Advanced Cojure Microservices
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The document discusses the implementation of microservices using Clojure, highlighting key concepts such as resource modeling, fault tolerance, and metrics. It emphasizes the use of tools like Liberator for resource handling and Hystrix for managing circuit breaking and fault tolerance, along with Prometheus for tracking metrics. The author illustrates these points with code snippets and examples relevant to building high-availability services on AWS.
![3
(defroutes app
(GET "/messages/:name" [name] {:body {:message (str "Hello World" " " name)}})
(route/resources "/")
(route/not-found "Not Found"))
(defn -main [& args]
(run-jetty app {:port 3000 :join? false }))
Microservices with Clojure is easy!](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-3-320.jpg)
![12
Resource Modeling with Liberator
(defroutes app
(ANY "/api/users" [] r/users)
(ANY "/api/users/:userhandle" [userhandle] (r/user userhandle))
(ANY "/api/authentication" [] r/authentication))](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-12-320.jpg)
![13
Resource Modeling with Liberator
(defresource users
:available-media-types ["application/user-v1+json"]
:allowed-methods [:post]
:malformed? (fn [ctx] (s/validate-user (body ctx)))
:handle-malformed (fn [ctx] (ring-response {:status 400
:body
{:message (str (s/validate-user (body ctx)))})}))
:post! (fn [ctx] (if (user-exists? (body ctx))
{:conflict true}
{:created-entity (create-user (body ctx))}))
:handle-created (fn [ctx] (if (:conflict ctx)
(ring-response {:status 409})
(r/user-output (:created-entity ctx)))))](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-13-320.jpg)
![(h/add-hook {:hystrix/timeout-ms (:HYSTRIX_TIMEOUT config/settings)
:hystrix/threads (:HYSTRIX_THREADS config/settings)})
15
Fault Tolerance with Hystrix
(defn search-customer [param]
(client/get
(str api-endpoint "/customers?search=" param)
{:content-type :json
:as :json
:hystrix/group-key "customers"
:hystrix/fallback-fn (constantly {:body {:name "Not" :firstname "Found"}})}))](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-15-320.jpg)
![(defroutes app
;; ...
(ANY "/internal/metrics" []
(prometheus/dump-metrics (:registry @metrics/metrics-store))))
(def handler
(-> app
; ...
(prometheus/instrument-handler "" (:registry @metrics/metrics-store))))
19
Metrics with Prometheus
prometheus-clj](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-19-320.jpg)
![(defonce metrics-store (atom (prometheus/init-defaults)))
(defn- register-metrics []
(-> @metrics-store
(prometheus/register-gauge "users" "users_count" "Number of users in DB" ["users_count"])
(prometheus/register-gauge "users" "users_disabled" "Number of disabled users in DB"
["users_disabled"])
(prometheus/register-counter "users" "cache_hits"
"Number of cache hits when requesting a customer" ["cache_hits"])
(prometheus/register-counter "users" "cache_misses"
"Number of cache misses when requesting a customer" ["cache_misses"])))
(defn init []
(reset! metrics-store (register-metrics))
(HystrixPrometheusMetricsPublisher/register (:registry @metrics-store)))
20
Metrics with Prometheus](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-20-320.jpg)
![(defn update-metrics []
(prometheus/set-gauge @metrics-store "users" "users_count" (p/count-users) ["users_count"])
(prometheus/set-gauge @metrics-store "users" "users_disabled"
(p/count-users {:enabled false}) ["users_disabled"]))
(defn inc-cache-hits []
(prometheus/increase-counter @metrics-store "users" "cache_hits" ["cache_hits"] 1))
(defn inc-cache-misses []
(prometheus/increase-counter @metrics-store "users" "cache_misses" ["cache_misses"] 1))
21
Metrics with Prometheus](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-21-320.jpg)
![(defn process-event [event]
(when (= (:eventType event) "SubscriptionChanged")
(log/info "Received event" event)
(handle-subscription-changed-event event)))
(defn start-worker! [fn-processor]
(kinesis/worker! :app (:APP_NAME config/settings)
:stream (:EVENT_STREAM config/settings)
:endpoint (:KINESIS_ENDPOINT config/settings)
:region-name (:AWS_REGION config/settings)
:processor (fn [records]
(doseq [record records]
(process-record record fn-processor)))))
22
Cloudability with Amazonica
AWS Kinesis](https://image.slidesharecdn.com/advanced-clojure-microservices-tobias-bayer-30-09-2016-161004072019/85/Advanced-Cojure-Microservices-22-320.jpg)
Advanced Cojure Microservices
- 1. Advanced Clojure Microservices Tobias Bayer Hamburg, 30.09.2016
- 2. Clojure, Java, Cloud tobias.bayer@inovex.de https://github.com/tobiasbayer 2 Tobias Bayer Senior Developer / Software Architect inovex GmbH
- 3. 3 (defroutes app (GET "/messages/:name" [name] {:body {:message (str "Hello World" " " name)}}) (route/resources "/") (route/not-found "Not Found")) (defn -main [& args] (run-jetty app {:port 3000 :join? false })) Microservices with Clojure is easy!
- 4. 4
- 5. ~ 20 Microservices High Availability Polyglot About 30% of services in Clojure Running on AWS 5 Project
- 6. 6 Resource Modeling Fault Tolerance Monitoring and Metrics Cloudability ... Real World Problems
- 7. 7 Resource Modeling with Liberator
- 8. 8 Resource Modeling with Liberator
- 9. 9 Decisions Resource Modeling with Liberator
- 10. 10 Actions Resource Modeling with Liberator
- 11. 11 Handlers Resource Modeling with Liberator
- 12. 12 Resource Modeling with Liberator (defroutes app (ANY "/api/users" [] r/users) (ANY "/api/users/:userhandle" [userhandle] (r/user userhandle)) (ANY "/api/authentication" [] r/authentication))
- 13. 13 Resource Modeling with Liberator (defresource users :available-media-types ["application/user-v1+json"] :allowed-methods [:post] :malformed? (fn [ctx] (s/validate-user (body ctx))) :handle-malformed (fn [ctx] (ring-response {:status 400 :body {:message (str (s/validate-user (body ctx)))})})) :post! (fn [ctx] (if (user-exists? (body ctx)) {:conflict true} {:created-entity (create-user (body ctx))})) :handle-created (fn [ctx] (if (:conflict ctx) (ring-response {:status 409}) (r/user-output (:created-entity ctx)))))
- 15. (h/add-hook {:hystrix/timeout-ms (:HYSTRIX_TIMEOUT config/settings) :hystrix/threads (:HYSTRIX_THREADS config/settings)}) 15 Fault Tolerance with Hystrix (defn search-customer [param] (client/get (str api-endpoint "/customers?search=" param) {:content-type :json :as :json :hystrix/group-key "customers" :hystrix/fallback-fn (constantly {:body {:name "Not" :firstname "Found"}})}))
- 19. (defroutes app ;; ... (ANY "/internal/metrics" [] (prometheus/dump-metrics (:registry @metrics/metrics-store)))) (def handler (-> app ; ... (prometheus/instrument-handler "" (:registry @metrics/metrics-store)))) 19 Metrics with Prometheus prometheus-clj
- 20. (defonce metrics-store (atom (prometheus/init-defaults))) (defn- register-metrics [] (-> @metrics-store (prometheus/register-gauge "users" "users_count" "Number of users in DB" ["users_count"]) (prometheus/register-gauge "users" "users_disabled" "Number of disabled users in DB" ["users_disabled"]) (prometheus/register-counter "users" "cache_hits" "Number of cache hits when requesting a customer" ["cache_hits"]) (prometheus/register-counter "users" "cache_misses" "Number of cache misses when requesting a customer" ["cache_misses"]))) (defn init [] (reset! metrics-store (register-metrics)) (HystrixPrometheusMetricsPublisher/register (:registry @metrics-store))) 20 Metrics with Prometheus
- 21. (defn update-metrics [] (prometheus/set-gauge @metrics-store "users" "users_count" (p/count-users) ["users_count"]) (prometheus/set-gauge @metrics-store "users" "users_disabled" (p/count-users {:enabled false}) ["users_disabled"])) (defn inc-cache-hits [] (prometheus/increase-counter @metrics-store "users" "cache_hits" ["cache_hits"] 1)) (defn inc-cache-misses [] (prometheus/increase-counter @metrics-store "users" "cache_misses" ["cache_misses"] 1)) 21 Metrics with Prometheus
- 22. (defn process-event [event] (when (= (:eventType event) "SubscriptionChanged") (log/info "Received event" event) (handle-subscription-changed-event event))) (defn start-worker! [fn-processor] (kinesis/worker! :app (:APP_NAME config/settings) :stream (:EVENT_STREAM config/settings) :endpoint (:KINESIS_ENDPOINT config/settings) :region-name (:AWS_REGION config/settings) :processor (fn [records] (doseq [record records] (process-record record fn-processor))))) 22 Cloudability with Amazonica AWS Kinesis
- 23. 23
- 24. jobs@inovex.de www.inovex.de/jobs +49 721 619 021 50 Wir suchen Verstärkung in den Bereichen • Digital Consulting • Web Frontend & Backend • Replatforming • Apps & Smart Devices • Big Data • Data Science • Search • Business Intelligence • DevOps • Cloud • Operations Hamburg, Köln, München, Karlsruhe, Pforzheim