Why does Powershell task truncate stderr?

[richardgavel]

If I use the Powershell task (with the errorActionPreference set to stop), if there is an error, it gets truncated, making it difficult to understand the underlying error. I have noticed the full errors shows when the errorActionPreference is set to continue, but then the pipeline will continue to execute even though an error occurred.

I then noticed this in the code and wonder why there is deliberate truncation (of both bytes in a line and number of lines) of the stderr steam and wonder why this was put in place?

https://github.com/microsoft/azure-pipelines-tasks/blob/master/Tasks/PowerShellV2/powershell.ts#L98

[richardgavel]

FYI, I think I'm seeing similar behavior with an extension that uses the Powershell3 handler.

[jtpetty]

@damccorm - can you take a look at this and comment as to why we truncate stderr?

[damccorm]

Hey @richardgavel - the code you're pointing to truncates the errors that we display at the end of the task (not actually in the script execution itself). We truncate the error here to avoid overwhelming the output if there are many errors or really long errors and so that we don't have to hold those in memory. The output should show up completely in the initial execution.

I think what you're describing here is different - could you give an example?

If I use the Powershell task (with the errorActionPreference set to stop), if there is an error, it gets truncated, making it difficult to understand the underlying error. I have noticed the full errors shows when the errorActionPreference is set to continue, but then the pipeline will continue to execute even though an error occurred.

[damccorm]

Closing due to inactivity

[MarkCallow]

I am seeing the exact problem described by @richardgavel. When my program being run by PowerShell writes something to stderr, PS shows only the first line of the output. When this happens in CI, where re-running is very difficult and time-consuming, it is infuriating. For example when there is an error in a CMake configuration the only thing printed by PS is (something like) "CMake error:" The entire useful part of the message is on the subsequent lines never shown by PS.

Should I open another bug? If I can't find out how to get the full error messages I will have to stop using ErrorActionPreference=Stop. This one exactly describes he issue. Whether the referenced source code is relevant I don't know.