How to create multiple resources (just different name) with one entry in CloudFormation

You could refactor your template to use nested stacks. Using nested stack you would define your dynamodb template table in a separate template and upload it to S3.

Then in your main template you would use AWS::CloudFormation::Stack to reference the dynamodb template.

You would still have three AWS::CloudFormation::Stack instances in your main template, they would be shorter and would follow good practices when developing with CloudFormation.

I found a solution that works for alarm ressources:

I create php script to generate resources alarms cloudformation and save theses resources into a yml file:

<?php

use Aws\CloudWatch\CloudWatchClient;
use Aws\Credentials\Credentials;
use Symfony\Component\Yaml\Yaml;

require 'vendor/autoload.php';

/**
 * Your AWS account credentials
 */
const AWS_REGION = 'eu-west-3';
const AWS_ACCESS_KEY_ID = '';
const AWS_SECRET_ACCESS_KEY = '';
const PROJECTS = [
    'project01',
    'project02',
    'project03'
];

$credentials = new Credentials(AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY);

$clientValues = [
    'version' => 'latest',
    'region' => AWS_REGION,
    'credentials' => $credentials
];

$cloudWatchClient = new CloudWatchClient($clientValues);

// Va permerttre de récupérer les métriques : Namespace Lambda, MetricName Errors
$args = [
    'Namespace' => 'AWS/Lambda',
    'MetricName' => 'Errors',
];

$metrics = [];

do {
    $listMetrics = $cloudWatchClient->listMetrics($args);

    // Ajoute NextToken à la requête listMetrics pour get les prochains résultats (limit 500/page)
    $args['NextToken'] = $listMetrics->hasKey('NextToken') ? $listMetrics->get('NextToken') : null;

    // Rempli un tableau avec les metrics récupérés; on prend FunctionName au lieu de RessourceName (même chose)
    foreach ($listMetrics->get('Metrics') as $metric) {
        if (isset($metric['Dimensions'])) {
            foreach ($metric['Dimensions'] as $dimension) {
                if ($dimension['Name'] === 'FunctionName') {
                    $metrics[] = $dimension['Value'];
                }
            }
        }
    }
} while ($listMetrics->hasKey('NextToken'));

asort($metrics);

$yaml = [];
$alarms = [];
$noAlarm = [];
$okAlarm = [];

foreach ($metrics as $item) {
    preg_match('/(?<=-)[a-zA-Z]*/', $item, $matches);

    if (empty($matches)) {
        $noAlarm[] = $item;
        continue;
    }

    // on check si $matches appartient à la liste des projets sinon on passe l'itération
    if (!in_array($matches[0], PROJECTS)) {
        $noAlarm[] = $item;
        continue;
    }

    $okAlarm[] = $item;

    $alarms['Resources'][sprintf('Alarm%s', str_replace('-', '', $item))] = [
        'Type' => 'AWS::CloudWatch::Alarm',
        'Properties' => [
            'AlarmActions' => [
                0 => '${self:custom.snsTopic}',
            ],
            'AlarmDescription' => sprintf('Lambda error %s', $item),
            'AlarmName' => sprintf('Alarm-%s', $item),
            'ComparisonOperator' => 'GreaterThanOrEqualToThreshold',
            'EvaluationPeriods' => 1,
            'MetricName' => 'Errors',
            'Dimensions' => [
                0 => [
                    'Name' => 'FunctionName',
                    'Value' => $item,
                ],
            ],
            'Namespace' => 'AWS/Lambda',
            'Period' => '${self:custom.period}',
            'Statistic' => 'Sum',
            'Threshold' => 1,
        ],
    ];
}

dump('No alarme = ' . count($noAlarm), 'Ok alarme = ' . count($okAlarm));
dump($noAlarm);

$yaml = Yaml::dump($alarms, 6, 2);

file_put_contents('/var/www/html/resources/resources.yml', $yaml);

Then, in my serverless:

# Usage
# --------------------------------
# serverless deploy
#   --aws-profile <AwsProfile>              [optional] AWS Profile name. Default profile if not set.
#   --stage [dev|sbx|prd]                   [required] Deployment stage : 'dev', 'sbx' or 'prd'.
#   --client <ClientName>                   [required] Client Name. Ex: 'Connect'.

service: Monitoring

provider:
  name: aws
  region: eu-west-3
  runtime: provided
  endpointType: regional
  deploymentBucket:
    name: ${lower:${opt:stage}}-${lower:${opt:client}}-slsdeploy
    blockPublicAccess: true
  deploymentPrefix: Monitoring

plugins:
  - ./sls

custom:
  period: 900
  snsTopic: "arn:aws:sns:${aws:region}:${aws:accountId}:monitoring-metrics"

resources:
  - ${file(resources/resources.yml)}

I hope this will help some people:)