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Configuring endpoints for local environments

Loading endpoints used by the applications

The endpoints for the front end and backend applications are located in the shared configuration library, located at libs/config/shared. The endpoints are loaded dynamically depending on the value of the env parameter provided when initializing the Endpoints class.

The loading of the endpoints differs slightly depending on whether the application is running a frontend (browser) or backend (server) application.

Frontend Applications

For front end applications, the default value of the env parameter is read from the @biosimulations/config/shared library, located at libs/shared/environments. This library contains several different environment definitions such as "development", "staging", "production", etc. The environment.ts file loads one of these definitions. The env parameter that is loaded is then fed into the Endpoints class as described above.

To configure which endpoints are loaded, change the name of the file being loaded in the environment.ts file. For example, to load the endpoints for the "local" environment, change the name of the file to environment.local.

import { environmentType } from './environment.type';
// Change the name of the file to environment.type.ts where type is the name of the environment you wish to load
import { environment as currentEnvironment } from './';
export const environment: environmentType = currentEnvironment;

Backend Applications

For back end applications, the developer must provide the value of the env parameter when initializing the Endpoints class. This value is then used to load the appropriate endpoints.

In most cases, the value of the env parameter should be loaded from the the configuration service provided by the @biosimulations/config/nest library located at libs/config/nest. The following is an example of how to load the endpoints for the current environment.

import { Injectable } from '@nestjs/common';
import { Endpoints } from '@biosimulations/config/common';
import { ConfigService } from '@nestjs/config';

export class SomeService {
  private endpoints: Endpoints;

  public constructor(
    private configService: ConfigService,
  ) {
    const env = configService.get('server.env');
    this.endpoints = new Endpoints(env);
Unlike, the front end applications, the backend applications are capable of loading endpoints dynamically. The Endpoints class loads overrides the default endpoints for the current environment by loading environment variables. In order to override a specific endpoint, set the environment variable with the name of the endpoint to the value you wish to use. For example, to override the combine-api endpoint, set the environment variable COMBINE_API_URL to the value you wish to use. A list of the environment variables that can be overridden is located in the EndpointLoader class of the @biosimulations/config/shared library.

External Endpoints

Due to the distributed architecture of the application, various endpoints may not be accessible from different locations. For example, if a developer is developing their application locally, they may set the API_URL environment to http://localhost:3333 to allow the locally running dispatch-service to post data to their locally running API. However, the HPC cluster would not be able to download the simulation project to execute from a localhost address, since this is not accessible from the HPC cluster.

For this reason, the Endpoints class provides an external variant of each endpoint. This is the endpoint that should be used when urls are being shared outside of the 'current local' environment. The application developers must be sure to load these endpoints from the Endpoint class at the appropriate points in the code. These endpoints can be overridden the same way as the default endpoints, but adding the EXTERNAL prefix. For example, to to address the above issue, the user would set the EXTERNAL_API_URL environment variable to an address that is accessible from the HPC cluster, such as, or a url provided by an tunneling service such as localtunnel.


Make sure you understand the security implications of exposing locally running applications on your machine to the world via public urls. In particular, make sure that these URLs are not accidentally committed to the repository.

Last update: 2022-05-18
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