# Maintenance

Some tasks in Solido, such as claiming staking rewards, need to happen periodically. We refer to these as maintenance tasks. The maintenance daemon (also called “bot”) watches the on-chain state, and executes maintenance tasks as necessary. It is fine, and even encouraged for redundancy, if multiple parties run a maintenance daemon.

## Trusted maintainers#

Most maintenance tasks can be executed by anybody. However, staking deposits is limited to a list of maintainers at the moment. This simplifies the on-chain program, but it also gives maintainers great power and responsibility over the stake distribution. The maintenance daemon that maintainers are expected to use, targets a uniform stake distribution, but maintainers in theory have the power to disturb this balance. We plan to move the stake distribution logic into the on-chain program in a future version, to eliminate the need for trusted maintainers.

## Maintainer operators#

Most of the Solido maintenance tasks can be executed by anybody, but there still needs to be somebody who submits the transaction. The maintenance bot automates this. The bot will also execute maintenance tasks that are restricted to the set of trusted maintainers. For v1 the set of trusted maintainers who run the bot consists of validators who are also part of the multisig:

• Chorus One
• Figment
• P2P
• Staking Facilities

Uptime of the maintenance bot is not critical. As long as somebody at least briefly runs the bot once every epoch, Solido will work fine. Because multiple parties run an instance, it is okay if an instance is inactive for a bit (e.g. to reboot the host).

## Obtaining the maintenance daemon#

The maintenance daemon is part of the solido utility. You can either build it from source with Cargo, or use the chorusone/solido-maintainer container image that includes a prebuilt version.

## Running the maintenance daemon#

The maintenance daemon is part of the solido utility and can be started with the run-maintainer subcommand. Like all solido commands, it can be configured either on the command line, with a json config file, or through environment variables. See also the section on solido configuration See solido --help and solido run-maintainer --help for the options specific to run-maintainer. Beware that:

• The public Solana RPC endpoints are rate-limited, and require trusting the server. If possible, point --cluster at the RPC endpoint of your own validator, instead of a public one like https://api.mainnet-beta.solana.com. See also the section about the RPC node requirements.

• The key used to sign (configured with --keypair-path) needs to be listed as a maintainer in the Solido instance. You can view the list of maintainers with solido show-solido. The account needs to be funded, as it pays for the transaction fees of maintenance transactions.

When running, the maintenance daemon periodically polls the on-chain state, and executes maintenances transactions if necessary. It also exposes an http server that serves a Prometheus /metrics endpoint. These metrics include both metrics about Solido in general (extracted from the on-chain state), and metrics about the daemon. The following metrics are useful for monitoring:

• solido_maintainer_balance_sol: The balance of the maintainer account (configured with --keypair-path). You can alert on this value dropping below e.g. 0.1 SOL; to top up the account in a timely fashion.

• solido_maintenance_polls_total: The number of times we refreshed the on-chain state. If this value stops increasing, something is wrong.

• solido_maintenance_errors_total: The number of times we encountered an error. If the rate of this metric gets close to the poll rate, that means most iterations are failing, and investigation is needed. Occasional errors are expected, especially when using a public RPC endpoint.

## RPC node requirements#

The Solido maintenance daemon puts some demands on the RPC node that it connects to:

• The RPC must be enabled with --full-rpc-api. Since Solana 1.9.6 by default only the minimal set of RPC methods is enabled, so the full set must be enabled explicitly.

• Set --max-multiple-accounts to a sufficiently large value. (1000 should be plenty for now.) Solido relies on GetMultipleAccounts to read atomic snapshots of the chain state. For correctness, it must be able to read all accounts in a single call. Solido needs to read multiple accounts per validator (multiple stake accounts, the vote account, the config account for metadata, etc.). Solido will log a warning to stdout when it can’t request all accounts in a single call.

• Enable account indexing of the config program with --account-index program-id and --account-index-include-key Config1111111111111111111111111111111111111. Due to the way Solana implements validator metadata, one needs to list all accounts owned by the config program to find the metadata for a particular validator. For this query to be fast, account indexing is needed. Without these flags, the GetProgramAccounts call will time out.

## Claiming validation fees#

For technical reasons, Solido holds on to any validation fees until the validator withdraws them into the validator’s stSOL account; they are not paid into the account automatically by the on-chain program. To alleviate this, the maintenance bot will withdraw the rewards automatically for all validators, into their stSOL accounts.