How to rename DynamoDB tables in Gen 2?

[AlexThomas90210]

Amplify CLI Version

Gen 2

Question

I really like Amplify but I find the resource name excruciatingly annoying, specially when deploying multiple branches/sandboxes in one AWS Account.

I am trying to rename core resources, such as userpool, lambda function etc, and I want to do the same with DynamoDB table but I don't seem to be able to get the Cloudformation reference because its in a nested stack, is it possible?

// Rename resources
backend.auth.resources.cfnResources.cfnUserPool.userPoolName = `${namePrefix}-userpool`;
backend.auth.resources.cfnResources.cfnIdentityPool.identityPoolName = `${namePrefix}-identitypool`;

// I want to rename here 
// backend.data.resources.cfnResources.cfnTables["Example"].tableName = `${namePrefix}-example-table`;

backend.data.resources.cfnResources.cfnGraphqlApi.name = `${namePrefix}-gqlapi`;
backend.stripeFunction.resources.cfnResources.cfnFunction.functionName = `${namePrefix}-payments-handler`;
backend.stripeWebhookCustomResource.resources.cfnResources.cfnFunction.functionName = `${namePrefix}-stripe-webhook-handler`;

[ykethan]

Hey,👋 thanks for raising this! I'm going to transfer this over to our API repository for better assistance 🙂

[dpilch]

It is not possible to change the DynamoDB table names currently.

The DynamoDB tables are stored in backend.data.resources.cfnResources.amplifyDynamoDbTables["TableName"]. However you will still run into a couple issues with changing the table name.

1. The CfnResource property is private on our wrapper class. You can ignore this with // @ts-expect-error but we cannot guarantee that there will be no breaking changes to a private property.

backend.data.resources.cfnResources.amplifyDynamoDbTables.Todo
  // @ts-expect-error
  .resource // private property
  .addPropertyOverride("tableName", "MyCustomTableName");

I don't know why resource is private in this case and it may be a mistake in the implementation. I will need to check with the team on this.

2. Even with the above workaround you will not be able to set the table name because the policy for our custom resource that creates the table is restricted to a certain naming pattern.

[AlexThomas90210]

@dpilch Thanks for the quick response, I appreciate it.

I guess I am making a feature request, to allow us to provide clean, user friendly names to not mess up the UI in the AWS Console and give a predictable outcome for the table names.

For example I have a project with 1 sandbox env, dev and prod with 7 models. The tables in the account look really messy and hard to understand/easy to make a mistake when selecting tables to perform actions on/inspect configuration etc

Other than that keep up the great work!

[cfernandezruns]

Any update on a solution for providing a name for Amplify generated tables? It'd be much better to allow user-defined, meaningful table names instead of relying on a random UUID table name.

I see that this PR was closed... is there another solution available?

[dpilch]

We discovered some issues in the implementation and are assessing some alternatives. I have a workaround, but it does have some issues. The resource property on the table is private so it isn't technically beholden to semantic version breaking changes. That being said I don't anticipate this changing anytime soon.

The workaround uses the private property and adds the necessary policy changes. Using the workaround would be at your own risk due to the private property.

import { Role, PolicyStatement, Effect } from 'aws-cdk-lib/aws-iam';

export const backend = defineBackend({
  auth,
  data,
});

backend.data.resources.cfnResources.amplifyDynamoDbTables.Todo
  // @ts-expect-error
  .resource // private property
  .addPropertyOverride("tableName", "MyCustomTableName");

// update Amplify DDB table manager policy to add custom table name
const policy = new PolicyStatement({
   effect: Effect.ALLOW,
    actions: [
        'dynamodb:CreateTable',
        'dynamodb:UpdateTable',
        'dynamodb:DeleteTable',
        'dynamodb:DescribeTable',
        'dynamodb:DescribeContinuousBackups',
        'dynamodb:DescribeTimeToLive',
        'dynamodb:UpdateContinuousBackups',
        'dynamodb:UpdateTimeToLive',
        'dynamodb:TagResource',
        'dynamodb:UntagResource',
        'dynamodb:ListTagsOfResource',
    ],
    resources: [
        Fn.sub('arn:aws:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${tableName}', {
            tableName,
        }),
    ],
});

const onEventRole = backend
    .data
    .resources
    .nestedStacks
    .AmplifyTableManager
    .node
    .findChild('AmplifyManagedTableOnEventRole') as Role;

const isCompleteRole = backend
    .data
    .resources
    .nestedStacks
    .AmplifyTableManager
    .node
    .findChild('AmplifyManagedTableIsCompleteRole') as Role;

onEventRole.addToPolicy(policy);
isCompleteRole.addToPolicy(policy);

backend.data.resources.cfnResources.cfnRoles.TodoIAMRole.addPropertyOverride(
  "Policies.0.PolicyDocument.Statement.0.Resource",
  [
    "arn:aws:dynamodb:us-west-2:<aws-account-id>:table/MyCustomTableName",
    "arn:aws:dynamodb:us-west-2:<aws-account-id>:table/MyCustomTableName/*",
  ]
);