# How to write a Python gRPC client for the Lightning Network Daemon #

This section enumerates what you need to do to write a client that communicates
with lnd in Python.

Lnd uses the gRPC protocol for communication with clients like lncli. gRPC is
based on protocol buffers and as such, you will need to compile the lnd proto
file in Python before you can use it to communicate with lnd. The following are
the steps to take.

* Create a virtual environment for your project
```
$ virtualenv lnd
```
* Activate the virtual environment
```
$ source lnd/bin/activate
```
* Install dependencies (googleapis-common-protos is required due to the use of
  google/api/annotations.proto)
```
(lnd)$ pip install grpcio grpcio-tools googleapis-common-protos
```
* Clone the google api's repository (required due to the use of
  google/api/annotations.proto)
```
(lnd)$ git clone https://github.com/googleapis/googleapis.git
```
* Copy the lnd rpc.proto file (you'll find this in lnrpc/rpc.proto) or just
  download it
```
(lnd)$ curl -o rpc.proto -s https://raw.githubusercontent.com/lightningnetwork/lnd/master/lnrpc/rpc.proto
```
* Compile the proto file
```
(lnd)$ python -m grpc_tools.protoc --proto_path=googleapis:. --python_out=. --grpc_python_out=. rpc.proto
```

After following these steps, two files `rpc_pb2.py` and `rpc_pb2_grpc.py` will
be generated. These files will be imported in your project while writing your
clients. Here's an example of a simple client that was built using these.

```python
# python-based lnd client to retrieve and display wallet balance

import grpc

import rpc_pb2 as ln
import rpc_pb2_grpc as lnrpc

channel = grpc.insecure_channel('localhost:10009')
stub = lnrpc.LightningStub(channel)

response = stub.WalletBalance(ln.WalletBalanceRequest(witness_only=True))
print(response.balance)
```

With the above, you should have all the `lnd` related `gRPC` dependencies
installed locally into your virtual environment. In order to get up to speed
with `protofbuf` usage from Python, see [this official `protobuf` tutorial for
Python](https://developers.google.com/protocol-buffers/docs/pythontutorial).
Additionally, [this official gRPC
resource](http://www.grpc.io/docs/tutorials/basic/python.html) details how to
drive `gRPC` from Python including the basics of making RPC calls, streaming
RPC's (bi-directional and uni-directional), etc.