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FeeGrant module for blobs submission ​

Overview ​

This guide provides developers with the knowledge to use the FeeGrant module on the Celestia's Mocha testnet chain for granting a data availability node's account to submit blobs without constantly funding it, enabling a third-party account to cover the transaction fees.

Pre-requisites ​

  • celestia-node binary (celestia) installed
  • Access to a Mocha node (e.g., https://rpc-mocha.pops.one:443)
  • Running DA Light node on Mocha testnet
  • One account with sufficient funds, the "granter"
  • One account with no funds, the "grantee"

Introduction ​

Each DA node contains a Celestia account that is used to pay for blobs submissions. To unify the fee payment process, the FeeGrant module allows a third-party account (granter) to pay for the fees incurred by a DA node's (grantee) account. You will need one account that will contain the funds, the granter, and another account that will be in the DA node you run to post blobs, the grantee. You will see the DA node's account once you initialize the node. Learn more about managing accounts with cel-key in create a wallet with celestia-node.

Granting fee allowances using celestia-node ​

To get started granting the fee allowance, you will need two separate keys to run the light node with. One to begin the FeeGrant as the granter and another to use the FeeGrant as the grantee.

Set some variables for your accounts for the remainder of the guide:

bash
export GRANTER_ADDRESS=<your-granter-account-address>
export GRANTEE_ADDRESS=<your-grantee-account-address>
export RPC_URL=rpc-mocha.pops.one
export GRANTER_ADDRESS=<your-granter-account-address>
export GRANTEE_ADDRESS=<your-grantee-account-address>
export RPC_URL=rpc-mocha.pops.one

FeeGrant module implementation in celestia-node ​

Using celestia-node, you can now easily give permission for other nodes to submit transactions on your behalf. It is also possible to revoke the grant.

The FeeGrant functionality can now be used during runtime without the need to restart the node.

Grant permission for an allowance as a granter ​

First, start your node:

bash
celestia light start --p2p.network mocha --core.ip $RPC_URL
celestia light start --p2p.network mocha --core.ip $RPC_URL

Then, grant the fee to the grantee:

bash
celestia state grant-fee $GRANTEE_ADDRESS --amount 2000
celestia state grant-fee $GRANTEE_ADDRESS --amount 2000

Note that the --amount flag specifies the spend limit (in utia) for the grantee. If not specified, the grantee does not have a spend limit.

Using a FeeGrant allowance as a grantee in celestia-node ​

Start your node:

bash
celestia light start --core.ip $RPC_URL --p2p.network=mocha
celestia light start --core.ip $RPC_URL --p2p.network=mocha

To check the balance of a light node, use the following command:

bash
celestia state balance
celestia state balance

Example response when the account balance does not exist:

json
{
  "result": {
    "denom": "utia",
    "amount": "0"
  }
}
{
  "result": {
    "denom": "utia",
    "amount": "0"
  }
}

This indicates that the light node currently does not have any funds.

Now submit a blob using the FeeGrant:

bash
celestia blob submit 0x42690c204d39600fddd3 'gm' --granter.address $GRANTER_ADDRESS
celestia blob submit 0x42690c204d39600fddd3 'gm' --granter.address $GRANTER_ADDRESS

You'll see the height and the commitment of your blob:

json
{
  "result": {
    "height": 1639397,
    "commitments": [
      "19L/C4iBEsqXGzC5ZxJ3vtuGBiAdQAMIEnbYjKEGcac="
    ]
  }
}
{
  "result": {
    "height": 1639397,
    "commitments": [
      "19L/C4iBEsqXGzC5ZxJ3vtuGBiAdQAMIEnbYjKEGcac="
    ]
  }
}

Checking account balances after submission ​

Light node account: After submitting a blob, you can check the light node account's balance to verify that the fees have been deducted:

bash
celestia state balance
celestia state balance

Example output showing fees are not deducted:

json
{
  "result": {
    "denom": "utia",
    "amount": "0"
  }
}
{
  "result": {
    "denom": "utia",
    "amount": "0"
  }
}

Optional: Revoke permission for a FeeGrant allowance as a granter ​

To revoke the feegrant, run:

bash
celestia state revoke-grant-fee $GRANTEE_ADDRESS
celestia state revoke-grant-fee $GRANTEE_ADDRESS

Optional: Submitting a blob from file input ​

To submit a blob from file input:

bash
celestia blob submit --input-file blob.json
celestia blob submit --input-file blob.json

Optional: Granting fee allowances using celestia-appd ​

To grant fee allowances, allowing a third-party (granter) account to pay for the fees incurred by a Celestia data availability node (grantee) account, use the following commands.

Set your account addresses for grantee and granter, and the RPC URL:

bash
export GRANTER_ADDRESS=<your-granter-account-address>
export GRANTEE_ADDRESS=<your-grantee-account-address>
export RPC_URL=https://rpc-mocha.pops.one:443
export GRANTER_ADDRESS=<your-granter-account-address>
export GRANTEE_ADDRESS=<your-grantee-account-address>
export RPC_URL=https://rpc-mocha.pops.one:443

Then, send the feegrant transaction:

bash
celestia-appd tx feegrant grant \
  $GRANTER_ADDRESS $GRANTEE_ADDRESS \
  --node $RPC_URL \
  --spend-limit 1000000utia \
  --allowed-messages "/cosmos.bank.v1beta1.MsgSend,/celestia.blob.v1.MsgPayForBlobs" \
  --chain-id mocha-4 \
  --keyring-backend test \
  --fees 20000utia \
  --broadcast-mode block \
  --yes
celestia-appd tx feegrant grant \
  $GRANTER_ADDRESS $GRANTEE_ADDRESS \
  --node $RPC_URL \
  --spend-limit 1000000utia \
  --allowed-messages "/cosmos.bank.v1beta1.MsgSend,/celestia.blob.v1.MsgPayForBlobs" \
  --chain-id mocha-4 \
  --keyring-backend test \
  --fees 20000utia \
  --broadcast-mode block \
  --yes

Example: FeeGrant transaction on Mocha

Optional: Checking the granter's account ​

To confirm that the fees have been deducted from the granter's account that granted the fee allowance, run:

bash
celestia-appd query bank balances $GRANTER_ADDRESS \
--node https://rpc-mocha.pops.one:443 --denom utia
celestia-appd query bank balances $GRANTER_ADDRESS \
--node https://rpc-mocha.pops.one:443 --denom utia

This output will show the remaining balance after fees have been deducted, confirming that the FeeGrant module is working as intended.