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This guide explains the use case for the EthBalanceMonitor contract. This Keeper contract monitors and funds Ethereum addresses that developers might need to top up frequently based on a configurable threshold. As a result, nodes are funded automatically.
After deploying the contract, developers can go to keepers.chain.link to register Upkeep and run the contract. To take full advantage of the Keepers automation infrastructure, read all of the documentation to understand the features of Chainlink Keepers.
Table of Contents
EthBalanceMonitor PropertiesEthBalanceMonitor is ownable, pausable, and Keepers-compatible:
KeeperCompatibleInterface is necessary to create Keepers-compatible contracts. To learn more about the KeeperCompatibleInterface and its uses and functions, refer to Making Keepers-compatible Contracts.You can open the contract in Remix:
️ Note on Owner Settings
Aside from certain features listed below, only owners can withdraw funds and pause or unpause the contract. If the contract is paused or unpaused, it will affect checkUpkeep, performUpkeep, and topUp functions.
Functions with an asterisk (*) denote features that only the owner can change. Click on each function to learn more about its parameters and design patterns:
| Function Name | Description |
|---|---|
setWatchList* | Addresses to watch minimum balance and how much to top it up. |
setKeeperRegistryAddress* | Updates the KeeperRegistry address. |
setMinWaitPeriodSeconds* | Updates the global minimum period between top ups. |
topUp | Used by performUpkeep. This function will only trigger top up if conditions are met. |
Below are the feed functions in EthBalanceMonitor:
| Read Function Name | Description |
|---|---|
getUnderfundedAddresses | View function used in checkUpkeep to find underfunded balances. |
getKeeperRegistryAddress | Views the KeeperRegistry address. |
getMinWaitPeriodSeconds | Views the global minimum period between top ups. |
getWatchList | Views addresses to watch minimum balance and how much to top it up. |
getAccountInfo | Provides information about the specific target address, including the last time it was topped up. This function is external only. |
setWatchList Function| Name | Description | Suggested Setting |
|---|---|---|
addresses | The list of addresses to watch | (not applicable) |
minBalancesWei | The minimum balances for each address | 5000000000000000000 (5 ETH) |
topUpAmountsWei | The amount to top up each address | 5000000000000000000 (5 ETH) |
Only the owner can setWatchList. Each of the parameters should be set with distinct requirements for each address.
setKeeperRegistryAddress Function| Name | Description |
|---|---|
keeperRegistryAddress | Address that requires updating in KeeperRegistry |
Only the keeperRegistryAddress can performUpkeep, which is a global setting. KeeperRegistry addresses can be found on the Keepers app. However, only the owner can set a new KeeperRegistry after deployment.
setMinWaitPeriodSeconds Function| Name | Description | Suggested Setting |
|---|---|---|
period | Minimum wait period (in seconds) for addresses between funding | 3600 (1 hour) |
period denotes the length of time between top ups for a specific address. This is a global setting that prevents draining of funds from the contract if the private key for an address is compromised or if a gas spike occurs. However, only the owner can set a different minimum wait period after deployment.
topUp Function| Name | Description |
|---|---|
needsFunding | List of addresses to fund (addresses must be pre-approved) |
Any address can trigger the topUp function. This is an intentional design pattern that shows how easy it is to make an existing contract Keepers-compatible while maintaining an open interface. All validations are performed before the funding is triggered. If the conditions are not met, any attempt to top up will revert.
