Sweetcomb : RESTCONF study

1. Sweetcomb: RESTCONF study Hongcheng Zhong & Tao Yu @ Intel Sweetcomb Community internal

2. Agenda • Architecture • RESTCONF vs NETCONF • RESTCONF in detail • Clixon example study • Netopeer2 study • Our design • What to do next? *Other names and brands may be claimed as the property of others.

3. Architecture 1. Supports three interfaces. 2. Three data stores for HA. 3. Framework with Plugins. Source: https://wiki.fd.io/view/File:Sweetcomb-overview.png *Other names and brands may be claimed as the property of others.

4. Compare to NETCONF • NETCONF • Need NETCONF Client • Transport upon SSH • Data format: only XML • RESTCONF • Don’t need special Client • Transport upon HTTPS • Data format: XML&JSON RESTCONF Protocol Stack NETCONF Protocol Stack Source: https://www.netacad.com/sites/default/files/images/careers/Webinars/DevNet/devnet_session_7_networkprogrammability_yang_netconf_restconf.pdf *Other names and brands may be claimed as the property of others.

5. RESTCONF’s operations are subset to NETCONF’s Source: https://www.netacad.com/sites/default/files/images/careers/Webinars/DevNet/devnet_session_7_networkprogrammability_yang_netconf_restconf.pdf

6. Source: https://www.netacad.com/sites/default/files/images/careers/Webinars/DevNet/devnet_session_7_networkprogrammability_yang_netconf_restconf.pdf

7. Source: https://www.netacad.com/sites/default/files/images/careers/Webinars/DevNet/devnet_session_7_networkprogrammability_yang_netconf_restconf.pdf

8. Source: https://www.netacad.com/sites/default/files/images/careers/Webinars/DevNet/devnet_session_7_networkprogrammability_yang_netconf_restconf.pdf

10. Study by clixon example • All implemented by clixon itself • Restconf • backend • YANG • XML Datastore • … Source: https://github.com/clicon/clixon *Other names and brands may be claimed as the property of others.

11. Study by clixon example frontend Curl –G http://localhost/restconf/data https Location /restconf { fastcgi_passunix:/www-data/fastcgi_restconf.sock; include fastcgi_params; } Web server nginx fastcgi_restconf.sock Clixon_restconf Parse http message, construct a <rpc> msg, send to backend, wait for return <CLICON_SOCK> Select system call watch socks + event to receive from restconf(or other clients) Decode <rpc> msg to xml data structure Invoke related callback function(NETCONF) Clixon_backend Xmldb_* API Xmldb operations by rpc_callback xmldb Source: https://github.com/clicon/clixon *Other names and brands may be claimed as the property of others.

12. http server: stunnel vs nginx • Stunnel (used in netopeer1): • Old • Use one threaded model • Nginx: • One of the most efficient web server • Use workers • Stud is unmaintained Source: https://vincent.bernat.ch/en/blog/2011-ssl-benchmark *Other names and brands may be claimed as the property of others.

13. Study by netopeer2 Parse cli command, construct <rpc> msg, Send it to server and wait for reply Netopeer2-cli ssh Workers polling Decode <rpc> msg to lyd_node, 1)rpc->lyxml_elem,2)lyxml_elem->lyd_node Check lys_node in lyd_node, Invoke related callback function(NETCONF), Netopeer2-server Sysrepo API (sr_*) sysrepo Source: https://github.com/CESNET/Netopeer2 *Other names and brands may be claimed as the property of others.

14. YANG data structure • ly_ctx – lys_node – lyd_node • *priv in lys_node is exactly callback function • In lyd_node, including a *schema *Other names and brands may be claimed as the property of others.

15. Our design: a restconf implement upon sysrepo frontend Curl –G http://localhost/restconf/data https nginx.conf setting: location /restconf { fastcgi_passunix:/www-data/fastcgi_restconf.sock; include fastcgi_params; } web server nginx fastcgi_restconf.sock Restconf server Parse http request to construct <rpc> msg, Decode <rpc> msg and get lyd_node invoke callback function (modified form NETCONF) to operating sysrepo Return http reply our_restconf & almost act like netopeer2-server after <rpc> msg is constructed. our_backend sysrepo API (sr_*) sysrepo *Other names and brands may be claimed as the property of others.

16. Our design: more details: initiate and parse frontend • server_init() • connect sysrepo [easy] • schemas [difficult but can modify it later] • server monitoring [not to do yet] • capability? Features? [not figure it out yet] • set callbacks • parse to lyd_node, 2 ways: • directly parse http request to lyd_node • construct <rpc> first, parse <rpc> to lyxml_elem, then to lyd_node • In first simplified implement, the most important thing is parsing http request to lyd_node. And the initiate part works for this purpose. https done! web server nginx fastcgi_restconf.sock Restconf server our_restconf & our_backend sysrepo API (sr_*) sysrepo *Other names and brands may be claimed as the property of others.

17. NETCONF related things • RESTCONF is independent to NETCONF • We want to use our RESTCONF implement to operate sysrepo • Learn from netopeer2 in use of libyang, libsysrepo • A question: • ietf-restconf.yang doesn’t have specific rpc / action • each lyd_node needs a lys_node (schema, defined by .yang) • What to do with RESTCONF implement? • We will temporary use NETCONF’s schema. *Other names and brands may be claimed as the property of others.

18. Some concern, difference between NETCONF & RESTCONF • HTTPS SSL/TLS and Authentication (NGINX + X.509) • Stream, notification (not to be done in basic implement) • Session to call sysrepo(what Yohan said is quite clear) • besidesietf-restconf.yang, how to do with other yangs? • For basic: ietf-restconf.yang + ietf-yang-library.yang(RFC 7895/8525) • Later on: ietf-monitoring.yang (mandatory) *Other names and brands may be claimed as the property of others.

19. What to do next, basic implement: • Get through server_init and initiate our restconf server rightly • Parse https request and construct right <rpc> • Implement basic function like • GET /restconf/data/ietf-yang-library:modules-state/ To do later: • Support more features • Eliminate the dependence on NETCONF (Our RESTCONF will just have dependence on libyang and libsysrepo) *Other names and brands may be claimed as the property of others.

20. Thank you ! Q & A 21