Save variables as environment variables

[RobSmyth]

When writing scripts to customise version formatting to our needs, it has been difficult to access GitVersion variables. It would be easier if GitVersion variable(s) could optionally be exposed as environment variables.

Detailed Description

When using a batch file (say) or an MsBuild task (target file) to customise version formatting to our needs we need to read the GitVersion variable from a file (this may be mutually exclusive to using command line output option of buildsystem).

If we could, by configuration, nominate all or some variables to be made available as system variables (current session only) then we could access those in many languages including even (shock) a batch file.

Context

Reduce dev time to use the tool.

Possible Implementation

Another retrospective solution. Done by awful means.

[asbjornu]

It's not well documented, but GitVersion already exposes all version variables as environment variables in the form GitVersion_<variable_name> such as GitVersion_FullSemVer.

[RobSmyth]

Thank you, I must be missing something as I tried that without success. I call version.exe as a Visual Studio prebuild event and then call set to list all variables. I do not see any GitVersion_... variables. Same on my box and the build box (TeamCity).

I've not been able to access the variable as %GitVersion_FullSemVer%.

[asbjornu]

I see. gitversion.exe should set environment variables if it detects that it's running within a supported build server.

itself, that's done by the different build tasks (as how environment variables are set differs from build server to build server). You can see how it's done in AzDO here:

GitVersion/src/GitVersion.Core/BuildAgents/AzurePipelines.cs

Lines 20 to 27 in dca8008

	public override string[] GenerateSetParameterMessage(string name, string value)
	{
	return new[]
	{
	$"##vso[task.setvariable variable=GitVersion.{name}]{value}",
	$"##vso[task.setvariable variable=GitVersion.{name};isOutput=true]{value}"
	};
	}

#2722 seeks to improve the documentation in this area.

[RobSmyth]

Well I was actually thinking of the host OS environment variables. That looks like a build system's variables/parameters.

[asbjornu]

GitVersion does write OS environment variables, but I don't know AzDO well enough to say for certain that's what the linked code does. I can, however, say for certain that the GitHub Actions integration does it as per the following lines of code:

GitVersion/src/GitVersion.Core/BuildAgents/GitHubActions.cs

Line 16 in dca8008

public const string GitHubSetEnvTempFileEnvironmentVariableName = "GITHUB_ENV";

GitVersion/src/GitVersion.Core/BuildAgents/GitHubActions.cs

Line 47 in dca8008

var gitHubSetEnvFilePath = this.Environment.GetEnvironmentVariable(GitHubSetEnvTempFileEnvironmentVariableName);

GitVersion/src/GitVersion.Core/BuildAgents/GitHubActions.cs

Lines 51 to 59 in dca8008

	writer($"Writing version variables to $GITHUB_ENV file for '{GetType().Name}'.");
	using var streamWriter = File.AppendText(gitHubSetEnvFilePath);
	foreach (var variable in variables)
	{
	if (!string.IsNullOrEmpty(variable.Value))
	{
	streamWriter.WriteLine($"GitVersion_{variable.Key}={variable.Value}");
	}
	}

In GitHub Actions, evironment variables are written to a file whose path is given in the environment variable GITHUB_ENV.

[stale]

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