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 administrative access keys, 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 - i.e. administrative access keys - 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"
      }
    ]
  }
}

More Options

For more advanced options like customizing ports, image name, or CI setup, see the Emulator Configuration section.