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Zebra with Docker

The foundation maintains a Docker infrastructure for deploying and testing Zebra.

Quick Start

To get Zebra quickly up and running, you can use an off-the-rack image from Docker Hub:

docker run --name zebra zfnd/zebra

If you want to preserve Zebra's state, you can create a Docker volume:

docker volume create zebrad-cache

And mount it before you start the container:

docker run \
  --mount source=zebrad-cache,target=/home/zebra/.cache/zebra \
  --name zebra \
  zfnd/zebra

You can also use docker compose, which we recommend. First get the repo:

git clone --depth 1 --branch v2.3.0 https://github.com/ZcashFoundation/zebra.git
cd zebra

Then run:

docker compose -f docker/docker-compose.yml up

Custom Images

If you want to use your own images with, for example, some opt-in compilation features enabled, add the desired features to the FEATURES variable in the docker/.env file and build the image:

docker build \
  --file docker/Dockerfile \
  --env-file docker/.env \
  --target runtime \
  --tag zebra:local \
  .

Alternatives

See Building Zebra for more information.

Building with Custom Features

Zebra supports various features that can be enabled during build time using the FEATURES build argument:

For example, if we'd like to enable metrics on the image, we'd build it using the following build-arg:

[!IMPORTANT] To fully use and display the metrics, you'll need to run a Prometheus and Grafana server, and configure it to scrape and visualize the metrics endpoint. This is explained in more detailed in the Metrics section of the User Guide.

# Build with specific features
docker build -f ./docker/Dockerfile --target runtime \
    --build-arg FEATURES="default-release-binaries prometheus" \
    --tag zebra:metrics .

All available Cargo features are listed at https://docs.rs/zebrad/latest/zebrad/index.html#zebra-feature-flags.

Configuring Zebra

To configure Zebra using Docker, you have a few options, processed in this order:

  1. Provide a specific config file path: Set the ZEBRA_CONF_PATH environment variable to point to your config file within the container.
  2. Use the default config file: By default, the docker-compose.yml file mounts ./default-zebra-config.toml to /home/zebra/.config/zebrad.toml using the configs: mapping. Zebra will use this file if ZEBRA_CONF_PATH is not set. To use environment variables instead, you must comment out the configs: mapping in docker/docker-compose.yml.
  3. Generate config from environment variables: If neither of the above methods provides a config file (i.e., ZEBRA_CONF_PATH is unset and the configs: mapping in docker-compose.yml is commented out), the container's entrypoint script will automatically generate a default configuration file at /home/zebra/.config/zebrad.toml. This generated file uses specific environment variables (like NETWORK, ZEBRA_RPC_PORT, ENABLE_COOKIE_AUTH, MINER_ADDRESS, etc.) to define the settings. Using the docker/.env file is the primary way to set these variables for this auto-generation mode.

You can see if your config works as intended by looking at Zebra's logs.

Note that if you provide a configuration file using methods 1 or 2, environment variables from docker/.env will not override the settings within that file. The environment variables are primarily used for the auto-generation scenario (method 3).

RPC

Zebra's RPC server is disabled by default. To enable it, you need to define the RPC settings in Zebra's configuration. You can achieve this using one of the configuration methods described above:

  • Using a config file (methods 1 or 2): Add or uncomment the [rpc] section in your zebrad.toml file (like the one provided in docker/default-zebra-config.toml). Ensure you set the listen_addr (e.g., "0.0.0.0:8232" for Mainnet).
  • Using environment variables (method 3): Set the ZEBRA_RPC_PORT environment variable (e.g., in docker/.env). This tells the entrypoint script to include an enabled [rpc] section listening on 0.0.0.0:<ZEBRA_RPC_PORT> in the auto-generated configuration file.

Cookie Authentication:

By default, Zebra uses cookie-based authentication for RPC requests (enable_cookie_auth = true). When enabled, Zebra generates a unique, random cookie file required for client authentication.

  • Cookie Location: The entrypoint script configures Zebra to store this file at /home/zebra/.cache/zebra/.cookie inside the container.

  • Viewing the Cookie: If the container is running and RPC is enabled with authentication, you can view the cookie content using:

    docker exec <container_name> cat /home/zebra/.cache/zebra/.cookie

    (Replace <container_name> with your container's name, typically zebra if using the default docker-compose.yml). Your RPC client will need this value.

  • Disabling Authentication: If you need to disable cookie authentication (e.g., for compatibility with tools like lightwalletd):

    • If using a config file (methods 1 or 2), set enable_cookie_auth = false within the [rpc] section:

      [rpc]
# listen_addr = ...
enable_cookie_auth = false

    • If using environment variables for auto-generation (method 3), set ENABLE_COOKIE_AUTH=false in your docker/.env file.

Remember that Zebra only generates the cookie file if the RPC server is enabled and enable_cookie_auth is set to true (or omitted, as true is the default).

Examples

To make the initial setup of Zebra with other services easier, we provide some example files for docker compose. The following subsections will walk you through those examples.

Running Zebra with Lightwalletd

The following command will run Zebra with Lightwalletd:

docker compose -f docker/docker-compose.lwd.yml up

Note that Docker will run Zebra with the RPC server enabled and the cookie authentication mechanism disabled since Lightwalletd doesn't support it. Instead of configuring Zebra via the recommended config file or docker/.env file, we configured the RPC server by setting environment variables directly in the docker/docker-compose.lwd.yml file. This takes advantage of the entrypoint script's auto-generation feature (method 3 described above).

Running Zebra with Prometheus and Grafana

The following commands will run Zebra with Prometheus and Grafana:

docker compose -f docker/docker-compose.grafana.yml build --no-cache
docker compose -f docker/docker-compose.grafana.yml up

In this example, we build a local Zebra image with the prometheus Cargo compilation feature. Note that we enable this feature by specifying its name in the build arguments. Having this Cargo feature specified at build time makes cargo compile Zebra with the metrics support for Prometheus enabled. Note that we also specify this feature as an environment variable at run time. Having this feature specified at run time makes Docker's entrypoint script configure Zebra to open a scraping endpoint on localhost:9999 for Prometheus.

Once all services are up, the Grafana web UI should be available at localhost:3000, the Prometheus web UI should be at localhost:9090, and Zebra's scraping page should be at localhost:9999. The default login and password for Grafana are both admin. To make Grafana use Prometheus, you need to add Prometheus as a data source with the URL http://localhost:9090 in Grafana's UI. You can then import various Grafana dashboards from the grafana directory in the Zebra repo.

Running CI Tests Locally

To run CI tests locally, first set the variables in the test.env file to configure the tests, then run:

docker-compose -f docker/docker-compose.test.yml up