update: SQL application to restart strategy

docs/products/flink/howto/create-jar-application.md

@@ -3,28 +3,20 @@ title: Create a JAR application
 limited: true
 ---
 
-Aiven for Apache Flink® enables you to upload and deploy
-[custom code as a JAR file](/docs/products/flink/concepts/custom-jars), enhancing your
-Flink applications with advanced data
-processing capabilities.
+Aiven for Apache Flink® enables you to upload and deploy [custom code as a JAR file](/docs/products/flink/concepts/custom-jars), enhancing your Apache Flink applications with advanced data processing capabilities.
 
 ## Prerequisite
 
 - Custom JARs for Aiven for Apache Flink is a **limited availability** feature.
-  To try this feature, request it by contacting
-  our [Sales team](mailto:sales@aiven.io).
-- Once activated on your Aiven account, enable it:
-  - For a new Aiven for Apache Flink service,
-    toggle the feature during service creation.
-  - For an existing service, in
-    [Aiven Console](https://console.aiven.io/):
-    1. Select your project and choose your Aiven for Apache Flink® service.
-    1. Click **Service settings** on the left sidebar.
-    1. Scroll to the **Advanced configuration** section, and click
-        **Configure**.
-    1. In the **Advanced configuration** screen, click **Add
-       configuration options**, and using the search box, find and set
-       `custom_code` configuration to **Enabled**.
+  To try this feature, request access by contacting the [sales team](mailto:sales@aiven.io).
+- Create a new Aiven for Apache Flink service and click **Upload and deploy custom JARs**
+  to enable custom JARs during service creation.
+
+:::note
+Enabling Custom JARs for existing services is currently not possible. If you did not
+enable this feature during service creation, you must create a new service with
+Custom JARs enabled.
+:::
 
 ## Create and deploy application
 
@@ -39,6 +31,12 @@ processing capabilities.
 1.  Click **Create application** to proceed.
 1.  Click **Upload first version** to upload the first version of the
     application.
+
+    :::note
+    There is a limit on the size of the custom JAR file you can upload to an Apache Flink
+    JAR application. For more information, contact the sales or support team.
+    :::
+
 1.  In the **Upload new version** dialog:
     1. Click **Choose file** to select your custom JAR file.
     1. Select the **Terms of Service** checkbox to indicate your
@@ -48,20 +46,21 @@ processing capabilities.
     page.
 1.  To deploy the application, click **Create deployment**. In the
     **Create new deployment** dialog:
-    1.   Select the application version to deploy.
-    1.   Select a
-        [savepoint](/docs/products/flink/concepts/savepoints) if you wish to deploy from
-        a specific state. No
-        savepoints are available for the first application deployment.
-    1.   Toggle **Restart on failure** to automatically restart Flink
-        jobs upon failure.
-    1.   In the **Program args** field, provide command-line arguments
-        consisting of variables and configurations relevant to your
-        application'slogic upon submission. Each argument is limited
-        to 64 characters, with a total limit of 32 separate items.
-    1.   Specify the number of [parallel
-        instances](https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/execution/parallel/)
-        you require for the task.
+    1. Select the application version to deploy.
+    1. Select a
+       [savepoint](/docs/products/flink/concepts/savepoints) if you wish to deploy from
+       a specific state. No
+       savepoints are available for the first application deployment.
+    1. Toggle **Restart on failure** to automatically restart Flink
+       jobs upon failure. See [Restart strategy in SQL and JAR applications](/docs/products/flink/howto/restart-strategy-jar-applications)
+       for details.
+    1. In the **Program args** field, provide command-line arguments
+       consisting of variables and configurations relevant to your
+       application'slogic upon submission. Each argument is limited
+       to 64 characters, with a total limit of 32 separate items.
+    1. Specify the number of [parallel
+       instances](https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/execution/parallel/)
+       you require for the task.
 1.  Click **Deploy without a savepoint** to begin the deployment
     process.
 1.  While deploying, the application status shows **Initializing**. Once

docs/products/flink/howto/create-sql-application.md

@@ -2,11 +2,7 @@
 title: Create an SQL application
 ---
 
-In Aiven for Apache Flink®, you can create an SQL application that uses
-Apache Flink SQL to streamline the process of building data processing
-pipelines. The SQL application simplifies the process of defining source
-and sink tables, implementing data processing logic, and managing
-application deployment.
+Build data processing pipelines in Aiven for Apache Flink® by creating SQL applications using Apache Flink SQL. Set up source and sink tables, define processing logic, and manage your deployments.
 
 ## Prerequisite
 
@@ -19,82 +15,83 @@ Flink applications.
 Create an SQL application in Aiven for Apache Flink® using the [Aiven
 Console](https://console.aiven.io/):
 
-1.  In the [Aiven Console](https://console.aiven.io/), select the Aiven
-    for Apache Flink service where you want to create and deploy a Flink
-    application.
+1. In the [Aiven Console](https://console.aiven.io/), select the Aiven
+   for Apache Flink service where you want to create and deploy a Flink
+   application.
 
-2.  From the left sidebar, click **Applications** and then click
-    **Create application**.
+1. From the left sidebar, click **Applications** and then click
+   **Create application**.
 
-3.  In the **Create application** dialog, enter the name of your
-    application and select **SQL** as the application type.
+1. In the **Create application** dialog, enter the name of your
+   application and select **SQL** as the application type.
 
-4.  Click **Create application**.
+1. Click **Create application**.
 
-5.  Click **Create first version** to create the first version of the
-    application.
+1. Click **Create first version** to create the first version of the
+   application.
 
-6.  Click **Add your first source table** to add a source table.
+1. Click **Add your first source table** to add a source table.
 
-    :::note
-    As this is your first application, no other applications are
-    available to import source tables.
-    :::
+   :::note
+   As this is your first application, no other applications are
+   available to import source tables.
+   :::
 
-7.  On the **Add new source table** screen:
+1. On the **Add new source table** screen:
 
-    -   Use the **Integrated service** drop-down to select the service.
-    -   In the **Table SQL** section, enter the SQL statement to create
-        the source table.
-    -   Optionally, click **Run** to test how data is being retrieved
-        from the data source. This may vary in time based on the data
-        volume and connection speed.
-    -   Click **Add table**.
+   - Use the **Integrated service** drop-down to select the service.
+   - In the **Table SQL** section, enter the SQL statement to create
+     the source table.
+   - Optionally, click **Run** to test how data is being retrieved
+     from the data source. This may vary in time based on the data
+     volume and connection speed.
+   - Click **Add table**.
 
-8.  Click **Next** to proceed to adding a sink table and click **Add
-    your first sink table**.
+1. Click **Next** to proceed to adding a sink table and click **Add
+   your first sink table**.
 
-    :::note
-    As this is your first application, no other applications are
-    available to import sink tables.
-    :::
+   :::note
+   As this is your first application, no other applications are
+   available to import sink tables.
+   :::
 
-9.  On the **Add new sink table** screen:
+1. On the **Add new sink table** screen:
 
-    -   Use the **Integrated service** drop-down to select the service.
-    -   In the **Table SQL** section, enter the SQL statement to create
-        the sink table.
-    -   Click **Add table**.
+   - Use the **Integrated service** drop-down to select the service.
+   - In the **Table SQL** section, enter the SQL statement to create
+     the sink table.
+   - Click **Add table**.
 
-10. Click **Next** to enter the **SQL statement** that transforms the
-    data from the source stream. Optionally, click **Run** to see how
-    the data is extracted from the source.
+1. Click **Next** to enter the **SQL statement** that transforms the
+   data from the source stream. Optionally, click **Run** to see how
+   the data is extracted from the source.
 
-11. Click **Save and deploy later** to save the application. You can
-    view and access the application you created on the application
-    overview page.
+1. Click **Save and deploy later** to save the application. You can
+   view and access the application you created on the application
+   overview page.
 
-    ![Application landing page with a view of the source table, SQL statement, and sink table](/images/products/flink/application_landingpage_view.png)
+   ![Application landing page with a view of the source table, SQL statement, and sink table](/images/products/flink/application_landingpage_view.png)
 
-12. To deploy the application, click **Create deployment**. In the
-    **Create new deployment** dialog:
+1. To deploy the application, click **Create deployment**. In the
+   **Create new deployment** dialog:
 
-    -   Select the application version to deploy. The default version
-        for the first deployment is **Version: 1**.
-    -   Select a
-        [savepoint](/docs/products/flink/concepts/savepoints) if you wish to deploy from a specific state. No
-        savepoints are available for the first application deployment.
-    -   Toggle **Restart on failure** to automatically restart Flink
-        jobs upon failure.
-    -   Specify the number of [parallel
-        instances](https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/execution/parallel/)
-        you require for the task.
+   - Select the application version to deploy. The default version
+     for the first deployment is **Version: 1**.
+   - Select a
+     [savepoint](/docs/products/flink/concepts/savepoints) if you wish to deploy from a specific state. No savepoints are available for the first
+     application deployment.
+   - Toggle **Restart on failure** to automatically restart Flink
+     jobs upon failure. See [Restart strategy in SQL and JAR applications](/docs/products/flink/howto/restart-strategy-jar-applications)
+     for details.
+   - Specify the number of [parallel
+     instances](https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/execution/parallel/)
+     you require for the task.
 
-13. Click **Deploy without a savepoint** to begin the deployment
-    process.
+1. Click **Deploy without a savepoint** to begin the deployment
+   process.
 
-14. While deploying, the application status shows **Initializing**. Once
-    deployed, the status changes to **Running**.
+1. While deploying, the application status shows **Initializing**. Once
+   deployed, the status changes to **Running**.
 
 ## Create SQL applications using Aiven CLI
 

docs/products/flink/howto/restart-strategy-jar-applications.md

@@ -1,48 +1,55 @@
 ---
-title: Restart strategy in JAR applications
+title: Restart strategy in SQL and JAR applications
 ---
+Learn how Aiven for Apache Flink® applications uses restart strategies to recover from job failures, ensuring high availability and fault tolerance for your distributed applications.
 
-A restart strategy is a set of rules that Apache Flink® adheres to when
-dealing with Flink job failures. These strategies enable the automatic
-restart of a failed Flink job under specific conditions and parameters,
-which is crucial for high availability and fault tolerance in
-distributed and scalable systems.
+## About restart strategy
 
-## Default restart strategy for JAR applications
+A restart strategy is a set of rules that Apache Flink® adheres to when dealing with
+Flink job failures. These strategies enable the automatic restart of a failed Flink job
+under specific conditions and parameters, which is crucial for high availability and fault
+tolerance in distributed and scalable systems. Aiven for Apache Flink® supports restart
+strategies for both JAR and SQL applications.
 
-Aiven for Apache Flink® includes a default restart strategy for JAR
-applications. This strategy uses the **exponential-delay** technique,
-incrementally increasing the delay time between restarts up to a
-specified maximum. Once this maximum delay is reached, it remains
-constant for any subsequent restarts. The default strategy is fully
-integrated into the Aiven for Apache Flink cluster configuration and
-automatically applies to all JAR applications.
+## Default restart strategy for JAR and SQL applications
 
-### View the default strategy
+Aiven for Apache Flink® uses the **exponential-delay** strategy as the default
+restart mechanism for both **JAR and SQL applications**. This strategy incrementally
+increases the delay between restarts, reaching a configurable maximum. After reaching
+the maximum, the delay remains constant. The strategy resets the exponential delay after
+a period of successful restarts, preventing it from staying at the maximum indefinitely.
+This default strategy is integrated into the Aiven for Apache Flink cluster configuration
+and automatically applies to JAR and SQL applications.
+
+## View the default strategy
 
 You can view the default restart strategy configurations for your Aiven
 for Apache Flink cluster in the Apache Flink Dashboard. Follow these
 steps to view the current settings:
 
-1.  Access the [Aiven Console](https://console.aiven.io/) and select the
-    Aiven for Apache Flink service.
-2.  From the **Connection information** section on the overview page,
-    copy the **Service URI** and paste it into your web browser's
-    address bar.
-3.  When prompted, log in using the **User** and **Password**
-    credentials specified in the **Connection information** section.
-4.  Once in the **Apache Flink Dashboard**, click the **Job Manager**
-    from the menu.
-5.  Switch to the **Configuration** tab.
-6.  Review the configurations and parameters related to the restart
-    strategy.
+1. Access the [Aiven Console](https://console.aiven.io/) and select the
+   Aiven for Apache Flink service.
+1. From the **Connection information** section on the overview page,
+   copy the **Service URI** and paste it into your web browser's
+   address bar.
+1. When prompted, log in using the **User** and **Password**
+   credentials specified in the **Connection information** section.
+1. Once in the **Apache Flink Dashboard**, click the **Job Manager**
+   from the menu.
+1. Switch to the **Configuration** tab.
+1. Review the configurations and parameters related to the restart
+   strategy.
 
 ## Disable default restart strategy
 
-While Aiven for Apache Flink® typically recommends using the default
-restart strategy for JAR applications, there are circumstances,
-particularly during testing or debugging, where disabling automatic
-restarts might be necessary. You cannot disable the default restart
+While Aiven for Apache Flink® typically recommends following the default restart strategy
+for high availability and fault tolerance, there might be scenarios,
+especially during testing or debugging, where disabling automatic restarts
+might be beneficial.
+
+### JAR applications
+
+For JAR applications, you cannot disable the default restart
 strategy in Aiven for Apache Flink® through configuration files.
 Instead, directly modify the code of your Jar application to achieve
 this.
@@ -52,28 +59,36 @@ StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironm
 env.setRestartStrategy(RestartStrategies.noRestart());
 ```
 
-This code sets the restart strategy to \'None\', preventing any restart
+This code sets the restart strategy to `None`, preventing any restart
 attempts in case of failures.
 
-### Key considerations when disabling default restarts
+### SQL applications
+
+For SQL applications, you have a simplified approach to
+restart strategies. You can enable or disable restarts on failure during
+application deployment, providing a straightforward way
+to manage applications without complex configurations.
+For more information, see [Create an SQL application](/docs/products/flink/howto/create-sql-application).
+
+## Key considerations when disabling default restarts
 
-Before choosing to disable the default restart strategy, consider the
+Before disabling the default restart strategy for your applications, consider the
 following:
 
--   **Persistent failures**: Disabling restarts means that if a Flink
-    Job fails, Flink will not attempt to recover it, leading to
-    permanent job failure.
--   **Testing and debugging**: Disabling is beneficial when identifying
-    issues in the application code, as it prevents the masking of errors
-    through automatic restarts.
--   **External factors**: Jobs can fail due to external factors, such as
-    infrastructure changes or maintenance activities. If you disable
-    restarts, your Flink jobs will become vulnerable to failures.
--   **Operational risks**: In production environments, it is generally
-    advisable to use the default restart strategy to ensure high
-    availability and fault tolerance.
+- **Persistent failures**: Disabling restarts means that if a Flink
+  Job fails, it will not attempt to recover it, leading to
+  permanent job failure.
+- **Testing and debugging**: Disabling is beneficial when identifying
+  issues in the application code, as it prevents the masking of errors
+  through automatic restarts.
+- **External factors**: Jobs can fail due to external factors, such as
+  infrastructure changes or maintenance activities. If you disable
+  restarts, your Flink jobs will become vulnerable to failures.
+- **Operational risks**: In production environments, it is generally
+  advisable to use the default restart strategy to ensure high
+  availability and fault tolerance.
 
 ## Related pages
 
--   [Restart strategies in Apache
-    Flink®](https://nightlies.apache.org/flink/flink-docs-release-1.18/docs/ops/state/task_failure_recovery/#restart-strategies)
+- [Restart strategies in Apache
+  Flink®](https://nightlies.apache.org/flink/flink-docs-release-1.18/docs/ops/state/task_failure_recovery/#restart-strategies)