# gRPCurl
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`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](https://developers.google.com/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](https://github.com/grpc/grpc/blob/master/src/proto/grpc/reflection/v1alpha/reflection.proto),
by reading proto source files, or by loading in compiled "protoset" files (files that contain
encoded file [descriptor protos](https://github.com/google/protobuf/blob/master/src/google/protobuf/descriptor.proto)).
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](https://godoc.org/github.com/jhump/protoreflect) library, and shows
off what they can do.

See also the [`grpcurl` talk at GopherCon 2018](https://www.youtube.com/watch?v=dDr-8kbMnaw).

## Features
`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 plain-text and TLS servers 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`.

## Installation

### Binaries

Download the binary from the [releases](https://github.com/fullstorydev/grpcurl/releases) page.

On macOS, `grpcurl` is available via Homebrew:
```shell
brew install grpcurl
```

### From Source
You can use the `go` tool to install `grpcurl`:
```shell
go get github.com/fullstorydev/grpcurl/...
go install github.com/fullstorydev/grpcurl/cmd/grpcurl
```

This installs the command into the `bin` sub-folder of wherever your `$GOPATH`
environment variable points. If this directory is already in your `$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, you could have out-dated versions of `grpcurl`'s
dependencies. You can update the dependencies by running `make updatedeps`. You can
also use [`vgo`](https://github.com/golang/vgo) to install, which will use the right
versions of dependencies. Or, if you are using Go 1.11, 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 in your `GOPATH`).

## Usage
The usage doc for the tool explains the numerous options:
```shell
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:
```shell
grpcurl grpc.server.com:443 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:
```shell
grpcurl -d '{"id": 1234, "tags": ["foo","bar"]}' \
    grpc.server.com:443 my.custom.server.Service/Method
```

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:
```shell
grpcurl -d @ grpc.server.com:443 my.custom.server.Service/Method <<EOM
{
  "id": 1234,
  "tags": [
    "foor",
    "bar"
  ]
}
EOM
```

### Listing Services
To list all services exposed by a server, use the "list" verb. When using `.proto` source
or protoset files instead of server reflection, this lists all services defined in the
source or protoset files.
```shell
# Server supports reflection
grpcurl localhost:8787 list

# Using compiled protoset files
grpcurl -protoset my-protos.bin list

# Using proto sources
grpcurl -import-path ../protos -proto my-stuff.proto list
```

The "list" verb also lets you see all methods in a particular service:
```shell
grpcurl localhost:8787 list my.custom.server.Service
```

### Describing Elements
The "describe" verb will print the type of any symbol that the server knows about
or that is found in a given protoset file. It also prints a description of that
symbol, in the form of snippets of proto source. It won't necessarily be the
original source that defined the element, but it will be equivalent.

```shell
# Server supports reflection
grpcurl localhost:8787 describe my.custom.server.Service.MethodOne

# Using compiled protoset files
grpcurl -protoset my-protos.bin describe my.custom.server.Service.MethodOne

# Using proto sources
grpcurl -import-path ../protos -proto my-stuff.proto describe my.custom.server.Service.MethodOne
```

## Descriptor Sources
The `grpcurl` tool can operate on a variety of sources for descriptors. The descriptors
are required, in order for `grpcurl` to understand the RPC schema, translate inputs
into the protobuf binary format as well as translate responses from the binary format
into text. The sections below document the supported sources and what command-line flags
are needed to use them.

### Server Reflection

Without any additional command-line flags, `grpcurl` will try to use [server reflection](https://github.com/grpc/grpc/blob/master/src/proto/grpc/reflection/v1alpha/reflection.proto).

Examples for how to set up server reflection can be found [here](https://github.com/grpc/grpc/blob/master/doc/server-reflection.md#known-implementations).

When using reflection, the server address (host:port or path to Unix socket) is required
even for "list" and "describe" operations, so that `grpcurl` can connect to the server
and ask it for its descriptors.

### Proto Source Files
To use `grpcurl` on servers that do not support reflection, you can use `.proto` source
files.

In addition to using `-proto` flags to point `grpcurl` at the relevant proto source file(s),
you may also need to supply `-import-path` flags to tell `grpcurl` the folders from which
dependencies can be imported.

Just like when compiling with `protoc`, you do *not* need to provide an import path for the
location of the standard protos included with `protoc` (which contain various "well-known
types" with a package definition of `google.protobuf`). These files are "known" by `grpcurl`
as a snapshot of their descriptors is built into the `grpcurl` binary.

When using proto sources, you can omit the server address (host:port or path to Unix socket)
when using the "list" and "describe" operations since they only need to consult the proto
source files.

### Protoset Files
You can also use compiled protoset files with `grpcurl`. If you are scripting `grpcurl` and
need to re-use the same proto sources for many invocations, you will see better performance
by using protoset files (since it skips the parsing and compilation steps with each
invocation).

Protoset files contain binary encoded `google.protobuf.FileDescriptorSet` protos. To create
a protoset file, invoke `protoc` with the `*.proto` files that define the service:
```shell
protoc --proto_path=. \
    --descriptor_set_out=myservice.protoset \
    --include_imports \
    my/custom/server/service.proto
```

The `--descriptor_set_out` argument is what tells `protoc` to produce a protoset,
and the `--include_imports` argument is necessary for the protoset to contain
everything that `grpcurl` needs to process and understand the schema.

When using protosets, you can omit the server address (host:port or path to Unix socket)
when using the "list" and "describe" operations since they only need to consult the
protoset files.