FirecREST in a nutshell

FirecREST is a web-enabled application programming interface (API) to High-Performance Computing (HPC) resources under development at CSCS.

Scientific platform developers can integrate the Firecrest API into their web-enabled portals and applications, allowing them to securely access authenticated and authorized CSCS services such as job submission, data mover and transfer on HPC systems.

FirecREST architecture

The core components and microservices that are part of FirecREST are the following:


The API gateway provides an interface to publish, maintain, monitor, and secure all the FirecREST API endpoints. The gateway is hosted on a machine within CSCS that is facing the internet. All interactions with the FirecREST API are first passed and validated before being redirected to any other FirecREST microservice. In this way, every request made to the FirecREST API arrives first at the gateway, which will proxy the request towards the requested microservice endpoint. However, before the request is passed on to the microservice, the gateway will enforce that the request is correctly authenticated and authorized by requiring and validating the Access Token that must accompany each API request. The current implementation of the gateway service is based on the Kong API gateway. Kong is a widely used opensource microservice API gateway that implements functionalities such as a variety of authentication and authorization mechanisms, support for OIDC, IP filtering, access control lists, analytics, rate limiting, among many others that have allowed us to configure the gateway to our requirements.

Status microservice

Checks systems and services availability. The Status microservice provides information of infrastructure and services.

Compute microservice

The compute microservice implements the interface to the workload manager, thus allowing applications to submit, stop, and query the status of jobs by using non-blocking asynchronous API calls. This service depends on: the tasks microservice that provides a temporal resource that tracks the state of each call; and, the delegation microservice that issues a restricted SHH certificate that allows the execution of operations on behalf of the user.

Storage microservice

This microservice enable users the upload and downloadof large files to/from CSCS, while also enabling the movement of data within the different filesystems available on the system . It does so by using non-blocking calls to high-performance storage services while immediately responding with a reference to a resource that tracks the state of the request.

Tasks microservice

The task microservice responds to the need of managing the state of request that are being resolved asynchronously. One clear example for the need of this microservice can be observed in the asynchronous data transfer operations handled by the storage microservice, as otherwise some of those workflows would not be possible. As such, FirecREST microservices during an asynchronous request can rapidly create and respond with a new task resource. The operational result of the request is then tracked as the originating microservice continuously updates the task as progress is being made. Thus, task resources allow a client to perform other activities while a FirecREST asynchronous tasks are completed.

Utilities microservice

The utilities microservice provides synchronous execution of some basic linux commands. As calls to the utilities microservice are blocking operations, these have a timeoutand are not recursive.

Delegation microservice

The delegation microservice is a FirecREST internal service that is not exposed to the user. This service takes avalid JWT access token as input and creates a short-lived SSH certificate to be used to user authentication.


The Identity and Access Management (IAM) infrastructure at CSCS ensures that users and web applications have the appropriate permissions to access resources at CSCS by using a secure protocol. From the whole of the IAM infrastructure at CSCS we will only discuss Keycloak, the Identity and Access Management solution deployed at thecenter. Keycloak allows to secure application and services by providing a mechanism for the authentication and authorization of CSCS users, CSCS services, and third party applications.

Among the many features of Keycloak we highlight the following:

  • single sign-on solution
  • integration with Kerberos authentication service
  • fine-grained authorization controls for services
  • client registration and authorization
  • support of OpenID Connect (OIDC) protocol

The integration of FirecREST with Keycloak has been achieved through the use of the OIDC protocol. OIDCis an authentication protocol that extends the OAuth 2.0 specification. OAuth 2.0 is an industry-standard protocol for token-based authorization that is commonly used as a mechanism for users to grant access permission to web application in order to access user-owned resources and services. The extensions provided by OIDC to the OAuth2.0 protocol add a user authentication layer, providing a mechanism that enables single sign-on to users. FirecREST leverages on Keycloak and OIDC for authentication and authorization of web applications, enabling the following capabilities:

  • enforce that all requests are authenticated
  • applications never manipulate user credentials
  • only allow requests from registered applications
  • user-managed access permissions per application
  • stateless security model by use of tokens
  • short lifespan for sensitive access tokens
  • extended client sessions allowed through refresh tokens

In a nutshell, FirecREST OIDC-based IAM enables theuser to login to a registered web application using their CSCS credentials and grant a web application with access to user-owned resource at the Center. Moreover, it does so without the user ever sharing their credentials with the web application.