os/user: Current fails with "unknown userid" when it finds no entry about the user in "/etc/passwd"

[mrik974]

What version of Go are you using (go version)?

1.11

Does this issue reproduce with the latest release?

I don't know, I'm reporting a (not a) bug issue from a software I'm trying to use

What operating system and processor architecture are you using (go env)?

debian x64 on openshift

What did you do?

I'm not a go developer, but I was trying to use a software based on go v 1.11, named jobber, on my openshift infrastructure.
Openshift uses, for security purposes, a policy called "arbitrary user id" to run its containers. This means when a container starts, a user with a "random" id is used to run all the processes in that container. This user is not "added" the unix way, and has no entry in /etc/passwd.
It has no name, and no home, but it has an ID.
The software couldn't start because it was failing when calling the method user.Current, which returned unknown userid: 1000140000

What did you expect to see?

I think user.Current() on Unix/Linux, should still create a user object if it finds a userid, even though it has no other information about it, and not fail.
Feel free (of course) to close this issue if you think it fails by design.

[ianlancetaylor]

In the normal case on a Unix system, user.Current is just returning what getpwuid_r returns. If you call getpwuid_r when there is no user ID, it will return NULL, and so user.Current returns a value of type user.UnknownUserIdError.

I guess the argument for doing something different would be that if the program is built with CGO_ENABLED=0, then user.Current tries to work out a user.User value based on the environment variables USER and HOME. If those environment variables are found, the function succeeds.

So, on the one hand, presumably C programs that rely on getpwuid_r also fail on Openshift. On the other hand, user.Current does try to work without additional information in some cases. I see an argument both ways.

Why is your Go program calling user.Current? Does Openshift provide USER and HOME environment variables?

[mrik974]

There is a userid, it's just not set in the passwd file.
The software I'm actually using does not seem to do other than getting the username and home.
I'll try and compile it myself with CGO_ENABLED=0.
I'll also open an issue on Jobber's git page.
I'm closing the issue, as it is not a bug. Thank you @ianlancetaylor for pointing me to the right direction.
I also think programs that rely on getpwuid_r fail on Openshift infrastructure. But not every program is meant to run there, openshift is mostly for webservices and databases.
Jobber was kind of "good to run" too because it's a "cron like" program with better output.