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Governance

Note
 This document is better viewed at https://docs.openzeppelin.com/contracts/api/governance

This directory includes primitives for on-chain governance.

Governor

This modular system of Governor contracts allows the deployment on-chain voting protocols similar to Compound’s Governor Alpha & Bravo and beyond, through the ability to easily customize multiple aspects of the protocol.

Tip

For a guided experience, set up your Governor contract using Contracts Wizard.

For a written walkthrough, check out our guide on How to set up on-chain governance.

  • {Governor}: The core contract that contains all the logic and primitives. It is abstract and requires choosing one of each of the modules below, or custom ones.

Votes modules determine the source of voting power, and sometimes quorum number.

  • {GovernorVotes}: Extracts voting weight from an {ERC20Votes} token.

  • {GovernorVotesComp}: Extracts voting weight from a COMP-like or {ERC20VotesComp} token.

  • {GovernorVotesQuorumFraction}: Combines with GovernorVotes to set the quorum as a fraction of the total token supply.

Counting modules determine valid voting options.

  • {GovernorCountingSimple}: Simple voting mechanism with 3 voting options: Against, For and Abstain.

Timelock extensions add a delay for governance decisions to be executed. The workflow is extended to require a queue step before execution. With these modules, proposals are executed by the external timelock contract, thus it is the timelock that has to hold the assets that are being governed.

  • {GovernorTimelockControl}: Connects with an instance of {TimelockController}. Allows multiple proposers and executors, in addition to the Governor itself.

  • {GovernorTimelockCompound}: Connects with an instance of Compound’s Timelock contract.

Other extensions can customize the behavior or interface in multiple ways.

  • {GovernorCompatibilityBravo}: Extends the interface to be fully GovernorBravo-compatible. Note that events are compatible regardless of whether this extension is included or not.

  • {GovernorSettings}: Manages some of the settings (voting delay, voting period duration and proposal threshold) in a way that can be updated through a governance proposal, without requiering an upgrade.

  • {GovernorProposalThreshold}: Restricts proposals to delegates with a minimum voting power. This is now deprecated as this feature moved to the core Governor contract, but kept for backward compatibility.

In addition to modules and extensions, the core contract requires a few virtual functions to be implemented to your particular specifications:

  • votingDelay(): Delay (in number of blocks) since the proposal is submitted until voting power is fixed and voting starts. This can be used to enforce a delay after a proposal is published for users to buy tokens, or delegate their votes.

  • votingPeriod(): Delay (in number of blocks) since the proposal starts until voting ends.

  • quorum(uint256 blockNumber): Quorum required for a proposal to be successful. This function includes a blockNumber argument so the quorum can adapt through time, for example, to follow a token’s totalSupply.

Note
 Functions of the Governor contract do not include access control. If you want to restrict access, you should add these checks by overloading the particular functions. Among these, {Governor-_cancel} is internal by default, and you will have to expose it (which the right access control mechanism) yourself if this function is needed.

Core

{{IGovernor}}

{{Governor}}

Modules

{{GovernorCountingSimple}}

{{GovernorVotes}}

{{GovernorVotesQuorumFraction}}

{{GovernorVotesComp}}

Extensions

{{GovernorTimelockControl}}

{{GovernorTimelockCompound}}

{{GovernorSettings}}

{{GovernorCompatibilityBravo}}

Timelock

In a governance system, the {TimelockController} contract is in carge of introducing a delay between a proposal and its execution. It can be used with or without a {Governor}.

{{TimelockController}}

Terminology

  • Operation: A transaction (or a set of transactions) that is the subject of the timelock. It has to be scheduled by a proposer and executed by an executor. The timelock enforces a minimum delay between the proposition and the execution (see operation lifecycle). If the operation contains multiple transactions (batch mode), they are executed atomically. Operations are identified by the hash of their content.

  • Operation status:

    • Unset: An operation that is not part of the timelock mechanism.

    • Pending: An operation that has been scheduled, before the timer expires.

    • Ready: An operation that has been scheduled, after the timer expires.

    • Done: An operation that has been executed.

  • Predecessor: An (optional) dependency between operations. An operation can depend on another operation (its predecessor), forcing the execution order of these two operations.

  • Role:

    • Admin: An address (smart contract or EOA) that is in charge of granting the roles of Proposer and Executor.

    • Proposer: An address (smart contract or EOA) that is in charge of scheduling (and cancelling) operations.

    • Executor: An address (smart contract or EOA) that is in charge of executing operations once the timelock has expired. This role can be given to the zero address to allow anyone to execute operations.

Operation structure

Operation executed by the TimelockController can contain one or multiple subsequent calls. Depending on whether you need to multiple calls to be executed atomically, you can either use simple or batched operations.

Both operations contain:

  • Target, the address of the smart contract that the timelock should operate on.

  • Value, in wei, that should be sent with the transaction. Most of the time this will be 0. Ether can be deposited before-end or passed along when executing the transaction.

  • Data, containing the encoded function selector and parameters of the call. This can be produced using a number of tools. For example, a maintenance operation granting role ROLE to ACCOUNT can be encode using web3js as follows:

const data = timelock.contract.methods.grantRole(ROLE, ACCOUNT).encodeABI()

  • Predecessor, that specifies a dependency between operations. This dependency is optional. Use bytes32(0) if the operation does not have any dependency.

  • Salt, used to disambiguate two otherwise identical operations. This can be any random value.

In the case of batched operations, target, value and data are specified as arrays, which must be of the same length.

Operation lifecycle

Timelocked operations are identified by a unique id (their hash) and follow a specific lifecycle:

Unset → Pending → Pending + Ready → Done

  • By calling schedule (or scheduleBatch), a proposer moves the operation from the Unset to the Pending state. This starts a timer that must be longer than the minimum delay. The timer expires at a timestamp accessible through the getTimestamp method.

  • Once the timer expires, the operation automatically gets the Ready state. At this point, it can be executed.

  • By calling execute (or executeBatch), an executor triggers the operation’s underlying transactions and moves it to the Done state. If the operation has a predecessor, it has to be in the Done state for this transition to succeed.

  • cancel allows proposers to cancel any Pending operation. This resets the operation to the Unset state. It is thus possible for a proposer to re-schedule an operation that has been cancelled. In this case, the timer restarts when the operation is re-scheduled.

Operations status can be queried using the functions:

  • isOperationPending(bytes32)

  • isOperationReady(bytes32)

  • isOperationDone(bytes32)

Roles

Admin

The admins are in charge of managing proposers and executors. For the timelock to be self-governed, this role should only be given to the timelock itself. Upon deployment, both the timelock and the deployer have this role. After further configuration and testing, the deployer can renounce this role such that all further maintenance operations have to go through the timelock process.

This role is identified by the TIMELOCK_ADMIN_ROLE value: 0x5f58e3a2316349923ce3780f8d587db2d72378aed66a8261c916544fa6846ca5

Proposer

The proposers are in charge of scheduling (and cancelling) operations. This is a critical role, that should be given to governing entities. This could be an EOA, a multisig, or a DAO.

Warning
 Proposer fight: Having multiple proposers, while providing redundancy in case one becomes unavailable, can be dangerous. As proposer have their say on all operations, they could cancel operations they disagree with, including operations to remove them for the proposers.

This role is identified by the PROPOSER_ROLE value: 0xb09aa5aeb3702cfd50b6b62bc4532604938f21248a27a1d5ca736082b6819cc1

Executor

The executors are in charge of executing the operations scheduled by the proposers once the timelock expires. Logic dictates that multisig or DAO that are proposers should also be executors in order to guarantee operations that have been scheduled will eventually be executed. However, having additional executors can reduce the cost (the executing transaction does not require validation by the multisig or DAO that proposed it), while ensuring whoever is in charge of execution cannot trigger actions that have not been scheduled by the proposers. Alternatively, it is possible to allow any address to execute a proposal once the timelock has expired by granting the executor role to the zero address.

This role is identified by the EXECUTOR_ROLE value: 0xd8aa0f3194971a2a116679f7c2090f6939c8d4e01a2a8d7e41d55e5351469e63

Warning
 A live contract without at least one proposer and one executor is locked. Make sure these roles are filled by reliable entities before the deployer renounces its administrative rights in favour of the timelock contract itself. See the {AccessControl} documentation to learn more about role management.