A library for building LTI 1.3 tools in Gleam
gleam add lightbulb@1The example below shows how to use the library in a Gleam Wisp application. It includes two endpoints: one for OIDC login and another for validating the launch request. For a complete example, see the lti-example-tool repository.
import gleam/dict.{type Dict}
import gleam/http
import gleam/http/cookie
import gleam/http/request
import gleam/http/response
import gleam/list
import gleam/option.{Some}
import gleam/string
import lightbulb.{type DataProvider}
import wisp.{type Request, type Response, redirect}
pub fn oidc_login(req: Request, data_provider: DataProvider) -> Response {
// Get all query and body parameters from the request.
use params <- all_params(req)
// Build the OIDC login state and URL response.
case lightbulb.oidc_login(data_provider, params) {
Ok(#(state, redirect_url)) -> {
use <- set_cookie(
"state",
state,
cookie.Attributes(
..cookie.defaults(http.Https),
same_site: Some(cookie.None),
max_age: option.Some(60 * 60 * 24),
),
)
redirect(to: redirect_url)
}
Error(error) ->
wisp.internal_server_error()
|> wisp.string_body("OIDC login failed: " <> error)
}
}
pub fn validate_launch(req: Request, data_provider: DataProvider) -> Response {
// Get all query and body parameters from the request.
use params <- all_params(req)
// Get the state cookie that was set during the OIDC login.
use state <- require_cookie(req, "state", or_else: fn() {
wisp.bad_request()
|> wisp.string_body("Required 'state' cookie not found")
})
// Validate the launch request using the parameters and state.
case lightbulb.validate_launch(data_provider, params, state) {
Ok(claims) -> {
wisp.ok()
|> wisp.string_body("Launch successful! " <> string.inspect(claims))
}
Error(e) -> {
wisp.bad_request()
|> wisp.string_body("Invalid launch: " <> string.inspect(e))
}
}
}
/// Helper functions
fn all_params(
req: Request,
cb: fn(Dict(String, String)) -> Response,
) -> Response {
use formdata <- wisp.require_form(req)
// Combine query and body parameters into a single dictionary. Body parameters
// take precedence over query parameters.
let params =
wisp.get_query(req)
|> dict.from_list()
|> dict.merge(dict.from_list(formdata.values))
cb(params)
}
fn set_cookie(
name: String,
value: String,
attributes: cookie.Attributes,
cb: fn() -> Response,
) -> Response {
cb()
|> response.set_cookie(name, value, attributes)
}
fn require_cookie(
req: Request,
cookie_name: String,
or_else bail: fn() -> Response,
cb cb: fn(String) -> Response,
) -> Response {
case get_cookie(req, cookie_name) {
Ok(cookie) -> cb(cookie)
Error(_) -> bail()
}
}
fn get_cookie(req: Request, name name: String) -> Result(String, Nil) {
req
|> request.get_cookies
|> list.key_find(name)
}Further documentation can be found at https://hexdocs.pm/lightbulb.
gleam test # Run the tests