Check out git-lfs files on VSTF build

Question

I\'ve a repository hosted on VSTS, containig a file stored through git-lfs. If I just let VSTS build checkout the repository it just downloads the git-lfs metadata file cont

Answer 1

Update

VSTS now supports git LFS out of the box. It's just a matter of activating the option Repository / Checkout files from LFS in the build definition. It is much simpler than the solution below.

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I tried Pascal's Enable Git Remote Access build task but I was not able to make it work. Calling git-lfs.exe does not crash but it does not convert the LFS files to the real files.

Here is how I was able to make it work. I first had to enable the Allow Scripts to Access OAuth Token option in my build definition. I then created a PowerShell script that pulls the LFS dependencies:

# Inspired from here: http://ss64.com/ps/syntax-set-eol.html
function Set-UnixLineEndings([string]$file)
{
    # Replace CR+LF with LF
    $text = [IO.File]::ReadAllText($file) -replace "`r`n", "`n"
    [IO.File]::WriteAllText($file, $text)

    # Replace CR with LF
    $text = [IO.File]::ReadAllText($file) -replace "`r", "`n"
    [IO.File]::WriteAllText($file, $text)
}

if ((Test-Path env:SYSTEM_ACCESSTOKEN) -eq $false)
{
    throw "OAuth token not available. Make sure that you select the option 'Allow Scripts to Access OAuth Token' in build 'Options' pane."
}

# git lfs needs the credentials of the git repository. When running
# under VSTS, these credentials are transfered to the git-lfs.exe
# application using the oauth token provided by VSTS. These
# credentials are stored in a file so that git lfs can find them.

$pwPath = Join-Path $PSScriptRoot pw.txt
$gitPwPath = $pwPath.Replace('\', '/')    # Needs to be in unix format.

$repoUri = New-Object Uri $env:BUILD_REPOSITORY_URI

git config credential.helper "store --file=$gitPwPath"
@"
https://OAuth:$env:SYSTEM_ACCESSTOKEN@$($repoUri.Host)
"@ | Set-Content $pwPath

# Again, needs to be in unix format... sigh...
Set-UnixLineEndings -file $pwPath

& ".\git-lfs.exe" pull
if ($LASTEXITCODE -ne 0)
{
    throw 'Failed to pull LFS files.'
}

This obviously assumes that you have stored git-lfs.exe in your git repository AND that this file is not tracked by LFS.