How can I use msbuild to download a file?

Question

Is there a built in way to download a file to a local directory using HTTP?

I can shell out to wget or write a custom task, but I wanted to make sure there wasn't an existing way to accomplish this.

Thanks in advance!

Answer 1

In MSBuild 4.0 you can use inline tasks to avoid needing to compile and deploy a custom task in a separate assembly.

  <UsingTask TaskName="DownloadFile" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">     <ParameterGroup>       <Address ParameterType="System.String" Required="true"/>       <FileName ParameterType="System.String" Required="true" />     </ParameterGroup>     <Task>       <Reference Include="System" />       <Code Type="Fragment" Language="cs">         <![CDATA[             new System.Net.WebClient().DownloadFile(Address, FileName);         ]]>       </Code>     </Task>   </UsingTask>    <Target Name="DownloadSomething">     <DownloadFile Address="http://somewebsite/remotefile" FileName="localfilepath" />   </Target> 

Answer 2

MSBuild Community Tasks has a task WebDownload which seems to be what you require.

Answer 3

If you're trying to download a file that requires authentication (such as TFS Web, or an IIS server attached to a domain), neither the MSBuild Extension Pack nor the MSBuild Community Tasks seem to have the ability to give a username or password to the HTTP server. In this case, I ended up writing a custom MSBuild task. Here's what I did.

I followed the advice of Stack Overflow user Doug, in his answer for Download a file which requires authentication using vb.net/c#?, in which he suggests some code to add to a method written by Tom Archer on the Code Guru web site.

So I used MS Visual Studio 2010 to create a new C# project with the following code to create an MSBuild target named Wget (full source code shown):

// Include references to the following frameworks in your solution:
// - Microsoft.Build.Framework
// - Microsoft.Build.Utilities.v4.0
// - System
// - System.Net

using System;
using System.Net;
using System.IO;

using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace Wget
{
    public class Wget: Task
    {
        [Required]
        public String Address // HTTP address to access
        { get; set; }

        [Required]
        public String LocalFilename // Local file to which the downloaded page will be saved
        { get; set; }

        public String Username // Credential for HTTP authentication
        { get; set; }

        public String Password // Credential for HTTP authentication
        { get; set; }

        public override bool Execute()
        {
            int read = DownloadFile(Address, LocalFilename, Username, Password);

            Console.WriteLine("{0} bytes written", read);

            return true;
        }

        public static int DownloadFile(String remoteFilename, String localFilename, String httpUsername, String httpPassword)
        {
            // Function will return the number of bytes processed
            // to the caller. Initialize to 0 here.
            int bytesProcessed = 0;

            // Assign values to these objects here so that they can
            // be referenced in the finally block
            Stream remoteStream = null;
            Stream localStream = null;
            WebResponse response = null;

            // Use a try/catch/finally block as both the WebRequest and Stream
            // classes throw exceptions upon error
            try
            {
                // Create a request for the specified remote file name
                WebRequest request = WebRequest.Create(remoteFilename);
                if (request != null)
                {
                    // If a username or password have been given, use them
                    if (httpUsername.Length > 0 || httpPassword.Length > 0)
                    {
                        string username = httpUsername;
                        string password = httpPassword;
                        request.Credentials = new System.Net.NetworkCredential(username, password);
                    }

                    // Send the request to the server and retrieve the
                    // WebResponse object 
                    response = request.GetResponse();
                    if (response != null)
                    {
                        // Once the WebResponse object has been retrieved,
                        // get the stream object associated with the response's data
                        remoteStream = response.GetResponseStream();

                        // Create the local file
                        localStream = File.Create(localFilename);

                        // Allocate a 1k buffer
                        byte[] buffer = new byte[1024];
                        int bytesRead;

                        // Simple do/while loop to read from stream until
                        // no bytes are returned
                        do
                        {
                            // Read data (up to 1k) from the stream
                            bytesRead = remoteStream.Read(buffer, 0, buffer.Length);

                            // Write the data to the local file
                            localStream.Write(buffer, 0, bytesRead);

                            // Increment total bytes processed
                            bytesProcessed += bytesRead;
                        } while (bytesRead > 0);
                    }
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
            finally
            {
                // Close the response and streams objects here 
                // to make sure they're closed even if an exception
                // is thrown at some point
                if (response != null) response.Close();
                if (remoteStream != null) remoteStream.Close();
                if (localStream != null) localStream.Close();
            }

            // Return total bytes processed to caller.
            return bytesProcessed;
        }
    }
}

With that in place, I can add the following task to my MSBuild project:

<!-- Get the contents of a Url-->
<Wget
    Address="http://mywebserver.com/securepage"
    LocalFilename="mydownloadedfile.html"
    Username="myusername"
    Password="mypassword">
</Wget>

The Wget task downloads the page served by mywebserver.com and saves it to a file in the current working directory as mydownloadedfile.html, using the username "myusername" and password "mypassword".

However, in order to use the custom Wget MSBuild task, I must tell MSBuild where to find the Wget assembly file (.dll). This is done with MSBuild's element:

<!-- Import your custom MSBuild task -->
<UsingTask AssemblyFile="MyCustomMSBuildTasks\Wget\bin\Release\Wget.dll" TaskName="Wget" />

If you want to get fancy, you can even have your MSBuild project build Wget before it's called. To do that, build the solution with the <MSBuild Projects> task, and import it with the <UsingTaks AssemblyFile> task, something like this:

<!-- Build the custom MSBuild target solution-->
<MSBuild Projects="MyCustomMSBuildTasks\CustomBuildTasks.sln" Properties="Configuration=Release" />

<!-- Import your custom MSBuild task -->
<UsingTask AssemblyFile="MyCustomMSBuildTasks\Wget\bin\Release\Wget.dll" TaskName="Wget" />

<!-- Get the contents of a Url-->
<Wget
    Address="http://mywebserver.com/securepage"
    LocalFilename="mydownloadedfile.html"
    Username="myusername"
    Password="mypassword">
</Wget>

If you've never created a custom MSBuild target before, it's not too difficult -- once you know the basics. Look at the C# code above, take a look at the official MSDN documentation, and search around on the web for more examples. A good place to start is:

• http://msdn.microsoft.com/en-us/library/t9883dzc.aspx

Answer 4

The DownloadFile task is available in MSBuild 15.8 and above (since August 14, 2018)

example:

    <PropertyGroup>  
      <LicenceUrl>https://raw.githubusercontent.com/Microsoft/msbuild/master/LICENSE</LicenceUrl>
    </PropertyGroup>  

    <Target Name="DownloadContentFiles" BeforeTargets="Build">
        <DownloadFile
            SourceUrl="$(LicenceUrl)"
            DestinationFolder="$(MSBuildProjectDirectory)">
        <Output TaskParameter="DownloadedFile" ItemName="Content" />
      </DownloadFile>
    </Target>

For more details: DownloadFile task