add document for Langflow

docs/en/solutions/How_to_install_and_use_Langflow.md

@@ -0,0 +1,282 @@
+---
+products:
+   - Alauda AI
+kind:
+   - Solution
+ProductsVersion:
+   - 4.x
+---
+# Langflow
+
+## Overview
+
+Langflow is an open-source low-code tool for visually building and deploying AI agents and workflows. It provides a drag-and-drop editor to quickly create, test, and iterate AI applications. Langflow is built on Python and includes a FastAPI backend and a React-based visual editor. It supports SQLite by default and recommends PostgreSQL in production.
+
+It contains the following main components:
+- **Frontend Interface**: React-based visual editor with drag-and-drop flow building and real-time testing
+- **Backend Service**: FastAPI-based web service providing REST API and MCP (Model Context Protocol) support
+- **Database**: Supports SQLite (default) and PostgreSQL (recommended for production)
+
+## Core Concepts
+
+Langflow is built around several core concepts: **Flows** (visual workflows organizing AI logic), **Components** (reusable functional units), **Agents** (intelligent agents with tool calling and reasoning capabilities), and **API/MCP** integration (REST API and Model Context Protocol support).
+
+Langflow provides a drag-and-drop visual interface for building AI applications with real-time testing capabilities and an extensive template library. It supports multiple LLM providers, embedding models, and vector databases, enabling flexible multi-model configurations. The platform offers both IDE mode for development and runtime mode for production deployment, making it suitable for both experimentation and enterprise use.
+
+For detailed information about core concepts, features, and usage, please refer to the [official documentation](https://docs.langflow.org/).
+
+## Documentation and References
+
+- **Official Documentation**: [https://docs.langflow.org/](https://docs.langflow.org/)
+- **GitHub Repository**: [https://github.com/langflow-ai/langflow](https://github.com/langflow-ai/langflow)
+
+# Langflow Deployment Guide
+
+This section provides detailed instructions on how to deploy Langflow to a Kubernetes cluster and common configuration parameters.
+
+## Publishing
+
+Download the Langflow installation file: `langflow.ALL.v1.6.4-1.tgz`
+
+Use the violet command to publish to the platform repository:
+```bash
+violet push --platform-address=platform-access-address --platform-username=platform-admin --platform-password=platform-admin-password langflow.ALL.v1.6.4-1.tgz
+```
+
+## Deployment
+
+### Prepare Storage
+
+Langflow supports two database modes:
+- **SQLite (Default)**: For development and testing, data is stored in persistent volumes
+- **PostgreSQL (Recommended)**: For production environments, providing better performance and scalability
+
+The cluster needs to have CSI pre-installed or `PersistentVolume` pre-prepared.
+
+### Prepare Database
+
+#### Using SQLite (Default)
+
+SQLite is Langflow's default database, suitable for development and testing environments:
+- Data is stored in persistent volumes
+- Simple configuration, no additional setup required
+- Supports single-instance deployment
+
+#### Using PostgreSQL (Recommended)
+
+Production environments strongly recommend using PostgreSQL for better performance and scalability:
+
+The `PostgreSQL operator` provided by `Data Services` can be used to create a `PostgreSQL cluster`.
+
+Check the access address and password in the `PostgreSQL` instance details in `Data Services`.
+
+**Note**:
+- PostgreSQL version 12 or higher is recommended
+- Need to create a separate database and user
+- Ensure network connectivity
+
+### Create Application
+
+1. Go to the `Alauda Container Platform` view and select the namespace where Langflow will be deployed.
+
+2. In the left navigation, select `Applications` / `Applications`, then click the `Create` button on the right page.
+
+3. In the popup dialog, select `Create from Catalog`, then the page will jump to the `Catalog` view.
+
+4. Find `3rdparty/chart-langflow` and click `Create` to create this application.
+
+5. On the `Catalog` / `Create langflow` form, fill in the `Name` (recommended as `langflow`) and `Custom` configuration in `Values`, then click the `Create` button to complete creation. The `Custom` content will be described below. It can also be modified after creation through the `Update` application method.
+
+## Configuration
+
+Users can modify the `Custom Values` of the `Application` to adjust configuration. The main configurations to focus on are as follows:
+
+### 1. Configure Storage
+
+#### 1.1 Configure SQLite Storage (Default)
+
+The storage class and size can be specified by adding the following configuration:
+
+```yaml
+langflow:
+  sqlite:
+    volume:
+      storageClassName: storage-class-name     # Replace with the actual storage class name
+      size: 1Gi                                # Replace with the actual required space size
+```
+
+**Note**: When using SQLite, only single-instance deployment (replicaCount = 1) is supported.
+
+### 2. Configure Database
+
+#### 2.1 Enable PostgreSQL
+
+PostgreSQL access information can be configured by setting the following fields:
+
+```yaml
+langflow:
+  externalDatabase:
+    enabled: true                              # Enable external database
+    driver:
+      value: "postgresql"
+    host:
+      value: postgres-host                     # PostgreSQL access address
+    port:
+      value: "5432"                            # PostgreSQL access port, default: 5432
+    database:
+      value: langflow                          # Database name, note: database will be created automatically
+    user:
+      value: langflow                          # Database username
+    password:
+      valueFrom:
+        secretKeyRef:
+          name: postgres-secret                # Secret name storing database access password
+          key: password                        # Secret key storing database access password
+```
+
+**Note**: Due to temporary storage limitations, the current version temporarily does not support multi-instance deployment. Even with PostgreSQL database configured, only single-instance deployment (replicaCount = 1) is supported.
+
+### 3. Configure Access Method
+
+By default, `LoadBalancer` is used to provide access address
+
+#### 3.1 Modify Service Type
+
+The `Service` type can be modified by setting the following fields:
+
+```yaml
+langflow:
+  service:
+    type: LoadBalancer                         # Can be changed to NodePort or ClusterIP
+    port: 7860                                 # Service port
+```
+
+#### 3.2 Enable Ingress
+
+Ingress can be configured by setting the following fields. After enabling Ingress, the Service type is usually changed to ClusterIP:
+
+```yaml
+ingress:
+  enabled: true                                # Enable Ingress functionality
+  hosts:
+    - host: langflow.example.com               # Access domain (must be DNS name, not IP address)
+      paths:
+        - path: /
+  tls:
+    - secretName: langflow-tls                 # Secret name storing TLS certificate
+      hosts:
+        - langflow.example.com
+```
+
+### 4. Configure Authentication and User Management (Optional)
+
+#### 4.1 Enable User Authentication
+
+User authentication can be enabled by setting the following fields:
+
+```yaml
+langflow:
+  auth:
+    enabled: true                              # Enable authentication
+    superuser:
+      username: langflow                       # Superuser name
+      password: ""                             # Superuser password, auto-generated if not set
+    secretKey: ""                              # Secret key, auto-generated if not set
+    newUserActive: false                       # Whether new users need activation
+    enableSuperuserCLI: false                  # Whether to enable CLI superuser
+    accessTokenExpireSeconds: 3600             # Access token expiration time (seconds)
+    refreshTokenExpireSeconds: 604800          # Refresh token expiration time (seconds)
+```
+
+After enabling authentication, by default:
+- Login is required to access
+- Superuser can be configured
+- New users can only be added by superuser through `/admin` page (self-registration is not supported)
+- New user account activation: If `newUserActive=true`, new user accounts are automatically activated; If `newUserActive=false` (default), superuser needs to manually activate
+
+
+### 5. Configure OAuth2 Proxy (Optional)
+
+OAuth2 proxy can be configured to provide single sign-on functionality by setting the following fields:
+
+```yaml
+oauth2_proxy:
+  enabled: true                                # Enable OAuth2 proxy
+  oidcIssuer: "https://x.x.x.com/dex"          # OIDC Issuer address
+  oidcClientID: "your-client-id"               # OIDC client ID
+  oidcClientSecret: "your-client-secret"       # OIDC client secret (recommended to use Secret)
+```
+
+If you want to configure `Alauda Container Platform` as OIDC Provider, configure as follows:
+- `oauth2_proxy.oidcIssuer` is the platform access address plus `/dex`
+- `oauth2_proxy.oidcClientID` is fixed as `langflow`
+- `oauth2_proxy.oidcClientSecret` is fixed as `ZXhhbXBsZS1hcHAtc2VjcmV0`
+
+You also need to create an OAuth2Client resource in the global cluster to configure Langflow's client information:
+
+```yaml
+apiVersion: dex.coreos.com/v1
+kind: OAuth2Client
+metadata:
+  name: nrqw4z3gnrxxps7sttsiiirdeu
+  namespace: cpaas-system
+id: langflow                                    # Consistent with oauth2_proxy.oidcClientID in values
+name: Langflow
+secret: ZXhhbXBsZS1hcHAtc2VjcmV0                # Consistent with oauth2_proxy.oidcClientSecret in values
+redirectURIs:
+- http://xxx.xxx.xxxx.xxx:xxxxx/*               # OAuth2-Proxy access address, acquisition method described below
+                                                # If multiple Langflow instances are deployed, add multiple access addresses here
+```
+
+**Note**: OAuth2 Proxy access address can be obtained from the `<Application Name>-oauth2-proxy` Service, use the appropriate access method based on Service type.
+
+After enabling OAuth2 Proxy, it is recommended to:
+- Set `langflow.service.type` to `ClusterIP`, allowing access only within the cluster, users need to access Langflow through OAuth2 Proxy address.
+- Set `langflow.auth.enabled` to `false`, use OAuth2 Proxy to handle login authentication.
+
+Users can log out by accessing `/oauth2/sign_out`.
+
+### 6. Configure Runtime Mode (Backend-Only)
+
+Runtime mode is the recommended deployment method for production environments, deploying only the Langflow backend API service without a visual interface.
+
+#### 6.1 Enable Runtime Mode
+
+Runtime mode (backend-only) can be enabled by setting the following fields:
+
+```yaml
+langflow:
+  backendOnly: true                              # Enable backend-only mode
+  env:
+    - name: LANGFLOW_LOAD_FLOWS_PATH             # Set the path to load Flows
+      value: "/app/flows"
+  volumes:
+    - name: flows                                # Load Flows content through volume
+      persistentVolumeClaim:
+        claimName: langflow-flows-pvc
+  volumeMounts:                                  # Mount volume to specified path
+    - name: flows
+      mountPath: /app/flows
+```
+When enabling `LANGFLOW_LOAD_FLOWS_PATH`, authentication must be disabled, i.e., `langflow.auth.enabled` must be set to `false`.
+
+## Access Address
+
+### 1. Access via Service
+
+`Langflow` provides external access through `Service`. Check its `Service` to get the access address.
+
+- If OAuth2 proxy is not enabled, Service name is: `<Application Name>`
+- If OAuth2 proxy is enabled, Service name is: `<Application Name>-oauth2-proxy`
+
+If the `Service` type is `LoadBalancer` and the load balancer controller in the environment has assigned an access address, please access through that address.
+
+If the `Service` type is `LoadBalancer` or `NodePort`, access is available through `node IP` with its `NodePort`.
+
+### 2. Access via Ingress
+
+If Ingress is enabled, please access through the configured domain name.
+
+# Langflow Quickstart
+
+For a quickstart guide, please refer to the official documentation: [https://docs.langflow.org/get-started-quickstart](https://docs.langflow.org/get-started-quickstart)