# Deploying a web application using the Java Servlet API Learn how to use the serverless technology and Java Servlet API to create a simple web application for managing a to-do list. To create a web app: 1. [Get your cloud ready](#before-begin). 1. [Set up your environment](#prepare). 1. [Create a Yandex Object Storage bucket](#create-bucket). 1. [Create a YDB](#create-db). 1. [Create Yandex Cloud Functions](#create-functions). 1. [Create an API gateway](#create-api-gw). 1. [Test your application](#test). If you no longer need the resources you created, [delete them](#clear-out). ## Getting started {#before-begin} Sign up for Yandex Cloud and create a [billing account](../../billing/concepts/billing-account.md): 1. Navigate to the [management console](https://console.yandex.cloud) and log in to Yandex Cloud or create a new account. 1. On the **[Yandex Cloud Billing](https://center.yandex.cloud/billing/accounts)** page, make sure you have a billing account linked and it has the `ACTIVE` or `TRIAL_ACTIVE` [status](../../billing/concepts/billing-account-statuses.md). If you do not have a billing account, [create one](../../billing/quickstart/index.md) and [link](../../billing/operations/pin-cloud.md) a cloud to it. If you have an active billing account, you can create or select a [folder](../../resource-manager/concepts/resources-hierarchy.md#folder) for your infrastructure on the [cloud page](https://console.yandex.cloud/cloud). [Learn more about clouds and folders here](../../resource-manager/concepts/resources-hierarchy.md). ### Required paid resources {#paid-resources} The web application support cost includes: * Fee for the number of requests to the API gateway and outgoing traffic (see [Yandex API Gateway pricing](../../api-gateway/pricing.md)). * Fee for YDB operations and data storage (see [Yandex Managed Service for YDB pricing](../../ydb/pricing/serverless.md)). * Fee for the number of function calls, computing resources allocated to run a function, and outgoing traffic (see [Cloud Functions pricing](../pricing.md)). ## Set up your environment {#prepare} 1. [Create](../../iam/operations/sa/create.md#create-sa) a service account and [assign](../../iam/operations/roles/grant.md#cloud-or-folder) it the `editor` role for your folder. 1. Clone the [repository](https://github.com/yandex-cloud-examples/yc-serverless-servlet) with the project: ```bash git clone https://github.com/yandex-cloud-examples/yc-serverless-servlet ``` 1. 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 functions in Yandex Cloud Functions. ## Create an Object Storage bucket {#create-bucket} Create a [bucket](../../storage/concepts/bucket.md) and upload `index.html` to it: {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), select the folder where you want to create a bucket. 1. Navigate to **Object Storage**. 1. Click **Create bucket**. 1. On the bucket creation page: 1. Enter a name for the bucket by following the [naming conventions](../../storage/concepts/bucket.md#naming). 1. Limit the maximum bucket size, if required. 1. In the **Read objects**, **Read object list**, and **Read settings** fields, select `With authorization`. 1. Select the default [storage class](../../storage/concepts/storage-class.md). 1. Click **Create bucket** to complete the operation. 1. Select the bucket you created. 1. Click **Upload** and select `src/main/resources/index.html` in the project directory. 1. Select the [storage class](../../storage/concepts/storage-class.md) for the file and click **Upload**. {% endlist %} ## Create a database in Managed Service for YDB {#create-db} 1. Create a database in [serverless mode](../../ydb/concepts/serverless-and-dedicated.md#serverless): {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), select the folder where you created the bucket. 1. Navigate to **Managed Service for YDB**. 1. Click **Create a database**. 1. Specify a **Name** for the database. The naming requirements are as follows: * Length: between 3 and 63 characters. * It can only contain lowercase Latin letters, numbers, and hyphens. * It must start with a letter and cannot end with a hyphen. 1. Under **Database type**, select `Serverless`. 1. Click **Create a database**. 1. Wait for the database to start. While being created, your database will have the `Provisioning` status. Once it is ready for use, its status will change to `Running`. 1. Select the created database. 1. Under **Connection**, find the **Endpoint** field and save its value. You will need it when creating functions. {% endlist %} 1. Create a table named `Tasks`: {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), select the folder where you created the database. 1. Navigate to **Managed Service for YDB**. 1. Select the database on the **Databases** page. 1. To open the database root directory, navigate to the **Navigation** tab. 1. To query your database, click **New SQL query** in the top-right corner. This will open the **Query** page. 1. In the **Query** field, enter: ```sql CREATE TABLE Tasks ( TaskId Utf8, Name Utf8, Description Utf8, CreatedAt Datetime, PRIMARY KEY (TaskId) ); ``` 1. Click **Run**. - CLI {#cli} Run this query: ```bash ydb -e grpcs:// -d \ scripting yql -s \ "CREATE TABLE Tasks ( TaskId Utf8, Name Utf8, Description Utf8, CreatedAt Datetime, PRIMARY KEY (TaskId) );" ``` {% endlist %} ## Create Cloud Functions {#create-functions} Create a [function](../concepts/function.md) for each servlet: {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), navigate to the folder where you created the bucket and the database. 1. Navigate to **Cloud Functions**. 1. Click **Create function**. 1. Enter a name, e.g., `add-task`, and description for the function. 1. Click **Create**. 1. Under **Editor**, select `java21` as the runtime, disable **Add files with code examples**, and click **Continue**. 1. Prepare the function code. To do this, select `ZIP archive` in the **Code source** field. 1. In the **File** field, click **Attach file** and select `servlet.zip` you created earlier. 1. In the **Entry point** field, enter `yandex.cloud.examples.serverless.todo.AddTaskServlet`. 1. Set **Timeout** to `10`. 1. In the **Service account** field, specify the account you created when [setting up your environment](#prepare). 1. Add these environment variables: * `ENDPOINT`: Enter the first part of the **Endpoint** field value you saved when [creating your YDB](#create-db) (the one between `grpcs://` and `/?database=`), e.g., `ydb.serverless.yandexcloud.net:2135`. * `DATABASE`: Enter the second part of the **Endpoint** field value you saved when [creating your YDB](#create-db) (the one following `/?database=`), e.g., `/ru-central1/r1gra875baom********/g5n22e7ejfr1********`. 1. Click **Save changes**. 1. On the **Overview** page, enable **Public function**. 1. Repeat steps 3 through 14 to create a function named `list-tasks` with the `yandex.cloud.examples.serverless.todo.ListTasksServlet` entry point. 1. Repeat steps 3 through 14 to create a function named `delete-task` with the `yandex.cloud.examples.serverless.todo.DeleteTaskServlet` entry point. - CLI {#cli} 1. Create a function named `add-task`: ```bash yc serverless function create --name=add-task ``` Result: ```text 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 ``` 1. Create a version of the `add-task` function: ```bash 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=,ENDPOINT= ``` Where: * `--function-name`: Name of the function whose version you want to create. * `--runtime`: Runtime environment. * `--entrypoint`: Entry point in ``.`` format. * `--memory`: Amount of RAM. * `--execution-timeout`: Maximum function running time before timeout. * `--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: ```text done (1s) id: d4evvn8obisa******** function_id: d4ejb1799eko******** ... tags: - $latest log_group_id: ckg3qh8h363p******** ``` 1. Make the function public: ```bash yc serverless function allow-unauthenticated-invoke add-task ``` Result: ```text done (1s) ``` 1. Repeat steps 1 through 3 to create a function named `list-tasks` with the `yandex.cloud.examples.serverless.todo.ListTasksServlet` entry point. 1. Repeat steps 1 through 3 to create a function named `delete-task` with the `yandex.cloud.examples.serverless.todo.DeleteTaskServlet` entry point. - API {#api} Use the [create](../functions/api-ref/Function/create.md), [createVersion](../functions/api-ref/Function/createVersion.md), and [setAccessBindings](../functions/api-ref/Function/setAccessBindings.md) API methods for the [Function](../functions/api-ref/Function/index.md) resource. {% endlist %} ## Create an API gateway {#create-api-gw} To enable interaction between services, create an API gateway: {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), select the folder where you created your bucket, database, and functions. 1. Navigate to **API Gateway**. 1. Click **Create API gateway**. 1. Enter a name and description for the gateway. 1. In the **Specification** field, add this specification: ```yaml openapi: 3.0.0 info: title: ToDo list version: 1.0.0 paths: /: get: x-yc-apigateway-integration: type: object-storage bucket: object: index.html presigned_redirect: false service_account_id: operationId: static /add: post: x-yc-apigateway-integration: type: cloud-functions function_id: operationId: addTask /list: get: x-yc-apigateway-integration: type: cloud-functions function_id: operationId: listTasks /delete: delete: x-yc-apigateway-integration: type: cloud-functions function_id: operationId: deleteTask ``` Where: * `bucket`: Name of the bucket containing `index.html`. * `service_account_id`: ID of the service account you created when [setting up your environment](#prepare). * `/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. 1. Click **Create**. - CLI {#cli} 1. Save the following specification to `todo.yaml`: ```yaml openapi: 3.0.0 info: title: ToDo list version: 1.0.0 paths: /: get: x-yc-apigateway-integration: type: object-storage bucket: object: index.html presigned_redirect: false service_account_id: operationId: static /add: post: x-yc-apigateway-integration: type: cloud-functions function_id: operationId: addTask /list: get: x-yc-apigateway-integration: type: cloud-functions function_id: operationId: listTasks /delete: delete: x-yc-apigateway-integration: type: cloud-functions function_id: operationId: deleteTask ``` Where: * `bucket`: Name of the bucket containing `index.html`. * `service_account_id`: ID of the service account you created when [setting up your environment](#prepare). * `/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. 1. Create an API gateway: ```bash yc serverless api-gateway create \ --name todo-list \ --spec=todo.yaml \ --description "simple todo list" ``` Result: ```text 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: d5dm1lba80md********.i9******.apigw.yandexcloud.net log_group_id: ckg2hdmevnvc******** ``` {% endlist %} ## Test the application {#test} To open the application, follow the link in the **Default domain** field of the API gateway you created. ## How to delete the resources you created {#clear-out} To stop paying for the resources you created: * [Delete the bucket](../../storage/operations/buckets/delete.md). * [Delete the database](../../ydb/operations/manage-databases.md#delete-db). * [Delete the functions](../operations/function/function-delete.md). * [Delete the API gateway](../../api-gateway/operations/api-gw-delete.md).