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gWhisper - A gRPC command line tool

A gRPC command line client. It allows to invoke gRPC Calls from the commandline, supports tab-completion and formats the replies in a human readable format.

The main features are:

• Reflection support (no proto files required)
• Tab completion (currently supported in fish and bash) for
  • services
  • methods
  • method arguments, including nested types
• Usable directly in the shell

Have a look at the project scope for details.

Synopsis:

gwhisper [OPTIONS] <hostname>[:port] <service> <method> [<fieldName>=FIELD_VALUE ]...

Execute gwhisper --help or click here to get detailed information and examples on how to use the tool.

Quick links:

• Usage Manual
• Project scope
• Contributing
• Technical Documentation for Developers
• Frequently Asked Questions

Getting started

Download

Release version: download
Development version: git clone https://github.com/IBM/gWhisper.git

Prerequisites

To be able to build and/or run gWhisper, you need to have the following dependencies installed on your system:

Mandatory:

• cmake(>=3.11)
• A C++ compiler, e.g. gcc
• Either bash, fish(>=v2.6)

Optional:

• openssl Required if building the test server to generate test certificates. To disable building the test server, have a look at Advanced Building
• gRPC If you have gRPC installed on your system this will be used to build against, otherwise the gWhisper build system will download, build and statically link gRPC automatically.

Build

To simply build gWhisper in default configuration (including the test server), just execute

./build.sh

Executables are now available in the build/bin folder.

If you do not want to install gWhisper, you need to source the completion file (for tab completion):

source ./complete.bash or source ./complete.fish

NOTE: By default gWhisper downloads, builds and links gRPC in a version known and tested with gWhisper as part of the build. We made this choice, as we experienced many breaking changes in gRPC and wrongly packaged gRPC installations out there. However if you like, you can also link against your system installation of gRPC to save some build time and executable size. See Chapter Advanced Building.

Install

You may use the cmake-provided install target:

cd build
make install

Alternatively just copy the following files to the appropriate locations:

cp build/bin/gwhisper /usr/local/bin/
cp complete.bash /usr/share/bash-completion/completions/gwhisper
cp complete.fish /usr/share/fish/vendor_completions.d/gwhisper.fish

Advanced building

If you plan to build gWhisper for packaging or as a developer / contributor, the following information might be useful:

Directly use CMake to build

Follow the usual CMake flow:

mkdir build
cd build
cmake .. <cmake-options>
make -j<numCores>

CMake options

You can list gWhisper related build options via

cmake -LAH .. | grep --context 1 GWHISPER

The following are the most relevant options:

• GWHISPER_BUILD_TESTS (default = OFF): Build unit and functional tests
• GWHISPER_BUILD_TESTSERVER (default = ON): Build the testserver. This requires openssl to be installed for certificate creation.
• GWHISPER_FORCE_BUILDING_GRPC (default = ON): Do not use a system installation of gRPC even if found. Instead always download and build gRPC from source

You can set options in CMake with the -D flag. For example:

cmake .. -D GWHISPER_BUILD_TESTSERVER=OFF

Examples and Test-Server

Every element except the hostname in the following example CLI invocations can be tab-completed in the bash or fish shell.

Simple example of an unary RPC with only one field in the request message:

gwhisper exampledomain.org bakery orderCookies amount=5

Nested arguments (the config field contains a sub-message):

gwhisper exampledomain.org bakery orderCookies config=:chocolate=true smarties=false: amount=5

IPv6 address and explicit TCP port with an enum typed field:

gwhisper [2001:db8::2:1]:50059 bakery orderCookies type=ChunkyStyle amount=0x7

Feel free to use the Test-Server shipped with gWhisper and try out gWhisper on your own. It is located in build/bin/testServer and implements example RPCs which cover almost the complete gRPC and protocol buffers function set.

Docker

gWhisper comes with a Dockerfile which may be used to build and run gWhisper.
You may also use this, to build for different platforms using dockerx/qemu.
To build the docker image execute (from repository root)

docker build -t gwhisper -f docker/Dockerfile .

To build for a different plattform that your host use buildx (you might need to have QEMU iinstalled):

docker buildx build --platform linux/s390x -t gwhisper -f docker/Dockerfile .

Current development status

Basic functionality is implemented, but you may experience bugs. Feel free to try it out and provide feedback/contributions.

What is working:

• Tab Completion (bash and fish only)
• Calling RPCs (unary + streaming)
• Input and output of all protocol buffer types
• Security: SSL is supported

Some notable things which are not yet working:

• Using Proto files instead of Reflection API (currently gWhisper only works with servers which have reflection enabled)
• Performance: Caching of reflection queries

Supported platforms

Development and testing is done on Fedora Linux 33 and Arch Linux. We expect no bigger problems with building and running this software on different linux distributions.

Reporting issues

We really appreciate any kind of feedback :-) So don't hesitate to open a new issue.
Please use the GitGub issues tab. Be sure to search issues first to avoid duplicate entries.

Contribute

Please have a look at CONTRIBUTE.md for general information about contributing. Some more technical documentation can be found here: Technical Documentation for Developers.