config-lib

README

SDS Configuration

This module provides packages to configure the service in the dev context.

The SDS framework doesn't provide a configuration for the entire application. For decentralization, there is no shared data by all services. That includes the configurations as well.

The SDS services created with service-lib, can access the command line arguments only.

Everything else must be retrieved from the configuration. Including the environment variables too.

The configuration is the key-value database. This database is running on a separated thread. As such, it's wrapped by the handler.

The handler code is defined in the handler package.

To access the configuration, other threads must use a client. The client code is defined in the client package.

The configuration data could be grouped into two categories. The first group is custom data. The second group is the service configuration itself.

todo

In the API reference group the routes by custom data and service meta

Custom Data

In the development context, there is only one way to set the custom parameters. Only by providing an environment variables or .env files.

For example, PRIVATE_KEY=0xdead environment variable will be available by PRIVATE_KEY key.

It's possible to pass the group of the environment variables as the .env files. The .env in the same directory as the binary is loaded automatically. Other .env file paths are passed as the command line arguments.

Example of passing environment files

/bin/sds-app --flag --flag2=value ./dev.env ./env_file "C:/Program Files/shared/app"

Engine

To turn the environment variables into the configuration parameters, this module uses spf13/viper. It's defined in the engine package.

Contributing

To include the configuration from .ini, .toml or .json edit the engine.

Service meta

The configuration is also responsible for generation, storage of the service parameters. The service parameters include the meta parameters such as a list of the handlers and their exposed port.

The services in the distributed systems must know the other services as well. In SDS Framework, the services know nearby services only.

Nearby services are the extensions and proxies.

The following diagram shows the configuration:

The green box is a service with the proxies and extensions. The white rectangular is the part stored in the configuration for the service

Proxy relationship

If there is a proxy chain, then the service knows the information about the last proxy. All front proxies are unknown for the service.

Extension relationship

If there is an extension, then the service has access to the front of the extension. Extension maybe behind the proxies. In this case, the service has access to the first proxy. Everything after the proxy is unknown.

Yaml

The service meta is defined in the service package.

In the developer context, the meta is stored as the yaml files. The yaml file operations are stored in the app package.