Feature: Add config option for fee granters

.changelog/unreleased/features/1633-allow-fee-granters.md

@@ -0,0 +1,2 @@
+- Added support for fee granters through config file
+  ([#1633](https://github.com/informalsystems/ibc-rs/issues/1633))

config.toml

@@ -223,6 +223,12 @@ memo_prefix = ''
 #   ['transfer', 'channel-0'],
 # ]
 
+# Specify that the transaction fees should be payed from this fee granter's account.
+# Optional. If unspecified (the default behavior), then no fee granter is used, and
+# the account specified in `key_name` will pay the tx fees for all transactions
+# submitted to this chain.
+# fee_granter = ''
+
 [[chains]]
 id = 'ibc-1'
 rpc_addr = 'http://127.0.0.1:26557'

guide/src/config.md

@@ -91,6 +91,7 @@ account_prefix = 'cosmos'
 key_name = 'testkey'
 store_prefix = 'ibc'
 max_gas = 2000000
+fee_granter = ''
 gas_price = { price = 0.001, denom = 'stake' }
 gas_adjustment = 0.1
 clock_drift = '5s'

relayer/src/chain/cosmos.rs

@@ -103,6 +103,8 @@ const DEFAULT_MAX_GAS: u64 = 300_000;
 /// Fraction of the estimated gas to add to the estimated gas amount when submitting a transaction.
 const DEFAULT_GAS_PRICE_ADJUSTMENT: f64 = 0.1;
 
+const DEFAULT_FEE_GRANTER: &str = "";
+
 /// Upper limit on the size of transactions submitted by Hermes, expressed as a
 /// fraction of the maximum block size defined in the Tendermint core consensus parameters.
 pub const GENESIS_MAX_BYTES_MAX_FRACTION: f64 = 0.9;
@@ -440,6 +442,14 @@ impl CosmosSdkChain {
         self.config.max_gas.unwrap_or(DEFAULT_MAX_GAS)
     }
 
+    /// Get the fee granter address
+    fn fee_granter(&self) -> &str {
+        self.config
+            .fee_granter
+            .as_deref()
+            .unwrap_or(DEFAULT_FEE_GRANTER)
+    }
+
     /// The gas price
     fn gas_price(&self) -> &GasPrice {
         &self.config.gas_price
@@ -644,7 +654,7 @@ impl CosmosSdkChain {
             amount: vec![self.max_fee_in_coins()],
             gas_limit: self.max_gas(),
             payer: "".to_string(),
-            granter: "".to_string(),
+            granter: self.fee_granter().to_string(),
         }
     }
 
@@ -655,7 +665,7 @@ impl CosmosSdkChain {
             amount: vec![self.fee_from_gas_in_coins(adjusted_gas_limit)],
             gas_limit: adjusted_gas_limit,
             payer: "".to_string(),
-            granter: "".to_string(),
+            granter: self.fee_granter().to_string(),
         }
     }
 

relayer/src/chain/mock.rs

@@ -459,6 +459,7 @@ pub mod test_utils {
             max_gas: None,
             gas_price: GasPrice::new(0.001, "uatom".to_string()),
             gas_adjustment: None,
+            fee_granter: None,
             max_msg_num: Default::default(),
             max_tx_size: Default::default(),
             clock_drift: Duration::from_secs(5),

relayer/src/config.rs

@@ -378,6 +378,7 @@ pub struct ChainConfig {
     pub default_gas: Option<u64>,
     pub max_gas: Option<u64>,
     pub gas_adjustment: Option<f64>,
+    pub fee_granter: Option<String>,
     #[serde(default)]
     pub max_msg_num: MaxMsgNum,
     #[serde(default)]

tools/integration-test/src/types/single/node.rs

@@ -137,6 +137,7 @@ impl FullNode {
             default_gas: None,
             max_gas: Some(3000000),
             gas_adjustment: Some(0.1),
+            fee_granter: None,
             max_msg_num: Default::default(),
             max_tx_size: Default::default(),
             max_block_time: Default::default(),