Golang implements self-update

With the development of Internet technology, application updates have become the norm. However, the traditional manual update method has problems such as low update efficiency and cumbersome operations. In order to better solve these problems, an automatic update method is needed. Go language is an excellent development language. Its own characteristics and rich third-party libraries are very suitable for automatic updates.

This article will introduce how to use Go language to implement automatic updates. We will use two different update methods: HTTP protocol update and FTP protocol update, so that readers can choose according to their own needs in actual applications.

1. HTTP protocol update

HTTP protocol update is a common method, which uses the HTTP protocol to transfer files and implement application updates. To implement HTTP protocol updates, you need to use the net/http package and io/ioutil package of the Go language. Next, we will introduce step by step how to implement HTTP protocol update.

1. Get the version number of the published application file

Before implementing automatic update, you need to obtain the version number of the published application file in order to compare whether it needs to be updated. There are many ways to obtain the version number. This article uses the file name as an example method for the version number.

func GetVersion(filePath string) (string, error) {
    file, err := os.Open(filePath)
    if err != nil {
        return "", err
    }
    defer file.Close()

    fileInfo, err := file.Stat()
    if err != nil {
        return "", err
    }

    version := fileInfo.Name()
    return version, nil
}

The above code opens the file and obtains the file information, returning the file name as the version number.

2. Download the published application

After obtaining the version number of the published application file, you need to download the new version of the application locally. In the Go language, you can use the net/http package to download files and the io/ioutil package to save them locally.

func Download(fromUrl, savePath string) error {
    resp, err := http.Get(fromUrl)
    if err != nil {
        return err
    }
    defer resp.Body.Close()

    bytes, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return err
    }

    err = ioutil.WriteFile(savePath, bytes, 0644)
    if err != nil {
        return err
    }

    return nil
}

In the above code, we use the http.Get() method to obtain the published application file, and then use the ReadAll() method of the ioutil package to read the file content into memory. Next, use the WriteFile() method of the ioutil package to save the file locally.

3. Compare versions and perform updates

After downloading the new version of the application to the local, you need to compare the version numbers of the current application and the new version of the application to determine Whether an update operation is required. After the comparison is completed, you can perform some necessary operations, such as backing up the current application or preparing to perform some cleanup operations before updating.

func Update(versionFile, updateUrl, savePath string) error {
    oldVersion, err := GetVersion(versionFile)
    if err != nil {
        return err
    }

    err = Download(updateUrl, savePath)
    if err != nil {
        return err
    }

    newVersion, err := GetVersion(savePath)
    if err != nil {
        return err
    }

    if newVersion != oldVersion {
        // 执行更新操作
    }

    return nil
}

In the above code, we first get the version number of the current application file, and then use the Download() method to download the new version of the application file. Next, obtain the version number of the new application and compare whether the new and old version numbers are the same. If they are different, perform an update operation.

2. FTP protocol update

In addition to HTTP protocol update, another common update method is to download and upload files through FTP protocol. Although the FTP protocol is not as secure as the HTTP protocol, using the FTP protocol can reduce the load on the server and make updates faster. In the Go language, you can use the ftp package to implement updates to the FTP protocol.

1. Connecting to the FTP server

When using the ftp package to connect to the FTP server, you need to provide the FTP server address, username and password.

func ConnectToFtp(ftpAddr, userName, password string) (*ftp.ServerConn, error) {
    config := &ftp.Config{
        User:     userName,
        Password: password,
    }
    conn, err := ftp.Dial(ftpAddr, ftp.DialWithConfig(config))
    if err != nil {
        return nil, err
    }
    return conn, nil
}

In the above code, we use the ftp.Dial() method to connect to the FTP server and provide the username and password.

2. Download published applications

Using the ftp package to download files requires first obtaining the file list on the FTP server through the List() method, and then obtaining it through the Retr() method document content. Since the FTP server's connection is based on commands and responses, the correct commands and data must be sent between opening and closing the connection.

func DownloadFromFtp(conn *ftp.ServerConn, remotePath, localPath string) error {
    file, err := os.Create(localPath)
    if err != nil {
        return err
    }
    defer file.Close()

    resp, err := conn.Retr(remotePath)
    if err != nil {
        return err
    }
    defer resp.Close()

    _, err = io.Copy(file, resp)
    if err != nil {
        return err
    }
    return nil
}

In the above code, we use the os package to create a local file, and then use the Retr() method of the ftp package to obtain the file content on the FTP server. Finally, the file contents are written to a local file.

3. Compare versions and perform updates

After downloading the file, the method of performing compare versions and update operations is similar to HTTP protocol update.

func UpdateWithFtp(versionFile, ftpAddr, userName, password, remotePath, localPath string) error {
    conn, err := ConnectToFtp(ftpAddr, userName, password)
    if err != nil {
        return err
    }
    defer conn.Quit()

    oldVersion, err := GetVersion(versionFile)
    if err != nil {
        return err
    }

    err = DownloadFromFtp(conn, remotePath, localPath)
    if err != nil {
        return err
    }

    newVersion, err := GetVersion(localPath)
    if err != nil {
        return err
    }

    if newVersion != oldVersion {
        // 执行更新操作
    }

    return nil
}

In the above code, we first connect to the FTP server and then obtain the version number of the current application file. Next, we download the new version of the application through the DownloadFromFtp() method and obtain the version number of the new application. Finally, compare whether the new and old version numbers are the same, and if they are different, perform an update operation.

Summary

This article introduces how to use Go language to implement automatic updates, including HTTP protocol updates and FTP protocol updates. Different update methods are suitable for different application scenarios, and readers can choose the appropriate method according to their own needs. In addition, there are some other update methods, such as cloud update, distributed update, etc., readers can learn to use them as needed during use.

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