daml/ledger/ledger-on-memory

Overview

This document is to help internal engineers work with ledger-on-memory.

ledger-on-memory is a key/value-based ledger that uses a simple in-memory map as an underlying storage. It uses either H2 or PostgreSQL as its index database.

Ledger On Memory

To build a fat JAR with the server built from HEAD run

bazel build //ledger/ledger-on-memory:app_deploy.jar

The application can be run from command line with the following command:

java -Xmx4G -XX:+UseG1GC -jar bazel-bin/ledger/ledger-on-memory/app_deploy.jar --participant participant-id=foo,port=6861

As run from the main project root directory (adjust the location of the JAR according to your working directory).

Alternatively, the application can be run using the Bazel command:

bazel run //ledger/ledger-on-memory:app -- --participant participant-id=foo,port=6861

Docker

Ledger On Memory can be put into a Docker container by first building it:

bazel build ledger/ledger-on-memory:app-image

Then by running the Bazel target that imports the image into your local Docker repository, and then runs a container from that image.

bazel run ledger/ledger-on-memory:app-image

The container will fail to run, but the image has now been loaded into your local Docker repository under the name bazel/ledger/ledger-on-memory.

It can then be run using Docker:

docker run \
    -it \
    --rm \
    --name ledger \
    --network docker_default \
    -p 6861:6865 \
    bazel/ledger/ledger-on-memory:app-image \
        --participant participant-id=foo,port=6865,address=0.0.0.0

The above command makes the ledger available to clients from the host machine at the address localhost:6861. It is also available to other docker containers on the docker_default network under ledger:6865.

Creating ledger exports

Ledger On Memory can be used to generate ledger exports through an environment variable:

export KVUTILS_LEDGER_EXPORT=/path/to/export/file

Then launch the ledger using the Bazel or Java command as described above.

In case the ledger is run from within the Docker container, use following syntax:

export KVUTILS_LEDGER_EXPORT=/path/to/export/directory"
docker run \
        -it \
        --rm \
        --name ledger \
        --network docker_default \
        -p 6861:6865 \
        -v ${KVUTILS_LEDGER_EXPORT}:/export \
        -e KVUTILS_LEDGER_EXPORT=/export/my-ledger.export \
        bazel/ledger/ledger-on-memory:app-image \
            --participant participant-id=foo,port=6865,address=0.0.0.0