grpcurl is a command-line tool designed to interact with gRPC servers, enabling users to invoke RPC methods directly from the terminal. It serves as a versatile alternative to curl for gRPC services, which rely on binary protocol buffer (protobuf) encoding.
Key Features:
JSON Input Handling: Accepts JSON-formatted requests, simplifying interaction for humans and scripts without requiring knowledge of protobuf syntax.
Service Schema Exploration: Browses gRPC service definitions via server reflection, proto source files, or protoset files, enabling schema-based request validation and transformation.
Streaming Support: Handles unary, client-streaming, server-streaming, and bidirectional streaming RPC methods, including interactive usage in terminals.
TLS Configuration: Supports secure communication with options for mutual TLS, custom certificate authorities, and plaintext connections.
Cross-Platform Compatibility: Installable via winget, ensuring accessibility across supported environments.
Audience & Benefit:
Ideal for developers, DevOps engineers, and API testers working with gRPC services. grpcurl streamlines testing, debugging, and exploration of gRPC endpoints without the need to write custom client code, enhancing productivity and efficiency in development workflows.
README
gRPCurl
grpcurl is a command-line tool that lets you interact with gRPC servers. It's
basically curl for gRPC servers.
The main purpose for this tool is to invoke RPC methods on a gRPC server from the
command-line. gRPC servers use a binary encoding on the wire
(protocol buffers, or "protobufs"
for short). So they are basically impossible to interact with using regular curl
(and older versions of curl that do not support HTTP/2 are of course non-starters).
This program accepts messages using JSON encoding, which is much more friendly for both
humans and scripts.
With this tool you can also browse the schema for gRPC services, either by querying
a server that supports server reflection,
by reading proto source files, or by loading in compiled "protoset" files (files that contain
encoded file descriptor protos).
In fact, the way the tool transforms JSON request data into a binary encoded protobuf
is using that very same schema. So, if the server you interact with does not support
reflection, you will either need the proto source files that define the service or need
protoset files that grpcurl can use.
This repo also provides a library package, github.com/fullstorydev/grpcurl, that has
functions for simplifying the construction of other command-line tools that dynamically
invoke gRPC endpoints. This code is a great example of how to use the various packages of
the protoreflect library, and shows
off what they can do.
grpcurl supports all kinds of RPC methods, including streaming methods. You can even
operate bi-directional streaming methods interactively by running grpcurl from an
interactive terminal and using stdin as the request body!
grpcurl supports both secure/TLS servers plain-text servers (i.e. no TLS) and has
numerous options for TLS configuration. It also supports mutual TLS, where the client is
required to present a client certificate.
As mentioned above, grpcurl works seamlessly if the server supports the reflection
service. If not, you can supply the .proto source files or you can supply protoset
files (containing compiled descriptors, produced by protoc) to grpcurl.
For platforms that support Docker, you can download an image that lets you run grpcurl:
# Download image
docker pull fullstorydev/grpcurl:latest
# Run the tool
docker run fullstorydev/grpcurl api.grpc.me:443 list
Note that there are some pitfalls when using docker:
If you need to interact with a server listening on the host's loopback network, you must specify the host as host.docker.internal instead of localhost (for Mac or Windows) OR have the container use the host network with -network="host" (Linux only).
If you need to provide proto source files or descriptor sets, you must mount the folder containing the files as a volume (-v $(pwd):/protos) and adjust the import paths to container paths accordingly.
If you want to provide the request message via stdin, using the -d @ option, you need to use the -i flag on the docker command.
Other Packages
There are numerous other ways to install grpcurl, thanks to support from third parties that
have created recipes/packages for it. These include other ways to install grpcurl on a variety
of environments, including Windows and myriad Linux distributions.
If you already have the Go SDK installed, you can use the go
tool to install grpcurl:
go install github.com/fullstorydev/grpcurl/cmd/grpcurl@latest
This installs the command into the bin sub-folder of wherever your $GOPATH
environment variable points. (If you have no GOPATH environment variable set,
the default install location is $HOME/go/bin). If this directory is already in
your $PATH, then you should be good to go.
If you have already pulled down this repo to a location that is not in your
$GOPATH and want to build from the sources, you can cd into the repo and then
run make install.
If you encounter compile errors and are using a version of the Go SDK older than 1.13,
you could have out-dated versions of grpcurl's dependencies. You can update the
dependencies by running make updatedeps. Or, if you are using Go 1.11 or 1.12, you
can add GO111MODULE=on as a prefix to the commands above, which will also build using
the right versions of dependencies (vs. whatever you may already have in your GOPATH).
Usage
The usage doc for the tool explains the numerous options:
grpcurl -help
In the sections below, you will find numerous examples demonstrating how to use
grpcurl.
Invoking RPCs
Invoking an RPC on a trusted server (e.g. TLS without self-signed key or custom CA)
that requires no client certs and supports server reflection is the simplest thing to
do with grpcurl. This minimal invocation sends an empty request body:
grpcurl grpc.server.com:443 my.custom.server.Service/Method
# no TLS
grpcurl -plaintext grpc.server.com:80 my.custom.server.Service/Method
To send a non-empty request, use the -d argument. Note that all arguments must come
before the server address and method name:
As can be seen in the example, the supplied body must be in JSON format. The body will
be parsed and then transmitted to the server in the protobuf binary format.
If you want to include grpcurl in a command pipeline, such as when using jq to
create a request body, you can use -d @, which tells grpcurl to read the actual
request body from stdin:
