How to use the command `grpcurl` (with examples)

grpcurl is a command-line tool that allows you to interact with gRPC servers. It is similar to curl, but specifically designed for gRPC. You can use grpcurl to send requests to gRPC servers, list services exposed by a server, and list methods in a particular service.

Use case 1: Send an empty request

Code:

grpcurl grpc.server.com:443 my.custom.server.Service/Method

Motivation: This use case is useful when you want to send a request without any specific headers or body. It can be used for testing connectivity with a gRPC server or checking if a particular service and method are available.

Explanation of arguments:

• grpc.server.com:443: The address of the gRPC server, including the port number (443 in this example).
• my.custom.server.Service/Method: The fully qualified name of the service and method you want to invoke.

Example output: This command will send an empty request to the specified gRPC server and return the response.

Use case 2: Send a request with a header and a body

Code:

grpcurl -H "Authorization: Bearer $token" -d '{"foo": "bar"}' grpc.server.com:443 my.custom.server.Service/Method

Motivation: This use case is useful when you need to send a request with specific headers and a body. It can be used to authenticate with the server using an authorization token and send data to the server in the request body.

Explanation of arguments:

• -H "Authorization: Bearer $token": Specifies the header to be included in the request. In this example, it sets the “Authorization” header with a bearer token. The value of the bearer token is specified using the environment variable $token.
• -d '{"foo": "bar"}': Specifies the data to be included in the request body. In this example, it sends a JSON object with a key-value pair of “foo”: “bar”.
• grpc.server.com:443: The same as in the previous use case.
• my.custom.server.Service/Method: The same as in the previous use case.

Example output: This command will send a request with the specified headers and body to the gRPC server and return the response.

Use case 3: List all services exposed by a server

Code:

grpcurl grpc.server.com:443 list

Motivation: This use case is useful when you want to obtain a list of all the services exposed by a gRPC server. It allows you to quickly identify the available services and their corresponding methods.

Explanation of arguments:

• list: This argument instructs grpcurl to list all the services exposed by the specified gRPC server.

Example output: Running this command will display a list of all the services exposed by the gRPC server.

Use case 4: List all methods in a particular service

Code:

grpcurl grpc.server.com:443 list my.custom.server.Service

Motivation: This use case is useful when you want to obtain a list of all the methods within a specific service. It helps you understand the capabilities and functionality of the service.

Explanation of arguments:

• my.custom.server.Service: The fully qualified name of the service you want to list the methods for.

Example output: Running this command will display a list of all the methods within the specified service.