Joplin Server

Joplin is an open source note-taking app, and Joplin Server is its self-hosted sync server. Since version 3.4.1, Joplin Server can sign users in through a SAML 2.0 identity provider (IdP). With Casdoor as the IdP, users sign in to Joplin Server, and to the Joplin apps that sync with it, with their Casdoor account.

Joplin Server checks the SAML response with samlify and xml-crypto. xml-crypto doesn't support XML canonicalization 1.1, which Casdoor signs with by default, so the application in Casdoor must have Enable SAML C14N10 on. Use the latest Casdoor version: older versions sign such responses in a way that Joplin Server rejects, with FAILED_TO_VERIFY_SIGNATURE or with an XML schema error.

The examples use https://joplin.example.com for Joplin Server and https://door.example.com for Casdoor.

Create the application in Casdoor

1. In the Casdoor admin console, open the organization of your users and add an application, or open an existing one.

2. Add the entity ID of Joplin Server and its Assertion Consumer Service (ACS) URL to Redirect URLs. The entity ID is the entityID in the service provider (SP) file that you write below, Joplin in the example. The ACS URL is <APP_BASE_URL>/api/saml:

   Joplin
   https://joplin.example.com/api/saml

3. On the SAML tab:

   • Turn on Enable SAML C14N10, and leave SAML C14N10 prefix empty.

   • Turn on Enable SAML POST binding. Joplin Server sends its request to Casdoor with the HTTP-POST binding, so the metadata must list the HTTP-POST endpoint of Casdoor.

   • Add two rows to SAML attributes. Joplin Server reads only these two attributes, and the names are case-sensitive: the Email and DisplayName attributes that Casdoor sends by default don't count.

     Name	Name format	Value
     email	Basic	$user.email
     displayName	Basic	$user.displayName

     Every user needs an email address in Casdoor. Joplin Server identifies the user by it.

4. Save, and click Copy SAML metadata URL. With Enable SAML POST binding on, the URL ends with enablePostBinding=true:

   https://door.example.com/api/saml/metadata?application=admin/<application-name>&enablePostBinding=true

5. Open the URL and save the XML as idp.xml. Joplin Server reads the IdP metadata from a file, not from a URL.

Prepare Joplin Server

1. Write the SP file sp.xml. Set entityID to the entity ID that you added to Redirect URLs, and Location to the ACS URL:

   <?xml version="1.0"?>
   <md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" entityID="Joplin">
     <md:SPSSODescriptor AuthnRequestsSigned="false" WantAssertionsSigned="false" protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol">
       <md:NameIDFormat>urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress</md:NameIDFormat>
       <md:AssertionConsumerService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="https://joplin.example.com/api/saml" index="1" />
     </md:SPSSODescriptor>
   </md:EntityDescriptor>

2. Put idp.xml and sp.xml where Joplin Server can read them. With Docker, mount a directory, for example ./saml:/saml:ro in docker-compose.yml.

3. Set the environment variables of Joplin Server, for example in its .env file:

   APP_BASE_URL=https://joplin.example.com
   API_BASE_URL=https://joplin.example.com
   SAML_ENABLED=true
   SAML_IDP_CONFIG_FILE=/saml/idp.xml
   SAML_SP_CONFIG_FILE=/saml/sp.xml
   SAML_ORGANIZATION_DISPLAY_NAME=Casdoor
   DELETE_EXPIRED_SESSIONS_SCHEDULE=

   Variable	Description
   APP_BASE_URL, API_BASE_URL	SAML needs both set to the same URL.
   SAML_ENABLED	Turns on SAML sign-in.
   SAML_IDP_CONFIG_FILE	The path of the IdP metadata from Casdoor.
   SAML_SP_CONFIG_FILE	The path of the SP file.
   SAML_ORGANIZATION_DISPLAY_NAME	Optional. The name that the sign-in page shows above the SAML button.
   DELETE_EXPIRED_SESSIONS_SCHEDULE	Joplin Server clears sessions every 6 hours by default, and SAML users then have to sign in again by hand. An empty value turns this off.

   To allow only SAML sign-in, also set LOCAL_AUTH_ENABLED=false.

4. Restart Joplin Server.

Ergebnis überprüfen

1. Open https://joplin.example.com/login in a private browser window and click Login using your organisation account.
2. Sign in to Casdoor. Joplin Server opens its home page with the Casdoor user signed in. A user who doesn't exist yet in Joplin Server is created at this first sign-in, with the email and display name from Casdoor.
3. In a Joplin app, choose Joplin Server (SAML) as the synchronization target and enter https://joplin.example.com. The app opens the sign-in in the browser. After you sign in to Casdoor, Joplin Server shows a code, which you enter in the app to start syncing.

Fehlerbehebung

Symptom	Cause and fix
Joplin Server logs FAILED_TO_VERIFY_SIGNATURE: POST /api/saml	Update Casdoor to the latest version. If it persists, download the metadata again: Joplin Server must have the certificate of the application's current Cert.
Joplin Server logs canonicalization algorithm 'http://www.w3.org/2006/12/xml-c14n11' is not supported	Turn on Enable SAML C14N10 on the application.
Joplin Server logs ERR_EXCEPTION_VALIDATE_XML, about xs:string without a namespace declaration	Update Casdoor to the latest version. Older versions drop the xs namespace from the response when they sign it.
email must be a string or displayName must be a string	Add the email and displayName rows to SAML attributes, with these exact names, and check that Disable SAML attributes is off.
Could not login using email "..."	Joplin Server already has a local account with a password for this email, and doesn't let SAML sign in to it. Delete or rename the local account in Joplin Server.
The browser opens a Joplin Server URL that ends with [object Object]	The IdP metadata has no HTTP-POST endpoint. Turn on Enable SAML POST binding, and download the metadata again with enablePostBinding=true.
Casdoor shows Issuer URI: Joplin doesn't exist in the allowed Redirect URI list	Add the entityID of sp.xml to Redirect URLs.
Casdoor shows AssertionConsumerServiceURL: ... doesn't match the SAML reply URL or the allowed Redirect URI list	Add <APP_BASE_URL>/api/saml to Redirect URLs.

Siehe auch

• Joplin Server SAML support in the Joplin documentation
• Casdoor als SAML-Identitätsanbieter verwenden