Merge pull request #1215 from ethereum-optimism/fix/configurable-gasprice-backend

dtl: configurable gas price backend

.changeset/ninety-dryers-brush.md

+---
+'@eth-optimism/data-transport-layer': patch
+---
+
+Allow the L1 gas price to be fetched from either the sequencer or a L1 provider based on the config `--l1-gas-price-backend` as well as overriding the config by using a query param. Valid values are `l1` or `l2` and it defaults to `l1`

packages/data-transport-layer/README.md

@@ -62,6 +62,8 @@ Here's the list of environment variables you can change:
 | DATA_TRANSPORT_LAYER__LEGACY_SEQUENCER_COMPATIBILITY    | false       | Whether or not to enable "legacy" sequencer sync (without the custom `eth_getBlockRange` endpoint)                                                            |
 | DATA_TRANSPORT_LAYER__NODE_ENV                          | development | Environment the service is running in: production, development, or test.                                                                                      |
 | DATA_TRANSPORT_LAYER__ETH_NETWORK_NAME                  | -           | L1 Ethereum network the service is deployed to: mainnet, kovan, goerli.                                                                                  |
+| DATA_TRANSPORT_LAYER__L1_GAS_PRICE_BACKEND                  | l1           | Where to pull the l1 gas price from (l1 or l2)                                                                                  |
+| DATA_TRANSPORT_LAYER__DEFAULT_BACKEND                  | l1           | Where to sync transactions from (l1 or l2)                                                                                  |
 
 To enable proper error tracking via Sentry on deployed instances, make sure `NODE_ENV` and `ETH_NETWORK_NAME` are set in addition to [`SENTRY_DSN`](https://docs.sentry.io/platforms/node/).
 
@@ -86,6 +88,24 @@ GET /eth/context/latest
 }
 ```
 
+### Latest Ethereum L1 Gas Price
+
+#### Request
+
+```
+GET /eth/gasprice
+```
+Defaults to pulling L1 gas price from config option `DATA_TRANSPORT_LAYER__L1_GAS_PRICE_BACKEND`. Can be overridden with query parameter `backend` (`/eth/gasprice?backend=l1`).
+
+#### Response
+
+```ts
+{
+    "gasPrice": string
+}
+```
+
+
 ### Enqueue by Index
 
 #### Request

packages/data-transport-layer/src/services/main/service.ts

@@ -34,6 +34,7 @@ export interface L1DataTransportServiceOptions {
   sentryDsn?: string
   sentryTraceRate?: number
   defaultBackend: string
+  l1GasPriceBackend: string
 }
 
 const optionSettings = {

packages/data-transport-layer/src/services/run.ts

@@ -46,6 +46,7 @@ type ethNetwork = 'mainnet' | 'kovan' | 'goerli'
         false
       ),
       defaultBackend: config.str('default-backend', 'l1'),
+      l1GasPriceBackend: config.str('l1-gas-price-backend', 'l1'),
       useSentry: config.bool('use-sentry', false),
       sentryDsn: config.str('sentry-dsn'),
       sentryTraceRate: config.ufloat('sentry-trace-rate', 0.05),

packages/data-transport-layer/src/services/server/service.ts

@@ -51,12 +51,23 @@ const optionSettings = {
       return validators.isUrl(val) || validators.isJsonRpcProvider(val)
     },
   },
+  l2RpcProvider: {
+    validate: (val: unknown) => {
+      return validators.isUrl(val) || validators.isJsonRpcProvider(val)
+    },
+  },
   defaultBackend: {
     default: 'l1',
     validate: (val: string) => {
       return val === 'l1' || val === 'l2'
     },
   },
+  l1GasPriceBackend: {
+    default: 'l1',
+    validate: (val: string) => {
+      return val === 'l1' || val === 'l2'
+    },
+  },
 }
 
 export class L1TransportServer extends BaseService<L1TransportServerOptions> {
@@ -69,6 +80,7 @@ export class L1TransportServer extends BaseService<L1TransportServerOptions> {
     server: any
     db: TransportDB
     l1RpcProvider: JsonRpcProvider
+    l2RpcProvider: JsonRpcProvider
   } = {} as any
 
   protected async _init(): Promise<void> {
@@ -82,6 +94,11 @@ export class L1TransportServer extends BaseService<L1TransportServerOptions> {
         ? new JsonRpcProvider(this.options.l1RpcProvider)
         : this.options.l1RpcProvider
 
+    this.state.l2RpcProvider =
+      typeof this.options.l2RpcProvider === 'string'
+        ? new JsonRpcProvider(this.options.l2RpcProvider)
+        : this.options.l2RpcProvider
+
     this._initializeApp()
   }
 
@@ -133,6 +150,26 @@ export class L1TransportServer extends BaseService<L1TransportServerOptions> {
     if (this.options.useSentry) {
       this.state.app.use(Sentry.Handlers.errorHandler())
     }
+
+    this.logger.info('HTTP Server Options', {
+      defaultBackend: this.options.defaultBackend,
+      l1GasPriceBackend: this.options.l1GasPriceBackend,
+    })
+
+    if (this.state.l1RpcProvider) {
+      this.logger.info('HTTP Server L1 RPC Provider initialized', {
+        url: this.state.l1RpcProvider.connection.url,
+      })
+    } else {
+      this.logger.warn('HTTP Server L1 RPC Provider not initialized')
+    }
+    if (this.state.l2RpcProvider) {
+      this.logger.info('HTTP Server L2 RPC Provider initialized', {
+        url: this.state.l2RpcProvider.connection.url,
+      })
+    } else {
+      this.logger.warn('HTTP Server L2 RPC Provider not initialized')
+    }
   }
 
   /**
@@ -271,8 +308,21 @@ export class L1TransportServer extends BaseService<L1TransportServerOptions> {
     this._registerRoute(
       'get',
       '/eth/gasprice',
-      async (): Promise<GasPriceResponse> => {
-        const gasPrice = await this.state.l1RpcProvider.getGasPrice()
+      async (req): Promise<GasPriceResponse> => {
+        const backend = req.query.backend || this.options.l1GasPriceBackend
+        let gasPrice: BigNumber
+
+        if (backend === 'l1') {
+          gasPrice = await this.state.l1RpcProvider.getGasPrice()
+        } else if (backend === 'l2') {
+          const response = await this.state.l2RpcProvider.send(
+            'rollup_gasPrices',
+            []
+          )
+          gasPrice = BigNumber.from(response.l1GasPrice)
+        } else {
+          throw new Error(`Unknown L1 gas price backend: ${backend}`)
+        }
 
         return {
           gasPrice: gasPrice.toString(),