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go-captcha-service

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🖖 GoCaptcha Service is a high-performance CAPTCHA service built in Go, supporting click, slide, drag, and rotate modes. It offers HTTP and gRPC interfaces, with integrated service discovery, distributed caching, and dynamic configuration.

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<h1 style="margin: 0; padding: 0">GoCaptcha Service</h1>
 
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`GoCaptcha Service` is a high-performance behavioral CAPTCHA service developed in Go, based on the **[GoCaptcha](https://github.com/wenlng/go-captcha)** core library. It supports click, slide, drag, and rotate modes. It offers HTTP and gRPC interfaces, with integrated service discovery, distributed caching, and dynamic configuration.

> English | [中文](README_zh.md)
 ⭐️ If this project is helpful, please give it a star!

## Related Projects

| Name | Description |
|----------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|
| [go-captcha](https://github.com/wenlng/go-captcha) | Golang CAPTCHA core library |
| [document](http://gocaptcha.wencodes.com) | GoCaptcha documentation |
| [online demo](http://gocaptcha.wencodes.com/demo/) | GoCaptcha online demo |
| [go-captcha-service](https://github.com/wenlng/go-captcha-service) | GoCaptcha service providing HTTP/gRPC interfaces, supporting standalone and distributed modes (service discovery, load balancing, dynamic configuration), deployable via binary or Docker images |
| [go-captcha-service-sdk](https://github.com/wenlng/go-captcha-service-sdk) | GoCaptcha service SDK toolkit, including HTTP/gRPC request interfaces, supporting static mode, service discovery, and load balancing |
| [go-captcha-jslib](https://github.com/wenlng/go-captcha-jslib) | JavaScript CAPTCHA library |
| [go-captcha-vue](https://github.com/wenlng/go-captcha-vue) | Vue CAPTCHA |
| [go-captcha-react](https://github.com/wenlng/go-captcha-react) | React CAPTCHA |
| [go-captcha-angular](https://github.com/wenlng/go-captcha-angular) | Angular CAPTCHA |
| [go-captcha-svelte](https://github.com/wenlng/go-captcha-svelte) | Svelte CAPTCHA |
| [go-captcha-solid](https://github.com/wenlng/go-captcha-solid) | Solid CAPTCHA |
| [go-captcha-uni](https://github.com/wenlng/go-captcha-uni) | UniApp CAPTCHA, compatible with APP, mini-programs, and quick apps |
| ... | |

## Features

- **Multiple CAPTCHA Modes**: Supports text/image click, slide, drag, and rotate CAPTCHAs.
- **Dual Protocol Support**: Provides RESTful HTTP and gRPC interfaces.
- **Service Discovery**: Integrates with Etcd, Nacos, Zookeeper, and Consul for distributed service registration and discovery.
- **Distributed Caching**: Supports Memory, Redis, Etcd, and Memcache for optimized CAPTCHA data storage.
- **Dynamic Configuration**: Enables real-time configuration updates via Etcd, Nacos, Zookeeper, or Consul.
- **Highly Configurable**: Supports customization of text, fonts, image resources, CAPTCHA dimensions, and generation rules.
- **High Performance**: Built on Go’s concurrency model, suitable for high-traffic scenarios, with distributed architecture ensuring high availability, performance, and responsiveness.
- **Cross-Platform**: Supports deployment via binary, command line, PM2, Docker, and Docker Compose.

## Installation and Deployment
`GoCaptcha Service` supports multiple deployment methods, including standalone (binary, command line, PM2, Docker) and distributed deployments (with service discovery, distributed caching, and optional dynamic configuration).

### Prerequisites
- Optional: Docker (for containerized deployment)
- Optional: Service discovery/dynamic configuration middleware (Etcd, Nacos, Zookeeper, Consul)
- Optional: Caching services (Redis, Etcd, Memcache)
- Optional: Node.js and PM2 (for PM2 deployment)
- Optional: gRPC client tools (e.g., `grpcurl`)

### Standalone Deployment

#### Binary Deployment

1. Download the latest binary executable for your platform from [Github Releases](https://github.com/wenlng/go-captcha-service/releases).

```bash
    ./go-captcha-service-[xxx]
    ```

2. Optional: Configure the application by copying the `config.json` and `gocaptcha.json` files from the repository to the same directory and specifying them at startup.

```bash
    ./go-captcha-service-[xxx] -config config.json -gocaptcha-config gocaptcha.json
    ```

3. Access the HTTP interface (e.g., `http://localhost:8080/api/v1/public/get-data?id=click-default-ch`) or gRPC interface (`localhost:50051`).

#### Deploying with Supervisorctl
`Supervisorctl` is a command-line tool provided by supervisord for managing background processes started by Supervisor.

1. Deploy the service using Supervisorctl as a background process:

```shell
sudo vi /etc/supervisord.conf
```

Add the following configuration to the `supervisord.conf` file:
```text
;go-captcha-service
[program:go-captcha-service]
command=/app/go-captcha-service-[xxx]
```

```shell
sudo supervisorctl update
```

2、Deploy the service using Systemd (Linux):

```shell
# 创建服务文件
sudo vi /etc/systemd/system/go-captcha.service
```

Add the following configuration:
```
[Unit]
Description=go-captcha-service
After=network.target

[Service]
ExecStart=/app/go-captcha-service-[xxx]
Restart=always
User=nobody
Group=nogroup

[Install]
WantedBy=multi-user.target
```

Start and enable the service:

```shell
sudo systemctl enable go-captcha
sudo systemctl start go-captcha
```

Check the service status:
```shell
sudo systemctl status go-captcha
```

#### PM2 Deployment
PM2 is a Node.js process manager that can manage Go services, providing process monitoring and log management.

1. Install Node.js and PM2:

```bash
   npm install -g pm2
   ```

2. Create a PM2 configuration file `ecosystem.config.js`:

```javascript
   module.exports = {
     apps: [{
       name: 'go-captcha-service',
       script: './go-captcha-service-[xxx]',
       instances: 1,
       autorestart: true,
       watch: false,
       max_memory_restart: '1G',
       env: {
         CONFIG: 'config.json',
         GO_CAPTCHA_CONFIG: 'gocaptcha.json',
         SERVICE_NAME: 'go-captcha-service',
         CACHE_TYPE: 'redis',
         CACHE_ADDRS: 'localhost:6379',
       },
       env_production: {
         CONFIG: 'config.json',
         GO_CAPTCHA_CONFIG: 'gocaptcha.json',
         SERVICE_NAME: 'go-captcha-service',
         CACHE_TYPE: 'redis',
         CACHE_ADDRS: 'localhost:6379',
       }
     }]
   };
   ```

3. Start the service:

```bash
   pm2 start ecosystem.config.js
   ```

4. View logs and status:

```bash
   pm2 logs go-captcha-service
   pm2 status
   ```

5. Enable auto-start on boot:

```bash
   pm2 startup
   pm2 save
   ```

#### Source Code And Docker Deployment

1. Create a `Dockerfile` for building from source:

```dockerfile
    FROM --platform=$BUILDPLATFORM golang:1.23 AS builder
    WORKDIR /app
    
    COPY go.mod go.sum ./
    RUN go mod download
    
    COPY . .
    
    ARG TARGETOS
    ARG TARGETARCH
    RUN CGO_ENABLED=0 GOOS=$TARGETOS GOARCH=$TARGETARCH go build -ldflags="-w -s" -v -a -trimpath -o go-captcha-service ./cmd/go-captcha-service
    
    FROM scratch AS binary
    WORKDIR /app
    
    COPY --from=builder /app/go-captcha-service .
    COPY config.json .
    COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
    
    EXPOSE 8080 50051
    
    HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
    CMD ["/app/go-captcha-service", "--health-check"] || exit 1
    
    CMD ["/app/go-captcha-service"]
   ```

2. Build the image:

```bash
   docker build -t go-captcha-service:1.0.0 .
   ```

3. Run the container with mounted configuration files:

```bash
   docker run -d -p 8080:8080 -p 50051:50051 \
     -v $(pwd)/config.json:/app/config.json \
     -v $(pwd_MAIN)/gocaptcha.json:/app/gocaptcha.json \
     -v $(pwd)/resource/gocaptcha:/app/resource/gocaptcha \
     --name go-captcha-service go-captcha-service:${VERSION_NUM}
   ```

#### Official Docker Image

1. Pull the official image:

```bash
   docker pull wenlng/go-captcha-service@${VERSION_NUM}
   ```

2. Run the container:

```bash
   docker run -d -p 8080:8080 -p 50051:50051 \
     -v $(pwd)/config.json:/app/config.json \
     -v $(pwd)/gocaptcha.json:/app/gocaptcha.json \
     -v $(pwd)/resource/gocaptcha:/app/resource/gocaptcha \
     --name go-captcha-service wenlng/go-captcha-service:${VERSION_NUM}
   ```

### Distributed Deployment

#### Distributed Caching

1. Configure distributed caching (e.g., Redis) in `config.json`:

```json
   {
     "cache_type": "redis",
     "cache_ttl": 1800,
     "cache_key_prefix": "GO_CAPTCHA_DATA:",
     "redis_addrs": "localhost:6379"
   }
   ```

2. Start Redis:

```bash
   docker run -d -p 6379:6379 --name redis redis:latest
   ```

#### Dynamic Configuration
Note: When dynamic configuration is enabled, both `config.json` and `gocaptcha.json` are applied simultaneously.

1. Enable dynamic configuration in `config.json` and select middleware (e.g., Etcd):

```json
   {
     "enable_dynamic_config": true,
     "dynamic_config_type": "etcd",
     "dynamic_config_addrs": "localhost:2379"
   }
   ```

2. Start Etcd:

```bash
   docker run -d -p 8848:8848 --name etcd bitnami/etcd::latest
   ```

3. Configuration Synchronization and Retrieval
    - At startup, the service decides whether to push or pull configurations based on the `config_version`. If the local version is higher than the remote (e.g., Etcd) version, the local configuration is pushed to override the remote one; otherwise, the remote configuration is pulled to update the local one (non-file-based update).
    - After startup, the dynamic configuration manager continuously monitors remote configuration changes (e.g., in Etcd). When a remote configuration change occurs, it is fetched and compared with the local version, overriding the local configuration if the remote version is higher.

#### Service Discovery

1. Enable service discovery in `config.json` and select middleware (e.g., Etcd):

```json
   {
     "enable_service_discovery": true,
     "service_discovery_type": "etcd",
     "service_discovery_addrs": "localhost:2379"
   }
   ```

2. Start Etcd:

```bash
   docker run -d -p 8848:8848 --name etcd bitnami/etcd::latest
   ```

3. Service Registration and Discovery
    - At startup, the service automatically registers its instance with the service discovery center (e.g., Etcd).
    - After startup, the service monitors changes in service instances. Refer to [go-captcha-service-sdk](https://github.com/wenlng/go-captcha-service-sdk) for load balancing implementations.

#### Docker Compose Multi-Instance Deployment

Create a `docker-compose.yml` file including multiple service instances, Consul, Redis, ZooKeeper, and Nacos:

```yaml
version: '3'
services:
  captcha-service-1:
    image: wenlng/go-captcha-service:${VERSION_NUM}  # example: wenlng/go-captcha-service:v1.0.5
    ports:
      - "8080:8080"
      - "50051:50051"
    volumes:
      - ./config.json:/app/config.json
      - ./gocaptcha.json:/app/gocaptcha.json
      - ./resources/gocaptcha:/app/resources/gocaptcha
    environment:
      - CONFIG=config.json
      - GO_CAPTCHA_CONFIG=gocaptcha.json
      - SERVICE_NAME=go-captcha-service
      - CACHE_TYPE=redis
      - CACHE_ADDRS=localhost:6379
      - ENABLE_DYNAMIC_CONFIG=true
      - DYNAMIC_CONFIG_TYPE=etcd
      - DYNAMIC_CONFIG_ADDRS=localhost:2379
      - ENABLE_SERVICE_DISCOVERY=true
      - SERVICE_DISCOVERY_TYPE=etcd
      - SERVICE_DISCOVERY_ADDRS=localhost:2379 
    depends_on:
      - etcd
      - redis
    restart: unless-stopped

captcha-service-2:
    image: wenlng/go-captcha-service:${VERSION_NUM}
    ports:
      - "8081:8080"
      - "50052:50051"
    volumes:
      - ./config.json:/app/config.json
      - ./gocaptcha.json:/app/gocaptcha.json
      - ./resources/gocaptcha:/app/resources/gocaptcha
    environment:
      - CONFIG=config.json
      - GO_CAPTCHA_CONFIG=gocaptcha.json
      - SERVICE_NAME=go-captcha-service
      - CACHE_TYPE=redis
      - CACHE_ADDRS=localhost:6379
      - ENABLE_DYNAMIC_CONFIG=true
      - DYNAMIC_CONFIG_TYPE=etcd
      - DYNAMIC_CONFIG_ADDRS=localhost:2379
      - ENABLE_SERVICE_DISCOVERY=true
      - SERVICE_DISCOVERY_TYPE=etcd
      - SERVICE_DISCOVERY_ADDRS=localhost:2379
    depends_on:
      - etcd
      - redis
    restart: unless-stopped
       
  etcd:
    image: bitnami/etcd:latest
    ports:
      - "2379:2379"
    environment:
      - ALLOW_NONE_AUTHENTICATION=yes
    privileged: true
    restart: unless-stopped

redis:
    image: redis:latest
    ports:
      - "6379:6379"
    restart: unless-stopped
```

Run:

```bash
docker-compose up -d
```

## Predefined APIs

* Get CAPTCHA
    ```shell
    curl http://127.0.0.1:8080/api/v1/public/get-data?id=click-default-ch
    ```

* Verify CAPTCHA
    ```shell
    curl -X POST -H "Content-Type:application/json" -d '{"id":"click-default-ch","captchaKey":"xxxx-xxxxx","value": "x1,y1,x2,y2"}' http://127.0.0.1:8181/api/v1/public/check-data
    ```

* Check Verification Status (`data == "ok"` indicates success)
  ```shell
  curl http://127.0.0.1:8080/api/v1/public/check-status?captchaKey=xxxx-xxxx
  ```

* Get Status Info
  ```shell
  curl -H "X-API-Key:my-secret-key-123" http://127.0.0.1:8080/api/v1/manage/get-status-info?captchaKey=xxxx-xxxx
  ```

* Upload Resources
  ```shell
  curl -X POST -H "X-API-Key:my-secret-key-123" -F "dirname=imagesdir" -F "files=@/path/to/file1.jpg" -F "files=@/path/to/file2.jpg" http://127.0.0.1:8080/api/v1/manage/upload-resource
  ```

* Delete Resources
  ```shell
  curl -X DELETE -H "X-API-Key:my-secret-key-123" http://127.0.0.1:8080/api/v1/manage/delete-resource?path=xxxxx.jpg
  ```

* Get Resource File List
  ```shell
  curl -H "X-API-Key:my-secret-key-123" http://127.0.0.1:8080/api/v1/manage/get-resource-list?path=imagesdir
  ```

* Get CAPTCHA Configuration
  ```shell
  curl -H "X-API-Key:my-secret-key-123" http://127.0.0.1:8080/api/v1/manage/get-config
  ```

* Update CAPTCHA Configuration
  ```shell
  curl -X POST -H "X-API-Key:my-secret-key-123" -H "Content-Type:application/json" -d '{"config_version":3,"resources":{ ... },"builder": { ... }}' http://127.0.0.1:8080/api/v1/manage/update-hot-config
  ```

For more details and gRPC APIs, refer to [go-captcha-service-sdk](https://github.com/wenlng/go-captcha-service-sdk).

## API Authentication Configuration
To access the management interface /api/v1/manage, you need to configure api-keys in config.json. Subsequently, include the X-API-Key in the request headers for authentication when making HTTP or gRPC API calls.

Although the built-in management API /api/v1/manage includes authentication, in a production environment, it is recommended to set api-keys with a length exceeding 128 characters and avoid exposing the management API to the public internet to prevent brute-force attacks.

For enhanced security, you can configure routing rules to block access to /api/v1/manage. This can be achieved by proxying requests to internal services using web application servers, reverse proxy servers, or gateway software such as Kong, Envoy, Tomcat, or Nginx.

Example of a public routing rule for Nginx reverse proxy:
```text
server {
    listen 80;
    server_name example.com;

# Proxy requests matching /api/v1/public to the backend
    location ^~ /api/v1/public {
        proxy_pass http://localhost:8080; # Assuming the service runs on port 8080
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

# Deny requests matching /api/v1/manage
    location ^~ /api/v1/manage {
        deny all; # Deny all requests, return 403
    }
}
```

## Configuration Details

### Startup Parameters
Note: Startup parameters correspond to fields in `config.json`. It is recommended to use the configuration file.

* `config`: Specifies the configuration file path, default `config.json`.
* `gocaptcha-config`: Specifies the GoCaptcha configuration file path, default `gocaptcha.json`.
* `service-name`: Sets the service name.
* `service-node`: Sets the service node number.
* `http-port`: Sets the HTTP server port.
* `grpc-port`: Sets the gRPC server port.
* `redis-addrs`: Sets Redis cluster addresses, comma-separated.
* `etcd-addrs`: Sets Etcd addresses, comma-separated.
* `memcache-addrs`: Sets Memcached addresses, comma-separated.
* `cache-type`: Sets the cache type, supports `redis`, `memory`, `etcd`, `memcache`.
* `cache-ttl`: Sets cache TTL in seconds.
* `cache-key-prefix`: Sets the cache key prefix, default `GO_CAPTCHA_DATA:`.

* `enable-dynamic-config`: Enables dynamic configuration service, default `false`.
* `dynamic-config-type`: Sets the dynamic configuration service type, supports `etcd`, `zookeeper`, `consul`, `nacos`.
* `dynamic-config-addrs`: Sets the dynamic configuration server addresses, comma-separated.
* `dynamic-config-ttl`: Sets the dynamic configuration service registration TTL in seconds, default `10`.
* `dynamic-config-keep-alive`: Sets the dynamic configuration service keep-alive interval in seconds, default `3`.
* `dynamic-config-max-retries`: Sets the maximum retry attempts for dynamic configuration operations, default `3`.
* `dynamic-config-base-retry-delay`: Sets the base retry delay for dynamic configuration in milliseconds, default `3`.
* `dynamic-config-username`: Sets the dynamic configuration service authentication username.
* `dynamic-config-password`: Sets the dynamic configuration service authentication password.
* `dynamic-config-tls-server-name`: Sets the dynamic configuration service TLS server name.
* `dynamic-config-tls-address`: Sets the dynamic configuration service TLS server address.
* `dynamic-config-tls-cert-file`: Sets the dynamic configuration service TLS certificate file path.
* `dynamic-config-tls-key-file`: Sets the dynamic configuration service TLS key file path.
* `dynamic-config-tls-ca-file`: Sets the dynamic configuration service TLS CA file path.

* `enable-service-discovery`: Enables service discovery, default `false`.
* `service-discovery-type`: Sets the service discovery type, supports `etcd`, `zookeeper`, `consul`, `nacos`.
* `service-discovery-addrs`: Sets the service discovery server addresses, comma-separated.
* `service-discovery-ttl`: Sets the service discovery registration TTL in seconds, default `10`.
* `service-discovery-keep-alive`: Sets the service discovery keep-alive interval in seconds, default `3`.
* `service-discovery-max-retries`: Sets the maximum retry attempts for service discovery operations, default `3`.
* `service-discovery-base-retry-delay`: Sets the base retry delay for service discovery in milliseconds, default `3`.
* `service-discovery-username`: Sets the service discovery authentication username.
* `service-discovery-password`: Sets the service discovery authentication password.
* `service-discovery-tls-server-name`: Sets the service discovery TLS server name.
* `service-discovery-tls-address`: Sets the service discovery TLS server address.
* `service-discovery-tls-cert-file`: Sets the service discovery TLS certificate file path.
* `service-discovery-tls-key-file`: Sets the service discovery TLS key file path.
* `service-discovery-tls-ca-file`: Sets the service discovery TLS CA file path.

* `rate-limit-qps`: Sets the rate limit QPS.
* `rate-limit-burst`: Sets the rate limit burst capacity.
* `api-keys`: Sets the API keys, comma-separated.
* `log-level`: Sets the log level, supports `error`, `debug`, `warn`, `info`.
* `health-check`: Runs a health check and exits, default `false`.
* `enable-cors`: Enables Cross-Origin Resource Sharing, default `false`.

### Environment Variables
Basic Configuration:

* `CONFIG`: Main configuration file path for loading application settings.
* `GO_CAPTCHA_CONFIG`: CAPTCHA service configuration file path.
* `SERVICE_NAME`: Service name to identify the service instance.
* `SERVICE_NODE`: Service node number to the service instance.
* `HTTP_PORT`: HTTP service listening port.
* `GRPC_PORT`: gRPC service listening port.
* `API_KEYS`: API keys for authentication or authorization.
* `LOG_LEVEL`: Log level.
* `ENABLE_CORS`: Enables Cross-Origin Resource Sharing, default "false".

Cache Configuration:
* `CACHE_TYPE`: Cache type (e.g., `redis`, `memcached`, `memory`, `etcd`).
* `CACHE_ADDRS`: Cache service address list.
* `CACHE_USERNAME`: Cache service authentication username.
* `CACHE_PASSWORD`: Cache service authentication password.

Dynamic Configuration Service:
* `ENABLE_DYNAMIC_CONFIG`: Enables dynamic configuration (`true` to enable).
* `DYNAMIC_CONFIG_TYPE`: Dynamic configuration type (e.g., `consul`, `zookeeper`, `nacos`, `etcd`).
* `DYNAMIC_CONFIG_ADDRS`: Dynamic configuration service address list.
* `DYNAMIC_CONFIG_USERNAME`: Dynamic configuration service authentication username.
* `DYNAMIC_CONFIG_PASSWORD`: Dynamic configuration service authentication password.

Service Discovery:
* `ENABLE_SERVICE_DISCOVERY`: Enables service discovery (`true` to enable).
* `SERVICE_DISCOVERY_TYPE`: Service discovery type (e.g., `consul`, `zookeeper`, `nacos`, `etcd`).
* `SERVICE_DISCOVERY_ADDRS`: Service discovery service address list.
* `SERVICE_DISCOVERY_USERNAME`: Service discovery service authentication username.
* `SERVICE_DISCOVERY_PASSWORD`: Service discovery service authentication password.

### Configuration Files
The service uses two configuration files: `config.json` for service runtime parameters and `gocaptcha.json` for CAPTCHA generation settings.

### config.json

`config.json` defines the basic service configuration.

```json
{
   "config_version": 1,
   "service_name": "go-captcha-service",
   "service_node": 1,
   "http_port": "8080",
   "grpc_port": "50051",
   "redis_addrs": "localhost:6379",
   "etcd_addrs": "localhost:2379",
   "memcache_addrs": "localhost:11211",
   "cache_type": "memory",
   "cache_db": "0",
   "cache_ttl": 1800,
   "cache_key_prefix": "GO_CAPTCHA_DATA:",
  
   "enable_dynamic_config": false,
   "dynamic_config_type": "etcd",
   "dynamic_config_addrs": "localhost:2379",
   "dynamic_config_username": "",
   "dynamic_config_password": "",
   "dynamic_config_ttl": 10,
   "dynamic_config_keep_alive": 3,
   "dynamic_config_max_retries": 3,
   "dynamic_config_base_retry_delay": 500,
   "dynamic_config_tls_server_name": "",
   "dynamic_config_tls_address": "",
   "dynamic_config_tls_cert_file": "",
   "dynamic_config_tls_key_file": "",
   "dynamic_config_tls_ca_file": "",
  
   "enable_service_discovery": false,
   "service_discovery_type": "etcd",
   "service_discovery_addrs": "localhost:2379",
   "service_discovery_username": "",
   "service_discovery_password": "",
   "service_discovery_ttl": 10,
   "service_discovery_keep_alive": 3,
   "service_discovery_max_retries": 3,
   "service_discovery_base_retry_delay": 500,
   "service_discovery_tls_server_name": "",
   "service_discovery_tls_address": "",
   "service_discovery_tls_cert_file": "",
   "service_discovery_tls_key_file": "",
   "service_discovery_tls_ca_file": "",
  
   "rate_limit_qps": 1000,
   "rate_limit_burst": 1000,
   "enable_cors": true,
   "log_level": "info",
   "api_keys": ["my-secret-key-123", "another-key-456", "another-key-789"]
}
```

#### Parameter Descriptions

- `config_version` (integer): Configuration file version for distributed dynamic configuration, default `1`.
- `service_name` (string): Service name, default `go-captcha-service`.
- `http_port` (string): HTTP port, default `8080`.
- `grpc_port` (string): gRPC port, default `50051`.
- `redis_addrs` (string): Redis address, default `localhost:6379`. Used when `cache_type: redis`.
- `etcd_addrs` (string): Etcd address, default `localhost:2379`. Used when `cache_type: etcd` or `service_discovery: etcd`.
- `memcache_addrs` (string): Memcache address, default `localhost:11211`. Used when `cache_type: memcache`.
- `cache_type` (string): Cache type, default `memory`:
    - `memory`: In-memory cache, suitable for standalone deployment.
    - `redis`: Distributed key-value store, suitable for high-availability scenarios.
    - `etcd`: Distributed key-value store, suitable for sharing with service discovery.
    - `memcache`: High-performance distributed cache, suitable for high concurrency.
- `cache_db` (string): Cache service db name, default `0`.
- `cache_ttl` (integer): Cache expiration time in seconds, default `1800`.
- `cache_key_prefix` (string): Cache key prefix, default `GO_CAPTCHA_DATA:`.

- `enable_dynamic_config` (boolean): Enables dynamic configuration service, default `false`.
- `dynamic_config_type` (string): Dynamic configuration service type, default `etcd`:
    - `etcd`: Suitable for high-consistency scenarios.
    - `nacos`: Suitable for cloud-native environments.
    - `zookeeper`: Suitable for complex distributed systems.
    - `consul`: Lightweight, supports health checks.
- `dynamic_config_addrs` (string): Dynamic configuration service addresses, e.g., Etcd: `localhost:2379`, Nacos: `localhost:8848`.
- `dynamic_config_username` (string): Username, e.g., Nacos default username is `nacos`, default empty.
- `dynamic_config_password` (string): Password, e.g., Nacos default password is `nacos`, default empty.
- `dynamic_config_ttl` (integer): Service lease time in seconds, default `10`.
- `dynamic_config_keep_alive` (integer): Heartbeat interval in seconds, default `3`.
- `dynamic_config_max_retries` (integer): Retry attempts, default `3`.
- `dynamic_config_base_retry_delay` (integer): Retry delay in milliseconds, default `500`.
- `dynamic_config_tls_server_name` (string): TLS server name, default empty.
- `dynamic_config_tls_address` (string): TLS server's address, default empty.
- `dynamic_config_tls_cert_file` (string): TLS certificate file, default empty.
- `dynamic_config_tls_key_file` (string): TLS key file, default empty.
- `dynamic_config_tls_ca_file` (string): TLS CA certificate file, default empty.

- `enable_service_discovery` (boolean): Enables service discovery, default `false`.
- `service_discovery_type` (string): Service discovery type, default `etcd`:
    - `etcd`: Suitable for high-consistency scenarios.
    - `nacos`: Suitable for cloud-native environments.
    - `zookeeper`: Suitable for complex distributed systems.
    - `consul`: Lightweight, supports health checks.
- `service_discovery_addrs` (string): Service discovery addresses, e.g., Etcd: `localhost:2379`, Nacos: `localhost:8848`.
- `service_discovery_username` (string): Username, e.g., Nacos default username is `nacos`, default empty.
- `service_discovery_password` (string): Password, e.g., Nacos default password is `nacos`, default empty.
- `service_discovery_ttl` (integer): Service registration lease time in seconds, default `10`.
- `service_discovery_keep_alive` (integer): Heartbeat interval in seconds, default `3`.
- `service_discovery_max_retries` (integer): Retry attempts, default `3`.
- `service_discovery_base_retry_delay` (integer): Retry delay in milliseconds, default `500`.
- `service_discovery_tls_server_name` (string): TLS server name, default empty.
- `service_discovery_tls_address` (string): TLS server's address, default empty.
- `service_discovery_tls_cert_file` (string): TLS certificate file, default empty.
- `service_discovery_tls_key_file` (string): TLS key file, default empty.
- `service_discovery_tls_ca_file` (string): TLS CA certificate file, default empty.

- `rate_limit_qps` (integer): API requests per second limit, default `1000`.
- `rate_limit_burst` (integer): API burst capacity limit, default `1000`.
- `enable_cors` (boolean): Enables CORS, default `true`.
- `log_level` (string): Log level (`debug`, `info`, `warn`, `error`), default `info`.
- `api_keys` (string array): API authentication keys.
- `auth_apis` (string array): Auth APIs：
    - default: ["/api/v1/manage/get-status-info",
      "/api/v1/manage/del-status-info",
      "/api/v1/manage/upload-resource",
      "/api/v1/manage/delete-resource",
      "/api/v1/manage/get-resource-list",
      "/api/v1/manage/get-config",
      "/api/v1/manage/update-hot-config",
      "/gocaptcha.GoCaptchaService/GetStatusInfo",
      "/gocaptcha.GoCaptchaService/DelStatusInfo" ]
  
### gocaptcha.json

`gocaptcha.json` defines resources and generation settings for CAPTCHAs.

```json
{
  "config_version": 1,
  "resources": {
    "version": "0.0.1",
    "char": {
      "languages": {
        "chinese": [],
        "english": []
      }
    },
    "font": {
      "type": "load",
      "file_dir": "./gocaptcha/fonts/",
      "file_maps": {
        "yrdzst_bold": "yrdzst-bold.ttf"
      }
    },
    "shape_image": {
      "type": "load",
      "file_dir": "./gocaptcha/shape_images/",
      "file_maps": {
        "shape_01": "shape_01.png",
        "shape_01.png":"c.png"
      }
    },
    "master_image": {
      "type": "load",
      "file_dir": "./gocaptcha/master_images/",
      "file_maps": {
        "image_01": "image_01.jpg",
        "image_02":"image_02.jpg"
      }
    },
    "thumb_image": {
      "type": "load",
      "file_dir": "./gocaptcha/thumb_images/",
      "file_maps": {

}
    },
    "tile_image": {
      "type": "load",
      "file_dir": "./gocaptcha/tile_images/",
      "file_maps": {
        "tile_01": "tile_01.png",
        "tile_02": "tile_02.png"
      },
      "file_maps_02": {
        "tile_mask_01": "tile_mask_01.png",
        "tile_mask_02": "tile_mask_02.png"
      },
      "file_maps_03": {
        "tile_shadow_01": "tile_shadow_01.png",
        "tile_shadow_02": "tile_shadow_02.png"
      }
    }
  },
  "builder": {
    "click_config_maps": {
      "click-default-ch": {
        "version": "0.0.1",
        "language": "chinese",
        "master": {
          "image_size": { "width": 300, "height": 220 },
          "range_length": { "min": 6, "max": 7 },
          "range_angles": [
            { "min": 20, "max": 35 },
            { "min": 35, "max": 45 },
            { "min": 290, "max": 305 },
            { "min": 305, "max": 325 },
            { "min": 325, "max": 330 }
          ],
          "range_size": { "min": 26, "max": 32 },
          "range_colors": [ "#fde98e", "#60c1ff", "#fcb08e", "#fb88ff", "#b4fed4", "#cbfaa9", "#78d6f8"],
          "display_shadow": true,
          "shadow_color": "#101010",
          "shadow_point": { "x": -1, "y": -1 },
          "image_alpha": 1,
          "use_shape_original_color": true
        },
        "thumb": {
          "image_size": { "width": 150, "height": 40 },
          "range_verify_length": { "min": 2, "max": 4 },
          "disabled_range_verify_length": false,
          "range_text_size": { "min": 22, "max": 28 },
          "range_text_colors": [ "#1f55c4", "#780592", "#2f6b00", "#910000", "#864401", "#675901", "#016e5c"],
          "range_background_colors": ["#1f55c4", "#780592", "#2f6b00", "#910000", "#864401", "#675901", "#016e5c"],
          "is_non_deform_ability": false,
          "background_distort": 4,
          "background_distort_alpha": 1,
          "background_circles_num": 24,
          "background_slim_line_num": 2
        }
      },
      "click-dark-ch": {
        "version": "0.0.1",
        "language": "chinese",
        // Same as above...
      },
      "click-default-en": {
        "version": "0.0.1",
        "language": "english",
        // Same as above...
      },
      "click-dark-en": {
        "version": "0.0.1",
        "language": "english",
        // Same as above...
      }
    },
    "click_shape_config_maps": {
      "click-shape-default":  {
        "version": "0.0.1",
        "master": {
          "image_size": { "width": 300, "height": 220 },
          "range_length": { "min": 6, "max": 7 },
          "range_angles": [
            { "min": 20, "max": 35 },
            { "min": 35, "max": 45 },
            { "min": 290, "max": 305 },
            { "min": 305, "max": 325 },
            { "min": 325, "max": 330 }
          ],
          "range_size": { "min": 26, "max": 32 },
          "range_colors": [ "#fde98e", "#60c1ff", "#fcb08e", "#fb88ff", "#b4fed4", "#cbfaa9", "#78d6f8"],
          "display_shadow": true,
          "shadow_color": "#101010",
          "shadow_point": { "x": -1, "y": -1 },
          "image_alpha": 1,
          "use_shape_original_color": true
        },
        "thumb": {
          "image_size": { "width": 150, "height": 40},
          "range_verify_length": { "min": 2, "max": 4 },
          "disabled_range_verify_length": false,
          "range_text_size": { "min": 22, "max": 28},
          "range_text_colors": [ "#1f55c4", "#780592", "#2f6b00", "#910000", "#864401", "#675901", "#016e5c"],
          "range_background_colors": [ "#1f55c4", "#780592", "#2f6b00", "#910000", "#864401", "#675901", "#016e5c" ],
          "is_non_deform_ability": false,
          "background_distort": 4,
          "background_distort_alpha": 1,
          "background_circles_num": 24,
          "background_slim_line_num": 2
        }
      }
    },
    "slide_config_maps": {
      "slide-default": {
        "version": "0.0.1",
        "master": {
          "image_size": { "width": 300, "height": 220 },
          "image_alpha": 1
        },
        "thumb": {
          "range_graph_size":  { "min": 60, "max": 70 },
          "range_graph_angles": [
            { "min": 20, "max": 35 },
          ],
          "generate_graph_number": 1,
          "enable_graph_vertical_random": false,
          "range_dead_zone_directions": ["left", "right"]
        }
      }
    },
    "drag_config_maps": {
      "drag-default": {
        "version": "0.0.1",
        "master": {
          "image_size": { "width": 300, "height": 220 },
          "image_alpha": 1
        },
        "thumb": {
          "range_graph_size":  { "min": 60, "max": 70 },
          "range_graph_angles": [
            { "min": 0, "max": 0 },
          ],
          "generate_graph_number": 2,
          "enable_graph_vertical_random": true,
          "range_dead_zone_directions": ["left", "right", "top", "bottom"]
        }
      }
    },
    "rotate_config_maps": {
      "rotate-default": {
        "version": "0.0.1",
        "master": {
          "image_square_size": 220
        },
        "thumb": {
          "range_angles":  [{ "min": 30, "max": 330 }],
          "range_image_square_sizes":  [140, 150, 160, 170],
          "image_alpha":  1
        }
      }
    }
  }
}
```

##### Top-Level Fields

- `config_version` (integer): Configuration file version for distributed dynamic configuration management, default `1`.

> resources

- `version` (string): Resource configuration version to control CAPTCHA instance recreation, default `0.0.1`.
- `char.languages.chinese` (string array): Chinese character set for click CAPTCHA text, default empty (uses built-in resources).
- `char.languages.english` (string array): English character set, default empty (uses built-in resources).
- `font.type` (string): Font loading method, fixed as `load` (load from file).
- `font.file_dir` (string): Font file directory, default `./gocaptcha/fonts/`.
- `font.file_maps` (object): Font file mappings, key is the font name, value is the file name.
    - Example: `"yrdzst_bold": "yrdzst-bold.ttf"` uses `yrdzst-bold.ttf` font.
- `shape_image.type` (string): Shape image loading method, fixed as `load`.
- `shape_image.file_dir` (string): Shape image directory, default `./gocaptcha/shape_images/`.
- `shape_image.file_maps` (object): Shape image mappings.
    - Example: `"shape_01": "shape_01.png"` uses `shape_01.png` as a shape.
- `master_image.type` (string): Main image loading method, fixed as `load`.
- `master_image.file_dir` (string): Main image directory, default `./gocaptcha/master_images/`.
- `master_image.file_maps` (object): Main image mappings.
    - Example: `"image_01": "image_01.jpg"` uses `image_01.jpg` as the background.
- `thumb_image.type` (string): Thumbnail image loading method, fixed as `load`.
- `thumb_image.file_dir` (string): Thumbnail image directory, default `./gocaptcha/thumb_images/`.
- `thumb_image.file_maps` (object): Thumbnail image mappings, default empty.
- `tile_image.type` (string): Tile image loading method, fixed as `load`.
- `tile_image.file_dir` (string): Tile image directory, default `./gocaptcha/tile_images/`.
- `tile_image.file_maps` (object): Tile image mappings.
    - Example: `"tile_01": "tile_01.png"`.
- `tile_image.file_maps_02` (object): Tile mask mappings.
    - Example: `"tile_mask_01": "tile_mask_01.png"`.
- `tile_image.file_maps_03` (object): Tile shadow mappings.
    - Example: `"tile_shadow_01": "tile_shadow_01.png"`.

> builder

Defines CAPTCHA generation styles, including configurations for click, shape click, slide, drag, and rotate CAPTCHAs.

#### click_config_maps

Defines text click CAPTCHA configurations, supporting Chinese and English with light and dark themes. The key is the ID passed in the CAPTCHA API request, e.g., `api/v1/public/get-data?id=click-default-ch`.

- `click-default-ch` (object): Default Chinese theme configuration.
- `version` (string): Configuration version to control CAPTCHA instance recreation, default `0.0.1`.
$
- `language` (string): Language, matches defined `char.languages`, e.g., `chinese` for Chinese.
- `master` (object): Main CAPTCHA image configuration.
- `image_size.width` (integer): Main image width, default `300`.
- `image_size.height` (integer): Main image height, default `200`.
- `range_length.min` (integer): Minimum number of CAPTCHA points, default `6`.
- `range_length.max` (integer): Maximum number of CAPTCHA points, default `7`.
- `range_angles` (object array): Text rotation angle ranges (degrees).
- Example: `{"min": 20, "max": 35}` for 20°-35°.
- `range_size.min` (integer): Minimum text size (pixels), default `26`.
- `range_size.max` (integer): Maximum text size, default `32`.
- `range_colors` (string array): Text color list (hexadecimal).
- Example: `"#fde98e"`.
- `display_shadow` (boolean): Display text shadow, default `true`.
- `shadow_color` (string): Shadow color, default `#101010`.
- `shadow_point.x` (integer): Shadow offset X coordinate, default `-1` (auto-calculated).
- `shadow_point.y` (integer): Shadow offset Y coordinate, default `-1`.
- `image_alpha` (float): Image opacity (0-1), default `1`.
- `use_shape_original_color` (boolean): Use original shape color, default `true`.
- `thumb` (object): Thumbnail (prompt text) configuration.
- `image_size.width` (integer): Thumbnail width, default `150`.
- `image_size.height` (integer): Thumbnail height, default `40`.
- `range_verify_length.min` (integer): Minimum verification points, default `2`.
- `range_verify_length.max` (integer): Maximum verification points, default `4`.
- `disabled_range_verify_length` (boolean): Disable verification point limit, default `false`.
- `range_text_size.min` (integer): Minimum text size, default `22`.
- `range_text_size.max` (integer): Maximum text size, default `28`.
- `range_text_colors` (string array): Text color list.
- `range_background_colors` (string array): Background color list.
- `is_non_deform_ability` (boolean): Disable deformation effect, default `false`.
- `background_distort` (integer): Background distortion level, default `4`.
- `background_distort_alpha` (float): Background distortion opacity, default `1`.
- `background_circles_num` (integer): Number of background circle interference points, default `24`.
- `background_slim_line_num` (integer): Number of background slim line interferences, default `2`.

- `click-dark-ch` (object): Chinese dark theme configuration, similar to `click-default-ch`, but `thumb.range_text_colors` uses brighter colors for dark backgrounds.

- `click-default-en` (object): Default English theme configuration, with `language: english`, larger `master.range_size` and `thumb.range_text_size` (`34-48`) for English characters.

- `click-dark-en` (object): English dark theme configuration, similar to `click-dark-ch`, with `language: english`.

#### click_shape_config_maps

Defines shape click CAPTCHA configurations.

- `click-shape-default` (object): Default shape click configuration, similar to `click_config_maps` `master` and `thumb` but for shape images instead of text.

#### slide_config_maps

Defines slide CAPTCHA configurations.

- `slide-default` (object):
- `version` (string): Configuration version to control CAPTCHA instance recreation, default `0.0.1`.
- `master` (object): Main CAPTCHA image configuration.
- `image_size.width` (integer): Main image width, default `300`.
- `image_size.height` (integer): Main image height, default `200`.
- `image_alpha` (float): Image opacity (0-1), default `1`.
- `thumb` (object): Slider configuration.
- `range_graph_size.min` (integer): Minimum slider graphic size (pixels), default `60`.
- `range_graph_size.max` (integer): Maximum slider graphic size, default `70`.
- `range_graph_angles` (object array): Slider graphic rotation angle ranges (degrees).
- Example: `{"min": 20, "max": 35}`.
- `generate_graph_number` (integer): Number of slider graphics to generate, default `1`.
- `enable_graph_vertical_random` (boolean): Enable vertical random offset, default `false`.
- `range_dead_zone_directions` (string array): Slider dead zone directions, default `["left", "right"]`.

#### drag_config_maps

Defines drag CAPTCHA configurations.

- `drag-default` (object):
- `version` (string): Configuration version to control CAPTCHA instance recreation, default `0.0.1`.
- `master` (object): Main CAPTCHA image configuration.
- `image_size.width` (integer): Main image width, default `300`.
- `image_size.height` (integer): Main image height, default `200`.
- `image_alpha` (float): Image opacity (0-1), default `1`.
- `thumb` (object): Drag graphic configuration.
- `range_graph_size.min` (integer): Minimum drag graphic size (pixels), default `60`.
- `range_graph_size.max` (integer): Maximum drag graphic size, default `70`.
- `range_graph_angles` (object array): Drag graphic rotation angle ranges (degrees).
- Example: `{"min": 0, "max": 0}` for no rotation.
- `generate_graph_number` (integer): Number of drag graphics to generate, default `2`.
- `enable_graph_vertical_random` (boolean): Enable vertical random offset, default `true`.
- `range_dead_zone_directions` (string array): Drag dead zone directions, default `["left", "right", "top", "bottom"]`.

#### rotate_config_maps

Defines rotate CAPTCHA configurations.

- `rotate-default` (object):
- `version` (string): Configuration version to control CAPTCHA instance recreation, default `0.0.1`.
- `master` (object): Main CAPTCHA image configuration.
- `image_square_size` (integer): Main image square side length (pixels), default `220`.
- `thumb` (object): Rotate graphic configuration.
- `range_angles` (object array): Rotation angle ranges (degrees).
- Example: `{"min": 30, "max": 330}` for 30°-330°.
- `range_image_square_sizes` (integer array): Rotate image square side length list, default `[140, 150, 160, 170]`.
- `image_alpha` (float): Image opacity (0-1), default `1`.

### Configuration Hot Reloading
Hot reloading for `gocaptcha.json` is determined by the `version` field of each configuration item.

Hot-reloadable fields in `config.json` include:
* `cache_type`
* `cache_addrs`
* `cache_username`
* `cache_password`
* `cache_db`
* `cache_ttl`
* `cache_key_prefix`
* `api_keys`
* `auth_apis`
* `log_level`
* `rate_limit_qps`
* `rate_limit_burst`

### Testing

- CAPTCHA Generation: Verify image, shape, and key validity.
- Verification Logic: Test handling of different inputs.
- Service Discovery: Simulate Etcd/Nacos/Zookeeper/Consul.
- Caching: Test Memory/Redis/Etcd/Memcache.
- Dynamic Configuration: Test Etcd|Nacos|Zookeeper|Consul configuration updates.

## LICENSE
Go Captcha Service source code is licensed under the Apache License, Version 2.0 [http://www.apache.org/licenses/LICENSE-2.0.html](http://www.apache.org/licenses/LICENSE-2.0.html)

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