BEST REST in OpenStackVikram Hosakote

Sr. Software Engineer, Cisco Systems

vhosakot@cisco.com

DEVNET-2004

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• What is a RESTful service?• REST methods• REST in OpenStack• Hands-on exercises• Troubleshooting / debugging REST APIs• Q & A

Agenda

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What is a RESTful service?

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What is a RESTful service?

• Representational State Transfer (REST) is a stateless, client-server based, cacheable web service

• Uses HTTP protocol for communication

• Data is considered as a “resource” and accessed using Uniform Resource Identifiers (URIs) that typically look like a web link

• URI is RFC RFC3986 (example: http://www.ciscolive.com/us/learn/sessions/session-catalog)

• Uses HTTP clients like curl, browsers (Google Chrome Postman) and wget

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REST in OpenStack

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REST in OpenStack

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Hands-on exercises

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Hands-on exercises

• Run OpenStack Neutron CLIs and analyze REST packets in WireShark

• REST for big data use cases – REST pagination in Neutron

• Implementing a RESTful server using Python Flask

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Hands-on exercises

• Run OpenStack Neutron CLIs and analyze REST packets in WireShark

• REST for big data use cases – REST pagination in Neutron

• Implementing a RESTful server using Python Flask

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• start-capture <your first name>-<GET|POST|PUT|DELETE>.pcap

• Run an OpenStack Neutron CLI

• stop-capture

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Hands-on exercises

• Run OpenStack Neutron CLIs and analyze REST packets in WireShark

• REST for big data use cases – REST pagination in Neutron

• Implementing a RESTful server using Python Flask

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• Enable neutron pagination and restart neutorn-server

• cd Cisco-Live-Workshop/scripts

• ./big_data_create_networks.py

• Run commands in Cisco-Live-Workshop/scripts/big_data_neutron_curl.txt on GitHub(https://github.com/vhosakot/Cisco-Live-Workshop)

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Hands-on exercises

• Run OpenStack Neutron CLIs and analyze REST packets in WireShark

• REST for big data use cases – REST pagination in Neutron

• Implementing a RESTful server using Python Flask

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• cd Cisco-Live-Workshop/scripts

• ./rest_server.py

• Run commands in Cisco-Live-Workshop/scripts/rest_client_steps.txt on GitHub(https://github.com/vhosakot/Cisco-Live-Workshop)

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Troubleshooting / debugging REST APIs

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Troubleshooting / debugging REST APIs

• curl -v (verbose mode)

• wget -v (verbose mode)

• wget -d or wget --debug (debug mode)

• neutron -v or neutron -d or neutron --debug (neutron debug mode)

• http://www.httpdebugger.com

• https://www.wireshark.org

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Troubleshooting / debugging REST APIs using Python

import httplibimport loggingimport requests

httplib.HTTPConnection.debuglevel = 1logging.basicConfig()logging.getLogger().setLevel(logging.DEBUG)requests_log = logging.getLogger("requests.packages.urllib3")requests_log.setLevel(logging.DEBUG)requests_log.propagate = True

result = requests.get('http://www.cisco.com/')

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Troubleshooting / debugging REST APIs using Python

>>> result = requests.get('http://www.cisco.com/')INFO:requests.packages.urllib3.connectionpool:Starting new HTTP connection (1): www.cisco.comsend: 'GET / HTTP/1.1\r\nHost: www.cisco.com\r\nConnection: keep-alive\r\nAccept-Encoding: gzip, deflate\r\nAccept: */*\r\nUser-Agent: python-requests/2.10.0\r\n\r\n'reply: 'HTTP/1.1 200 OK\r\n'header: Server: Apacheheader: ETag: "10839-53789488e5b33"header: Accept-Ranges: bytesheader: Content-Encoding: gzipheader: CDCHOST: wemxweb-publish-prod1-01header: Content-Length: 14215header: Content-Type: text/htmlheader: Expires: Wed, 13 Jul 2016 20:25:27 GMTheader: Cache-Control: max-age=0, no-cache, no-storeheader: Pragma: no-cacheheader: Date: Wed, 13 Jul 2016 20:25:27 GMTheader: Connection: keep-aliveheader: access-control-allow-origin: *DEBUG:requests.packages.urllib3.connectionpool:"GET / HTTP/1.1" 200 14215

>>> print result<Response [200]>

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Thank you

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Q & A

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Additional slides

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Mocking a REST server to unit-test REST APIs

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Mocking a REST server to unit-test REST APIs

• https://github.com/openstack/requests-mock

>>> import requests>>> import requests_mock

>>> session = requests.Session()>>> adapter = requests_mock.Adapter()>>> session.mount('mock', adapter)

>>> adapter.register_uri('GET', 'mock://test.com', text='data')>>> resp = session.get('mock://test.com')>>> resp.status_code, resp.text(200, 'data')

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Mocking a REST server to unit-test REST APIs

• https://pypi.python.org/pypi/mock-server/0.3.7

• https://github.com/gabrielfalcao/HTTPretty

• http://python-mock-tutorial.readthedocs.io/en/latest/mock.html

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REST API caching and cache-aware REST clients

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REST API caching and cache-aware REST clients

• RFC 7234 - https://tools.ietf.org/html/rfc7234#section-5

• REST supports HTTP cache-control headers:max-agemax-stalemin-freshno-cacheno-storeno-transformonly-if-cachedmust-revalidatePublicprivate

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REST API caching and cache-aware REST clients

• Keystone caching• http://docs.openstack.org/admin-guide/keystone_caching_layer.html• http://docs.openstack.org/developer/keystone/configuration.html#caching-layer

• Glance image caching• http://docs.openstack.org/developer/glance/cache.html

• OSLO caching• http://docs.openstack.org/developer/oslo.cache/api.html• https://specs.openstack.org/openstack/api-wg/guidelines/http.html#http-caching-and-pro

xy-behavior

• Memcached• http://docs.openstack.org/ha-guide/controller-ha-memcached.html

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REST API caching and cache-aware REST clients

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Bulk REST operations and REST API batching

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Bulk REST operations and REST API batching

• http://developer.openstack.org/api-ref-networking-v2.html#bulkCreateNetwork

• https://wiki.openstack.org/wiki/Neutron/APIv2-specification#Bulk_version

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Bulk REST operations and REST API batching

• Bulk REST API JSON request format:

POST v2.0/networks.json

Content-Type: application/jsonAccept: application/json

{"networks": [ { "name": "sample_network_1", "admin_state_up": false }, { "name": "sample_network_2", "admin_state_up": false }]}