Improve handling of table migrations

[domdomegg]

Currently createTable attempts to slightly tweak the CloudFormation resource and then submit this to the CreateTable API:

serverless-dynamodb/index.js

Lines 337 to 396 in d22bc88

	createTable(dynamodb, migration) {
	return new Promise((resolve, reject) => {
	if (migration.StreamSpecification && migration.StreamSpecification.StreamViewType) {
	migration.StreamSpecification.StreamEnabled = true;
	}
	if (migration.TimeToLiveSpecification) {
	delete migration.TimeToLiveSpecification;
	}
	if (migration.SSESpecification) {
	migration.SSESpecification.Enabled = migration.SSESpecification.SSEEnabled;
	delete migration.SSESpecification.SSEEnabled;
	}
	if (migration.PointInTimeRecoverySpecification) {
	delete migration.PointInTimeRecoverySpecification;
	}
	if (migration.Tags) {
	delete migration.Tags;
	}
	if (migration.BillingMode === "PAY_PER_REQUEST") {
	delete migration.BillingMode;
	const defaultProvisioning = {
	ReadCapacityUnits: 5,
	WriteCapacityUnits: 5
	};
	migration.ProvisionedThroughput = defaultProvisioning;
	if (migration.GlobalSecondaryIndexes) {
	migration.GlobalSecondaryIndexes.forEach((gsi) => {
	gsi.ProvisionedThroughput = defaultProvisioning;
	});
	}
	}
	if(migration.ContributorInsightsSpecification) {
	delete migration.ContributorInsightsSpecification;
	}
	if(migration.GlobalSecondaryIndexes) {
	migration.GlobalSecondaryIndexes.forEach((gsi) => {
	if (gsi.ContributorInsightsSpecification) {
	delete gsi.ContributorInsightsSpecification;
	}
	});
	}
	dynamodb.raw.createTable(migration, (err) => {
	if (err) {
	if (err.name === 'ResourceInUseException') {
	this.serverlessLog(`DynamoDB - Warn - table ${migration.TableName} already exists`);
	resolve();
	} else {
	this.serverlessLog("DynamoDB - Error - ", err);
	reject(err);
	}
	} else {
	this.serverlessLog("DynamoDB - created table " + migration.TableName);
	resolve(migration);
	}
	});
	});
	}

However, this often doesn't comply with the API spec when adding extra things to CloudFormation (see #1, #10) and https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_CreateTable.html.

I think a better approach would be to just construct the API request body directly, rather than try to massage the CloudFormation into the API body. We could add warnings for unsupported properties.

[domdomegg]

Unfortunately on further investigation I think we are always going to have to do some translation of CloudFormation into AWS DynamoDB API calls given the two really do differ. Closing as not possible for now.