central-ledger

The central ledger is a series of services that facilitate clearing and settlement of transfers between DFSPs, including the following functions:

Brokering real-time messaging for funds clearing
Maintaining net positions for a deferred net settlement
Propagating scheme-level and off-transfer fees

The following documentation represents the services, APIs and endpoints responsible for various ledger functions.

central-ledger

Running Locally

Please follow the instruction in Onboarding Document to setup and run the service locally.

Configuration

Environment variables

The Central Ledger has many options that can be configured through environment variables.

Environment variable	Description	Example values
CLEDG_DATABASE_URI	The connection string for the database the central ledger will use. Postgres is currently the only supported database.	postgres://<username>:<password>@localhost:5432/central_ledger
CLEDG_PORT	The port the API server will run on.	3000
CLEDG_ADMIN_PORT	The port the Admin server will run on.	3001
CLEDG_HOSTNAME	The URI that will be used to create and validate links to resources on the central ledger.	http://central-ledger
CLEDG_ENABLE_BASIC_AUTH	Flag to enable basic auth protection on endpoints that require authorization. Username and password would be the account name and password.	false
CLEDG_ENABLE_TOKEN_AUTH	Flag to enable token protection on endpoints that require authorization. To create a token, reference the API documentation.	false
CLEDG_LEDGER_ACCOUNT_NAME	Name of the account setup to receive fees owed to the central ledger. If the account doesn't exist, it will be created on start up.	LedgerName
CLEDG_LEDGER_ACCOUNT_PASSWORD	Password of the account setup to receive fees owed to the central ledger.	LedgerPassword
CLEDG_ADMIN_KEY	Key used for admin access to endpoints that require validation.	AdminKey
CLEDG_ADMIN_SECRET	Secret used for admin access to endpoints that require validation. Secret also used to sign JWTs used for Admin API.	AdminSecret
CLEDG_TOKEN_EXPIRATION	Time in milliseconds for Admin API tokens to expire.	3600000
CLEDG_EXPIRES_TIMEOUT	Time in milliseconds to determine how often transfer expiration process runs.	5000
CLEDG_AMOUNT__PRECISION	Numeric value used to determine precision recorded for transfer amounts on this ledger.	10
CLEDG_AMOUNT__SCALE	Numeric value used to determine scale recorded for transfer amounts on this ledger.	2

API

For endpoint documentation, see the API documentation.

For help preparing and executing transfers, see the Transfer Guide

Logging

Logs are sent to standard output by default.

Tests

Tests include unit, functional, and integration.

Running the tests:

    npm run test:all

Tests include code coverage via istanbul. See the test/ folder for testing scripts.

Running Integration Tests interactively

If you want to run integration tests in a repetitive manner, you can startup the test containers using docker-compose via one of the following methods:

Running locally

Start containers required for Integration Tests
```
docker-compose -f docker-compose.yml up -d kafka mysql
```
Run wait script which will report once all required containers are up and running
```
npm run wait-4-docker
```
Run the Integration Tests
```
npm run test:int
```
Running inside docker

Start containers required for Integration Tests, including a central-ledger container which will be used as a proxy shell.
```
docker-compose -f docker-compose.yml -f docker-compose.integration.yml up -d kafka mysql central-ledger
```
Run the Integration Tests from the central-ledger container
```
docker exec -it cl_central-ledger sh
export CL_DATABASE_HOST=mysql
npm run test:int
```

Auditing Dependencies

We use npm-audit-resolver along with npm audit to check dependencies for node vulnerabilities, and keep track of resolved dependencies with an audit-resolve.json file.

To start a new resolution process, run:

npm run audit:resolve

You can then check to see if the CI will pass based on the current dependencies with:

npm run audit:check

And commit the changed audit-resolve.json to ensure that CircleCI will build correctly.

Container Scans

As part of our CI/CD process, we use anchore-cli to scan our built docker container for vulnerabilities upon release.

If you find your release builds are failing, refer to the container scanning in our shared Mojaloop CI config repo. There is a good chance you simply need to update the mojaloop-policy-generator.js file and re-run the circleci workflow.

For more information on anchore and anchore-cli, refer to:

Automated Releases

As part of our CI/CD process, we use a combination of CircleCI, standard-version npm package and github-release CircleCI orb to automatically trigger our releases and image builds. This process essentially mimics a manual tag and release.

On a merge to master, CircleCI is configured to use the mojaloopci github account to push the latest generated CHANGELOG and package version number.

Once those changes are pushed, CircleCI will pull the updated master, tag and push a release triggering another subsequent build that also publishes a docker image.

Potential problems

There is a case where the merge to master workflow will resolve successfully, triggering a release. Then that tagged release workflow subsequently failing due to the image scan, audit check, vulnerability check or other "live" checks.

This will leave master without an associated published build. Fixes that require a new merge will essentially cause a skip in version number or require a clean up of the master branch to the commit before the CHANGELOG and bump.

This may be resolved by relying solely on the previous checks of the merge to master workflow to assume that our tagged release is of sound quality. We are still mulling over this solution since catching bugs/vulnerabilities/etc earlier is a boon.
It is unknown if a race condition might occur with multiple merges with master in quick succession, but this is a suspected edge case.

kleyow/central-ledger