Creating tokens locally

In this tutorial, we’ll create a BTC/USD token collateralized with an ERC-20 token (a stand in for DAI) via the UMA token builder. We will spin up the system locally on Ganache, push a price for BTC/USD, and create a token.

Prerequisites

All of our tutorials require that you complete the steps in Prerequisites.

Deploy smart contracts to Ganache

First, we’ll start a blockchain locally using Ganache and deploy the UMA smart contracts to it. The underlying products we can track are configured via a json file identifiers.json.

TODO: Add detailed doc on identifiers.json.

Run all commands in this section from the core/ directory.

  1. Start the Ganache UI.

  2. Switch to a test identifier config:

mv core/config/identifiersTest.json core/config/identifiers.json
  1. Deploy smart contracts to the locally running Ganache instance via:

$(npm bin)/truffle migrate --reset --network test

After this step, the smart contracts are deployed and can be interacted with.

Pushing prices (manually)

Run all commands in this section from the core/ directory.

In production, we can run a job on a cloud provider that fetches prices from a data API and pushes them to the blockchain. An example of such a script is core/scripts/PublishPrices.js.

Locally, however, let’s skip the step of setting up a data feed and manually push a price for BTCUSD via:

$(npm bin)/truffle exec scripts/ManualPublishPriceFeed.js --identifier BTCUSD --price <price> --time <time>

where <price> is the current price of Bitcoin in USD and <time> is the current UNIX timestamp in seconds.

For example, if the price of Bitcoin were $8,923 at 10/21/2019 15:40 EDT, run:

$(npm bin)/truffle exec scripts/ManualPublishPriceFeed.js --identifier BTCUSD --price 8293 --time 1571686800

UMA token builder

Run all commands in this section from the sponsor-dapp-v2/ directory.

  1. Run npm start to start the UMA token builder GUI.

  2. Chrome should automatically load the UI. If not, navigate to localhost:3000.

  3. Click on "Get Started".

  4. Click on "Testnet DAI faucet" to get some of the ERC-20 token we’ll be using as collateral.

  5. Click "Open token facility" and select "BTCUSD" as the price index. Go through the remaining set up flow.

We now have a synthetic token tracking the BTCUSD price.

To see our token valuation change as the BTC price changes, we can either push more prices using ManualPublishPriceFeed.js, as above, or see the price-feed-configuration.md doc to set up a real price feed.

© UMA Project 2018-2019