ADD userguide/managingApp/secret-management (#6412)

* ADD managingApp/secret-management

Signed-off-by: rahulshendre <rahulshendre789@gmail.com>

* Enchance wording

Signed-off-by: rahulshendre <rahulshendre789@gmail.com>

* removed lambda fuction

Signed-off-by: rahulshendre <rahulshendre789@gmail.com>

---------

Signed-off-by: rahulshendre <rahulshendre789@gmail.com>

Author: rahulshendre

docs/content/en/docs-v1.0.x/user-guide/managing-application/secret-management.md

@@ -0,0 +1,114 @@
+---
+title: "Secret management"
+linkTitle: "Secret management"
+weight: 9
+description: >
+  Storing secrets safely in the Git repository.
+---
+
+GitOps workflows use Git as the single source of truth for application configurations. Storing sensitive data such as credentials, API keys, and secrets directly in Git repositories poses security risks.
+
+PipeCD's secret management feature allows you to store encrypted secrets in your Git repository alongside application manifests. The encrypted secrets are decrypted by `piped` during deployment operations.
+
+## Prerequisites
+
+Before using this feature, `piped` needs to be started with a key pair for secret encryption.
+
+You can use the following command to generate a key pair:
+
+``` console
+openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out private-key
+openssl pkey -in private-key -pubout -out public-key
+```
+
+Then specify them while [installing](../../../installation/install-piped/installing-on-kubernetes) `piped` with these options:
+
+``` console
+--set-file secret.data.secret-public-key=PATH_TO_PUBLIC_KEY_FILE \
+--set-file secret.data.secret-private-key=PATH_TO_PRIVATE_KEY_FILE
+```
+
+Finally, enable this feature in the Piped configuration file with the `secretManagement` field as below:
+
+``` yaml
+apiVersion: pipecd.dev/v1beta1
+kind: Piped
+spec:
+  pipedID: your-piped-id
+  ...
+  secretManagement:
+    type: KEY_PAIR
+    config:
+      privateKeyFile: /etc/piped-secret/secret-private-key
+      publicKeyFile: /etc/piped-secret/secret-public-key
+```
+
+## How it works
+
+The secret management workflow is as follows:
+
+- Encrypt secret data using PipeCD's Web UI and store the encrypted data in Git
+- `piped` automatically decrypts the encrypted secrets before performing deployment tasks
+
+## Encrypting secret data
+
+To encrypt secret data, navigate to the Applications page and click the "Encrypt Secret" button located in the top-left corner. Then, select a piped from the dropdown list, enter your secret data, and click the "ENCRYPT" button.
+Copy the encrypted data to store in Git.
+
+![Sealed Secret Button](/images/sealed-secret-button.png)
+<p style="text-align: center;">
+Applications page
+</p>
+
+<br>
+
+![Sealed Secret Encrypting Drawer Form](/images/sealed-secret-encrypting-drawer-form.png)
+<p style="text-align: center;">
+The form for encrypting secret data
+</p>
+
+## Storing encrypted secrets in Git
+
+To make encrypted secrets available to an application, specify them in the application configuration file.
+
+- `encryptedSecrets` contains a list of the encrypted secrets.
+- `decryptionTargets` contains a list of files that use one of the encrypted secrets and should be decrypted by `piped`.
+
+``` yaml
+apiVersion: pipecd.dev/v1beta1
+# One of Piped defined app, for example: using the Kubernetes plugin
+kind: Application
+spec:
+  encryption:
+    encryptedSecrets:
+      password: encrypted-data
+    decryptionTargets:
+      - secret.yaml
+```
+
+## Accessing encrypted secrets
+
+Any file in the application directory can use the `.encryptedSecrets` context to access secrets you have encrypted and stored in the application configuration.
+
+For example:
+
+- Accessing by a Kubernetes Secret manifest
+
+``` yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: simple-sealed-secret
+data:
+  password: "{{ .encryptedSecrets.password }}"
+```
+
+In all cases, `piped` decrypts the encrypted secrets and renders the decryption target files before using them to handle any deployment tasks.
+
+<!-- ## Examples
+
+- [examples/kubernetes/secret-management](https://github.com/pipe-cd/examples/tree/master/kubernetes/secret-management)
+- [examples/cloudrun/secret-management](https://github.com/pipe-cd/examples/tree/master/cloudrun/secret-management)
+- [examples/terraform/secret-management](https://github.com/pipe-cd/examples/tree/master/terraform/secret-management)
+- [examples/ecs/secret-management](https://github.com/pipe-cd/examples/tree/master/ecs/secret-management) -->
+