GM world rollup

🌞 Introduction

This tutorial will guide you through building a sovereign gm-world rollup (gm stands for "good morning") using Rollkit. Unlike the quick start guide, this tutorial provides a more practical approach to understanding sovereign rollup development.

We will cover:

• Building and configuring a Cosmos-SDK application-specific rollup blockchain.
• Posting rollup data to a Data Availability (DA) network.
• Executing transactions (the end goal).

No prior understanding of the build process is required, just that it utilizes the Cosmos SDK for blockchain applications.

TIP

This tutorial explores Rollkit, currently in Alpha. If you encounter bugs, please report them via a GitHub issue ticket or reach out in our Telegram group.

🛠️ Dependencies

As we move into more advanced use cases, we use ignite to help with managing all the services we need to run. You can install ignite here.

Once installed, you can verify the installation by running:

ignite version

Ignite CLI version:             v28.7.0
Ignite CLI build date:          2025-01-15T08:23:41Z
Ignite CLI source hash:         2f83cfe6114cfc58bd6add791143fe43963c1b5c
Ignite CLI config version:      v1
Cosmos SDK version:             v0.50.11
Your OS:                        darwin
Your arch:                      arm64
Your go version:                go version go1.24.2 darwin/arm64
Your uname -a:                  Darwin Markos-MacBook-Pro.local 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan  2 20:24:16 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6000 arm64
Your cwd:                       /Users/markobaricevic/code/CoTend/rollkit1/docs
Is on Gitpod:                   false

Generate your App

ignite scaffold chain gm --address-prefix gm
cd gm

Install a specific version of ignite to use rollkit

ignite app install -g github.com/ignite/apps/rollkit

Install your app locally:

make install

Add Rollkit Features

Enhance your blockchain by adding Rollkit features. Use the following command:

ignite rollkit add

Build your chain

Build your chain using the following command:

ignite chain build

This will create a ~/.gm folder with all the necessary files to run a chain.

Initialize Your Blockchain

Before starting your blockchain, you need to initialize it with Rollkit support. Initialize the blockchain with Local DA as follows:

ignite rollkit init

It will also initialize 2 accounts alice and bob:

🚀 Starting your rollup

Now that we have our gm app generated and installed, we can launch our GM rollup along with the local DA by running the following command:

First lets start the local DA network:

curl -sSL https://rollkit.dev/install-local-da.sh | bash

you should see logs like:

4:58PM INF NewLocalDA: initialized LocalDA module=local-da
4:58PM INF Listening on host=localhost maxBlobSize=1974272 module=da port=7980
4:58PM INF server started listening on=localhost:7980 module=da

After which we can start the app:

gmd start --rollkit.node.aggregator

You should see an output like this:

2:50PM INF creating new client module=rollkit namespace=
2:50PM INF No state found in store, initializing new state module=BlockManager
2:50PM INF Initializing chain chainID=gm genesisTime=2025-06-26T12:50:11Z initialHeight=1 module=rollkit
2:50PM INF InitChain chainID=gm initialHeight=1 module=baseapp
2:50PM INF initializing blockchain state from genesis.json module=baseapp
2:50PM INF chain initialized successfully appHash=E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855 module=rollkit
2:50PM INF using default mempool ttl MempoolTTL=25 module=BlockManager
2:50PM INF service start impl=EventBus module=events msg="Starting EventBus service"
2:50PM INF service start impl=PubSub module=pubsub msg="Starting PubSub service"
2:50PM INF service start impl=IndexerService module=txindex msg="Starting IndexerService service"
2:50PM INF rollkit node run loop launched in background goroutine module=server
2:50PM INF serving HTTP listen address=[::]:26657 module=rollkit
2:50PM INF starting P2P client module=rollkit
2:50PM INF started RPC server addr=127.0.0.1:7331 module=rollkit
2:50PM INF listening on address=/ip4/127.0.0.1/tcp/7676/p2p/12D3KooWPN1jqkgZcuF8UMZEa7nSjoF7zPmGHRrCDVrXrpfTLpfJ module=p2p
2:50PM INF listening on address=/ip4/192.168.0.54/tcp/7676/p2p/12D3KooWPN1jqkgZcuF8UMZEa7nSjoF7zPmGHRrCDVrXrpfTLpfJ module=p2p
2:50PM INF no peers - only listening for connections module=p2p
2:50PM INF working in aggregator mode block time=1s module=rollkit
2:50PM INF Reaper started interval=1000 module=Reaper
2:50PM INF using pending block height=1 module=BlockManager
2:50PM INF Executing block height=1 module=rollkit num_txs=0 timestamp=2025-06-26T14:50:11+02:00
2:50PM INF block executed successfully appHash=678DE6BBA6E23B000DC5AC86B60245E6EAC503C5C7085495F3B71B22A762EB19 height=1 module=rollkit
2:50PM INF indexed block events height=1 module=txindex
2:50PM INF attempting to start executor (Adapter.Start) module=server
2:50PM INF executor started successfully module=server
2:50PM INF creating empty block height=2 module=BlockManager
2:50PM INF Executing block height=2 module=rollkit num_txs=0 timestamp=2025-06-26T14:50:30+02:00
2:50PM INF starting API server... address=tcp://0.0.0.0:1317 module=api-server
2:50PM INF serve module=api-server msg="Starting RPC HTTP server on [::]:1317"
2:50PM INF starting gRPC server... address=localhost:9090 module=grpc-server
2:50PM INF block executed successfully appHash=0B3973A50C42D0184FB86409FC427BD528A790FA45BA2C9E20FDF14A3628CEC8 height=2 module=rollkit

Ignite has successfully launched the GM rollup and the local DA network. The GM rollup is running on port 7331 and the local DA network is running on port 7980.

Good work so far, we have a Rollup node, DA network node, now we can start submitting transactions.

💸 Transactions

First, list your keys:

gmd keys list --keyring-backend test

You should see an output like the following

- address: gm17rpwv7lnk96ka00v93rphhvcqqztpn896q0dxx
  name: alice
  pubkey: '{"@type":"/cosmos.crypto.secp256k1.PubKey","key":"A5WPM5WzfNIPrGyha/TlHt0okdlzS1O4Gb1d1kU+xuG+"}'
  type: local
- address: gm1r2udsh4za7r7sxvzy496qfazvjp04j4zgytve3
  name: bob
  pubkey: '{"@type":"/cosmos.crypto.secp256k1.PubKey","key":"A+jOX/CWInFer2IkqgXGo0da9j7Ubq+e1LJWzTMDjwdt"}'
  type: local

For convenience we export two of our keys like this:

export ALICE=gm17rpwv7lnk96ka00v93rphhvcqqztpn896q0dxx
export BOB=gm1r2udsh4za7r7sxvzy496qfazvjp04j4zgytve3

Now let's submit a transaction that sends coins from one account to another (don't worry about all the flags, for now, we just want to submit transaction from a high-level perspective):

gmd tx bank send $BOB $ALICE 42069stake --keyring-backend test --chain-id gm --fees 5000stake

You'll be prompted to accept the transaction:

auth_info:
  fee:
    amount: []
    gas_limit: "200000"
    granter: ""
    payer: ""
  signer_infos: []
  tip: null
body:
  extension_options: []
  memo: ""
  messages:
  - '@type': /cosmos.bank.v1beta1.MsgSend
    amount:
    - amount: "42069"
      denom: stake
    from_address: gm1r2udsh4za7r7sxvzy496qfazvjp04j4zgytve3
    to_address: gm17rpwv7lnk96ka00v93rphhvcqqztpn896q0dxx
  non_critical_extension_options: []
  timeout_height: "0"
signatures: []
confirm transaction before signing and broadcasting [y/N]: // [!code focus]

Confirm and sign the transaction as prompted. now you see the transaction hash at the output:

//...

txhash: 677CAF6C80B85ACEF6F9EC7906FB3CB021322AAC78B015FA07D5112F2F824BFF

⚖️ Checking Balances

Query balances after the transaction:

gmd query bank balances $ALICE

The receiver’s balance should show an increase.

balances: // [!code focus]
- amount: "42069" // [!code focus]
  denom: stake
pagination:
  next_key: null
  total: "0"

For the sender’s balance:

gmd query bank balances $BOB

Output:

balances: // [!code focus]
- amount: "99957931" // [!code focus]
  denom: stake
pagination:
  next_key: null
  total: "0"

🎉 Next steps

Congratulations! You've experienced connecting to a rollup from the user side — simple and straightforward. Now, you might consider exploring how to add more application logic to your rollup using the Cosmos SDK, as demonstrated in our Wordle App tutorial.