How do I get 'git log' in the terminal or using a shell script when not in a repository

Question

I have Teamcity build agent, where I need to extract the git log from a repository. The trouble is, when my shell script runs, it's not in git repository, so git log doesn't work out of the box.

Does anyone know how to achieve this.

I have search the documentation, but I can't seem to find any way of doing it.

Problem solving so far

1. When Teamcity "clones" a project from Github on to the agent, it doesn't actually clone the whole thing. So the working directory is not a repository.

2. I do not have SSH access to github when running my shell script, which I need

Thanks in advance.

Solution

See accepted answer below.

Answer 1

Use the -C flag of the git command. It allows you to specify the git directory.

git -C 'git-working-dir' log

Answer 2

My solution, ended up being as follows:

1. Register SSH credentials to access Github on the TC Agent.

2. git clone ssh://git@github.com/account-name/repo.git /var/tmp/projectname_tmp

3. cd to the directory /var/tmp/projectname_tmp

4. git log >> output.file

For bonus points, you can extract from a given date like so:

5. git log --since='2016-11-01 03:00' >> output.log

Answer 3

You don't need to clone the repo to get the log. TeamCity already has a list of files and commit messages that triggered the build. You can simply query the TeamCity API in a script step and get the log. Here are the two Powershell functions I use to do this.

TeamCityGetChangeLog, requires the server url, the username, password, and a build ID (which you can pass in from the TeamCity parameters).

# Gets the change log for the specified build ID
function TeamCityGetChangeLog([string] $serverUrl, [string] $username, [string] $password, [int] $buildId){
    $changelog = ''

    # If the build is running inside TeamCity
    if ($env:TEAMCITY_VERSION) {
        $buildUrl = "$serverUrl/httpAuth/app/rest/changes?build=id:$($buildId)"
        $authToken = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes($username + ":" + $password))

        # Get all the changes
        $request = [System.Net.WebRequest]::Create($buildUrl)
        $request.Headers.Add("Authorization", "Basic $authToken");
        $xml = [xml](new-object System.IO.StreamReader $request.GetResponse().GetResponseStream()).ReadToEnd()

        # Get all commit messages for each of them
        $changelog = Microsoft.PowerShell.Utility\Select-Xml $xml -XPath `
            "/changes/change" | Foreach {
                TeamCityGetCommitMessage $serverUrl $username $password $_.Node.id
            }
    }

    return $changelog
}

That relies on TeamCityGetCommitMessage which also requires the change set ID.

# Get the commit messages, and files changed for the specified change id
# Ignores empty lines, lines containing "#ignore", "merge branch"" or "TeamCity"
function TeamCityGetCommitMessage([string]$serverUrl, [string]$username, [string]$password, [int]$changeId)
{
    $getFilesChanged = $false;
    $request = [System.Net.WebRequest]::Create("$serverUrl/httpAuth/app/rest/changes/id:$changeId")
    $authToken = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes($username + ":" + $password))
    $request.Headers.Add("Authorization", "Basic $authToken");

    $xml = [xml](new-object System.IO.StreamReader $request.GetResponse().GetResponseStream()).ReadToEnd()

    Microsoft.PowerShell.Utility\Select-Xml $xml -XPath "/change" |
        where { ($_.Node["comment"].InnerText.Length -ne 0) `
        -and (-Not $_.Node["comment"].InnerText.Contains('#ignore')) `
        -and (-Not $_.Node["comment"].InnerText.StartsWith("Merge branch")) `
        -and (-Not $_.Node["comment"].InnerText.StartsWith("TeamCity change"))} |
        foreach {
            $getFilesChanged = $true
            $username = (&{If($_.Node["user"] -ne $null) {$_.Node["user"].name.Trim()} Else { $_.Node.Attributes["username"].Value }})
            "<br /><strong>$($username + " on " + ([System.DateTime]::ParseExact($_.Node.Attributes["date"].Value, "yyyyMMddTHHmmsszzzz", [System.Globalization.CultureInfo]::InvariantCulture)))</strong><br /><br />"

            "$($_.Node["comment"].InnerText.Trim().Replace("`n", "`n<br />"))"
        }

    if ($getFilesChanged) {
        "<br /><br /><strong>Files Changed</strong><br /><br />"
        Microsoft.PowerShell.Utility\Select-Xml $xml -XPath "/change/files" |
        where { ($_.Node["file"].Length -ne 0)} |
        foreach { Select-Xml $_.Node -XPath 'file' |
            foreach { "$($_.Node.Attributes["file"].Value)<br />" }
        }
    }
}