# Error: sudo: sorry, you must have a tty to run sudo (Packer provisioner)

## TL;DR
The remote sudo requires a TTY and Packer's SSH session does not allocate one. Set `ssh_pty` to `true` in the builder configuration.

## The error

```
sudo: sorry, you must have a tty to run sudo
```

(often surfacing as `Build 'amazon-ebs' errored: Error installing Chef: Install script exited with non-zero exit status 1` or a shell provisioner failure)

## Fix it

1. Add `"ssh_pty": true` to the builder block (JSON) or `ssh_pty = true` (HCL).
   - Success check: the setting is present in the builder, not the provisioner.
2. Re-run `packer build`.
   - Success check: sudo commands in provisioners execute instead of failing.
3. If you control the image, the alternative is removing `requiretty` from sudoers, but `ssh_pty` is the portable fix.
   - Success check: either path eliminates the error.

## When to use this
You hit this when provisioner scripts calling `sudo` fail on AMIs whose sudoers has `requiretty` (notably Amazon Linux and RHEL-family images).

## When NOT to use this
Do not use this for password prompts from sudo (`sudo: no tty present` is different; provide `ssh_password` or NOPASSWD) or for non-sudo script failures.

## Compatibility
Packer 1.x, SSH communicator, sudo with `requiretty`.

## Variants
- `Error installing Chef: Install script exited with non-zero exit status 1` with the tty message buried in the log
- Shell provisioner scripts failing only on their `sudo` lines

## Root cause
Some distributions ship sudoers with `Defaults requiretty`. Packer's SSH sessions run without a pseudo-terminal by default, so sudo refuses to run at all.

## Edge cases
- `ssh_pty` can change output buffering slightly; if a script parses interactive output, test it.
- WinRM/Windows builders do not use this setting; it is SSH-only.