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https://github.com/sap-samples/cloud-cf-feature-flags-sample

A sample application that demonstrates the consumption of Feature Flags service on SAP Cloud Platform, Cloud Foundry environment
https://github.com/sap-samples/cloud-cf-feature-flags-sample

cloud-foundry feature-flags feature-toggles sample sample-code sap-cloud-platform scp

Last synced: 6 months ago
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A sample application that demonstrates the consumption of Feature Flags service on SAP Cloud Platform, Cloud Foundry environment

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# Feature Flags Service Demo Application



## Description



Feature Flags service Demo Application is a simple Spring Boot application that consumes the [Feature Flags service](https://help.sap.com/viewer/2250efa12769480299a1acd282b615cf/Cloud/en-US) on SAP BTP, Cloud Foundry environment. It implements a [feature toggle](https://en.wikipedia.org/wiki/Feature_toggle) (evaluation call to the Feature Flags service) and exposes this feature toggle through a Web user interface. There is also one REST end-point that reads the value of `VCAP_SERVICES` environment variable.



## Requirements



* You have set up [Maven 3.0.x](http://maven.apache.org/install.html).

* You have an [SAP BTP enterprise (productive) account](https://help.sap.com/docs/btp/sap-business-technology-platform/getting-started-with-enterprise-account-in-cloud-foundry-environment) on Cloud Foundry environment. 



  💡**NOTE:** You can also use a [trial account](https://help.sap.com/docs/btp/sap-business-technology-platform/getting-started-with-trial-account-in-cloud-foundry-environment) but some functionalities won't be available for you.

* You have a space on a Cloud Foundry instance - [productive](https://help.sap.com/docs/btp/sap-business-technology-platform/create-spaces) or [trial](https://help.sap.com/docs/btp/sap-business-technology-platform/cf-env-setting-up-your-trial-account#create-your-trial-space).

* You have set up the [curl](https://curl.haxx.se/download.html) plug-in for `cmd`.

* You have installed [cf CLI](https://docs.cloudfoundry.org/cf-cli/install-go-cli.html).



## Running the Application on SAP BTP



💡**NOTE:** This guide uses the **eu20** region (https://emea.cockpit.btp.cloud.sap/cockpit#). 



> To use a different SAP BTP region, you need to modify the domain in the requests. See: [Cloud Foundry Regions and API Endpoints](https://help.sap.com/viewer/65de2977205c403bbc107264b8eccf4b/Cloud/en-US/350356d1dc314d3199dca15bd2ab9b0e.html)



Follow the steps below to run `Feature Flags Demo Application` on SAP BTP, Cloud Foundry environment.



  * [1. Build the feature-flags-demo Application](#1-build-the-feature-flags-demo-application)

  * [2. Edit application name in manifest file](#2-edit-application-name-in-manifest-file)

  * [3. Deploy feature-flags-demo on SAP BTP](#3-deploy-feature-flags-demo-on-sap-btp)

  * [4. Create a Service Instance of Feature Flags service](#4-create-a-service-instance-of-feature-flags-service)

    + [4.1 Ensure the feature-flags service exists in the Service Marketplace](#41-ensure-the-feature-flags-service-exists-in-the-service-marketplace)

    + [4.2 Create a Service Instance of Feature Flags with Plan `standard`](#42-create-a-service-instance-of-feature-flags-with-plan-standard)

  * [5. Call the feature-flags-demo Application's /vcap_services End-Point](#5-call-the-feature-flags-demo-applications-vcap_services-end-point)

  * [6. Bind feature-flags-demo to feature-flags-instance](#6-bind-feature-flags-demo-to-feature-flags-instance)

  * [7. Restage feature-flags-demo](#7-restage-feature-flags-demo)

  * [8. Ensure that feature-flags-instance is bound to feature-flags-demo](#8-ensure-that-feature-flags-instance-is-bound-to-feature-flags-demo)

  * [Accessing the Demo Application](#accessing-the-demo-application)

  * [Accessing the Feature Flags Dashboard](#accessing-the-feature-flags-dashboard)

  * [9. Evaluate a Missing Feature Flag](#9-evaluate-a-missing-feature-flag)

  * [10. Create a New Boolean Feature Flag](#10-create-a-new-boolean-feature-flag)

  * [11. Evaluate the Newly Created Boolean Feature Flag](#11-evaluate-the-newly-created-boolean-feature-flag)

  * [12. Enable the Boolean Feature Flag](#12-enable-the-boolean-feature-flag)

  * [13. Verify that the Boolean Feature Flag is Enabled](#13-verify-that-the-boolean-feature-flag-is-enabled)

  * [14. Create a New String Feature Flag](#14-create-a-new-string-feature-flag)

  * [15. Evaluate the Newly Created String Feature Flag](#15-evaluate-the-newly-created-string-feature-flag)

  * [16. Enable the String Feature Flag](#16-enable-the-string-feature-flag)

  * [17. Verify that the String Feature Flag is Enabled](#17-verify-that-the-string-feature-flag-is-enabled)

  * [18. Specify Direct Delivery Strategy of a Variation of the String Flag](#18-specify-direct-delivery-strategy-of-a-variation-of-the-string-flag)

  * [19. Evaluate the String Feature Flag Using Identifier](#19-evaluate-the-string-feature-flag-using-identifier)

- [Contributing](#contributing)

- [Code of Conduct](#code-of-conduct)

- [Licensing](#licensing)



### 1. Build the feature-flags-demo Application



Run the following commands, consequently:



    $ git clone git@github.com:SAP/cloud-cf-feature-flags-sample.git

    $ cd cloud-cf-feature-flags-sample

    $ mvn clean install



> **Note:** Alternatively, you can use the Eclipse IDE. Choose the `clean install` goal from the _Run As > Maven Build..._ menu.



### 2. Edit application name in manifest file



It's quite possible that someone else has already deployed the `Feature Flags Demo Application` with the name **feature-flags-demo** (as it is currently set in the `manifest.yml` file). 

Cloud Foundry does not allow two applications with the same name to be deployed in the same region! Therefore, we **highly recommend** that you change the application name in the `manifest.yml` file before deploying. For example:



    ---

    applications:

    - name: feature-flags-demo123

      path: target/feature-flags-demo.jar



💡**NOTE:** Use the modified value in all commands that require application name, as well as when requesting the application in a browser or via `curl`.



### 3. Deploy feature-flags-demo on SAP BTP



 1. Log in to your Cloud Foundry landscape. (The `eu20` region is just an example.) Run:



    ```

    $ cf login -a https://api.cf.eu20.hana.ondemand.com

    ```



2. Choose your subaccount (org) and space.



3. Deploy the application. Run:



    ```

    $ cf push

    ```



### 4. Create a Service Instance of Feature Flags service



#### 4.1 Ensure the feature-flags service exists in the Service Marketplace



Run the following command:   

  ```

  $ cf marketplace

  ```  

Result:



    -----

    Getting services from marketplace in org  / space  as ...

    OK

    service          	plans    	description

    ...

    feature-flags    	lite, standard     	Feature Flags service for controlling feature rollout

    ...



**NOTE:**  If you're using a trial account, the only available service plan will be `lite`.



#### 4.2 Create a Service Instance of Feature Flags



* For a productive account, run:

  

    ```

    $ cf create-service feature-flags standard feature-flags-instance

    ```



* For a trial account, run:



    ```

    $ cf create-service feature-flags lite feature-flags-instance

    ```



**Note:** Alternatively, you can use the SAP BTP cockpit. See [Create a Service Instance](https://help.sap.com/docs/feature-flags-service/sap-feature-flags-service/initial-setup#loioc7b30b5bf54149148d2302617917dc3e).



### 5. Call the feature-flags-demo Application's /vcap_services End-Point



> **Note**: Expect to receive an empty JSON code - {}.



The `/vcap_services` end-point simply returns the content of the _VCAP_SERVICES_ environment variable. As for now, there is no service instance bound to `feature-flags-demo`, thus you receive an empty JSON.



In the command you use the following URL: `\/vcap_services`. 



To find the value of `\`, go to the SAP BTP cockpit > **feature-flag-demo** > **Overview** > **Application Routes**.



To call the application, run (for example):



    $ curl https://feature-flags-demo.cfapps.eu20.hana.ondemand.com/vcap_services



### 6. Bind feature-flags-demo to feature-flags-instance



    $ cf bind-service feature-flags-demo feature-flags-instance



    -----

    Binding service feature-flags-instance to app feature-flags-demo in org  / space  as ...

    OK

    TIP: Use 'cf restage feature-flags-demo' to ensure your env variable changes take effect



> **Note:** Alternatively, you can use the SAP BTP cockpit. See [Bind Your Application to the SAP Feature Flags Service Instance](https://help.sap.com/docs/feature-flags-service/sap-feature-flags-service/initial-setup#loioe7ef0ce6d4b14ae387de5bb18549c250).



### 7. Restage feature-flags-demo



Restage `feature-flags-demo` application so the changes in the application environment take effect.



    $ cf restage feature-flags-demo



### 8. Ensure that feature-flags-instance is bound to feature-flags-demo



> **Note**: Expect to receive the injected environment variables by the Feature Flags service.



    $ curl https://feature-flags-demo.cfapps.eu10.hana.ondemand.com/vcap_services



Sample JSON response:

```json

{

  "feature-flags": [

    {

      "credentials": {

        "x509": {

          "certificate": "...",

          "key": "...",

          "clientid": "...",

          "...": "..."

        },

        "password": "aa_12345678XYZZZZZ000mnopRE+qs0e=",

        "uri": "https://feature-flags.cfapps.eu20.hana.ondemand.com",

        "username": "sbss_x234osj//pmabsuskr6nshmb2arw6dld4hfb3cj4m2bonkqmm3ts6c68mdpzxz2fma="

      },

      "syslog_drain_url": null,

      "volume_mounts": [ ],

      "label": "feature-flags",

      "provider": null,

      "plan": "standard",

      "name": "feature-flags-instance",

      "tags": [

        "feature-flags"

      ]

    }

  ]

}

```



### Accessing the Demo Application



The web interface of the demo application will be accessed multiple times throughout this tutorial. Here is how to open it: 



1. Go to the SAP BTP cockpit.

2. Navigate to the `feature-flags-demo` application overview.

3. Open the link from the **Application Routes** section. For example: `https://feature-flags-demo-happy-bear.cfapps.eu20.hana.ondemand.com`

4. The **Evaluation Form** opens.



### Accessing the Feature Flags Dashboard



The `Feature Flags Dashboard` will be accessed multiple times throughout this tutorial. Here is how to open it: 



1. Go to the SAP BTP cockpit.

2. Navigate to your subaccount.

3. Create a subscription to **Feature Flags Dashboard**. To do that, create an instance of the Feature Flags service, with plan `dashboard`.

4. Access **Feature Flags Dashboard** from the list of subscribed applications.

5. Select the service instance you are currently working with.



💡**NOTE:** The dashboard URL always has the following pattern: 



`https://.feature-flags-dashboard.cfapps.eu20.hana.ondemand.com/manageinstances/`



> The  is a unique ID of your Feature Flag service instance.



### 9. Evaluate a Missing Feature Flag



> **Note**: Expect the feature flag to be missing.



1. Open the demo application as described [here](#accessing-the-demo-application).

2. Enter a feature flag with a random name, for example `my-boolean-flag`.

3. Choose **Evaluate**.

4. The result should state that a feature flag with this name is missing.



### 10. Create a New Boolean Feature Flag



1. Open the `Feature Flags Dashboard` as described [here](#accessing-the-feature-flags-dashboard).

2. Choose **New Flag**.

3. Fill in the required fields. For example:

   * **Name**:  `my-boolean-flag`

   * **Description**: `Super cool feature`

   * **State**: `OFF`

5. Choose **Save**.



### 11. Evaluate the Newly Created Boolean Feature Flag



> **Note**: Expect the variation to be `false`.



1. Open the demo application as described [here](#accessing-the-demo-application).

2. Enter the Boolean feature flag name.

3. Choose **Evaluate**.

4. The result should state that the feature flag is of type `BOOLEAN` and its variation is `false`.



### 12. Enable the Boolean Feature Flag



1. Open the `Feature Flags Dashboard` as described [here](#accessing-the-feature-flags-dashboard).

2. Enable the Boolean feature flag using the switch in the **Active** column.



### 13. Verify that the Boolean Feature Flag is Enabled



> **Note**: Expect the variation to be `true`.



1. Open the demo application as described [here](#accessing-the-demo-application).

2. Enter the Boolean feature flag name.

3. Choose **Evaluate**.

4. The result should state that the feature flag is of type `BOOLEAN` and its variation is `true`.



> ### CAUTION!

> The next procedures (14 - 19) are only applicable for productive accounts, which means plan `standard`.



### 14. Create a New String Feature Flag



1. Open the `Feature Flags Dashboard` as described [here](#accessing-the-feature-flags-dashboard).

2. Choose **New Flag**.

3. Fill in the required fields. For example:

    * **Name**: `my-string-flag`

    * **Description**: `Coolest of features`

    * **Type**: `String`

    * **State**: `OFF`

4. Enter the following values as different variations of the flag:

    * **Var. 1**: `variation-when-inactive`

    * **Var. 2**: `variation-when-active`

    * **Var. 3** (choose the **Add** button with the '+' sign to add a new field): `variation-for-friends-and-family`

5. From the **Default Variation**, open the **Deliver** combo box and select `Var. 2`.

6. Choose **Save**.



### 15. Evaluate the Newly Created String Feature Flag



> **Note**: Expect the variation to be `variation-when-inactive`.



1. Open the demo application as described [here](#accessing-the-demo-application).

2. Enter the string feature flag name.

3. Choose **Evaluate**.

4. The result should state that the feature flag is of type `STRING` and its variation is `variation-when-inactive`.



### 16. Enable the String Feature Flag



1. Open the `Feature Flags Dashboard` as described [here](#accessing-the-feature-flags-dashboard).

2. Enable the string feature flag using the switch in the **Active** column.



### 17. Verify that the String Feature Flag is Enabled



> **Note**: Expect the variation to be `variation-when-active`.



1. Open the demo application as described [here](#accessing-the-demo-application).

2. Enter the string feature flag name.

3. Choose **Evaluate**.

4. The result should state that the feature flag is of type `STRING` and its variation is `variation-when-active`.



### 18. Specify Direct Delivery Strategy of a Variation of the String Flag



1. Open the `Feature Flags Dashboard` as described [here](#accessing-the-feature-flags-dashboard).

2. Select the string feature flag.

3. Choose the **Edit Flag** button.

4. Go to the **Strategy** section, subsection **Direct Delivery**, and choose the '+' button.

5. Select **Var. 3** from the combobox and enter `friends-and-family` in the text input.

6. Choose **Save**.



### 19. Evaluate the String Feature Flag Using Identifier



> **Note**: Expect the variation to be `variation-for-friends-and-family`.



1. Open the demo application as described [here](#accessing-the-demo-application).

2. Enter the string feature flag name.

3. For the **Identifier (optional)** field, enter `friends-and-family`.

4. Choose **Evaluate**.

5. The result should state that the feature flag is of type `STRING` and its variation is `variation-for-friends-and-family`.



> Once **Direct Delivery** is configured, the Feature Flags service requires providing an identifier. If such is not present, an error is thrown.



💡**NOTE:** `variation-when-active` is returned for all identifiers - except for those explicitly configured in the `Feature Flags Dashboard` for which the provided rules apply (like the `friends-and-family` identifier).



## Contributing



Refer to the [contrubuting guideline](/CONTRIBUTING.md).



## Code of Conduct

Refer to the [SAP Open Source Code of Conduct](https://github.com/SAP-samples/.github/blob/main/CODE_OF_CONDUCT.md).



## Licensing

See [LICENSE](/LICENSE) file.