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The app.json File

For Portal to recognize your app, you have to provide an app.json file containing some metadata and instructions on how to run your app.

The app.json contains all metadata about your app. It tells the Portal what to run by defining a docker image and how to run it. And it contains information that is important to display in the app store, like the official name and a description.

Full Example

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{
  "v": "2.0",
  "name": "myapp",
  "image": "myapp:1.2.3",
  "port": 8080,
  "data_dirs": [
    "/user_data",
    {
      "path": "/more_data",
      "uid": 1000,
      "gid": 1000
    }
  ],
  "services": ["postgres"],
  "env_vars": {
    "DATABASE_URL": "{{ postgres.connection_string }}",
    "DEBUG": "true"
  },
  "paths": {
    "": {
      "access": "private",
      "headers": {
        "X-Ptl-Client-Id": "{{ client_id }}",
        "X-Ptl-Client-Name": "{{ client_name }}",
        "X-Ptl-Client-Type": "{{ client_type }}",
        "X-Ptl-Foo": "bar"
      }
    },
    "/public/": {
      "access": "public",
      "headers": {
        "X-Ptl-Client-Type": "{{ client_type }}",
        "X-Ptl-Foo": "baz"
      }
    }
  },
  "lifecycle": {
    "always_on": false,
    "idle_time_for_shutdown": 60
  },
  "store_info": {
    "description_short": "A great app",
    "description_long": [
      "A really great app that serves as an example.",
      "It also has a description that is two paragraphs long."
    ],
    "hint": [
      "This app is not really part of the app store",
      "In fact, this app does not really exist"
    ],
    "is_featured": true
  }
}

Description of Fields

field description
v The version of the app.json format. Should be "1.0".
name Your app's name as seen in the app store, on the Portal home screen, and in the URL
image The docker image reference of your app; this is what you usually use with docker run
port The port at which your app publishes its GUI or API; this port will be forwarded to the user's browser
data_dirs (optional) A list of directories inside your image; Portal will create matching directories inside its file system and mount those into them; see Persisting Data for details
services (optional) A list of built-in services that your app uses; Portal will prepare them for you and provide access information in the form of template variables; see Portal's Internal Services for details
env_vars (optional) A dictionary of environment variables that are set for your app
paths An object which you can use to define access control rules for your app by defining how each URL path should be handled; for more details see Routing and Access Control
lifecycle An object which defines if and when your app is automatically shut down in order to conserve resources.
store_info (optional) Information that is read by the app store and displayed there.

Templating for environment variables

You can include variables in the values of the env_vars section that are substituted during install time. They help you include values that are specific to each individual Portal. Use Jinja-like double curly brackets for this.

Example

With this snippet, you can tell your app the actual full domain at which it is published.

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"env_vars": {
  "url": "https://myapp.{{ portal.domain }}/"
}

Variables

variable description example
portal.domain The fully qualified domain name of the Portal 8271dd.p.getportal.org
portal.id The full-length hash-ID of the Portal 8271ddlqxa5fcp7a5l0s61pbqqtglba31d65jg2fqhdwdw2kkr7l94b2q54hfdl2zfn5s5g1nkjy1z1a3f02tl8yln14050l8s598f2

More variables are provided by Portal's built-in services if your app defines them as dependencies. See Portal's Internal Services for details.

Versioning

Since the format of the app.json evolves over time, it is important to include the version of the format in which it is written. It is contained in the v attribute. The current version is 2.0.

When new versions are released, we will attempt to make them backwards compatible. That means that Portal still can process the previous version and translate it to the current one.

Past Updates

version 3.0 to version 3.1

  • Added the lifecycle section.

version 2.0 to version 3.0

  • Changed the way, variables of internal services are addressed by env_vars templates. Example before: {{ apps[\"myapp\"].postgres.connection_string }} vs. example after: {{ postgres.connection_string }}.

version 1.0 to version 2.0

  • Removed the description field and instead added the store_info section.

version 0.0 to version 1.0

  • Removed the authentication section and instead added the paths section.
  • Added the v attribute to indication the schema version - an app.json without v is assumed to be version 0.0.
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