How to view and deploy parachains¶
The guide has been updated to work with the Alexander testnet.
How to view parachains¶
On the Polkadot UI navigate to the
Chain State tab. Select the
parachains module and the
parachains() then hit the
+ button. It will return an array of the currently active parachains.
How to deploy the Adder parachain¶
You will need to have the minimum deposit needed to create a referendum. Currently this minimum is 5 DOTs.
adder parachain is a simple parachain which will keep a value in storage and add to this value as messages are sent to it. It can be found in the Polkadot repository under the
A slightly out-of-date video version of this guide presented by Adrian Brink is available here. When the two guides diverge, please refer to this written text as definitive and updated.
Building the code¶
The first step is to download locally the Polkadot code and switch to the
git clone https://github.com/paritytech/polkadot.git cd polkadot git checkout v0.4
Now make sure you have Rust installed.
curl https://sh.rustup.rs -sSf | sh sudo apt install make clang pkg-config libssl-dev rustup update
Now navigate to the
test-parachains folder in the Polkadot code repository and run the build script.
cd test-parachains ./build.sh
This will create the Wasm executable of the simple
adder parachain contained in this folder. This parachain will simply add messages that are sent to it. The Wasm executable will output into the
parachains/test/res/adder.wasm path so make sure you are able to find it there.
You will need to build and run the collator node in order to get the genesis state of this parachain.
Navigate to the
test-parachains/adder/collator directory and run the
cargo build cargo run [ctrl-c]
Feel free to stop the collator node right away. You will get some output that looks like this:
Starting adder collator with genesis: Dec: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 27, 77, 3, 221, 140, 1, 241, 4, 145, 67, 207, 156, 76, 129, 126, 75, 22, 127, 29, 27, 131, 229, 198, 240, 241, 13, 137, 186, 30, 123, 206] Hex: 0x00000000000000000000000000000000000000000000000000000000000000000000000000000000011b4d03dd8c01f1049143cf9c4c817e4b167f1d1b83e5c6f0f10d89ba1e7bce
The important information is the hex string. This is your genesis state and you will need to save it for the next steps.
Deploying the parachain¶
Go to Polkadot UI on the
Extrinsics tab. Select the account you wish to deploy the parachain from. You will need to create a referendum to deploy the parachain.
id input enter in the id of the parachain. In the case of the simple adder it will be
100. In the
code field click on the page button and then upload the
adder.wasm binary that was compiled from before. In the
initial_head_data we will copy and paste the hex data that we got from running the collator node. In the
value field you will need to input the minimum required value for creating a referendum. At the time of writing this is 5 DOTs on the Alexander testnet.
If you navigate to the
Democracy tab you will be able to see your proposal in the proposals section.
Once you wait for the proposal to become a referendum you will be able to vote
Aye on it. Assumably, you will vote Aye as this will be a vote for the deployment of your parachain.
After the voting period of your referendum goes through you will be able to query the state of your parachain.
You can go to the
Chain State tab and by querying the
parachains state you should be able to see some information on your parachain.
Interacting with the parachain¶