Centralized Application Configuration with Spring and Apache Zookeeper
- 1. Centralized Application Configuration with Spring and Apache ZooKeeper By Ryan Gardner, Dealer.com © 2014 SpringOne 2GX. All rights reserved. Do not distribute without permission.
- 2. How do you configure your applications? 2 http://b.socrative.com/login/student/ config2gx
- 3. Who is Dealer.com? We make software that car dealers use to fulfill their digital marketing vision. 3
- 4. The Remote Configuration Project 4
- 5. Some ways we had configured our applications • Hardcoded values in code • Properties file – per environment or merged • Host files for database • JNDI context files 5
- 6. Motivating factors • Developer Efficiency • Redeploying an application just to change a configuration is a drag • Having to edit N config files whenever a single application changed is a hassle • Security Compliance • Limit access to production databases • Auditing and approval process for configuration changes • Systems Engineering • Can’t make certain changes without involving developers 6
- 7. Framework Development – Guns n Roses style "Welcome to the jungle" Thanks. "We've got fun and games" Cool. "You're in the jungle" We've established this "You're gonna die!" Wait what? https://twitter.com/OhNoSheTwitnt/status/469838190141255680 7
- 8. High Level Overview 8
- 10. 10
- 11. Key Concepts in the Remote Configuration Configuration A set of properties or values necessary to create an object. Examples: Database configuration, FTP endpoint configuration, HTTP Proxy Factory Bean Configuration, 11
- 12. Tripoli – editing a configuration 12
- 13. Separation of environments • We edit our configurations in one spot, but applications are only able to retrieve configurations for the environment they are running in • Secrets – such as passwords or encryption keys – are encrypted with an environment-specific key • Tripoli has all the keys, each environment will only have a key specific to it 13
- 14. Configuration inheritance – avoiding copy & paste By Environment • Configuration can be set at a global level and overridden at each environment By Path • Nodes added with /’s in the name will inherit data from nodes above them. • /remoting/core-services/UserLocator inherits values from /remoting/core-services 14
- 15. Key Concepts in the Remote Configuration Bindings Identifying which configurations an application uses, and what the application wants to call them Example: An application that needs to talk to a certain database, look up users from a remote service, and send data to a remote SFTP site would have bindings such as: jdbc/user-database is bound to the configuration called user-database-config 15
- 16. Tripoli – editing bindings 16
- 17. Creating objects, not properties* • Configure once – use everywhere • Avoid having to copy-and-paste boilerplate setup code * properties are supported too 17
- 18. Behind the Scenes 18
- 19. Apache Zookeeper • Hierarchical data registers • Designed for high-throughput, low-latency, highly-available • Nodes in zookeeper are called “znodes” • Each path can stored data • Designed for storing small amounts of data in the znodes (KB, not MB) • For more info: • https://cwiki.apache.org/confluence/display/ZOOKEEPER/ProjectDescriptio n 19
- 20. Where do we store this data? 20 • Versioned configuration in ZooKeeper as JSON • In ZooKeeper znodes: • /bindings/<binding name> overrides: • /bindings/<habitat>/<datacenter>/<binding name> • /configurations/<configuration name>/
- 21. Talking to ZooKeeper • Use Curator framework • We use ACLs in ZooKeeper ensure apps can’t read data for other environments • We use a SASL config file on the machines to provide the ZooKeeper credentials 21
- 22. Exhibitor – makes managing ZooKeeper easier 22
- 23. How do the objects get created? • Two classes for each remotely-configurable object, the config and the creator • Configs use bean-validation annotations and a special annotation on the config-field to explain what the config field does. • This populates the tool-tips in the browser window and is used to ensure that only valid entries are put into the fields 23
- 24. An example config class 24 @ConfigCategory("ftp”) public class SpringIntegrationSftpSessionFactoryConfig extends Config { @Required @ConfigField(description = "The host name of the SFTP server.”) private String host; @Port @ConfigField(description = "The port of the SFTP server. Defaults to 22.”) private Integer port; …
- 25. A config class (continued) 25 @Required @Password @ConfigField(description = "The private key used to establish the SFTP connection.”) private ConfigPassword privateKey; @Password @ConfigField(description = "The passphrase for the private key. Defaults to empty string.”) private ConfigPassword privateKeyPassphrase;
- 26. Creators take the config and return an object 26 public class ExampleObjectCreator extends ObjectCreator<SomeConfig,ExampleObject> { @Override public ExampleObject create(SomeConfig) { // do whatever is needed to create the object return new ExampleObject(); } }
- 27. Kinds of creators we have made • Database connection (various connection pools) • Mongo connection pools • RPC remoting proxies (Spring HTTP Invoker, etc) • REST resources • Redis connections • Properties / System properties • FTP and SFTP connections • Executor services • RabbitMQ • SOLR • ElasticSearch • … more 27
- 28. How do apps use this? 28
- 29. First pass – XML namespace parser 29 <beans … xmlns:remote-config=“http://www.dealer.com/schema/remote-config” …> <remote-config:lookup id="dataSource" name=”jdbc/my-datasource" /> <remote-config:remote-config-property-source id="myProps" name="properties/my-props" /> </beans>
- 30. Second pass – Auto-config with XML 30 <beans … xmlns:remote-config=“http://www.dealer.com/schema/remote-config” …> … <remote-config:auto-create /> … </beans>
- 31. Third pass - @EnableRemoteConfig 31 @EnableRemoteConfig public class ApplicationConfig { // insert tweetable app here. }
- 33. Integrating remote properties into spring • We create a PropertySource • And we create a PropertySourcesPlaceholderConfigurer 33
- 34. Using properties via @Value 34 @Bean public SomeBean someBean (@Value(“${some.value}”) someValue) { return new SomeBean(someValue) } … @Value(“${some.remote.property.value}”) private String someValue;
- 35. Deeper dive – demo & look at some of the code 35
- 36. Future plans & extensions for this 36
- 37. Questions? 37
- 38. 38 Learn More. Stay Connected Tweet: “#s2gx talk about zookeeper blew my mind! Thanks @ryebrye and @springcentral” @springcentral | spring.io/video
Editor's Notes
- #4: Websites Advertising Inventory management Analytics CRM (and more)
- #5: There is a slide shown at the keynotes -
- #8: There are often surprises as you develop things – you think you are on the right path but then… wooops.
- #18: How many people have ever started a project, realized they needed a certain data source – so they went to another project that they had opened and then copied the configuration out of it and pasted it into the new one.
- #21: Apache Zookeeper. Good project. Horible logo. “ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. “
- #31: Simplify cruft – eliminate duplicate entry… but… still XML
- #32: We can now create tweetable apps that run in any of our environments and use the proper datasources or service endpoints for that environment.
- #34: Transparently use @Value annotated properties in your classes.
- #36: Look at property sources configurer. Point out bean definitions vs beans. Look at a creator or two.