Microservices To-Go mit Dropwizard

Transcription

1 Microservices To-Go mit Dropwizard Mario Goller Software Engineer, Swisscom AG Java Forum Stuttgart 2017

2 Excursion: Architecture Comparison Monolith: multiple modules in the same container / process Microservices: Modules running in di!erent processes

3 Dropwizard is a Java framework for developing opsfriendly, high-performance, RESTful web services

4 History Created by Yammer Yammer was migrating IT infrastructure to mircoservices -> common patterns where extracted in one framework First Release: ( Dropwizard 0.1.0) Independent project since 2014 ( Dropwizard 0.7.0) Current Release: Dropwizard 1.1.2

5 How the Dropwizard Framework can help us to easily build microservices...

6 Dropwizard... pulls together stable, mature libraries from the Java ecosystem into a simple, lightweight package that lets you focus on getting things done

7 Dropwizard's Library set Jetty for HTTP servin' Jersey for REST modelin' Jackson for JSON parsin' and generatin' Logback for loggin' Hibernate Validator for validatin' Metrics for "gurin' out what your application is doin' in production JDBI and Hibernate for databasin' Liquibase for migratin'

8 How to get started...? Use existing Maven archetype to generate simple Dropwizard project this is setting up the required base implementation (already executable) mvn archetype:generate -DarchetypeGroupId=io.dropwizard.archetypes -DarchetypeArtifactId=java-simple -DarchetypeVersion=1.1.2

9 Dropwizard Components Overview

10 Application main() - starts app (Jetty server) initialize() - bundles, con"guration options, etc. run() - register Jersey resources & servlet "lters and more public class MyApplication extends Application<MyConfiguration> { public static void main(string[] args) throws Exception { new public void initialize(bootstrap<addressmoduleconfiguration> bootstrap) public void run(final AddressModuleConfiguration configuration, final Environment environment) throws Exception { environment.jersey().register(...); environment.lifecycle().manage(...); environment.healthchecks().register(...); environment.admin().addtask(...);

11 Configuration public class MyConfiguration extends Configuration private String hellomessage; public void setcustomsetting(string message) { this.hellomessage = message; public String gethellomessage() { return hellomessage; Con"guration "le (Yaml)# server: applicationcontextpath: /myapplication rootpath: /rest applicationconnectors: - type: http port: 8080 adminconnectors: - type: http port: 8082 hellomessage: 'Hello Dropwizard!' logging: level: INFO appenders: - type: console threshold: ALL target: stdout

12 Creating a REST Resource using "plain" JAX-RS 2.0 to create resources or = public class HelloResource { private final MyConfiguration conf; public HelloResource(MessagesConfiguration conf) { this.conf = public String sayhello() { return conf.gethellomaessage();

13 How it works together

14 Full Application Class Example public class MyApplication extends Application<MyConfiguration> { public static void main(string[] args) throws Exception { new public String getname() { return "My public void initialize(bootstrap<addressmoduleconfiguration> bootstrap) { bootstrap.addbundle(new AssetsBundle("/frontend-assets/", "/", "index.html", "frontend-assets")); bootstrap.addbundle(new public void run(final AddressModuleConfiguration configuration, final Environment environment) throws Exception { environment.jersey().register(constraintviolationexceptionmapper.class); environment.jersey().register(new JsonProcessingExceptionMapper()); environment.jersey().packages("org.jfs.dw.rest"); environment.servlets().addfilter("mdcloggingservletfilter",mdcloggingservletfilter.class).addmappingforurlpatterns(of(dispatchertype.request, DispatcherType.FORWARD, DispatcherType.ASYNC), false, "/*"); environment.servlets().addservletlisteners(new RequestResponseHolderListener());

15 Build the Application Fat Jar with Maven <plugin> <groupid>org.apache.maven.plugins</groupid> <artifactid>maven-shade-plugin</artifactid> <configuration> <filters> <filter> <artifact>*:*</artifact> <excludes> <exclude>meta-inf/*.sf</exclude> <exclude>meta-inf/*.dsa</exclude> <exclude>meta-inf/*.rsa</exclude> </excludes> </filter> </filters> </configuration> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> <configuration> <transformers> </execution> </executions> </plugin> <plugin> <groupid>org.apache.maven.plugins</groupid> <artifactid>maven-enforcer-plugin</artifactid> <configuration> <rules> <DependencyConvergence/> </rules> </configuration> <executions> <execution> <id>enforce</id> <configuration> <rules> <DependencyConvergence/> </rules> </configuration> <goals> <goal>enforce</goal> </goals> <phase>package</phase> </execution> </executions> </plugin> Use also maven enforcer plugin! <transformer implementation="org.apache.maven.plugins.shade.resource.servicesresourcetransformer"/> <transformer implementation="org.apache.maven.plugins.shade.resource.manifestresourcetransformer"> <mainclass>org.jfs.dw.myapplication</mainclass> </transformer> </transformers> </configuration> $ mvn package

16 Running the Application Jar java -jar myapplication.jar server myconfig.yaml Two arguments are needed in order to run the JAR server which instructs Dropwizard to run as server. path to YAML con"guration "le. INFO org.eclipse.jetty.util.log - Logging INFO io.dropwizard.server.defaultserverfactory - Registering jersey handler with root path prefix: /myapp INFO io.dropwizard.server.defaultserverfactory - Registering admin handler with root path prefix: / INFO io.dropwizard.assets.assetsbundle - Registering AssetBundle with name: frontend-assets for path /* INFO io.dropwizard.server.defaultserverfactory - Registering jersey handler with root path prefix: /myapp INFO io.dropwizard.server.defaultserverfactory - Registering admin handler with root path prefix: / INFO io.dropwizard.server.serverfactory - Starting My fancy Application INFO org.eclipse.jetty.setuid.setuidlistener - Opened application@4905c46b{http/1.1,[http/1.1]{ :8080 INFO org.eclipse.jetty.setuid.setuidlistener - Opened application@17ae7628{ssl,[ssl, http/1.1]{ :8443 INFO org.eclipse.jetty.setuid.setuidlistener - Opened admin@1136b469{http/1.1,[http/1.1]{ :8082 INFO org.eclipse.jetty.setuid.setuidlistener - Opened admin@6579c3d9{ssl,[ssl, http/1.1]{ :8444 INFO org.eclipse.jetty.server.server - jetty v INFO org.eclipse.jetty.server.handler.contexthandler - Started i.d.j.mutableservletcontexthandler@7a364e1c{/,null,ava INFO org.eclipse.jetty.server.abstractconnector - Started application@4905c46b{http/1.1,[http/1.1]{ :8080 INFO org.eclipse.jetty.server.abstractconnector - Started application@17ae7628{ssl,[ssl, http/1.1]{ :8443 INFO org.eclipse.jetty.server.abstractconnector - Started admin@1136b469{http/1.1,[http/1.1]{ :8082 INFO org.eclipse.jetty.server.abstractconnector - Started admin@6579c3d9{ssl,[ssl, http/1.1]{ :8444

17 Bundles reusable group of functionality, used to de"ne blocks of an application s behavior public interface Bundle { void initialize(bootstrap<?> bootstrap); void run(environment environment); public interface ConfiguredBundle<T> { void initialize(bootstrap<?> bootstrap); void run(t configuration, Environment environment) throws public void initialize(final Bootstrap<BeachBarClientConfiguration> bootstrap) { VersionSupplier supplier = new MavenVersionSupplier("org.jfs.dw", "my-appication"); bootstrap.addbundle(new VersionBundle(supplier));

18 Using Databases you can chose your preferred API: Hibernate ORM JDBI Data Access #DataSource con"guration via YAML database: driverclass : org.postgresql.driver url: 'jdbc:postgresql://db.example.com/db-prod' user: pg-user password: iams00persecreet

19 JDBI the "dropwizard-jdbi" module allows us to create a database connections and Data Access Objects (DAO) through which we will query the database making use of the API provided by the JDBI project ( ) public void run(exampleconfiguration config, Environment environment) { final DBIFactory factory = new DBIFactory(); final DBI jdbi = factory.build(environment, config.getdatasourcefactory(), "postgresql"); final UserDAO dao = jdbi.ondemand(userdao.class); environment.jersey().register(new UserResource(dao)); public interface UserDAO into users (sessionid, name) values (:sessionid, int insert(@bind("sessionid") String * from users") List<User> getallusers();

20 Managed Objects (Example MongoDB) public class ManagedMongoClient extends MongoClient implements Managed { public ManagedMongoClient(MongoClientURI uri) throws UnknownHostException { public void start() throws Exception public void stop() throws Exception { close(); public class App extends Application<AppConfiguration> public void run(appconfiguration config, Environment environment) { ManagedMongoClient mongoclient = config.getmongo().build(); environment.lifecycle().manage(mongoclient); DB db = mongoclient.getdb(config.getmongo().getdbname());

21 Operations friendly Dropwizard provides some handy features to support operational work Healthchecks Commands (executable actions via CL) Tasks (executable actions via HTTP) Metrics (via Dropwizard Metrics) Easy con"gurable Logging (Logback, SLF4J)

22 Application Healthchecks

23 Healthchecks a runtime test which you can use to verify your application s behaviour, depencencies etc. in its environment Health checks should lightly test service dependencies, e.g. databases, downstream services, etc. $ curl {"deadlocks":{"healthy":true,"database":{"healthy":true

24 Healthcheck Class Example public class DatabaseHealthCheck extends HealthCheck { private final HibernateBundle hibernate; public DatabaseHealthCheck(HibernateBundle hibernate) { super("database"); this.hibernate = protected Result check() throws Exception { if(!hibernate.getsessionfactory().isclosed()) { return Result.healthy(); else { return Result.unhealthy("Cannot connect to database"); adding the healthcheck to the application environment.addhealthcheck(new DatabaseHealthCheck(hibernate));

25 Deployment into the Cloud Example of deploying a Dropwizard App to the Heroku Cloud heroku create web: java $JAVA_OPTS -Ddw.http.port=$PORT -Ddw.http.adminPort=$PORT -jar target/myproject-1.0-snapshot.jar server config.yaml git push heroku master -----> Discovering process types Procfile declares types -> web -----> Compiled slug size: 57.7MB -----> Launching... done, v9 deployed to Heroku

26 Metrics almost all applications need the ability to report key statistics metrics library written by Dropwizard team supports Meters, Gauges, Histograms, and Timers

27 Monitoring a Dropwizard Application (visualize pushed metrics)

28 Testing a Dropwizard Application "dropwizard-testing" module can be easily used for testing your application representation classes and resource classes Fixtures for unit testing representations Easily unit test resources using mock DAOs Excellent integration test support Prefer AssertJ $uent-assertions JUnit rule for full-stack testing of your entire app!resourcetestrule DropwizardClientRule DropwizardAppRule DropwizardTestSupport

29 Integration Test Example public class HelloResourceTest public ResourceTestRule resource = ResourceTestRule.builder().addResource(new public void testgetgreeting() { String expected = "Hello world!"; //Obtain client Client client = resource.client(); //Get WebTarget from client using URI of root resource. WebTarget hellotarget = client.target(" //To invoke response we use Invocation.Builder //and specify the media type of representation asked from resource. Invocation.Builder builder = hellotarget.request(mediatype.text_plain); //Obtain response. Response response = builder.get(); //Do assertions. assertequals(response.status.ok, response.getstatusinfo()); String actual = response.readentity(string.class); assertequals(expected, actual);

30 Dropwizard vs. Spring Boot Main di!erence is dependency injection support Spring s core comes with it s built in dependency injection support Dropwizard doesn t come out of the box with DI Dropwizard o!ers integrations with other DI frameworks like Guice, CDI both frameworks have a special module for testing including JUnit and Mockito dependencies. Spring Boot is a part of Spring ecosystem and suits best for Springoriented projects Spring o!ers broader list of supported services - REST, JMS, Messaging... Dropwizard owns popular metrics library

31 Dropwizard vs. Spring Boot

32 Anything else?

33 Additional Dropwizard Modules and Tooling

34 Dropwizard and Dependency Injection only Jersey H2K dependency injection support out-of-the-box useful for simple cases for more features a existing DI framework must be included Google Guice Weld CDI Spring public void run(exampleserviceconfiguration conf, Environment env) throws Exception { Injector injector = Guice.createInjector(); env.addresource(injector.getinstance(helloresource.class)); an additional "H2K-bridge" is needed to avoid clashes in DI <dependency> <groupid>org.glassfish.hk2</groupid> <artifactid>guice-bridge</artifactid> <version>2.4.0-b31</version> </dependency>

35 Database Migration with Liquibase Validation View Templates Authentication

36 Questions

37