Code with Ktor and Auth0

Cui Cui Follow Aug 15, 2021 · 2 mins read
Code with Ktor and Auth0
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This is the article trying to study:

Setup API app

  1. Setup Auth0 account.

  2. Install Ktor Authentication plugin
     val jwkProvider = JwkProviderBuilder(System.getenv("ISSUER"))
     .cached(10, 24, TimeUnit.HOURS)
     .rateLimited(10, 1, TimeUnit.MINUTES)
     install(Authentication) {
         jwt("auth0") {
             verifier(jwkProvider, System.getenv("ISSUER"))
             validate { credential -> validateCreds(credential) }
  3. Add validate Credentials method
    fun validateCreds(credential: JWTCredential): JWTPrincipal? {
     val containsAudience = credential.payload.audience.contains(System.getenv("AUDIENCE"))
     if (containsAudience) {
         return JWTPrincipal(credential.payload)
     return null
  4. Add authenticate layer to the routes
    routing {
     authenticate("auth0") {
         get("/api/messages/protected") {
                 """{"message": "The API successfully validated your access token."}""",
                 contentType = ContentType.Application.Json
  5. Environment security variables for API app
     export ISSUER=https://<yourdomain>.auth0.com
     export AUDIENCE=<api audience>
  6. Run the API app

Setup Frontend app

  1. Environment security variables for UI app
     export REACT_APP_AUTH0_DOMAIN=yourdomain.auth0.com
     export REACT_APP_AUTH0_CLIENT_ID=abcdefghigklmnop
     export REACT_APP_AUTH0_AUDIENCE=ktordemo
     export REACT_APP_API_SERVER_URL=http://localhost:6060
  2. Run the API and UI apps
    npm install
    npm start

Bullet points to take away:

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Written by Cui Follow
Hi, I am Cui, the colourful coder for colourful.codes!