Manually Configuring LTI Advantage Tools

For versions of LTI previous to LTI 1.3, please refer to the older documentation

For a successful launch to occur, LTI Advantage Tools require configuration on both Canvas and inside the tool:

But first, the importance of each configuration setting can only be understood with a basic understanding of how an LTI launch occurs.

Overview of an LTI Launch

The IMS Security Framework uses an Open ID Connect (OIDC) third-party flow. You'll want to read these specifications in detail, but the following is a Canvas-specific summary:

Step 1: Login Initiation

Canvas initiates a login request to the oidc_initiation_url that is configured on the LTI developer key. This requests contains an issuer identifier (iss) to recognize Canvas is launching the tool. As the issuer, Instructure-hosted Canvas instances all use the following, regardless of the specific account domain(s) that the tool was launched from:

The request also includes a login_hint that is passed in the next step. Last, the request include the target_link_uri that has been configured on the Developer key; this is later used by the tool as a recommended final redirect.

Parameter Description
iss The issuer, as described above.
login_hint Opaque value that must be passed back to Canvas in the next step.
target_link_uri The recommended final redirect for the tool; not required.
client_id The OAuth2 client id, or Developer Key id, for convenience.
deployment_id Unique identifier for the specific deployment of this tool, for convenience.
canvas_region For hosted Canvas, the AWS region (e.g. us-east-1) in which the institution that provided this token resides. For local or open source Canvas, this will have a value of "unknown". This field is safe to ignore. This can be used for tools that are hosted in multiple regions to launch to one url and redirect to the correct region.
canvas_environment For hosted Canvas, the environment (e.g. "production", "beta", or "test") from which the tool is being launched. For local or open source Canvas, this will have a value of "production". This field is safe to ignore. Tools can use this to redirect to beta- or test-specific instances of their tool on launch. This is in place of the LTI 1.1 `environments` tool config option, which is not recognized for 1.3 tools.

Step 1.5: Optional Tool-to-tool Redirect

There are situations where a tool wants to use a region-specific or environment-specific instance of itself to respond to the LTI launch, like keeping traffic within the same region as the instance of Canvas, or using a different domain or even launch URL when launched from beta Canvas vs normal production.

Tools can use the canvas_region or canvas_environment parameters specified above, or even the Canvas URL from the request's referrer, to decide if they want to redirect.

Example of redirecting to a different domain based on region and environment:

Example of redirecting to a different launch URL based on environment:

Tools that wish to utilize this redirect need to make sure that all possible initiation URLs, whether the domains or paths vary, are added to the redirect URIs list on their corresponding Developer Key, so that the auth request in Step 2 succeeds.

Tools that utilize different instances for beta and test must also make sure that they are storing the correct corresponding values for Canvas URLS like the OIDC Auth URL, JWKs URL, and the Issuer/iss, and that they use the beta or test versions of all of those URLs when the tool is launched from beta or test Canvas.

Using the oidc_initiation_urls option described in the JSON tool config can also produce a similar outcome while removing the need for the tool to perform an internal redirect.

Step 2: Authentication Request

To complete authentication, tools are expected to send back an authentication request to an "OIDC Authorization end-point". This can be a GET or POST, however, this request needs to be a redirect in the user’s browser and not made server to server as we need to validate the current user's session data. For cloud-hosted Canvas, regardless of the domain used by the client, the endpoint is always:

The domain for this endpoint used to be https://canvas.instructure.com. The impetus for this change and other exact details are described in this Canvas Community article. Tools wishing to implement the Platform Storage spec are required to use the new domain for this endpoint, and all other tools should update this endpoint in their configuration store as soon as possible. This change will eventually be enforced, but for now is not a breaking change - the old domain will continue to work. Any questions or issues are either addressed in the linked article or can be filed as a standard support/partner support case, referencing the OIDC Auth endpoint change.

Among the required variables the request should include:

Step 3: Authentication Response (LTI Launch)

Canvas will use the client_id to lookup which developer key to use and then check the redirect_uri that was sent in the previous step and ensure that there is a exact-matching redirect_uri on the developer key. Canvas then sends its authentication response to the redirect_uri that the tool provided in Step 2. The request will include an id_token which is a signed JWT containing the LTI payload (user identifiers, course contextual data, custom data, etc.). Tools must validate the request is actually coming from Canvas using Canvas' public JWKs.

Step 4: Resource Display

The tool then validates the state parameter matches the one sent in Step 2 and redirects the User Agent to the target_link_uri that was sent in Step 1 (or some other location of its choice) to display the final resource. This redirect occurs in an iframe unless the tool is configured otherwise.

Launching without Cookies

Safari blocking cookies inside 3rd-party iframes made it necessary to create a workaround for storing the state property between the login and launch requests, to prevent MITM attacks. The newly finalized LTI Platform Storage spec provides a way for tools that are launching in Safari or another situation where cookies can't get set to still store data across requests in a secure fashion. Tools can send window.postMessages to Canvas asking it to store and retrieve arbitrary data, which acts as a cookie-like proxy.

The LTI Platform Storage spec includes an implementation guide which needs to be the primary resource for implementing this, though a brief usage overview is included below.

Support for this API is determined by either:

  1. the presence of the lti_storage_target as an extra body parameter in both the login (Step 1) and launch (Step 3) requests, or
  2. a response postMessage to the lti.capabilities postMessage that contains the lti.get_data and lti.put_data subjects.

If the lti_storage_target parameter is absent, or the tool doesn't receive a response postMessage for lti.capabilities, then the tool should not attempt to use this API and should fall back to cookies to verify the launch state parameter.

When the tool sees either of the above signals that Canvas supports this API, then:

  1. In Step 2, instead of storing the state parameter in a cookie the tool should store it in Canvas's LTI Platform Storage using the lti.put_data postMessage. It's recommended that the key include the value (eg key: "state-1234", value: "1234") to avoid any collisions during multiple launches, and to make recovering the value easy.

  2. In Step 4, instead of comparing the state parameter to the stored value in the cookie, the tool should retrieve it using the lti.get_data postMessage. Since this comparison has to happen in Javascript instead of on the server, the tool should render something, then check these values. If the values don't match, the tool can then log the user out or render an error.

According to the spec, the target origin for these postMessages must be the OIDC Auth domain (e.g. https://sso.canvaslms.com). Since every institution's domain varies, Canvas renders a frame at this domain that will respond to postMessages, and the name of this frame is supplied in the lti_storage_target parameter, provided as a body parameter in both login and launch requests. Tools should send their lti.put_data and lti.get_data postMessages to that frame, but can continue to send all other postMessage types to the parent window.

The LTI Platform Storage spec docs:

Configuring Canvas in the Tool

Tools will need to be aware of some Canvas-specific settings in order to accept a launch from Canvas and use the LTI Advantage Services:

Configuring the Tool in Canvas

With LTI Advantage, Canvas moved to using Developer Keys to store tool configuration information. After a developer key is created and enabled, tools can be deployed to accounts/sub-accounts or courses.

Developer Keys allow tools to set the required parameters to complete the OpenID Connect Launch Flow, leverage LTI Advantage Services, and configure other important settings.

With guidance from the tool developer, developer keys settings can be manually entered by Account Admins. Tools providers can also supply Account Admins with a JSON configuration or configuration URL containing the settings the tool provider has verified to work.

In the manual case, since many of the extensions listed here require more than a few lines of configuration, there is not currently an interface for every extension to be manually configured. Instead, we encourage tool providers to expose a set of URL endpoints that return working configuration options for their tool services.

If providing a URL configuration endpoint is not an option, you can also provide your users with raw JSON that they can paste in for configuration.

Anatomy of a JSON configuration

In this section, an example JSON configuration is shown followed by a table describing the relevance of each field.

NOTE: Certain placement-specific settings may not be described here. Some examples of JSON configuration snippets and placement-specific settings are also found in the placements sub-menu in the left-navigation of this documentation.

{
  "title": "The Best Tool",
  "description": "1.3 Test Tool used for documentation purposes.",
  "oidc_initiation_url": "https://your.oidc_initiation_url",
  "oidc_initiation_urls": {
    "eu-west-1": "https://your.eu-specific1.oidc_initiation_url",
    "eu-central-1": "https://your.eu-specific2.oidc_initiation_url"
  },
  "target_link_uri": "https://your.target_link_uri",
  "scopes": [
    "https://purl.imsglobal.org/spec/lti-ags/scope/lineitem",
    "https://purl.imsglobal.org/spec/lti-ags/scope/result.readonly"
  ],
  "extensions": [
    {
      "domain": "thebesttool.com",
      "tool_id": "the-best-tool",
      "platform": "canvas.instructure.com",
      "privacy_level": "public",
      "settings": {
        "text": "Launch The Best Tool",
        "labels": {
          "en": "Launch The Best Tool",
          "en-AU": "G'day, Launch The Best Tool",
          "es": "Lanzar la mejor herramienta",
          "zh-Hans": "启动最佳工具"
        },
        "icon_url": "https://some.icon.url/tool-level.png",
        "selection_height": 800,
        "selection_width": 800,
        "placements": [
          {
            "text": "User Navigation Placement",
            "icon_url": "https://some.icon.url/my_dashboard.png",
            "placement": "user_navigation",
            "message_type": "LtiResourceLinkRequest",
            "target_link_uri": "https://your.target_link_uri/my_dashboard",
            "canvas_icon_class": "icon-lti",
            "custom_fields": {
              "foo": "$Canvas.user.id"
            }
          },
          {
            "text": "Editor Button Placement",
            "icon_url": "https://some.icon.url/editor_tool.png",
            "placement": "editor_button",
            "message_type": "LtiDeepLinkingRequest",
            "target_link_uri": "https://your.target_link_uri/content_selector",
            "selection_height": 500,
            "selection_width": 500
          },
          {
            "text": "Course Navigation Placement",
            "icon_url": "https://static.thenounproject.com/png/131630-200.png",
            "placement": "course_navigation",
            "message_type": "LtiResourceLinkRequest",
            "target_link_uri": "https://your.target_link_uri/launch?placement=course_navigation",
            "required_permissions": "manage_calendar",
            "selection_height": 500,
            "selection_width": 500
          }
        ]
      }
    }
  ],
  "public_jwk": {
    "kty": "RSA",
    "alg": "RS256",
    "e": "AQAB",
    "kid": "8f796169-0ac4-48a3-a202-fa4f3d814fcd",
    "n": "nZD7QWmIwj-3N_RZ1qJjX6CdibU87y2l02yMay4KunambalP9g0fU9yZLwLX9WYJINcXZDUf6QeZ-SSbblET-h8Q4OvfSQ7iuu0WqcvBGy8M0qoZ7I-NiChw8dyybMJHgpiP_AyxpCQnp3bQ6829kb3fopbb4cAkOilwVRBYPhRLboXma0cwcllJHPLvMp1oGa7Ad8osmmJhXhM9qdFFASg_OCQdPnYVzp8gOFeOGwlXfSFEgt5vgeU25E-ycUOREcnP7BnMUk7wpwYqlE537LWGOV5z_1Dqcqc9LmN-z4HmNV7b23QZW4_mzKIOY4IqjmnUGgLU9ycFj5YGDCts7Q",
    "use": "sig"
  },
  "custom_fields": {
    "bar": "$Canvas.user.sisid"
  }
}

Parameter Type Description
title Required string

The default name of the tool in the app index. This value is also displayed if no "text" field is provided within extension settings or placements.

description Required string

A description of the tool.

oidc_initiation_url Required string

The login initiation url that Canvas should redirect the User Agent to.

oidc_initiation_urls JSON object

Optional region-specific login initiation urls that Canvas should redirect the User Agent to. Each institution's Canvas install lives in a particular AWS region, typically one close to the institution's physical region. If ths AWS region is listed as a key in this object, the URL in the value will override the default `oidc_initiation_url`. As of 2023, the regions used by Canvas are: us-east-1, us-west-2, ca-central-1, eu-west-1, eu-central-1, ap-southeast-1, ap-southeast-2.

target_link_uri Required string

The target_link_uri that Canvas should pass in the to the login initiation endpoint. This allows tools to determine which redirect_uri to pass Canvas in the authorization redirect request and should be verified during the final launch. This can be set at the tool-level, or within the "placements" JSON object for placement-specific target_link_uri's.

scopes string array

The comma separated list of scopes to be allowed when using the client_credentials grant to access LTI services.

Allowed values: "https://purl.imsglobal.org/spec/lti-ags/scope/lineitem", "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://purl.imsglobal.org/spec/lti-ags/scope/lineitem.readonly", "https://canvas.instructure.com/lti/public_jwk/scope/update"

extensions array of JSON objects

The set of Canvas extensions, including placements, that the tool should use.

domain string

The domain Canvas should use to match clicked LTI links against. This is recommended if deep linking is used.

tool_id string

Allows tools to set a unique identifier for the tool.

platform string

The LMS platform that the extensions belong to. This should always be set to "canvas.instructure.com" for cloud-hosted Canvas.

privacy_level Required string

What level of user information to send to the external tool. Setting this to "name_only" will include fields that contain the user's name and sourcedid in the launch claims. "email_only" will include only the user's email. "public" includes all fields from "name_only", "email_only", and fields like the user's picture. "anonymous" will not include any of these fields. Note that the "sub" claim containing the user's ID is always included.

Allowed values: anonymous, public name_only, email_only

settings JSON object

The set of platform-specific settings to be used.

text string

The default text to show for this tool. Can be set within "settings" for the tool-level display text, or within "placements" object for placement-specific display text.

labels JSON object

An object for translations of the "text", used to support internationalization (i18n) / localization (l10n). If the user's Canvas interface is set to one of the languages listed, the tool will display the translated text in place of the value in the "text" field. More specific locales ("en-AU") are preferred over less specific ones ("en"). Can be set within "settings" or individual placements.

icon_url string

The url of the icon to show for this tool. Can be set within the "settings" object for tool-level icons, or in the "placement" object for placement-specific icons. NOTE: Not all placements display an icon.

selection_height string

The display height of the iframe. This may be ignored or overridden for some LTI placements due to other UI requirements set by Canvas. Tools are advised to experiment with this setting to see what makes the most sense for their application.

selection_width string

The display width of the iframe. This may be ignored or overridden for some LTI placements due to other UI requirements set by Canvas. Tools are advised to experiment with this setting to see what makes the most sense for their application.

enabled boolean

Optional, defaults to `true`. Set within the "placements" object to to determine if the placement is enabled.

message_type string

The IMS message type to be sent in the launch. This is set at the placement level. Not all placements support both message_types.

Allowed values: "LtiResourceLinkRequest", "LtiDeepLinkingRequest"

required_permissions string

Limits tool visibility to users with certain permissions, as defined on the user's built-in Canvas user roles AND the custom roles that you may have created in Canvas. This is a comma-separated string of one or more required permissions, such as manage_groups_add,manage_groups_delete or read_outcomes. The tool will be hidden for users without all specified permissons. If set in placement-specific settings, that placement will be hidden; if set at the tool-level (e.g. under extensions[0]), each of the tool's placements will be hidden. For true access control, please use (instead or in addition) the Canvas.membership.permissions<> custom variable expansion, and check its value in your tool. To learn more about roles and permissions, and to see the permissions available for this parameter, visit the Roles API docs.

environments Ignored JSON object

LTI 1.1 tools support environment-specific domains and launch urls, used for launching from beta or test instances of Canvas. This config option is not supported for LTI 1.3. Tools instead should use the canvas_environment parameter of the OIDC Login request to redirect to environment-specific launch urls or instances of the tool, as specified in Step 1.5 above, and/or use the region-specific oidc_initiation_urls.

public_jwk required, see notes JSON object

Required if public_jwk_url is omitted. The tools public key to be used during the client_credentials grant for accessing LTI Advantage services.

public_jwk_url required, see notes string

Required if public_jwk is omitted. The tools public key uri to be used during the client_credentials grant for accessing LTI Advantage services.

custom_fields JSON object

Custom fields that will be sent to the tool consumer; can be set at the tool-level or within the "placement" JSON object for placement-specific custom fields.