Tutorial: Coda Quickstart
Hello! We'll walk you through a short demo to get a local testnet running using Coda.
Specifically, you'll download a docker image, run it, then play around with the command line interface to create a wallet and send/receive payments.
While you don't need to be a seasoned OCaml hacker to follow this guide, you should have a background or familiarity with common development patterns. If you know how to use the terminal, install a docker image, read developer documentation, and have access to a Linux-based operating system, you should be able to follow this guide.
At a high level, you'll follow these steps:
We'll walk through them one by one.
Verify your operating system
Software: You need to be running a Debian 9 or Ubuntu 18 distribution, either natively or in a VM. These are the only operating systems we have tested against. If you don't have this running locally, there are instructions in the appendix to set up a Google Compute instance.
Hardware: We'll be running three nodes on your machine, including a node that is performing intensive zk-SNARK proving work. Therefore, we recommend the following system requirements: 12GB ram (you may be able to get away with less), 4 cores.
Download the docker image
WARNING: Most of these commands won't work as shown unless you manage Docker as a non-root user. You can either follow the linked instructions OR run the following commands as root.
Now, create a directory where you can work, and run the docker image:
$ docker run -d --name coda codaprotocol/coda:demo
Now, connect to the docker process with the following command:
$ docker exec -it coda /bin/bash
Interact with the network
At a high level, here's what just happened: you started three Coda nodes, all of which are running locally on your machine over your localhost network.
There are a few ways you can interact with this network right away:
- Check the network status
- Create a wallet
- Send payments
- Check account balances
- Add additional nodes to the network
We'll show some code snippets for each of these actions below.
Check the network status
We use this general command to check the network's status (from the view of a particular node):
$ coda client status
Since you're running three nodes, the command above will fail. You have to specify the port that your nodes are running on. The following commands should work -- and give a consistent view of the network:
$ coda client status -daemon-port 8301 $ coda client status -daemon-port 8401 $ coda client status -daemon-port 8501
If you just want to have a running status page of the entire network, try running this:
$ watch coda client status -daemon-port 8301
Create a wallet
A wallet in Coda is just a public/private key pair. The public key corresponds to your publicly available address, and the private key is like a password, required to authorize sending funds from that address.
First, create a directory for your wallet:
$ mkdir wallet
The following command will generate a public/private keypair and prompt you for a password to encrypt the private key file:
$ coda client generate-keypair -privkey-path ./wallet/key
That creates an encrypted private key file at
./wallet/key and a corresponding public key file at
./wallet/key.pub. To check your public key, you can run
$ cat ./wallet/key.pub
For ease of setup and experimentation, we've already given you a well-funded account, which you can use to send payments to new accounts. Here's how you can send a payment from this account:
$ coda client send-txn -amount <AMOUNT> -privkey-path ./funded-wallet/key -receiver <RECEIVER_ADDRESS>
<AMOUNT> argument with an integer value and the
<RECEIVER_ADDRESS> with the public key of the account you're sending money to. It will prompt you for the private key password but it is blank.
Check account balances
Naturally, you might be interested in seeing how and when the network processes your payments. You can do that by either inquiring for a specific address or all account balances. Here are the commands to do so:
Checking account balance
$ coda client get-balance -address <PUBLIC_KEY>
Checking everyone's account balances
$ coda client get-public-keys -with-balances
Add additional nodes to the network
To spin up additional nodes, you'll need to point them to existing, running nodes. You can see how we spin up the nodes used in your network by reading through
./scripts/cluster.sh, and if you want to spin up new nodes, you can follow the patterns there.
Then, you can check whether this node is up and running with the following status command:
$ coda client status -daemon-port <PORT>
This will show you how to get up and running with an appropriate Linux distribution on Google Cloud. We'll cover a few steps: 1) getting the instance set up, 2) interacting with the machine on the command line.
Setting up the instance
To get the instance set up, follow these instructions, with the following changes:
Ubuntu 18.04 LTSas the OS.
- Instead of 1 vCPU, choose to have 4 vCPUs
- If you're on the west coast, instead of choosing us-east1 choose a west coast region
- Change the amount of ram to 12GB
Interacting with the CLI
To interact with the CLI, go to the compute engine -> VM instances page.
Then, select the VM, start the VM, and click the SSH button to open up a terminal window.