nextline-graphql

The plugin-based framework of the Nextline backend API server

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Table of Contents

• Introduction
• Citation
• Packages
  • Backend API server (Python)
    • Core package
    • Plugin system
    • Plugins
    • Utility
  • Frontend web app (TypeScript)
• How to run the Nextline backend API server
  • As a Docker container
  • In a virtual environment
• Configuration
  • CORS
  • Logging
• Check out code for development

Introduction

Nextline is a DAQ sequencer of the Observatory Control System (OCS). Nextline allows line-by-line execution of concurrent Python scripts, which control telescopes, by multiple users simultaneously from web browsers.

Nextline consists of multiple packages. This package, nextline-graphql, provides the framework for the backend API server. It is a plugin-based framework. Features are added by plugins.

Citation

Please use the following DOI for the core package to cite Nextline in general unless you need to refer to a specific package.

Packages

Package	Release	Build	Coverage
nextline
apluggy
nextline-graphql
nextline-rdb
nextline-schedule
nextline-alert
nextline-test-utils
nextline-web

Backend API server (Python)

Core package

• nextline: The core functionality of Nextline. It controls the execution of the Python scripts. It is used by the plugin ctrl.

Plugin system

The plugin system of nextline-graphql is apluggy.

• apluggy: A wrapper of pluggy to support asyncio and context managers.

Plugins

Internal plugins

These plugins are included in this package.

• graphql: The entry point of the GraphQL API, implemented with strawberry-graphql.
• ctrl: The core plugin that controls the execution of the Python scripts. It uses the package nextline.

External plugins

These plugins are not included in this package. They can be installed separately.

• nextline-rdb: A relational database for nextline. It stores configuration, execution history, and other information. It is implemented with SQLAlchemy 2.
• nextline-schedule: The auto mode. The queue system. An interface to the SO scheduler.
• nextline-alert: An interface to the alert system campana.

Utility

• nextline-test-utils: A collection of test utilities for backend development

Frontend web app (TypeScript)

The frontend web app is currently in a single package. The development of a plugin-based system is planned.

• nextline-web: The frontend web app of Nextline. It is a Vue.js app.

How to run the Nextline backend API server

The section shows how to run the Nextline backend API server. How to run the frontend web app is described elsewhere.

As a Docker container

Docker images of the Nextline backend API server are created as ghcr.io/simonsobs/nextline-graphql. These images are created by the Dockerfile. No external plugins are included in the images.

Use, for example, the following command to run as a Docker container.

docker run -p 8080:8000 ghcr.io/simonsobs/nextline-graphql

If you access to the API server with a web browser, you will see the GraphQL IDE: http://localhost:8080/.

To include external plugins, you can create a new Docker image with ghcr.io/simonsobs/nextline-graphql as the base image. For example, nextline-rdb shows how to create a new Docker image with nextline-rdb as an external plugin.

In a virtual environment

You can create a virtual environment, install packages, and run the API server as follows.

python -m venv venv
source venv/bin/activate
pip install nextline-graphql
pip install uvicorn
uvicorn --lifespan on --factory --port 8080 nextlinegraphql:create_app

Check with a web browser at http://localhost:8080/.

If you check out external plugins, nextline-graphql automatically detects them as plugins. An example can be described in nextline-rdb.

Configuration

nextline-graphql uses dynaconf for configuration management. nextline-graphql itself has configuration for CORS and logging. External plugins can extend the configuration.

CORS

These CORS (Cross-Origin Resource Sharing) settings will be given to allow_origin and allow_headers of Starlette's CORSMiddleware.

Environment variable	Default value	Description
NEXTLINE_CORS__ALLOW_ORIGINS	['*']	A list of allowed origins, e.g., ["http://example.com:8080"]. The default value ("*") allows any origins.
NEXTLINE_CORS__ALLOW_HEADERS	['*']	A list of allowed HTTP request headers. For example, ['remote-user', 'remote-name', 'remote-email'] can be appropriate values if Authelia is used. Some headers such as Content-Type are always allowed (See the Starlette doc). The default value ("*") allows any headers.
NEXTLINE_CORS__ALLOW_CREDENTIALS	false	Whether to support cookies. If true, the wildcard ("*") cannot be used for NEXTLINE_CORS__ALLOW_ORIGINS or NEXTLINE_CORS__ALLOW_HEADERS. They need to be listed explicitly.

Logging

See default.toml.

Check out code for development

This section shows an example way to check out code from GitHub for development.

python -m venv venv
source venv/bin/activate
git clone git@github.com:simonsobs/nextline.git
git clone git@github.com:simonsobs/nextline-graphql.git
pip install -e ./nextline/"[tests,dev]"
pip install -e ./nextline-graphql/"[tests,dev]"

To run

uvicorn --port 8080 --lifespan on --factory --reload --reload-dir nextline-graphql --reload-dir nextline nextlinegraphql:create_app