Use Service Connect to connect Amazon ECS services with short names - Amazon Elastic Container Service
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Use Service Connect to connect Amazon ECS services with short names

Amazon ECS Service Connect provides management of service-to-service communication as Amazon ECS configuration. It builds both service discovery and a service mesh in Amazon ECS. This provides the complete configuration inside each service that you manage by service deployments, a unified way to refer to your services within namespaces that doesn't depend on the VPC DNS configuration, and standardized metrics and logs to monitor all of your applications. Service Connect only interconnects services.

The following diagram shows an example Service Connect network with 2 subnets in the VPC and 2 services. A client service that runs WordPress with 1 task in each subnets. A server service that runs MySQL with 1 task in each subnet. Both services are highly available and resilient to task and Availability Zone issues because each service runs multiple tasks that are spread out over 2 subnets. The solid arrows show a connection from WordPress to MySQL. For example, a mysql --host=mysql CLI command that is run from inside the WordPress container in the task with the IP address 172.31.16.1. The command uses the short name mysql on the default port for MySQL. This name and port connects to the Service Connect proxy in the same task. The proxy in the WordPress task uses round-robin load balancing and any previous failure information in outlier detection to pick which MySQL task to connect to. As shown by the solid arrows in the diagram, the proxy connects to the second proxy in the MySQL task with the IP Address 172.31.16.2. The second proxy connects to the local MySQL server in the same task. Both proxies report connection performance that is visible in graphs in the Amazon ECS and Amazon CloudWatch consoles so that you can get performance metrics from all kinds of applications in the same way.

Example Service Connect network showing minimal HA services

The following terms are used with Service Connect.

port name

The Amazon ECS task definition configuration that assigns a name to a particular port mapping. This configuration is only used by Amazon ECS Service Connect.

client alias

The Amazon ECS service configuration that assigns the port number that is used in the endpoint. Additionally, the client alias can assign the DNS name of the endpoint, overriding the discovery name. If a discovery name isn't provided in the Amazon ECS service, the client alias name overrides the port name as the endpoint name. For endpoint examples, see the definition of endpoint. Multiple client aliases can be assigned to an Amazon ECS service. This configuration is only used by Amazon ECS Service Connect.

discovery name

The optional, intermediate name that you can create for a specified port from the task definition. This name is used to create a AWS Cloud Map service. If this name isn't provided, the port name from the task definition is used. Multiple discovery names can be assigned to a specific port an Amazon ECS service. This configuration is only used by Amazon ECS Service Connect.

AWS Cloud Map service names must be unique within a namespace. Because of this limitation, you can have only one Service Connect configuration without a discovery name for a particular task definition in each namespace.

endpoint

The URL to connect to an API or website. The URL contains the protocol, a DNS name, and the port. For more information about endpoints in general, see endpoint in the AWS glossary in the Amazon Web Services General Reference.

Service Connect creates endpoints that connect to Amazon ECS services and configures the tasks in Amazon ECS services to connect to the endpoints. The URL contains the protocol, a DNS name, and the port. You select the protocol and port name in the task definition, as the port must match the application that is inside the container image. In the service, you select each port by name and can assign the DNS name. If you don't specify a DNS name in the Amazon ECS service configuration, the port name from the task definition is used by default. For example, a Service Connect endpoint could be http://blog:80, grpc://checkout:8080, or http://_db.production.internal:99.

Service Connect service

The configuration of a single endpoint in an Amazon ECS service. This is a part of the Service Connect configuration, consisting of a single row in the Service Connect and discovery name configuration in the console, or one object in the services list in the JSON configuration of an Amazon ECS service. This configuration is only used by Amazon ECS Service Connect.

For more information, see ServiceConnectService in the Amazon Elastic Container Service API Reference.

namespace

The short name or full Amazon Resource Name (ARN) of the AWS Cloud Map namespace for use with Service Connect. The namespace must be in the same AWS Region as the Amazon ECS service and cluster. The type of namespace in AWS Cloud Map doesn't affect Service Connect.

Service Connect uses the AWS Cloud Map namespace as a logical grouping of Amazon ECS tasks that talk to one another. Each Amazon ECS service can belong to only one namespace. The services within a namespace can be spread across different Amazon ECS clusters within the same AWS Region in the same AWS account. You can freely organize services by any criteria.

client service

A service that runs a network client application. This service must have a namespace configured. Each task in the service can discover and connect to all of the endpoints in the namespace through a Service Connect proxy container.

If any of your containers in the task need to connect to an endpoint from a service in a namespace, choose a client service. If a frontend, reverse proxy, or load balancer application receives external traffic through other methods such as from Elastic Load Balancing, it could use this type of Service Connect configuration.

client-server service

An Amazon ECS service that runs a network or web service application. This service must have a namespace and at least one endpoint configured. Each task in the service is reachable by using the endpoints. The Service Connect proxy container listens on the endpoint name and port to direct traffic to the app containers in the task.

If any of the containers expose and listen on a port for network traffic, choose a client-server service. These applications don't need to connect to other client-server services in the same namespace, but the client configuration is needed. A backend, middleware, business tier, or most microservices can use this type of Service Connect configuration. If you want a frontend, reverse proxy, or load balancer application to receive traffic from other services configured with Service Connect in the same namespace, these services should use this type of Service Connect configuration.

The Service Connect feature creates a virtual network of related services. The same service configuration can be used across multiple different namespaces to run independent yet identical sets of applications. Service Connect defines the proxy container in the Amazon ECS service. This way, the same task definition can be used to run identical applications in different namespaces with different Service Connect configurations. Each task that the service makes runs a proxy container in the task.

Service Connect is suitable for connections between Amazon ECS services within the same namespace. For the following applications, you need to use an additional interconnection method to connect to an Amazon ECS service that is configured with Service Connect:

  • Tasks that are configured in other namespaces

  • Tasks that aren’t configured for Service Connect

  • Other applications outside of Amazon ECS

These applications can connect through the Service Connect proxy but can’t resolve Service Connect endpoint names.

For these applications to resolve the IP addresses of Amazon ECS tasks, you need to use another interconnection method.

Pricing

Amazon ECS Service Connect pricing depends on whether you use AWS Fargate or Amazon EC2 infrastructure to host your containerized workloads. When using Amazon ECS on AWS Outposts, the pricing follows the same model that's used when you use Amazon EC2 directly. For more information, see Amazon ECS Pricing.

AWS Cloud Map usage is completely free, when Service Connect uses it.