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Overview

The Quorum client is a modified geth client. One of the unique enhancements is the pluggable architecture which allows adding additional features as plugins to the core geth, providing extensibility, flexibility, and isolation of Quorum features.

Benefits¶

This enhancement provides a number of benefits, including:

Allowing the implementation of certain components of the Quorum client to be changed at configuration time.
Supporting our community to improve the Quorum client with their own innovative implementations of the supported pluggable components.
Decoupling new Quorum-specific features from core geth thereby simplifying the process of pulling in changes from upstream geth.

How it works?¶

Each plugin exposes an implementation for a specific plugin interface (or see Pluggable Architecture -> Plugins for more details) Plugins are executed as a separate process and communicate with the main Quorum client geth process over a gRPC interface.

The plugin implementation must adhere to certain gRPC services defined in a .proto file corresponding to the plugin interface. Plugins can be written in different languages as gRPC provides a mechanism to generate stub code from .proto files.

The network communication and RPC are handled automatically by the high-level plugin library.

Installing Plugins¶

Currently plugins must be manually installed into a directory (defaults to plugins directory inside geth data directory - default can be overriden by setting baseDir in plugins settings).

Using Plugins¶

Plugins settings file contains a JSON that describes what plugins to be used. Then start geth with --plugins as below:

geth ... \
     --plugins file:///<path>/<to>/plugins.json

Plugin Integrity Verification¶

Plugin Central Server can be used to download and verify plugin integrity using PGP. The architecture enables the same verification process locally via --plugins.localverify and --plugins.publickey flags or remotely with custom plugin central - reference the Settings section for more information on how to support custom plugin central.

If the flag --plugins.skipverify is provided at runtime the plugin verification process will be disabled.

Warning

Using --plugins.skipverify is not advised for production settings and it should be avoided as it introduces security risks.

Example: `HelloWorld` plugin¶

The plugin interface is implemented in Go and Java. In this example, HelloWorld plugin exposes a JSON RPC endpoint to return a greeting message in the configured language. This plugin is reloadable. It means that the plugin can take changes from its JSON configuration.

Build plugin distribution file¶

Clone plugin repository

› git clone --recursive https://github.com/jpmorganchase/quorum-plugin-hello-world.git
› cd quorum-plugin-hello-world

Here we will use Go implementation of the plugin
```
quorum-plugin-hello-world› cd go
quorum-plugin-hello-world/go› make
```
quorum-plugin-hello-world-1.0.0.zip is now created in build directory. Noticed that there’s a file hello-world-plugin-config.json which is the JSON configuration file for the plugin.

Start Quorum with plugin support¶

Build Quorum

› git clone https://github.com/jpmorganchase/quorum.git
› cd quorum
quorum› make geth

Copy HelloWorld plugin distribution file and its JSON configuration hello-world-plugin-config.json to build/bin

Create geth-plugin-settings.json

quorum› cat > build/bin/geth-plugin-settings.json <<EOF
{
  "baseDir": "./build/bin",
  "providers": {
    "helloworld": {
      "name":"quorum-plugin-hello-world",
      "version":"1.0.0",
      "config": "file://./build/bin/hello-world-plugin-config.json"
    }
  }
}
EOF

Run geth with plugin

quorum› PRIVATE_CONFIG=ignore \
geth \
     --nodiscover \
     --verbosity 5 \
     --networkid 10 \
     --raft \
     --raftjoinexisting 1 \
     --datadir ./build/_workspace/test \
     --rpc \
     --rpcapi eth,debug,admin,net,web3,plugin@helloworld \
     --plugins file://./build/bin/geth-plugin-settings.json \
     --plugins.skipverify

ps -ef | grep helloworld would reveal the HelloWorld plugin process

Test the plugin¶

Call the JSON RPC

quorum› curl -X POST http://localhost:8545 \
     -H "Content-type: application/json" \
     --data '{"jsonrpc":"2.0","method":"plugin@helloworld_greeting","params":["Quorum Plugin"],"id":1}'
{"jsonrpc":"2.0","id":1,"result":"Hello Quorum Plugin!"}

Update plugin config to support es language

# update language to "es"
quorum› vi build/bin/hello-world-plugin-config.json

Reload the plugin

quorum› curl -X POST http://localhost:8545 \
     -H "Content-type: application/json" \
     --data '{"jsonrpc":"2.0","method":"admin_reloadPlugin","params":["helloworld"],"id":1}'
{"jsonrpc":"2.0","id":1,"result":true}