I am following the documentation to create a healthcheck for my dropwizard application for database connectivity. I wanted to know how does the healthScript get a Database class? What do I need to import in order to use teh Database class mentioned in the Documentation?
http://dropwizard.io/0.8.0-rc1/docs/manual/core.html#health-checks
This is just an example providing a general idea of what can be accomplished with healthchecks. There isn't a concrete Database class that you can import. The actual healthcheck would depend on your choice of DB connection: JDBI or Hibernate. Dropwizard also easily allows you to define your own DAO for whatever vendor / protocol you need. And if you read through that documentation you'll see that those database objects are configured just like everything else - with YAML.
Note that you can upgrade to the 0.8.0 release instead of the release candidate.
Related
I'm reading through Derby documentation and following all the instructions. I've successfully installed it (extracted it to my Linux machine and set the DERBY_HOME path). I have a complete REST API project with Angular 7 front-end and Dropwizard backend. I hard coded some data in the backend, and created all the HTTP API methods I need (GET, POST, PATCH, DELETE).
The application is fully functional, but now I need to implement the Embedded version of Derby into it. I have 0 experience with such databases, and because Dropwizard gave me enough trouble already, I cannot figure out how to get started.
Do I create a new class and get started there, how to create those SQL files and how to store data? I can't find a concrete answer to similar questions, if there are detailed explanations and examples already out there, please feel free to provide me with the resources. I know this is a noob question, but I just barely learned how HTTP works (the basics) and managed to completely create a functional REST using Angular and Dropwizard.
Consider the embedded database like a full-fledged database, that instead of being in a different environment, and maybe requiring a network connection, is packed along with your application and run in the same JVM. The same mechanisms applies between the two.
The embedded Derby Driver is located inside the derby.jar file, so it is required to have it in the classpath of your application. It should be located under %DERBY_INSTALL%\lib\, where %DERBY_INSTALL% is the installation directory. You can see by the image where it is contained.
From Oracle
Any JDBC 4.0 drivers that are found in your class path are
automatically loaded. (However, you must manually load any drivers
prior to JDBC 4.0 with the method Class.forName.)
What that means is that if the Derby driver is a JDBC 4.0 driver, you don't have to do anything else besided getting a connection via DriverManager.
If it is not a JDBC 4.0 driver, you'll have to instantiate the Driver with
Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();
Appartently you'll need that piece of code above.
Now simply get a hold on a Connection object.
DriverManager.getConnection("jdbc:derby:dbName;create=true");
From there on, you can create Statement(s) as you like. Which means you can create tables, insert rows, update rows, delete rows, etc.
To gracefully shutdown the embedded Derby database, you need to use
DriverManager.getConnection("jdbc:derby:dbName;shutdown=true"); // see the same database name "dbName"
prior to quitting the main application. It is not mandatory, but recommended.
You can create a utility class to hold an EmbeddedDataSource (docs), which will provide connections around your application.
public final class EmbeddedDerby {
private static final DataSource DATA_SOURCE;
static {
// Initialize DATA_SOURCE with EmbeddedDataSource
}
...
public static Connection getConnection() {
return DATA_SOURCE.getConnection();
}
}
I have a multi-module maven based project which has a number of Spring Boot applications, a couple of which (lets call them A and B) connect to a database (I have a separate module with the database related code on which both applications depend.) I am also using Flyway to maintain the database versioning and maintain the database structure.
What is the best approach to maintain the database properties? At the moment I have 3 places where I am repeating the same thing. I have the application.yml of module A and application.yml of module B, since both are separate Spring Boot applications. Then I have the Flyway plugin configuration again which needs the properties in the pom.xml to be able to perform its tasks, like clean, repair and migrate.
What is the proper approach to centralise and externalise this information, like the database URL, username and password? I am also facing the issue that each time I pull the new code onto the test system I have to update the same data again because it gets overwritten, and the database configuration on the test system is different from my local development environment.
What is the best strategy to manage this?
Externalize your configuration into a configuration module. This, of course, depends on how flexible Flyway / Spring Boot are from using classpath based properties.
Look at something like archaius and make your configuration truly externalized, centralized and dynamic by having it backed by, say, an external datastore. More work involved here but gives you additional benefits, like being able to change config in one place and have them dynamically picked up in running applications everywhere.
It's not an easy problem to solve and definitely involves some work to make your tools cooperate by hooking into their lifecycle.
For your flyway you could use the maven-properties-plugin. In that way you can externalize the credential to a properties file. An example is described here.
For the spring-boot application I will recommend the spring cloud config . With the spring cloud config you can externalize your config to a git repository which can be discovered over an Eureka Service, e.g. like here. I will consider to restructure the modules to independent microservices. A good infrastructure for a microservice based architecture provides the JHipster project.
I am working on Adobe CQ. I created 2-3 versions(1.2,1.2,1.3) for a particular page in my author instance. Now I tried to package my content page and installed it in another instance. I couldn't see the versions of the page which I installed in another instance.
Can anyone help me out doing this?? I want to migrate my content pages along with their versions from one CQ instance to another??
We are in the same situation. You can extract prior version details using the packaging approach, but you will be precluded from reloading them in due to the new Oak security model. The next issue is that you would need to extract and transform the data, and then reinsert due to the node ID's potentially differing, especially if you are using partial data sets to extract.
Where we have gotten to, and are proving now, is to use the new migration tool to move content from instance to instance, which purportedly has a version extract tool. I will update details here when we get our results back.
UPDATE:
We have tested the CRX2OAK migration tool, and it indeed does move versions across. Using the tool, you can specify filters to only migrate a subset of content, which will then drag the version details across as well.
It seems this approach works quite well for both single tenancy and multi tenancy approaches as it used to using a package for content.
Unfortunately, it can't be used as a portable backup system, as it is an instance to instance solution. It does, however, work well for blue/green deployment strategies.
Versions are stored by path '/jcr:system/jcr:versionStorage' in AEM.
To transfer pages with their versions just create a package with filters for content which you want to move and the version storage path as well, download package and install in other AEM.
If anyone comes across this question like me, here is the summarised answer:
You can use crx2oak utility available from link below to migrate pages and page version across instances:
https://repo.adobe.com/nexus/content/groups/public/com/adobe/granite/crx2oak/
This is a powerful utility with multiple uses (especially in upgrades) as documented in links below:
https://docs.adobe.com/docs/en/aem/6-2/deploy/upgrade/using-crx2oak.html
https://jackrabbit.apache.org/oak/docs/migration.html
The source and destination repositories need to be offline while running this utility so best to plan ahead for this type of migration.
HTH
I'm currently working on a Grails project which has a static production database with a lot of data in it. I would like to test my application using the production data, but instead of having to clone the production database I'd like to setup a proxy database to the production database.
Essentially reads of the database would go all the way to production database while writes would stop at a proxy database (preferably an h2 database). If a row was updated that came from the production database the row would be saved to the proxy database and returned, instead of the production's row, on subsequent queries.
I'd like to do all of this as transparently to the application as possible. My currently line of thinking is that I'd need to fork the Hibernate GORM implementation and make it support this use case. Has this been done before? Is there a better way?
Forking the Hibernate GORM implementation may not be a good idea. You will be stuck in your version and will have to, somehow, make this up to date with the original plugin (eg. bug fix, new implementations).
Maybe a custom TestMixin that allows you to override all registered domain classes, with new implementations of save(), get(), find() and etc can be an option. You can work with the metaClass to override this static methods and this will be triggered only on tests with the annotated mixin.
With this you can use multiple datasources in the test environment to determine which will be used.
I've been following this tutorial to get accustomed to the Play framework:
http://www.playframework.org/documentation/2.0.2/ScalaTodoList
When reaching the "Persist the tasks in a database" segment, it is unclear to me whether I have to do anything to start up the database or if this is done automatically for me. I am currently receiving this error:
[Exception: DB plugin is not registered.]
It depends on the type of database you use.
H2 database (the one used in Play! tutorial) can be used as an in-memory database or as a disk based database. Play will handle all for you if you go for this database. You don't have to run a specific service to have the persistent database.
But you will have to describe in your application.conf which driver to use and which url to access :
db.default.driver=org.h2.Driver
db.default.url="jdbc:h2:mem:play"
As you probably don't have the right driver in your classpath, you would have to include this driver lib. As explained in Play2 documentation, you can manage this in project/Build.scala. For h2 driver lib the dependency will be :
val appDependencies = Seq(
"com.h2database" % "h2" % "1.3.167"
)
After having changed your dependencies, you will need to reload the application build file and update the dependencies :
//in sbt
reload
update
How to link your play application with a database is explained here
If you want to use an other database (Mysql, Postgresql...) you will have to run the database service yourself and repeat the steps described here.