In SAML, what are the actions that need to be performed in the client and service provider to logout?

I have gotten SAML Login working in a Go program using crewjam/samlwith a Keycloak IDP in SAML mode (I believe this is using SAMLv2 but not positive). The basics are that upon a good login, the IDP send the program the user's SAML attributes, the Go SAML Library translates this to a JWT and sets it as the HTTP Cookie. At this point the IDP marks that the user has a session with the Service and the user can access the API via the JWT.

The problem I am having is that I am unclear how to Logout. The library has a URL for logging out:

// SloURL is the full URL to the SAML Single Logout endpoint on this host.
// i.e. https://example.com/saml/slo
SloURL url.URL

But navigating to this page just returns a 404.

So how do I tell the IDP that the user's session is done? Should I remove the JWT cookie myself or will this be handled?

The following appears to accomplish what I asked for:

type Logout struct {
	SP *samlsp.Middleware
}

func (l *Logout) ServeHTTP(w http.ResponseWriter, r *http.Request) {
      //Get the JWT information
	session, err := l.SP.Session.GetSession(r)
	if err != nil {
		WebErrorWarn("error get signouturl session: "+err.Error(), http.StatusForbidden, w)
		return
	}
       //Get the JWT information part 2
	attr := session.(samlsp.JWTSessionClaims)
	if err != nil {
		WebErrorWarn("error get signouturl session claims: "+err.Error(), http.StatusForbidden, w)
		return
	}

	//use this as the name for the logout request
	url, err := l.SP.ServiceProvider.MakeRedirectLogoutRequest(attr.Subject, "")
	if err != nil {
		WebErrorWarn("error get signouturl: "+err.Error(), http.StatusInternalServerError, w)
		return
	}

    //delete the session token from teh browser 
	err = l.SP.Session.DeleteSession(w, r)
	if err != nil {
		WebErrorWarn("error get signouturl: "+err.Error(), http.StatusInternalServerError, w)
		return
	}

    //redirect to the IDP Single log out URLwith the SAMLRequests for logout embedded
	http.Redirect(w, r, url.String(), http.StatusFound)
}

I make my own logout URL to serve this on

	http.Handle("/logout", samlSP.RequireAccount(&Logout{samlSP}))

Finally the IDP redirect the client back to the SLO URL, it is sent in the metadata file and also defaults to /saml/slo in crewjam/gosaml. I just have a handler on that URL to give the user a confirmation that they are no longer signed in.

	http.Handle("/saml/slo", &SLOHandle{})

Note the /saml/slo URL should not be SAML protected otherwise you will trigger SAML login all over again.

The Single Logout Service (SLO) URL is in the IdP metadata, e.g.

<EntityDescriptor ... entityID="https://idp.com/shibboleth">
  <IDPSSODescriptor ... >
    <SingleLogoutService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="https://idp.com/idp/profile/SAML2/POST/SLO"/>
  </IDPSSODescriptor>
</EntityDescriptor>

you then construct a logout request to send to the SLO for the NameID that was previously sent by the IdP (with the entityID https://idp.com/shibboleth) when that user logged in:

<samlp:LogoutRequest xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ID="ONELOGIN_21df91a89767879fc0f7df6a1490c6000c81644d" Version="2.0" IssueInstant="2014-07-18T01:13:06Z" Destination="https://idp.com/idp/profile/SAML2/POST/SLO">
  <saml:Issuer>https://idp.com/shibboleth</saml:Issuer>
  <saml:NameID SPNameQualifier="https://idp.com/shibboleth" Format="urn:oasis:names:tc:SAML:2.0:nameid-format:transient">ONELOGIN_f92cc1834efc0f73e9c09f482fce80037a6251e7</saml:NameID>
</samlp:LogoutRequest>

and receive the logout response:

<samlp:LogoutResponse xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ID="_6c3737282f007720e736f0f4028feed8cb9b40291c" Version="2.0" IssueInstant="2014-07-18T01:13:06Z" Destination="http://sp.example.com/demo1/index.php?acs" InResponseTo="ONELOGIN_21df91a89767879fc0f7df6a1490c6000c81644d">
  <saml:Issuer>https://idp.com/shibboleth</saml:Issuer>
  <samlp:Status>
    <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>
  </samlp:Status>
</samlp:LogoutResponse>

Send logout SAML request to http://{url}:{port}/auth/realms/{realm}/protocol/saml