Expo Classic迁移至EAS后，无法复现Release Channel环境切换功能

旧版环境切换实现 #

此前通过Updates.releaseChannel实现环境专属配置，根据发布渠道动态切换API地址，代码如下：

export function getEnvConst() {
  if (Updates.releaseChannel.startsWith("prod")) {
    return { apiUrl: "https://prodUrl.com/" };
  } else if (Updates.releaseChannel.startsWith("staging")) {
    return { apiUrl: "https://stagingUrl.com/" };
  } else if (Updates.releaseChannel.startsWith("uat")) {
    return { apiUrl: "https://uatUrl.com/" };
  } else {
    return { apiUrl: "https://devUrl.com/" };
  }
}

发布时通过指定渠道命令切换环境：

expo publish --release-channel prod
expo publish --release-channel uat
expo publish --release-channel staging

开发时执行npm start会自动进入else分支使用开发环境地址（无发布渠道）。

迁移eas build后的问题 #

尝试两种方法均未复现原有逻辑：

1. EAS Channel配置无效
   在eas.json中配置了不同profile对应不同channel，将代码中releaseChannel替换为channel后无效果，执行eas build -p android --profile staging未达到预期。eas.json配置如下：

{
  "cli": {
    "version": ">= 3.8.1"
  },
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal",
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "dev"
    },
    "staging": {
      "android": {
        "buildType": "apk"
      },
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "staging"
    },
    "uat": {
      "distribution": "internal",
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "uat"
    },
    "production": {
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "production"
    }
  },
  "submit": {
    "production": {}
  }
}

2. 环境变量在开发模式无法读取
   在eas.json中添加env配置后，代码中export const apiUrl = process.env.API_URL在执行npm start时无法读取到值，暂未测试eas build。相关配置如下：

{
  "cli": {
    "version": ">= 3.8.1"
  },
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal",
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "dev",
      "env": {
        "API_URL": "http://devUrl.com/"
      }
    },
    "production": {
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "production",
      "env": {
        "API_URL": "https://prodUrl.com/"
      }
    }
  },
  "submit": {
    "production": {}
  },
  "development": {
    "client": "local"
  },
  "env": {
    "development": {
      "API_URL": "https://devUrl.com/"
    }
  }
}

解决方案 #

方案1：使用EAS Channel结合Updates.channel #

EAS的Channel和旧版releaseChannel逻辑类似，调整代码即可适配：

import * as Updates from 'expo-updates';

export function getEnvConst() {
  // 开发模式下Updates.channel可能为空，做兼容处理
  const currentChannel = Updates.channel ?? '';
  if (currentChannel.startsWith("prod")) {
    return { apiUrl: "https://prodUrl.com/" };
  } else if (currentChannel.startsWith("staging")) {
    return { apiUrl: "https://stagingUrl.com/" };
  } else if (currentChannel.startsWith("uat")) {
    return { apiUrl: "https://uatUrl.com/" };
  } else {
    return { apiUrl: "https://devUrl.com/" };
  }
}

发布更新时需指定对应channel：eas update --channel staging，开发模式下npm start会自动进入else分支使用开发地址，和旧逻辑一致。

方案2：使用环境变量配合expo-constants（推荐） #

EAS环境变量需通过expo-constants读取，同时补充开发模式的配置：

1. 安装依赖：npm install expo-constants
2. 项目根目录创建.env.development文件：

API_URL=https://devUrl.com/

3. 完善eas.json的环境变量配置：

{
  "cli": {
    "version": ">= 3.8.1"
  },
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal",
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "dev",
      "env": {
        "API_URL": "https://devUrl.com/"
      }
    },
    "staging": {
      "android": {
        "buildType": "apk"
      },
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "staging",
      "env": {
        "API_URL": "https://stagingUrl.com/"
      }
    },
    "uat": {
      "distribution": "internal",
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "uat",
      "env": {
        "API_URL": "https://uatUrl.com/"
      }
    },
    "production": {
      "ios": {
        "resourceClass": "m-medium"
      },
      "channel": "production",
      "env": {
        "API_URL": "https://prodUrl.com/"
      }
    }
  },
  "submit": {
    "production": {}
  }
}

4. 修改代码读取环境变量：

import Constants from 'expo-constants';

export const apiUrl = Constants.expoConfig?.extra?.API_URL ?? 'https://devUrl.com/';

EAS会将env变量注入到Constants.expoConfig.extra，开发模式下expo start自动读取.env.development的变量，实现开发、构建环境统一适配。

内容的提问来源于stack exchange，提问作者Lawrence