fix: simplify DENCUN_FORK_EPOCH validation

Simplify validation of the `DENCUN_FORK_EPOCH` environment variable. Now
the validation is based on these two assumptions:

1. If the value of the `DENCUN_FORK_EPOCH` variable is not provided, it
is now implicitly set to the maximum integer for any unknown networks.
So, the app assumes that by default the Dencun fork is not applied to
any unknown network.

2. For the 3 officially supported networks correct values for the
`DENCUN_FORK_EPOCH` variable are set implicitly. For these 3 networks
values that the user sets for the `DENCUN_FORK_EPOCH` variable are
silently ignored.

Custom validation directive and complex transform function have been
removed.

The app now logs the actual value of the `DENCUN_FORK_EPOCH` variable
when it starts.

src/app/app.service.ts

@@ -30,6 +30,7 @@ export class AppService implements OnModuleInit, OnApplicationBootstrap {
     this.logger.log(`DRY RUN ${this.configService.get('DRY_RUN') ? 'enabled' : 'disabled'}`);
     this.logger.log(`Slot time: ${this.configService.get('CHAIN_SLOT_TIME_SECONDS')} seconds`);
     this.logger.log(`Epoch size: ${this.configService.get('FETCH_INTERVAL_SLOTS')} slots`);
+    this.logger.log(`Dencun fork epoch: ${this.configService.get('DENCUN_FORK_EPOCH')}`);
   }
 
   public async onApplicationBootstrap(): Promise<void> {

src/common/config/env.validation.ts

@@ -15,13 +15,11 @@ import {
   Min,
   MinLength,
   ValidateIf,
-  ValidationArguments,
-  registerDecorator,
   validateSync,
 } from 'class-validator';
 import { Epoch } from 'common/consensus-provider/types';
 
-import { DencunForkEpoch, Environment, LogFormat, LogLevel } from './interfaces';
+import { Environment, LogFormat, LogLevel } from './interfaces';
 
 export enum Network {
   Mainnet = 1,
@@ -41,6 +39,15 @@ export enum WorkingMode {
   Head = 'head',
 }
 
+const dencunForkEpoch = {
+  /**
+   * @todo This should be corrected once the particular epoch of the Dencun hard fork on Mainnet is known.
+   */
+  '1': 300000,
+  '5': 231680,
+  '17000': 29696,
+};
+
 const toBoolean = (value: any): boolean => {
   if (typeof value === 'boolean') {
     return value;
@@ -170,9 +177,11 @@ export class EnvironmentVariables {
 
   @IsInt()
   @IsPositive()
-  @IsValidDencunEpoch()
   @Expose()
-  @Transform(transformDencunEpoch)
+  @Transform(
+    ({ value, obj }) =>
+      dencunForkEpoch[obj.ETH_NETWORK] || (value != null && value.trim() !== '' ? parseInt(value, 10) : Number.MAX_SAFE_INTEGER),
+  )
   @ValidateIf((vars) => vars.NODE_ENV !== Environment.test)
   public DENCUN_FORK_EPOCH: Epoch;
 
@@ -304,55 +313,3 @@ export function validate(config: Record<string, unknown>) {
 
   return validatedConfig;
 }
-
-// ====================================================================================================================
-// PRIVATE FUNCTIONS
-// ====================================================================================================================
-function IsValidDencunEpoch() {
-  return function (object: Object, propertyName: string) {
-    registerDecorator({
-      name: 'isValidDencunEpoch',
-      target: object.constructor,
-      propertyName: propertyName,
-      validator: {
-        validate(value: Epoch, args: ValidationArguments) {
-          switch ((args.object as any).ETH_NETWORK) {
-            case Network.Mainnet:
-              return value === DencunForkEpoch.Mainnet;
-            case Network.Holesky:
-              return value === DencunForkEpoch.Holesky;
-            case Network.Goerli:
-              return value === DencunForkEpoch.Goerli;
-            default:
-              return true;
-          }
-        },
-      },
-    });
-  };
-}
-
-function transformDencunEpoch({ value, obj }) {
-  if (value == null) {
-    value = '';
-  }
-
-  value = value.trim();
-
-  if (value === '') {
-    const chainId = parseInt(obj.ETH_NETWORK, 10);
-
-    switch (chainId) {
-      case Network.Mainnet:
-        return DencunForkEpoch.Mainnet;
-      case Network.Holesky:
-        return DencunForkEpoch.Holesky;
-      case Network.Goerli:
-        return DencunForkEpoch.Goerli;
-      default:
-        return null;
-    }
-  }
-
-  return parseInt(value, 10);
-}

src/common/config/interfaces/environment.interface.ts

@@ -18,12 +18,3 @@ export enum LogFormat {
   json = 'json',
   simple = 'simple',
 }
-
-export enum DencunForkEpoch {
-  /**
-   * @todo This should be corrected once the particular epoch of the Dencun hard fork on Mainnet is known.
-   */
-  Mainnet = 300000,
-  Goerli = 231680,
-  Holesky = 29696,
-}