ksync

README

@ksync

Fast Sync archived and validated blocks from KYVE to every Tendermint based Blockchain Application

What is KSYNC?

Since KYVE is validating and archiving blocks from several blockchains permanently this data can be used to bootstrap nodes. This is especially helpful since most nodes today are pruning nodes and therefore finding peers which have the requested blocks becomes harder each day. With KSYNC nodes can retrieve the data from KYVE and directly feed the blocks into every Tendermint based Blockchain Application in order to sync blocks and join the network.

How does it work?

KSYNC comes with two sync modes which can be applied depending on the type of application. There is DB-SYNC which syncs blocks by directly communicating with the app and writing the data directly to the database and then there P2P-SYNC where KSYNC pretends to be a peer in the network which has all the required blocks, streaming them over the dedicated block channels over to the node.

After a node has been successfully synced with KSYNC the node simply can fetch remaining blocks and switch to live mode like it would have if synced normally. This makes operating nodes way cheaper and even may make archival nodes obsolete since blocks archived by KYVE can then be safely dropped in the nodes and synced again once needed with this tool.

Installation

To install the latest version of ksync, run the following command:

go install github.com/KYVENetwork/ksync/cmd/ksync@latest

To install a previous version, you can specify the version.

go install github.com/KYVENetwork/ksync/cmd/ksync@v0.1.0

Run ksync version to check the ksync version.

You can also install from source by pulling the ksync repository and switching to the correct version and building as follows:

git clone git@github.com:KYVENetwork/ksync.git
cd ksync
git checkout tags/vx.x.x -b vx.x.x
make ksync

This will build ksync in /build directory. Afterwards you may want to put it into your machine's PATH like as follows:

cp build/ksync ~/go/bin/ksync

Usage

Depending on the blockchain application you are trying to sync the following sync modes can be used.

Whichever sync mode you're using you still have to make sure that the blocks for your node are actually available. You can check out available storage pools for every KYVE network below:

• KYVE (Mainnet): https://app.kyve.network/#/pools
• Kaon (Testnet): https://app.kaon.kyve.network/#/pools
• Korellia (Devent): https://app.korellia.kyve.network/#/pools

Limitations

If you want to sync a node from genesis and the genesis file is bigger than 100MB you have to use P2P because of a message size limitation in the Tendermint Socket Protocol (TSP).

Currently, p2p sync is only supported for nodes using github.com/tendermint/tendermint. If nodes use CometBFT db sync has to be used. CometBFT support will be added in the future.

P2P-SYNC

In this sync mode this tool pretends to be a peer which has all the blocks the actual peer node needs. The blocks are then streamed over the dedicated block channels and storing them is handled by the node itself.

Requirements

It does not matter if you want to sync a node from genesis or from an existing height, the following settings have to be changed in order to run p2p sync.

Make sure that persistent_peers are empty in the config.toml config file:

~/.<chain>/config/config.toml

[p2p]

persistent_peers = ""

Make sure that your addrbook.json is empty or delete it entirely:

rm ~/.<chain>/config/addrbook.json

And finally enable the following setting:

~/.<chain>/config/config.toml

[p2p]

allow_duplicate_ip = true

Sync node

Now you can start your node simply with the start command like you would start the node normally.

./<chaind> start

When you see that the node is trying to search for peers but is unable to find any you can start KSYNC.

ATTENTION: If the node actually finds peers the configuration is wrong, in this case double-check the settings above

You can then start KSYNC in a new terminal with the following command. Please make sure to replace <user> and <chain> with your specific values. This of course is also true for <pool> and <network-api-endpoint>.

ksync start mode=p2p --home="/Users/<user>/.<chain>" --pool-id=<pool> --rest=<network-api-endpoint>

Available rest endpoints for every network maintained by KYVE:

• KYVE (Mainnet)
  • https://api-eu-1.kyve.network
  • https://api-us-1.kyve.network
• Kaon (Testnet)
  • https://api-eu-1.kaon.kyve.network
  • https://api-us-1.kaon.kyve.network
• Korellia (Devent)
  • https://api.korellia.kyve.network

Once KSYNC starts it automatically continues from the latest height found in the node and starts downloading the blocks from the storage provider and validates the checksum. You should see blocks streaming over and the node committing those blocks. If you run this command without a --target-height it will sync all blocks which are available in the pool. You can simply exit the sync process by killing KSYNC with CMD+C.

DB-SYNC

In this sync mode this tool pretends to be the tendermint process which communicates directly with the blockchain application over ABCI and replays the blocks against the app and manually writes the results to the DB directly.

Requirements

It does not matter if you want to sync a node from genesis or from an existing height, the following settings have to be changed in order to run DB sync.

Make sure that proxy_app and abci have the following default values in the config.toml config file:

~/.<chain>/config/config.toml

#######################################################################
###                   Main Base Config Options                      ###
#######################################################################

proxy_app = "tcp://127.0.0.1:26658"
abci = "socket"

Sync node

Now you can start your node with a special flag, so it does not start with tendermint as an embedded process:

./<chaind> start --with-tendermint=false

If you see that the abci server is waiting for new connections you can proceed with starting KSYNC in a new terminal with the following command. Please make sure to replace <user> and <chain> with your specific values. This of course is also true for <pool> and <network-api-endpoint>.

ksync start mode=db --home="/Users/<user>/.<chain>" --pool-id=<pool> --rest=<network-api-endpoint>

Available rest endpoints for every network maintained by KYVE:

• KYVE (Mainnet)
  • https://api-eu-1.kyve.network
  • https://api-us-1.kyve.network
• Kaon (Testnet)
  • https://api-eu-1.kaon.kyve.network
  • https://api-us-1.kaon.kyve.network
• Korellia (Devent)
  • https://api.korellia.kyve.network

Once KSYNC starts it automatically continues from the latest height found in the node and starts downloading the blocks from the storage provider and validates the checksum. You should KSYNC committing blocks against the app. If you run this command without a --target-height it will sync all blocks which are available in the pool. KSYNC will automatically exit once a target height is reached, or you can simply exit the sync process by killing KSYNC with CMD+C.

Live Example: Sync Cosmos Hub over P2P-SYNC

To sync cosmos you have to download and set up the correct gaia binary. To sync from genesis the version v4.2.1 has to be used. You can download them here or build them from source: https://github.com/cosmos/gaia

Verify installation with

./gaiad version
4.2.1

After the installation init the project

./gaiad init <your-moniker> --chain-id cosmoshub-4

download the genesis

wget https://raw.githubusercontent.com/cosmos/mainnet/master/genesis/genesis.cosmoshub-4.json.gz
gzip -d genesis.cosmoshub-4.json.gz
mv genesis.cosmoshub-4.json ~/.gaia/config/genesis.json

and edit the following in ~/.gaia/config/config.toml. TIP: those settings can be found under "p2p"

allow_duplicate_ip = true

Important: Don't include an addrbook.json and make sure persistent_peers and etc. are empty for now or else the node will connect to other peers. It should only connect to our peer.

when the config is done the node can be started. NOTE: this can take a while (~5mins) since the genesis file is quite big.

./gaiad start --x-crisis-skip-assert-invariants

After you see that the node is searching for peers you can start the tool. You can see the latest height which KYVE has archived here under Latest Key

ksync start --mode=p2p --home="/Users/<user>/.gaia" --pool-id=24 --rest=https://api.korellia.kyve.network

You should see the peer connecting and sending over blocks to the gaia node. After all the blocks have been applied the tool shows Done and you can safely exit the process with CMD+C.

When you want to continue to sync normally you can now add an addrbook or add peers in persistent_peers. When you start the node again the node should continue normally and tries to sync the remaining blocks.