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CREATED BY CHAINLINK LABS

Vault Harvester

Automated DeFi vault harvesting — check if yield is profitable, then harvest and compound using CRE.

Get the template
cre init --template=vault-harvester-ts
View on GitHub

What This Template Does

This template automates DeFi vault harvesting — a specialized version of the keeper pattern for vault-specific operations like yield harvesting and compounding.

The workflow:

  1. Cron trigger fires every 5 minutes (configurable)
  2. Reads vault state: shouldHarvest(), pendingYield(), totalHarvested(), harvestCount()
  3. If profitable (time elapsed AND yield > threshold): Sends a signed report to trigger harvest on-chain
  4. If not profitable: Logs and skips — no wasted gas on unprofitable harvests
  5. On-chain: Harvests pending yield, resets state, and emits an event

This pattern is compatible with vault protocols like Beefy, Yearn, and Alchemix.

Key Technologies:

  • CRE (Chainlink Runtime Environment) — Orchestrates periodic workflows with DON consensus
  • Profitability checking — Time + yield threshold validation off-chain
  • Yield tracking — Harvest counter and history

How It Works

Getting Started

1 Install dependencies 
cd my-workflow && bun install && cd .. && cd contracts && bun install && cd ..
2 Run tests 
cd my-workflow && bun test
3 Simulate the workflow

Dry run:

cre workflow simulate my-workflow --target staging-settings

With broadcast (writes on-chain):

cre workflow simulate my-workflow --target staging-settings --broadcast
4 Deploy your own contract

Deploy VaultHarvester with constructor arguments: forwarder address, harvest interval in seconds, and minimum yield threshold in wei:

forge create src/VaultHarvester.sol:VaultHarvester \
  --broadcast --private-key <KEY> --rpc-url <RPC> \
  --constructor-args 0x15fc6ae953e024d975e77382eeec56a9101f9f88 300 1000000000000000000

Simulate yield accrual for testing:

cast send <YOUR_CONTRACT> "accrueYield(uint256)" 2000000000000000000

Then update contractAddress in my-workflow/config.staging.json.

Customization

  • Change schedule — Edit schedule in config.staging.json (cron syntax)
  • Change profitability check — Modify shouldHarvest() in the contract
  • Change harvest logic — Update _processReport() for your vault's harvest + compound strategy

For full details, see the TypeScript README on GitHub.

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