c13n Development


While you can always deploy a fully fledged lightning daemon and a c13n node, it is always useful to set up a testbench during development. In this guide, we will deploy a local testbench with a Neutrino backed lnd on testnet, a c13n node and an example application consuming the c13n API.

The testbench is using the following containerized elements via Docker and docker-compose:

  • lnd: Lightning node using Neutrino as a BTC backend in Testnet
  • envoy: Proxy to provide gRPC-web support for the c13n RPC server
  • c13n: The main stack element
  • arc: An instant messaging web interface leveraging c13n functionality

During development, some of the testbench elements may not be required. For this reason, the docker-compose definition is using profiles. Each stack element should be explicitly declared when starting the stack using --profile.


  • Docker
  • docker-compose >=1.29.2
  • openssl


  1. Download the deployment stack definition

    git clone https://github.com/c13n-io/c13n-dev-stack.git
    cd c13n-dev-stack

  2. Generate TLS certificates for c13n

    cd c13n/certs
    openssl req -nodes -x509 -newkey ec -pkeyopt ec_paramgen_curve:prime256v1 -config cert.conf -extensions v3_exts -days 365 -keyout c13n.key -out c13n.pem

  3. Generate TLS certificates for envoy

    cd envoy/certs
    openssl req -x509 -newkey rsa:4096 -keyout envoy.key -out envoy.crt -nodes -batch -days 365 -addext 'subjectAltName=IP:'
    Before proceeding to the next step, ensure that both envoy.crt and envoy.key are readable from inside the container (usually a chmod o+r envoy.* is enough).

  4. Generate encryption key for c13n database

    This should be avoided in production. Encryption keys should not be stored in the same host with the encrypted database

    cd c13n/conf
    tr -dc 'a-zA-Z0-9' < /dev/urandom | dd bs=1 count=32 of=store.key

  5. Configure stack elements Configuration for each stack element is located in the following paths:

    • lnd: lnd/conf/lnd.conf
    • c13n: c13n/conf/config.yml
    • envoy: envoy/conf/envoy.yml
  6. Start the stack The stack is now ready to be initialized.

    docker-compose --profile arc --profile c13n-go --profile lnd --profile envoy up

  7. Create the lnd wallet Even though the stack is initialized, a lightning wallet should first be created before c13n can connect with the lnd node.

    docker-compose exec lnd bash
    # lncli --network testnet create

  8. Unlock lnd wallet

    docker-compose exec lnd bash
    # lncli --network testnet unlock

  9. Access stack elements

    • c13n RPC service:
    • arc:
    • lnd:
      • RPC:
      • REST:

With this, the c13n development node is up and running, exposing the c13n RPC API.

Custom testbench elements

Testbench elements are pluggable and can be replaced with custom implementations during development and testing. The testbench setup is based on docker-compose, making the usage of custom elements as easy as replacing the image: tag value for each particular image. For example, the following steps enable the usage of a custom c13n-go testbench image:

  1. Build a custom c13n-go image with the desired changes:

    git clone https://github.com/c13n-io/c13n-go.git
    cd c13n
    # Modify c13n
    # ...
    docker build -t test_c13n_go -f docker/c13n/Dockerfile . 

    The last command builds a modified docker image, tagging it as test_c13n_go in the local Docker registry.

  2. Modify the docker-compose definition, Replacing image: ghcr.io/c13n-io/c13n-go:latest with image: test_c13n_go under the c13n service definition.

  3. Start the modified stack:
    docker-compose --profile arc --profile c13n-go --profile lnd --profile envoy up


When directly consuming the RPC API provided by c13n, there is no need for a reverse proxy deployment so the only profiles needed are the following:

docker-compose --profile lnd --profile c13n up

The certificates generated during setup for c13n can then be used to consume RPC with TLS.


By using the --profile envoy, we are placing an Envoy reverse proxy in front of the c13n RPC service. Envoy is needed in order to enable web applications (like arc) to normally communicate with the c13n RPC API.

Spawning the testbench with gRPC-web support is just a matter of executing docker compose as following:

docker-compose --profile envoy --profile c13n --profile lnd up

The gRPC-web root API path is