Tutorial: Setting Up a Pool
Here we'll walk through a step-by-step guide to deploying and setting up a new pool. The deployment can be carried out using simple scripts, the blend-sdk may be helpful for writing these scripts. We recommend deploying your pool on testnet before doing so on mainnet.
Step 1: Decide on an oracle
The oracle is backbone of a pool, and cannot be changed once an oracle is set.
Please review Selecting an Oracle.
Step 2: Deploy a new Pool Contract
We first deploy a new pool contract by calling the deploy()
function on the Pool Factory Contract. The function takes the following parameters:
admin
name
The Pool name. Used by UI's to render a name for the pool.
salt
Random bytes used to generate the pool contract address
oracle
backstop_take_rate
max_positions
The deployment function will return the new Pool Contract's address.
The Pool Factory contract address can be found here: Deployments
Many of the pool setup functions can only be called by the pool admin. If the pool creator intends for the admin to be a DAO or multisig it may be preferable for them to continue using their account to finish setting up the pool, then transfer pool ownership to the final admin using the Pool Contract's set_admin()
function.
Step 3: Add Pool Reserves
After the pool is deployed we add assets (reserves) to it by calling the Pool Contract's queue_set_reserve()
function. The function takes the following parameters:
asset
Token Contract address of the asset being added to the pool
metadata
The reserve configuration for the new asset.
The ReserveConfig struct is constructed as follows:
The reserve
index
will be assigned by theset_reserve()
function, the parameter does not matter when setting up the asset.The reserve
decimals
must match the number of decimals the new asset has, as defined by the asset's Token Contract. Stellar Classic assets have 7 decimals.More information on reserve
c_factor
,l_factor
, andmax_util
, can be found here: Risk ParametersMore information on reserve
util
,r_base
,r_one
,r_two
,r_three
, andreactivity
can be found here: Interest Rates
After the reserve is queued we finalize the addition by calling set_reserve()
function. The function takes the following parameters:
asset
Token Contract address of the asset being added to the pool
Pool creator's should be careful not to update the pool status before adding all initial reserves. If they do there will be a manditory 7 day delay between calling queue_set_reserve() and set_reserve()
Step 4: Set up Pool Emissions
After reserves are added, we set up pool emissions by calling the set_emissions_config()
function. The function takes the following parameters:
res_emission_metadata
A vector of ReserveEmissionMetadata structs. These structs govern how pool emissions are distributed between pool assets.
The ReserveEmissionMetadata struct is constructed as follows:
res_index
is the index of the reserve defined by the ReserveConfig struct. It was returned by theset_reserve()
function. Reserve index's are set based on the order the reserves were added to the pool (the first reserve will have index 0, the next index 1, etc.).res_type
designates whether lenders or borrowers of the reserve will receive emissions. If liabilities are designated borrowers receive emissions, if supply is designated lenders receive emissions. It is possible for both to receive emissions, the vec input into theset_emissions_config()
function just must include aReserveEmissionMetadata
struct for both reserve liabilities and supply.share
is the percent of total pool emissions the reserve (and reserve type) should receive. The total of all inputReserveEmissionMetadata
share's must equal10000000
.
Step 5 (optional): Set up Pool Backstop
If the pool creator wishes to, they can fund the pool's backstop at this point so that the pool meets the minimum backstop threshold allowing it to be activated and potentially added to the backstop reward zone.
It is highly recommended to test your pool before depositing into the backstop.
For example, is there is a reserve that cannot have a priced fetched on the oracle, you will not be able to use the pool.
An easy way to preview pool configuration is to navigate to your pool via the Blend UI. Searching /dashboard?poolId=C...
will attempt to load the pool via the UI.
How many Backstop Tokens do I need?
To reach the minimum backstop threshold a blend pool's backstop must have enough backstop LP tokens for their associated reserves to reach a product constant value of 200,000. This can be calculated with the following formula
Where:
k = Product Constant
x = Blend Amount
y = USDC amount
BLND_amount^0.8*USDC_amount^0.2 = product_constant
At current rates each LP token's associated reserves have a product constant of around 2. So 100,000 LP tokens are sufficient to reach the backsttop threshold.
Acquiring Backstop Tokens
To fund the backstop module we first need to acquire backstop tokens (80:20 BLND:USDC comet LP tokens). These can be acquired in 3 different ways depending on the assets we have on hand.
Individuals based outside of restricted jurisdictions can acquire backstop tokens via any of these options using the Blend UI https://mainnet.blend.capital/
Option 1: Acquiring Backstop tokens using only USDC
To acquire backstop tokens with only USDC we must execute a single sided deposit on the Comet Liquidity Pool by calling the dep_lp_tokn_amt_out_get_tokn_in
function. The function has the following parameters:
token_in
Address of the token being deposited (in this case USDC)
pool_amount_out
The number of pool tokens to mint
max_amount_in
The maximum amount of tokens (in this case USDC) you're willing to deposit
user
Address of the user depositing
Option 2: Acquiring Backstop Tokens using Both BLND and USDC
We use the Comet Liquidity Pool's join_pool
function to mint backstop tokens using both BLND and USDC. It has the following parameters:
pool_amount_out
The number of pool tokens to mint
max_amounts_in
The maximum amount of tokens you're willing to deposit. BLND amount is first in the Vec, USDC amount is second.
user
Address of the user depositing
Option 3: Aquiring Backstop Tokens using BLND
To acquire backstop tokens with only BLND we execute a single sided deposit on the Comet Liquidity Pool by calling the dep_lp_tokn_amt_out_get_tokn_in
function. This is much the same as option 1, except the deposit token is BLND and the max amount in is the maximum BLND you're willing to deposit.
Depositing Backstop Tokens
We can deposit backstop tokens into the backstop by calling deposit()
on the Backstop contract. It has the following parameters:
from
The address of the user depositing the tokens
pool_address
The address of the pool the backstop deposit is being made to. In this case it's the address of your pool.
amount
The number of backstop tokens you wish to deposit.
Other Options to Fund the Backstop
If the pool creator does not wish to fund the entire backstop themselves they have 2 options.
Backstop Bootstrapping
A pool creator with a large amount of BLND or USDC that does not wish to create significant market impact by setting up their backstop can choose to use the Backstop Bootstrapper contract to faciliate a community backstop deposit.
More details can be found here:
Community Funding
If the creator does not want to put much (or any) capital into the pool's backstop they can still deploy the pool without depositing into the backstop and just publicize the deployment to the blend community, inviting them to deposit.
The contract addresses for the Comet Pool contract, the Backstop contract, and the Backstop Bootstrapper contract can be found here: Deployments
Step 5: Activating the Pool
Now that all pool parameters are set we need to turn the pool on. We can do so using the Pool contract's set_status()
function. It has the following parameters:
pool_status
Pool Status:
0 = admin active - requires that the backstop threshold is met. Allows both deposits and borrowing
2 = admin on-ice - allows deposits but not borrowing
4 = admin frozen - does not allow deposits or borrowing
Here we recommend that you set the pool to on_ice
then, if the backstop has been funded, call the Pool contract's update_status()
function (no parameters) which will set the status to active. Admin active is a elevated status which makes it harder for the backstop to shut the pool down.
Step 6 (optional): Add Pool to Reward Zone
At this point if the pool's backstop was funded in Step 4 so that it has met the backstop threshold we can add the pool to the Backstop Contract's reward zone so it begins receiving emissions.
We do so by calling the add_reward()
function on the Backstop contract. It has the following parameters:
to_add
The address of the pool being added to the reward zone. In this case your pool's contract address.
to_remove
The address of the pool being removed from the reward zone. This parameter only matters if the reward zone is full (it currently isn't), in which case your pool must have a larger backstop than one currently in the reward zone. In that case this parameter will be the address of the pool your pool is replacing.
And that's it! Your done! If you've completed all 6 steps your pool will now show up in the markets page at https://mainnet.blend.capital/
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