feat(api): show a user pool's Lambda triggers

packages/api/src/adapter-aws/AwsUserPoolsAdapter.test.ts

@@ -125,9 +125,31 @@ describe('AwsUserPoolsAdapter', () => {
             mfaConfiguration: 'OFF',
             deletionProtection: 'INACTIVE',
             appClients: [{clientId: 'a8e5c7d38d3b4a1a97c9d822de', clientName: 'orders-users-client'}],
+            lambdaTriggers: [],
         })
     })
 
+    test('lists the pool\'s Lambda triggers in sign-in order, with the trigger version when set', async () => {
+        const arn = (name: string) => `arn:aws:lambda:us-east-1:000000000000:function:${name}`
+        const {client} = stubCognito((command) => {
+            if (command instanceof DescribeUserPoolCommand) return {UserPool: {...pool, LambdaConfig: {
+                PreTokenGeneration: arn('claims'),
+                PreTokenGenerationConfig: {LambdaArn: arn('claims'), LambdaVersion: 'V2_0'},
+                PreSignUp: `${arn('signup')}:live`,
+                CustomEmailSender: {LambdaArn: arn('mailer'), LambdaVersion: 'V1_0'},
+                KMSKeyID: 'arn:aws:kms:us-east-1:000000000000:key/1',
+            }}}
+            return {}
+        })
+
+        const resource = await new AwsUserPoolsAdapter(client).get(POOL_ID)
+        expect(resource?.metadata.lambdaTriggers).toEqual([
+            {trigger: 'PreSignUp', label: 'Pre sign-up', functionArn: `${arn('signup')}:live`, functionName: 'signup', version: null},
+            {trigger: 'PreTokenGeneration', label: 'Pre token generation', functionArn: arn('claims'), functionName: 'claims', version: 'V2_0'},
+            {trigger: 'CustomEmailSender', label: 'Custom email sender', functionArn: arn('mailer'), functionName: 'mailer', version: 'V1_0'},
+        ])
+    })
+
     test('counts users itself, since the runtime leaves EstimatedNumberOfUsers at 0', async () => {
         const {client} = stubCognito((command) => {
             if (command instanceof DescribeUserPoolCommand) return {UserPool: {...pool, EstimatedNumberOfUsers: 0}}

packages/api/src/adapter-aws/AwsUserPoolsAdapter.ts

@@ -460,10 +460,43 @@ function toResource(pool: UserPoolType, clients: UserPoolClientDescription[], us
             mfaConfiguration: pool.MfaConfiguration ?? null,
             deletionProtection: pool.DeletionProtection ?? null,
             appClients: clients.map((client) => ({clientId: client.ClientId ?? '', clientName: client.ClientName ?? ''})),
+            lambdaTriggers: lambdaTriggersOf(pool.LambdaConfig),
         },
     }
 }
 
+// Labels as the AWS console names them, in the order a sign-up and sign-in reach them.
+const LAMBDA_TRIGGERS = [
+    ['PreSignUp', 'Pre sign-up'],
+    ['UserMigration', 'User migration'],
+    ['CustomMessage', 'Custom message'],
+    ['PostConfirmation', 'Post confirmation'],
+    ['PreAuthentication', 'Pre authentication'],
+    ['DefineAuthChallenge', 'Define auth challenge'],
+    ['CreateAuthChallenge', 'Create auth challenge'],
+    ['VerifyAuthChallengeResponse', 'Verify auth challenge response'],
+    ['PostAuthentication', 'Post authentication'],
+    ['PreTokenGeneration', 'Pre token generation'],
+    ['CustomEmailSender', 'Custom email sender'],
+    ['CustomSMSSender', 'Custom SMS sender'],
+] as const
+
+type LambdaTrigger = {trigger: string; label: string; functionArn: string; functionName: string; version: string | null}
+
+function lambdaTriggersOf(config: UserPoolType['LambdaConfig']): LambdaTrigger[] {
+    if (!config) return []
+    return LAMBDA_TRIGGERS.flatMap(([trigger, label]) => {
+        // PreTokenGenerationConfig carries the trigger version and supersedes the older PreTokenGeneration field.
+        const versioned = trigger === 'PreTokenGeneration' ? config.PreTokenGenerationConfig
+            : trigger === 'CustomEmailSender' ? config.CustomEmailSender
+                : trigger === 'CustomSMSSender' ? config.CustomSMSSender
+                    : undefined
+        const functionArn = versioned?.LambdaArn ?? config[trigger]
+        if (typeof functionArn !== 'string' || !functionArn) return []
+        return [{trigger, label, functionArn, functionName: functionArn.split(':')[6] ?? functionArn, version: versioned?.LambdaVersion ?? null}]
+    })
+}
+
 function toUserItem(
     username: string | undefined,
     attributes: AttributeType[] | undefined,