Showing posts with label Spring Boot. Show all posts
Showing posts with label Spring Boot. Show all posts

Friday, June 5, 2020

Auditing in MySQL

One of the important requirements in many RDBMS based workloads is to have audit log where any row in any table is stamped with who changed it and  when was it changed? To do this in every place where the table is modified is extremely cumbersome. In this blog post we look at how we can enable the springframework based auditing framework to perform this activity.

Before we do that, we need to upgrade the versions for our dependencies since I have been using this project for quite sometime. Also I decided to use lombok logging annotation and removed all the dependencies on log4j.

Here are the modifications to the pom.xml for setting dependencies.

Now we look at our User entity. We need to add auditing fields to this table. Since in a realistic project one would have multiple entities, we create a abstract entity base class with all the audit fields. We also move the primary key to the abstract base class. When we do that, hibernate provides multiple ways of mapping the entities to the database schema. We want all the parent attributes to be stored in a single table with the child class attribute. To accomplish that, we need to add @MappedSuperClass to the base class.

As we can see, we have added five attributes in the base class. One is the id for all our entities and rest four will be used for auditing purposes.
At this time we also add another layer to our code. Currently all the Endpoints directly call the Repository layer, this causes a problem if we want to write functions that can be reused across different endpoints. An example of this need is retrieveUser method that takes an argument that could be a username or a email. Currently this method lies in the Endpoint layer as a private method. This is a useful method in many different contexts, so we create a new UserService layer and move this method there.

Now, let's get to the original task of enabling auditing. First we define a Auditing Config as below.

We had earlier defined a ThreadLocal that is used by the auditAware method defined above to extract currently logged in user and return its userId. As we can see the audit fields in the AbstractBaseEntity expects a Long for @createdBy and  @LastModifiedBy fields. The EntityAuditConfig also has annotation @EnableJpaAuditing which is required.
At this point we also add a new endpoint called ProfileEndpoint which can be used to manage the entity that represents a user profile. This entity currently only contains a url.
Now if we perform any operation on any of the endpoint, we will see the auditing fields automatically populated. Give it a spin. It is a life saver in many productions applications. I have had situations where users changed their passwords, forgot them and then complained saying that they have been hacked. 
The complete code for this and previous posts can be found at my github repository. This tutorial changes are under v1.5.

Wednesday, April 10, 2019

Kafka and Spring

Kafka has become a very popular platform and is being used as a stream, journal and even eventing system. In this post, we explore how to integrate Kafka with spring framework application. First, we add the Kafka bootstrap server details in the file.

Let's also add dependencies in pom.xml.

Now, for each Kafka topic, we create a listener class. The listener class provides a callback method that is called when any message is retrieved on that topic.

Now we create an endpoint through which we inject a message in the queue. The message is sent to the queue and is retrieved by the listener.

We autowire a KafkaTemplate instance that is used to send the message to the queue.

$ curl -X POST \
>   'http://localhost:8081/send?token=3193fa24-a0ba-451b-83ff-eb563c3fd43b-cdf12811-7e41-474b-8fa6-e8fefd4a738c' \
>   -H 'Content-Type: application/json' \
>   -H 'Postman-Token: e281e3c5-0dae-4bb7-ac8d-6555f66a18c6' \
>   -H 'cache-control: no-cache' \
>   -H 'token: 3193fa24-a0ba-451b-83ff-eb563c3fd43b-cdf12811-7e41-474b-8fa6-e8fefd4a738c' \
>   -d '{
> "message" : "This is my message!"
> }'
Message sent successfully!.
The receipt of message is indicated in the spring server log.

2019-04-10 14:28:03.969  INFO 31091 --- [ntainer#0-0-C-1] i.s.b.t.listeners.MyTopicKafkaListener   : Received Promise message This is my message!

Sunday, March 10, 2019

Spring Boot and Docker Containers

With microservices based deployment, the first step is to dockerize your software. In our case, we want to create docker images for each of our microservices so that we can orchestrate them better. I have decided to use container registry provided by Google to build and upload the images.

The first thing we need to do is to create a dependency to spring-cloud-dependencies pom. Then we add a dependency to spring-cloud-config-server. Then we add a dockerfile-maven-plugin. Now we need to keep in mind that in the configuration for dockerfile-maven-plugin we need to provide the repository. If can see that our repository starts with This makes sure that the image after creation is pushed to the container registry hosted by Google. If you want to have some other registry, you need to provide it in the form hostname:portnumber.
Now we can issue the following command the docker image would be build and pushed to google registry.

$ mvn deploy -DskipTests
[INFO] --- dockerfile-maven-plugin:1.4.10:push (default) @ customer ---
[INFO] Using Google application default credentials
[INFO] loaded credentials for user account with
[INFO] The push refers to repository []
[INFO] Image 967d96afcc46: Preparing
[INFO] Image 36e051842720: Preparing
[INFO] Image d1646aaa6540: Preparing
[INFO] Image 19382582b926: Preparing
[INFO] Image 41715d8d7d2b: Preparing
[INFO] Image f3a38968d075: Preparing
[INFO] Image a327787b3c73: Preparing
[INFO] Image 5bb0785f2eee: Preparing
[INFO] Image f3a38968d075: Waiting
[INFO] Image a327787b3c73: Waiting
[INFO] Image 5bb0785f2eee: Waiting
[INFO] Image 36e051842720: Layer already exists
[INFO] Image 41715d8d7d2b: Layer already exists
[INFO] Image d1646aaa6540: Layer already exists
[INFO] Image 19382582b926: Layer already exists
[INFO] Image 967d96afcc46: Pushing
[INFO] Image a327787b3c73: Layer already exists
[INFO] Image 5bb0785f2eee: Layer already exists
[INFO] Image f3a38968d075: Layer already exists
[INFO] Image 967d96afcc46: Pushed
[INFO] 0.0.1-SNAPSHOT: digest: sha256:f6bad4811f867dd75225797bee684ea43c0ddaf2b83de1b419a9f75e9a3941bc size: 2001
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 47.638 s
[INFO] Finished at: 2019-03-10T19:58:27+05:30
[INFO] Final Memory: 55M/857M
[INFO] ------------------------------------------------------------------------

We can see below that the image is now pushed to google container registry.
$ docker images
REPOSITORY                     TAG                 IMAGE ID            CREATED             SIZE   0.0.1-SNAPSHOT      a566e2f28705        19 seconds ago      518MB                       8c61d1a5aef4        13 minutes ago      518MB