Deploy a Smart Contract

Clone cw-template

For this example, we will use the cw-template repo with counter example.

cargo generate --git --name my-first-contract

Select false

🔧   Destination: /home/angelo/Progetti/my-first-contract ...
🔧   Generating template ...
? 🤷   Would you like to generate the minimal template?
The full template includes some example logic in case you're new to CosmWasm smart contracts.
The minimal template assumes you already know how to write your own logic, and doesn't get in your way. 
cd my-first-contract

Compile the wasm contract

To deploy smart contracts, you must compile the code and make it an executable wasm binary file. We will compile the wasm contract with stable toolchain.

Compile using the command below:

# Set 'stable' as the default release channel:
rustup default stable
cargo wasm

After this compiles, it should produce a file in target/wasm32-unknown-unknown/release/my_first_contract.wasm. If you check the size of the file by using the ls -lh command, it shows around 1.9M. This is a release build, but not stripped of all unneeded code. To produce a much smaller version, you can run this which tells the compiler to strip all unused code out:

RUSTFLAGS='-C link-arg=-s' cargo wasm

This produces a file about 155K. To reduce gas costs, the binary size should be as small as possible. This will result in a less costly deployment, and lower fees on every interaction. Also, if you don’t use compilation optimization, CosmWasm smart contract will not be deployed well due to exceeds limit error.

Optimized Compilation

You can do further optimization using rust-optimizer. rust-optimizer produces reproducible builds of CosmWasm smart contracts and does heavy optimization on the build size, using binary stripping and wasm-opt.

docker run --rm -v "$(pwd)":/code \
    --mount type=volume,source="$(basename "$(pwd)")_cache",target=/code/target \
    --mount type=volume,source=registry_cache,target=/usr/local/cargo/registry \

Binary file will be at artifacts/my_first_contract.wasm folder and its size will be about 130K, which is more smaller than when only RUTFLAGS was used.

Store to BitSong Cosmwasm Testnet

We have the wasm binary executable ready. Now it is time to store the code to the BitSong Cosmwasm Testnet.

RES=$(bitsongd tx wasm store artifacts/my_first_contract.wasm --from mywallet --gas-prices 0.1ubtsg --gas auto --gas-adjustment 1.3 -y --output json -b block)
  • bitsongd tx wasm store : upload a wasm binary

  • --from : name or address of private key with which to sign.

  • --gas-prices : gas prices in decimal format to determine the transaction fee.

  • --gas : gas limit to set per-transaction. set to “auto” to calculate sufficient gas automatically

  • --gas-adjustment : adjustment factor to be multiplied against the estimate returned by the tx simulation.

  • -y : to skip tx broadcasting prompt confirmation.

  • --output : output format.

  • -b : transaction broadcasting mode

Once that is complete, you can get the CODE_ID easily using jq.

jq is an open source that helps extract data from JSON. Install it according to your OS using the following command:

# Linux
sudo apt-get install jq

# Mac
brew install jq

Run the following command to set the CODE_ID as a variable:

# get CODE_ID
CODE_ID=$(echo $RES | jq -r '.logs[0].events[-1].attributes[1].value')
echo $CODE_ID

Instantiate the contract

We can now create an instance of this wasm contract. First, set the initial state of the instance in the INIT variable and run the instantiate command.

# set the initial state of the instance

# instantiate the contract
bitsongd tx wasm instantiate $CODE_ID "$INIT" \
    --from mywallet --label "my first contract" --gas-prices 0.025ubtsg --gas auto --gas-adjustment 1.3 -b block -y --no-admin
  • bitsongd tx wasm instantiate : instantiate a wasm contract using CODE_ID of the uploaded binary.

  • --label : human-readable name for this contract in lists.

  • --no-admin : you must set this explicitly if you don’t want an admin.

Get the contract address using the command following:

CONTRACT_ADDR=$(bitsongd query wasm list-contract-by-code $CODE_ID --output json | jq -r '.contracts[0]')

Query the contract

Now, let’s see if the contract we deployed works well.

Get contract’s count

Send a get_count query to check the count value. The previously set INIT state is output as it is.: {"data":{"count":100}}

bitsongd query wasm contract-state smart $CONTRACT_ADshDR "$QUERY" --output json

The output will be

  • bitsongd query wasm contract-state smart : calls contract with given address with query data and prints the returned result

Execute the Contract

Increment contract’s count

This time, let’s send an increment transaction that increases the count value by +1. Because the transaction changes the internal state of the contract, you must pay gas fees.

If you run the get_count query again after sending the increment transaction, you can see that +1 has increased from the previous count value.

TRY_INCREMENT='{"increment": {}}'
bitsongd tx wasm execute $CONTRACT_ADDR "$TRY_INCREMENT" --from mywallet --gas-prices 0.025ubtsg --gas auto --gas-adjustment 1.3 -y

Reset contract’s count

Lastly, let’s send a reset transaction. Like increment, reset transaction also changes the internal state of contract, so you must pay gas fees.

RESET='{"reset": {"count": 0}}'
bitsongd tx wasm execute $CONTRACT_ADDR "$RESET" --from mywallet --gas-prices 0.025ubtsg --gas auto --gas-adjustment 1.3 -y

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