Registering an LTI Tool

In order to enable an Administrator to install an application in Canvas, a tool can support the automated registration process, built on the Dynamic Registration specification mentioned here. This replaces the manual configuration process previously used to install applications to Canvas.

Overview

The automated registration process allows tools to install themselves into Canvas automatically without requiring an Administrator to manually enter configuration values. Tools provide a Canvas administrator with a pre-determined URL, which the user enters into Canvas. Canvas will direct the user to that URL, where the tool can request Canvas' OpenID configuration and provide the user with an installation UI, where they can choose tool-specific settings. The tool then installs itself using a registration token to access the registration REST JSON service. After installing, the user is returned to Canvas to confirm the installation and enable the tool.

Initiation Request

The first part of the registration process is the registration initiation request. When an administrator enters the tool's dynamic registration URL, Canvas redirects the user with a GET request by embedding an iframe pointed to that URL with two parameters added, openid_configuration, and registration_token. The openid_configuration parameter contains the URL that the tool can use to retrieve Canvas' OpenID Configuration, and the registration_token parameter is the token used to access that URL.

At the registration initiation url, the tool should show a UI that guides the user through setting up a registration. This can include deployment-specific options for the tool. The tool can also guard this UI with a login, access code, or some other form of authentication, since the dynamic registration URL is meant to be shared publicly.

Canvas OpenID Configuration

During registration, the tool can request Canvas' OpenID configuration by sending a GET request to the url included in the openid_configuration redirect url. The tool also needs to include the registration_token in the GET request, as the bearer token in the Authorization http header:

curl -v https://canvas.instructure.com/api/lti/security/openid-configuration \
  -H "Accept: application/json" \
  -H "Authorization: Bearer {registration_token}"

Canvas' Open ID configuration contains details about itself that the tool can use to make decisions. It contains claims supported, message types, placements, variables, and information about the account the administrator is installing the tool into.

A example response looks like:

{
  "issuer": "http://canvas.instructure.com",
  "authorization_endpoint": "http://canvas.instructure.com/api/lti/authorize_redirect",
  "registration_endpoint": "http://canvas.instructure.com/api/lti/registrations",
  "jwks_uri": "http://canvas.instructure.com/login/oauth2/jwks",
  "token_endpoint": "http://canvas.instructure.com/login/oauth2/token",
  "token_endpoint_auth_methods_supported": ["private_key_jwt"],
  "token_endpoint_auth_signing_alg_values_supported": ["RS256"],
  "scopes_supported": [
    "https://purl.imsglobal.org/spec/lti-ags/scope/lineitem",
    "https://purl.imsglobal.org/spec/lti-ags/scope/lineitem.readonly",
    "https://purl.imsglobal.org/spec/lti-ags/scope/result.readonly",
    "https://purl.imsglobal.org/spec/lti-ags/scope/score",
    "https://purl.imsglobal.org/spec/lti-nrps/scope/contextmembership.readonly",
    "https://canvas.instructure.com/lti/public_jwk/scope/update",
    "https://canvas.instructure.com/lti/account_lookup/scope/show",
    "https://canvas.instructure.com/lti-ags/progress/scope/show"
  ],
  "response_types_supported": ["id_token"],
  "id_token_signing_alg_values_supported": ["RS256"],
  "claims_supported": [
    "sub",
    // ... more here
    "locale"
  ],
  "subject_types_supported": ["public"],
  "authorization_server": "canvas.instructure.com",
  "https://purl.imsglobal.org/spec/lti-platform-configuration": {
    "product_family_code": "canvas",
    "version": "vCloud",
    "messages_supported": [
      {
        "type": "LtiResourceLinkRequest",
        "placements": [
          "account_navigation",
          // ... more here
          "wiki_page_menu"
        ]
      },
      {
        "type": "LtiDeepLinkingRequest",
        "placements": [
          "assignment_selection",
          // ... more here
          "submission_type_selection"
        ]
      }
    ],
    "notice_types_supported": [
      "LtiHelloWorldNotice"
      // ... more here
    ],
    "variables": [
      "ResourceLink.id",
      // ... more here
      "Canvas.environment.test"
    ],
    "https://canvas.instructure.com/lti/account_name": "Test University",
    "https://canvas.instructure.com/lti/account_lti_guid": "pNu5F9EoIATW6XqZ33C5tiqomb7bFJ4IGWFoCFy6:canvas-lms"
  }
}

Registration Creation

Canvas includes a URL in the OpenID configuration under the registration_endpoint key which can be used by the tool to create a registration. The tool must send a POST request to this endpoint with the tool's LTI Registration in the body and the registration_token as the bearer token in the Authorization http header.

An example request looks like:

curl \
  --header "Content-Type: application/json" \
  --request POST \
  --data '<lti_registration_body>' \
  http://canvas.instructure.com/api/lti/registrations

LTI Registration schema

LTI Tool Configuration schema

LTI Message schema

example LTI Registration body:

{
  "application_type": "web",
  "client_name": "Lti Tool",
  "client_uri": "http://tool.com",
  "grant_types": ["client_credentials", "implicit"],
  "jwks_uri": "http://tool.com/jwks",
  "initiate_login_uri": "http://tool.com/login",
  "redirect_uris": ["http://tool.com/launch"],
  "response_types": ["id_token"],
  "scope": "https://purl.imsglobal.org/spec/lti-nrps/scope/contextmembership.readonly https://purl.imsglobal.org/spec/lti-ags/scope/lineitem.readonly",
  "token_endpoint_auth_method": "private_key_jwt",
  "logo_uri": "http://tool.com/icon.svg",
  "https://purl.imsglobal.org/spec/lti-tool-configuration": {
    "claims": [
      "sub",
      "iss",
      "name",
      "given_name",
      "family_name",
      "nickname",
      "picture",
      "email",
      "locale"
    ],
    "custom_parameters": {},
    "domain": "tool.com",
    "messages": [
      {
        "type": "LtiResourceLinkRequest",
        "icon_uri": "http://tool.com/icon.svg",
        "label": "Lti Tool",
        "custom_parameters": {
          "foo": "bar",
          "context_id": "$Context.id"
        },
        "placements": ["course_navigation"],
        "roles": [],
        "target_link_uri": "http://tool.com/launch?placement=course_navigation"
      }
    ],
    "target_link_uri": "http://tool.com/launch",
    "https://canvas.instructure.com/lti/tool_id": "toolid-123",
    "https://canvas.instructure.com/lti/privacy_level": "public"
  }
}

Registration Response

Upon successful creation, the registration endpoint will respond with the created registration, along with an additional field, client_id:

{
  "application_type": "web",
  "client_name": "Lti Tool",
  ...
  "client_id": "10000000000001"
}

The tool will use this client_id when requesting tokens and accessing LTI Services.

Returning the Administrator to Canvas

After the registration is created successfully, the tool should return the user to Canvas by sending a post message to the parent Canvas window:

window.parent.postMessage({subject: 'org.imsglobal.lti.close'}, '*')

Canvas will listen for this message and close the iframe, presenting the user with a summary of the registration the tool returned. The administrator will then be able to make some modifications to the registration. It's important to note that these modifications may alter how the tool is finally configured and launched. For example, the tool may request a certain number of scopes, but the administrator could restrict access to certain scopes. The tool should detect this and warn the user if modifications need to be made to the configuration.