Run a Spring Boot application on OCI Compute Instance

In this article, we will see how to deploy a spring boot application in Oracle cloud compute instance.

Creating a new Spring Boot app and running it locally

We will create a spring boot app and test locally. 

start.spring.io can be used to start. Or there is a sample Hello World project I have created can be referred https://github.com/pallabrath/myexpjava/tree/master/spring-boot/spring-web-rest-demo

package myexpjava.demo; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.ResponseBody; @Controllerpublic class DemoController { @GetMapping("/hello") @ResponseBody public String sayHello() { return "Hello World !!!"; } } ./gradlew bootRun This command will run the application and we can test the same in any browser in the url http://localhost:8080/hello/ It should print Hello World !!! in browser Creating an OCI compute instance and deploy the app. We will try to deploy this app directly to a single OCI compute instance and we will run it.  For this example, we have used the standard Oracle-Linux-7.8 image. To create a compute instance in OCI console, we need to navigate compute and create instance. To access the instance we need ssh keys, to genarte the same please refer https://docs.cloud.oracle.com/en-us/iaas/Content/Compute/Tasks/managingkeypairs.htm  Once the compute is ready. We need to install Java, as our Spring Boot App requires a java environment to run. 1. ssh to compute instance ssh -i ~/.ssh/oci_compute opc@<public ip> of the compute instance> 2. Install java in the compute instance, for this example jre is enough. sudo yum install jre-12.x86_64 3. Configure the firewall to open port 8080, as our app will run in 8080 sudo firewall-cmd --zone=public --permanent --add-port=8080/tcp sudo firewall-cmd --reload Make a directory where we will copy our spring app mkdir spring-app/ 4. Network configuration to allow Internet traffic to our compute instance.      a) We need an internet gateway configured in the VCN where the compute instance belongs      b) Route table entry to allow the traffic through the internet gateway     c) Security Ingress rule needs to be added to allow traffic.  5. Copy our Spring Boot app from laptop to compute instance and run. ./gradlew clean build This will build and create the spring-web-rest-demo-1.0.jar in ./build/libs To copy the same to our compute instance scp -i ~/.ssh/oci_compute build/libs/spring-web-rest-demo-1.0.jar opc@<public ip>:spring-app/ Now ssh to the compute and run the app ssh -i ~/.ssh/oci_compute opc@<public ip> of the compute instance> java -jar spring-app/spring-web-rest-demo-1.0.jar Our spring app should run in port 8080. If all the configs are correct  we should able to see Hello World !!! in the browser, by trying compute's  http://<public ip>:8080/hello If you don't see please revisit step 3 and 4

Connecting Google cloud SQL from App engine.

Google cloud platform support PHP application in its app engine. App Engine is an elastic container it automatically scales up and down based on the traffic.

Here is the https://cloud.google.com/appengine/docs/standard/php7/quickstart explaining how to deploy PHP application into GCP app.

The scope of this article is how to connect to the cloud sql in your PHP from app engine. To deploy into app engine we need to configure some meta information in app.yaml

If we are connecting by dsn we don't need any special configuration. we can refer to the database directly like

mysql:unix_socket=/cloudsql/<MY-PROJECT>:<INSTANCE-REGION>:<MY-DATABASE>;dbname=<my_db>

I am assuming both your app engine and cloud database in the same project. Else we have to explicitly give access.

$dbdsn = "mysql:unix_socket=/cloudsql/<MY-PROJECT>:<INSTANCE-REGION>:<MY-DATABASE>;dbname=<my_db>";

$conn = new PDO($dbdsn, $username, $password);

We can add the dsn in app.yaml read as an environment variable.

In app.yaml

env_variables:

  DB_DSN: mysql:unix_socket=/cloudsql/<MY-PROJECT>:<INSTANCE-REGION>:<MY-DATABASE>;dbname=<my_db>

DB_USER: my-db-user

DB_PASS: my-db-pass

DB_NAME: my_db 

DB_SERVER: my_server

And in the code

$dbdsn = getenv('DB_DSN');

$username = getenv('DB_USER');

$password = getenv('DB_PASS');

$conn = new PDO($dbdsn, $username, $password);

If we want to do tcp connection by providing host and port

$conn = new mysqli($servername, $username, $password, $dbname);

Then app.yaml we have to add 

beta_settings:

  cloud_sql_instances: <INSTANCE_CONNECTION_NAME>=tcp:<PORT>

And in the code $servername= 172.17.0.1:<PORT>;

For more details # https://cloud.google.com/sql/docs/mysql/connect-app-engine

My example code # https://github.com/pallabrath/myexpjava/tree/master/vlog/gcp/php-mysql-appEngine-clouddb%20/src

Rest apis powered by GraphQL

We can understand "Rest Api" means any system expose its functionality over http. So the consumer of api can make a http request to avail the functionalities. JSON is the data format in which client and server communicate over http.

GraphQL is a query language for api which enable the client of rest apis to ask what they need exactly. The same time server side its super easy to expose more functionaries in a generic way and cater lots of specialized request. 

more details # https://graphql.org/

GarphQL in Java # https://www.graphql-java.com/

In this article we will see an example where GraphQL is used with JAX-RS (Jersey) based rest implementation. And we will use Hibernate as Data Fetcher for GraphQL.

Its a standard gradle project, created with eclipse.  Here is the link to my github.

https://github.com/pallabrath/myexpjava/tree/master/GqlDemo

1. Lets start with build.gradle

We have the dependencies for jersey, graphql, hibernate, ojdbc driver and some helpers like gson and gauva.

2. In web.xml we have initialised the jersey servlet, there we have specified init parameters to look for com.rest package.

3. Inside source we have com.rest.Employee.java which expose the rest end point GqlDemo/rest/employee

We have the Query() method to handle the incoming http post request for graph ql queries.

4. We have created GraphQl provider which load the schema definitions from resources/schema.graphqls
we have defined the wiring for query employeeById.

5. In GraphQLDataFetcher we have the implementation for employeeById. where we get the request parameter value and process. Here I have used hibernate to query the database.

Here is a screen shot of postman request/response.

I will try to answer if any question on this. Please let me know your feedback.