Downgrade pty to v1.1.19

[moskyb]

Description

1.1.20 and 1.1.21 appear to have a bug where occasionally, running processes under the pty will return a fork/exec: operation not permitted error

fixes #2790

Context

#2790
Coda escalations 1 and 2

Testing

• Tests have run locally (with go test ./...). Buildkite employees may check this if the pipeline has run automatically.
• Code is formatted (with go fmt ./...)

[flokli]

I get "open /dev/pts/0: permission denied" with buildkite-agent-3.59.0, which is using creack/[email protected] creack/[email protected], so I'm not sure this downgrade actually fixes the issue so I'll upgrade buildkite-agent to check if the pty downgrade fixes the issue for me too. See #2912 for details.

[danktec]

I just started getting Error running job: error starting pty: fork/exec /usr/bin/buildkite-agent: permission denied on the latest agent version.
I tried downgrading back to v3.36.0 and i'm now getting fork/exec /usr/bin/buildkite-agent: permission denied
so i'm at a loss... i have no idea how this was introduced

[DrJosh9000]

Just checking @danktec, /usr/bin/buildkite-agent is where the agent is installed, and it is executable by the user you're running as? e.g.

$ docker run --rm -it --entrypoint sh buildkite/agent:latest
/ # which buildkite-agent
/usr/local/bin/buildkite-agent
/ # stat $(which buildkite-agent)
  File: /usr/local/bin/buildkite-agent
  Size: 44301452  	Blocks: 86528      IO Block: 4096   regular file
Device: f5h/245d	Inode: 571703      Links: 1
Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2024-08-08 02:50:50.000000000 +0000
Modify: 2024-08-08 02:50:50.000000000 +0000
Change: 2024-08-08 05:43:06.593159640 +0000

[danktec]

@DrJosh9000 I did ensure all permissions were correct in all the places.
I have since rebuild my image and made some changes which have made this issue go away.

The only thing i can point to potentially is having a bad git-clone hook in the cfg file.

PS: I was running the agent via the apt installer on Ubuntu. (Agent runs on the host, then it calls docker on the same host, (trying to avoid other DinD issues))

[DrJosh9000]

Thanks @danktec , just have to make sure we aren't missing something.

If you (or anyone) suspects pty problems, and are particularly motivated to help debug: part of the process of blaming pty for the bug was running the agent under strace -f, poring over the output, and noticing EPERM from an ioctl call involved in setting up a pty.