI Registration#

The simplest path. Go to automation.chain.link, connect a wallet, and follow the guided flow. The UI handles LINK approval, registrar interaction, and parameter encoding behind the scenes.

Good for one-off upkeeps and initial experimentation.

Chainlink Automation Registrar

Mon, 01 Jan 0001 00:00:00 +0000

The Automation Registrar is the on-chain contract that accepts and processes upkeep registration requests for Chainlink Automation. It acts as the gatekeeper between users who want to register upkeeps and the Automation registry that actually tracks and executes them.

How It Works#

The registrar exposes a registerUpkeep function that accepts a RegistrationParams struct and a LINK payment. On receiving a valid request, it:

Transfers the LINK funding from the caller to the registry.
Creates a new upkeep entry in the registry.
Returns the upkeepId — a uint256 that uniquely identifies the upkeep.

Depending on the network and configuration, registration may be auto-approved (instant) or require manual approval by the registry owner. Mainnet deployments typically auto-approve; testnets vary.

Chainlink Automation Registry

Mon, 01 Jan 0001 00:00:00 +0000

The Automation Registry is the core on-chain contract that stores, funds, and coordinates execution of all registered upkeeps in Chainlink Automation. While the registrar handles onboarding new upkeeps, the registry is where they live for the rest of their lifecycle.

Responsibilities#

Upkeep storage — maintains the list of active upkeeps, their configurations, and LINK balances.
Node coordination — Automation nodes read the registry to discover which upkeeps to monitor and simulate.
Execution accounting — tracks gas used per performUpkeep call, deducts LINK accordingly, and pays node operators.
Admin operations — exposes functions for upkeep owners to fund, pause, cancel, and reconfigure their upkeeps.

Upkeep Lifecycle (Post-Registration)#

Once an upkeep is registered through the registrar, all further interaction goes through the registry:

Chainlink Automation Forwarder

Mon, 01 Jan 0001 00:00:00 +0000

An Automation Forwarder is a per-upkeep proxy contract that sits between the Chainlink Automation network and your target contract. Instead of Automation nodes calling performUpkeep directly on your contract, they call it through the forwarder — giving your contract a stable, predictable msg.sender to verify.

Why It Exists#

Without a forwarder, performUpkeep is called by whichever Automation node wins the turn. The caller address rotates across a set of node-operated transmitter addresses that can change over time. This makes access control difficult: you can’t simply check msg.sender against a known address.

Securing performUpkeep

Mon, 01 Jan 0001 00:00:00 +0000

performUpkeep is an external function that anyone can call — not just Chainlink Automation nodes. If your implementation has side effects (transferring funds, changing critical state), you need to ensure that unauthorized callers can’t exploit it.

There are two complementary strategies: re-validation (making the function safe for anyone to call) and access control (restricting who can call it). Use both when possible.

Strategy 1: Re-Validate On-Chain#

The simplest defense. Inside performUpkeep, re-check the same condition that checkUpkeep evaluated off-chain. If the condition no longer holds, revert.