API Nifi + Token + SAML2

Welcome to the community @Gutao. Perhaps @MattWho or @SAMSAL will be able to lead you in the right direction.  

Thanks @cjervis !

I'll wait and see if someone can help me.

@Gutao 
When interacting with the NiFi rest-api, I'd recommend creating a client certificate to use in your automation.  A secured NiFi will always WANT a client certificate and will only try another configured auth method if a client certificate is not provide in the TLS exchange.  Using a certificate for your rest-api automation removes the need for obtaining a token completely.  You simply pass your client certificate with every rest-api call.   Another advantage here over auth is token expiration. With no token involved with certificate based auth, your certificate will continuously work until it expires (typical default is 1 or 2 years). 

You'll need to setup authorization policies for your certificate user (Certificate DN used as user identity) for the various endpoints you are trying to interact with through the rest-api.

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Thank you,

Matt