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Deploying a web application using the Java Servlet API and YDB

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Updated at September 24, 2024

Learn how to use serverless technologies and the Java Servlet API to create a simple web application for managing a task list.

To create a web application:

  1. Prepare your cloud.
  2. Prepare the environment.
  3. Create an Yandex Object Storage bucket.
  4. Create a YDB database.
  5. Create functions Yandex Cloud Functions.
  6. Create an API gateway.
  7. Test your application.

If you no longer need the resources you created, delete them.

Getting started

Sign up for Yandex Cloud and create a billing account:

  1. Go to the management console and log in to Yandex Cloud or create an account if you do not have one yet.
  2. On the Yandex Cloud Billing page, make sure you have a billing account linked and it has the ACTIVE or TRIAL_ACTIVE status. If you do not have a billing account, create one.

If you have an active billing account, you can go to the cloud page to create or select a folder for your infrastructure to operate in.

Learn more about clouds and folders.

The cost of resources to support a web application includes:

Prepare the environment

  1. Create a service account and assign it the editor role for your folder.

  2. Clone the repository with the project:

    git clone https://github.com/yandex-cloud-examples/yc-serverless-servlet

  3. Add the contents of the yc-serverless-servlet local repository you cloned to the servlet.zip archive. You will need this archive later to create Yandex Cloud Functions functions.

Create an Object Storage bucket

Create a bucket and upload index.html there:

  1. In the management console, select the folder where you wish to create the bucket.
  2. Select Object Storage.
  3. Click Create bucket.
  4. On the bucket creation page:
    1. Enter a name for the bucket according to the naming requirements.
    2. Limit the maximum bucket size, if required.
    3. In the Object read access, Object listing access, and Read access to settings fields, select Restricted.
    4. Select the default storage class.
    5. Click Create bucket to complete the operation.
  5. Select the created bucket.
  6. Click Upload and select the src/main/resources/index.html file in the project folder.
  7. Select the storage class for the file and click Upload.

Create a Managed Service for YDB database

  1. Create a database in Serverless mode:

    1. In the management console, select the folder where you created the bucket.

    2. Select Managed Service for YDB.

    3. Click Create a database.

    4. Enter the database Name. The naming requirements are as follows:

      • The name must be from 3 to 63 characters long.
      • It may contain lowercase Latin letters, numbers, and hyphens.
      • The first character must be a letter and the last character cannot be a hyphen.

    5. Under Database type, select Serverless.

    6. Click Create a database.

    7. Wait until the database starts. While being created, your database will have the Provisioning status. Once it is ready for use, its status will change to Running.

    8. Select the database created.

    9. Under Connection, find the Endpoint field and save its value. You will need it when creating functions.

  2. Create a table named Tasks:

    1. In the management console, select the folder where you created the database.

    2. Select Managed Service for YDB.

    3. Select a database on the Databases page.

    4. To open the DB root directory, go to the Navigation tab.

    5. To make a query to the database, click New SQL query in the top-right corner. The Query page opens.

    6. In the Query field, enter:

      CREATE TABLE Tasks (
  TaskId Utf8,
  Name Utf8,
  Description Utf8,
  CreatedAt Datetime,
  PRIMARY KEY (TaskId)
);

    7. Click Run.

    Run the following query:

    ydb -e grpcs://<YDB_endpoint> -d <db_name> \
scripting yql -s \
"CREATE TABLE Tasks
(
  TaskId Utf8,
  Name Utf8,
  Description Utf8,
  CreatedAt Datetime,
  PRIMARY KEY (TaskId)
);"

Create Cloud Functions functions

Create a function for each servlet:

  1. In the management console, go to the folder where you created the bucket and database.
  2. Select Cloud Functions.
  3. Click Create function.
  4. Enter a name, e.g., add-task, and description for the function.
  5. Click Create.
  6. Under Editor, select the java21 runtime environment, disable Add files with code examples and click Continue.
  7. Prepare the function code. To do this, select ZIP archive in the Method field.
  8. In the File field, click Attach file and select the servlet.zip archive created earlier.
  9. In the Entry point field, enter yandex.cloud.examples.serverless.todo.AddTaskServlet.
  10. Set Timeout, sec to 10.
  11. In the Service account field, enter the account that you created when preparing the environment.
  12. Add environment variables:
    • ENDPOINT: Enter the first part of the Endpoint field value saved when creating the YDB database (the one between grpcs:// and /?database=), e.g., ydb.serverless.yandexcloud.net:2135.
    • DATABASE: Enter the second part of the Endpoint field value saved when creating the YDB database (the one following /?database=), e.g., /ru-central1/r1gra875baom********/g5n22e7ejfr1********.
  13. Click Save changes.
  14. On the Overview page, enable Public function.
  15. Repeat steps 3-14 and create a function named list-tasks with the yandex.cloud.examples.serverless.todo.ListTasksServlet entry point.
  16. Repeat steps 3-14 and create a function named delete-task with the yandex.cloud.examples.serverless.todo.DeleteTaskServlet entry point.

  1. Create a function named add-task:

    yc serverless function create --name=add-task

    Result:

    id: d4ejb1799eko********
folder_id: aoek49ghmknn********
created_at: "2021-03-08T14:07:32.134Z"
name: add-task
log_group_id: eolm8aoq9vcp********
http_invoke_url: https://functions.yandexcloud.net/d4ejb1799eko********
status: ACTIVE

  2. Create a version of the add-task function:

    yc serverless function version create \
  --function-name=add-task \
  --runtime java21 \
  --entrypoint yandex.cloud.examples.serverless.todo.AddTaskServlet \
  --memory 128m \
  --execution-timeout 10s \
  --source-path ./servlet.zip \
  --environment DATABASE=<db_name>,ENDPOINT=<YDB_endpoint>

    Where:

    • --function-name: Name of the function a version of which you want to create.
    • --runtime: Runtime environment.
    • --entrypoint: Entry point in the following format: <function_file_name>.<handler_name>.
    • --memory: Amount of RAM.
    • --execution-timeout: Maximum function running time before the timeout is reached.
    • --source-path: Path to the previously created servlet.zip archive with the function code and required dependencies.
    • --environment: Environment variables in key=value format.

    Result:

    done (1s)
id: d4evvn8obisa********
function_id: d4ejb1799eko********
...
tags:
- $latest
log_group_id: ckg3qh8h363p********

  3. Make the function public:

    yc serverless function allow-unauthenticated-invoke add-task

    Result:

    done (1s)

  4. Repeat steps 1-3 and create a function named list-tasks with the yandex.cloud.examples.serverless.todo.ListTasksServlet entry point.

  5. Repeat steps 1-3 and create a function named delete-task with the yandex.cloud.examples.serverless.todo.DeleteTaskServlet entry point.

Use the create, createVersion, and setAccessBindings API methods for the Function resource.

You can create a function and its version using the Yandex Cloud Toolkit plugin for the IDE family on the IntelliJ platform from JetBrains.

Create an API gateway

To ensure interaction between services, create an API gateway:

  1. In the management console, select the folder where you created your bucket, database, and functions.

  2. Select API Gateway.

  3. Click Create API gateway.

  4. Enter a name and description of the gateway.

  5. In the Specification field, add the specification:

    openapi: 3.0.0
info:
  title: ToDo list
  version: 1.0.0
paths:
  /:
    get:
      x-yc-apigateway-integration:
        type: object-storage
        bucket: <bucket>
        object: index.html
        presigned_redirect: false
        service_account: <service_account>
      operationId: static
  /add:
     post:
       x-yc-apigateway-integration:
         type: cloud-functions
         function_id: <add-task_ID>
       operationId: addTask
  /list:
    get:
      x-yc-apigateway-integration:
        type: cloud-functions
        function_id: <list-tasks_ID>
      operationId: listTasks
  /delete:
    delete:
      x-yc-apigateway-integration:
        type: cloud-functions
        function_id: <delete-task_ID>
      operationId: deleteTask

    Where:

    • bucket: Name of the bucket containing index.html.
    • service_account: ID of the service account you created when preparing the environment.
    • /add section, function_id parameter: add-task function ID.
    • /list section, function_id parameter: list-tasks function ID.
    • /delete section, function_id parameter: delete-task function ID.

  6. Click Create.

  1. Save the following specification to the todo.yaml file:

    openapi: 3.0.0
info:
  title: ToDo list
  version: 1.0.0
paths:
  /:
    get:
      x-yc-apigateway-integration:
        type: object-storage
        bucket: <bucket>
        object: index.html
        presigned_redirect: false
        service_account: <service_account>
      operationId: static
  /add:
    post:
      x-yc-apigateway-integration:
        type: cloud-functions
        function_id: <add-task_ID>
      operationId: addTask
  /list:
    get:
      x-yc-apigateway-integration:
        type: cloud-functions
        function_id: <list-tasks_ID>
      operationId: listTasks
  /delete:
    delete:
      x-yc-apigateway-integration:
        type: cloud-functions
        function_id: <delete-task_ID>
      operationId: deleteTask

    Where:

    • bucket: Name of the bucket containing index.html.
    • service_account: ID of the service account you created when preparing the environment.
    • /add section, function_id parameter: add-task function ID.
    • /list section, function_id parameter: list-tasks function ID.
    • /delete section, function_id parameter: delete-task function ID.

  2. Create an API gateway:

    yc serverless api-gateway create \
  --name todo-list \
  --spec=todo.yaml \
  --description "simple todo list"

    Result:

    done (41s)
id: d5delqeel34q********
folder_id: b1g86q4m5vej********
created_at: "2021-03-08T14:07:32.134Z"
name: todo-list
description: simple todo list
status: ACTIVE
domain: d5delqeel34q********.apigw.yandexcloud.net
log_group_id: ckg2hdmevnvc********

You can create an API gateway using the Yandex Cloud Toolkit plugin for the IDE family on the IntelliJ platform from JetBrains.

Test the application

To open the app, follow the link in the Default domain field of the created API gateway.

How to delete the resources you created

To stop paying for the resources you created:

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