Satellite

Unlike Skylab, the image junobuild/satellite runs a single Satellite in a sandboxed local environment.

You can configure the behavior of Satellite with a specific configuration file to define Datastore and Storage collections, additional controllers, and optional serverless extensions. Like Skylab, it also supports live reloading for these serverless functions through a shared folder.

The CLI watches configuration files and a dedicated deploy folder, automatically applying changes and upgrading modules as needed.

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Configuration

The behavior of the Satellite running in the Docker container can be configured with the help of a local configuration file commonly named juno.dev.config.ts (or JavaScript or JSON).

This configuration file enables you to define the collections of the Datastore and Storage that run locally, but it also allows for defining additional controllers for your satellite.

The definition is as follows:

export type PermissionText = "public" | "private" | "managed" | "controllers";
export type MemoryText = "heap" | "stable";
export type RulesType = "db" | "storage";

export interface Rule {
  collection: string;
  read: PermissionText;
  write: PermissionText;
  memory: MemoryText;
  createdAt?: bigint;
  updatedAt?: bigint;
  maxSize?: number;
  maxCapacity?: number;
  mutablePermissions: boolean;
  maxTokens?: number;
}

export type SatelliteDevDbCollection = Omit<
  Rule,
  "createdAt" | "updatedAt" | "maxSize"
>;

export type SatelliteDevStorageCollection = Omit<
  Rule,
  "createdAt" | "updatedAt" | "maxCapacity"
>;

export interface SatelliteDevCollections {
  db?: SatelliteDevDbCollection[];
  storage?: SatelliteDevStorageCollection[];
}

export interface SatelliteDevController {
  id: string;
  scope: "write" | "admin";
}

export interface SatelliteDevConfig {
  collections: SatelliteDevCollections;
  controllers?: SatelliteDevController[];
}

export interface JunoDevConfig {
  satellite: SatelliteDevConfig;
}

Example

If, for example, we want to configure a "metadata" collection in the Datastore, a "content" collection in the Storage, and provide an additional controller, we could use the following configuration:

juno.dev.config.json

{
  "satellite": {
    "collections": {
      "db": [
        {
          "collection": "metadata",
          "read": "managed",
          "write": "managed",
          "memory": "stable",
          "mutablePermissions": true
        }
      ],
      "storage": [
        {
          "collection": "content",
          "read": "public",
          "write": "public",
          "memory": "stable",
          "mutablePermissions": true
        }
      ]
    },
    "controllers": [
      {
        "id": "535yc-uxytb-gfk7h-tny7p-vjkoe-i4krp-3qmcl-uqfgr-cpgej-yqtjq-rqe",
        "scope": "admin"
      }
    ]
  }
}

Path and name

The configuration can be placed in a location other than next to the compose file and can be named whatever suits your needs. If you do so, make sure to adapt the compose file accordingly.

docker-compose.yml

services:
  juno-satellite:
    image: junobuild/satellite:latest
    ports:
      - 5987:5987
      - 5999:5999
    volumes:
      - my_dapp:/juno/.juno
      - /your/custom/path/your_config_file.json:/juno/juno.dev.config.json # <-------- Modify location and file name of the left hand part

volumes:
  my_dapp: