feat(config): add fallbacks (#12593)

## Overview

Again like #12589
this is added after a chat with
charlie where we want to remove the need for a complex script. 

#12566 asks the user
for a private key as it needs
to set two env vars to the same key. 

This pr introduces the notion of a fallback, such that a config variable
will also check a list of fallbacks before
using the default value.

In this case, if `VALIDATOR_PRIVATE_KEY` is set, then
`SEQ_PUBLISHER_PRIVATE_KEY`` does not need to be set, removing the
need for it in the script.

Author: Maddiaa0

yarn-project/aztec/src/cli/cmds/start_node.ts

@@ -26,10 +26,17 @@ export async function startNode(
 ): Promise<{ config: AztecNodeConfig }> {
   // options specifically namespaced with --node.<option>
   const nodeSpecificOptions = extractNamespacedOptions(options, 'node');
+
+  // All options set from environment variables
+  const configFromEnvVars = getConfigEnvVars();
+
+  // Extract relevant options from command line arguments
+  const relevantOptions = extractRelevantOptions(options, aztecNodeConfigMappings, 'node');
+
   // All options that are relevant to the Aztec Node
   let nodeConfig: AztecNodeConfig = {
-    ...getConfigEnvVars(),
-    ...extractRelevantOptions(options, aztecNodeConfigMappings, 'node'),
+    ...configFromEnvVars,
+    ...relevantOptions,
   };
 
   if (options.proverNode) {
@@ -96,22 +103,26 @@ export async function startNode(
   if (!options.sequencer) {
     nodeConfig.disableValidator = true;
   } else {
-    const sequencerConfig = extractNamespacedOptions(options, 'sequencer');
+    const sequencerConfig = {
+      ...configFromEnvVars,
+      ...extractNamespacedOptions(options, 'sequencer'),
+    };
     let account;
     if (!sequencerConfig.publisherPrivateKey || sequencerConfig.publisherPrivateKey === NULL_KEY) {
-      if (!options.l1Mnemonic) {
+      if (sequencerConfig.validatorPrivateKey) {
+        sequencerConfig.publisherPrivateKey = sequencerConfig.validatorPrivateKey as `0x${string}`;
+      } else if (!options.l1Mnemonic) {
         userLog(
           '--sequencer.publisherPrivateKey or --l1-mnemonic is required to start Aztec Node with --sequencer option',
         );
         throw new Error('Private key or Mnemonic is required to start Aztec Node with --sequencer option');
       } else {
         account = mnemonicToAccount(options.l1Mnemonic);
         const privKey = account.getHdKey().privateKey;
-        nodeConfig.publisherPrivateKey = `0x${Buffer.from(privKey!).toString('hex')}`;
+        sequencerConfig.publisherPrivateKey = `0x${Buffer.from(privKey!).toString('hex')}`;
       }
-    } else {
-      nodeConfig.publisherPrivateKey = sequencerConfig.publisherPrivateKey;
     }
+    nodeConfig.publisherPrivateKey = sequencerConfig.publisherPrivateKey;
   }
 
   if (nodeConfig.p2pEnabled) {

yarn-project/end-to-end/scripts/native-network/validator.sh

@@ -11,7 +11,7 @@ exec > >(tee -a "$(dirname $0)/logs/${SCRIPT_NAME}.log") 2> >(tee -a "$(dirname
 PORT="$1"
 P2P_PORT="$2"
 ADDRESS="${3:-${ADDRESS:-}}"
-export VALIDATOR_PRIVATE_KEY="${4:-${VALIDATOR_PRIVATE_KEY:-}}"
+validator_private_key="${4:-${VALIDATOR_PRIVATE_KEY:-}}"
 
 # Starts the Validator Node
 REPO=$(git rev-parse --show-toplevel)
@@ -47,15 +47,16 @@ export BOOTSTRAP_NODES=$(echo "$output" | grep -oP 'Node ENR: \K.*')
 echo "BOOTSTRAP_NODES: $BOOTSTRAP_NODES"
 
 # Generate a private key for the validator only if not already set
-if [ -z "${VALIDATOR_PRIVATE_KEY:-}" ] || [ -z "${ADDRESS:-}" ]; then
+if [ -z "${validator_private_key:-}" ] || [ -z "${ADDRESS:-}" ]; then
   echo "Generating new L1 Validator account..."
   json_account=$(node --no-warnings "$REPO"/yarn-project/aztec/dest/bin/index.js generate-l1-account)
   export ADDRESS=$(echo $json_account | jq -r '.address')
-  export VALIDATOR_PRIVATE_KEY=$(echo $json_account | jq -r '.privateKey')
+  validator_private_key=$(echo $json_account | jq -r '.privateKey')
 fi
 
-export L1_PRIVATE_KEY=$VALIDATOR_PRIVATE_KEY
-export SEQ_PUBLISHER_PRIVATE_KEY=$VALIDATOR_PRIVATE_KEY
+## We want to use the private key from the cli
+unset VALIDATOR_PRIVATE_KEY
+
 export DEBUG=${DEBUG:-""}
 export LOG_LEVEL=${LOG_LEVEL:-"verbose"}
 export L1_CONSENSUS_HOST_URL=${L1_CONSENSUS_HOST_URL:-}
@@ -90,4 +91,4 @@ else
 fi
 
 # Start the Validator Node with the sequencer and archiver
-node --no-warnings "$REPO"/yarn-project/aztec/dest/bin/index.js start --port="$PORT" --node --archiver --sequencer
+node --no-warnings "$REPO"/yarn-project/aztec/dest/bin/index.js start --port="$PORT" --node --archiver --sequencer --sequencer.validatorPrivateKey="$validator_private_key"

yarn-project/foundation/src/config/index.ts

@@ -10,6 +10,7 @@ export interface ConfigMapping {
   description: string;
   isBoolean?: boolean;
   nested?: Record<string, ConfigMapping>;
+  fallback?: EnvVar[];
 }
 
 export function isBooleanConfigValue<T>(obj: T, key: keyof T): boolean {
@@ -18,20 +19,59 @@ export function isBooleanConfigValue<T>(obj: T, key: keyof T): boolean {
 
 export type ConfigMappingsType<T> = Record<keyof T, ConfigMapping>;
 
+/**
+ * Shared utility function to get a value from environment variables with fallback support.
+ * This can be used by both getConfigFromMappings and CLI utilities.
+ *
+ * @param env - The primary environment variable name
+ * @param fallback - Optional array of fallback environment variable names
+ * @param parseFunc - Optional function to parse the environment variable value
+ * @param defaultValue - Optional default value to use if no environment variable is set
+ * @returns The parsed value from environment variables or the default value
+ */
+export function getValueFromEnvWithFallback<T>(
+  env: EnvVar | undefined,
+  parseFunc: ((val: string) => T) | undefined,
+  defaultValue: T | undefined,
+  fallback?: EnvVar[],
+): T | undefined {
+  let value: string | undefined;
+
+  // Try primary env var
+  if (env) {
+    value = process.env[env];
+  }
+
+  // If primary not found, try fallbacks
+  if (value === undefined && fallback && fallback.length > 0) {
+    for (const fallbackEnv of fallback) {
+      const fallbackVal = process.env[fallbackEnv];
+      if (fallbackVal !== undefined) {
+        value = fallbackVal;
+        break;
+      }
+    }
+  }
+
+  // Parse the value if needed
+  if (value !== undefined) {
+    return parseFunc ? parseFunc(value) : (value as unknown as T);
+  }
+
+  // Return default if no env var found
+  return defaultValue;
+}
+
 export function getConfigFromMappings<T>(configMappings: ConfigMappingsType<T>): T {
   const config = {} as T;
 
   for (const key in configMappings) {
-    const { env, parseEnv, defaultValue: def, nested } = configMappings[key];
+    const { env, parseEnv, defaultValue, nested, fallback } = configMappings[key];
     if (nested) {
       (config as any)[key] = getConfigFromMappings(nested);
     } else {
-      const val = env ? process.env[env] : undefined;
-      if (val !== undefined) {
-        (config as any)[key] = parseEnv ? parseEnv(val) : val;
-      } else if (def !== undefined) {
-        (config as any)[key] = def;
-      }
+      // Use the shared utility function
+      (config as any)[key] = getValueFromEnvWithFallback(env, parseEnv, defaultValue, fallback);
     }
   }
 

yarn-project/sequencer-client/src/config.ts

@@ -16,6 +16,7 @@ import { Fr } from '@aztec/foundation/fields';
 import { FunctionSelector } from '@aztec/stdlib/abi';
 import { AztecAddress } from '@aztec/stdlib/aztec-address';
 import { type AllowedElement, type ChainConfig, type SequencerConfig, chainConfigMappings } from '@aztec/stdlib/config';
+import { type ValidatorClientConfig, validatorClientConfigMappings } from '@aztec/validator-client';
 
 import {
   type PublisherConfig,
@@ -31,6 +32,7 @@ export type { SequencerConfig };
  * Configuration settings for the SequencerClient.
  */
 export type SequencerClientConfig = PublisherConfig &
+  ValidatorClientConfig &
   TxSenderConfig &
   SequencerConfig &
   L1ReaderConfig &
@@ -113,6 +115,7 @@ export const sequencerConfigMappings: ConfigMappingsType<SequencerConfig> = {
 };
 
 export const sequencerClientConfigMappings: ConfigMappingsType<SequencerClientConfig> = {
+  ...validatorClientConfigMappings,
   ...sequencerConfigMappings,
   ...l1ReaderConfigMappings,
   ...getTxSenderConfigMappings('SEQ'),

yarn-project/sequencer-client/src/publisher/config.ts

@@ -50,6 +50,7 @@ export const getTxSenderConfigMappings: (
     description: 'The private key to be used by the publisher.',
     parseEnv: (val: string) => (val ? `0x${val.replace('0x', '')}` : NULL_KEY),
     defaultValue: NULL_KEY,
+    fallback: ['VALIDATOR_PRIVATE_KEY'],
   },
 });