## What this PR does
The Proxmox lane's Stage step writes `PROXMOX_SSH_KEY` to disk with
`printf '%s'`, so the key file ends exactly where the secret value does.
`gh secret set` strips the trailing newline from a value it reads from
stdin, which is the usual way to set a key (`gh secret set
PROXMOX_SSH_KEY < key`). OpenSSH refuses a private key whose last line
has no newline:
```
Load key ".../.ssh-pve": error in libcrypto
e2e-ro@10.60.0.1: Permission denied (publickey).
[20:45:58] FAILED: VM 124 has no scsi0
```
That is `vm-shape-on-the-hypervisor`, the first test that reaches the
hypervisor over SSH. Every run so far stopped before it, so nothing had
exercised the key. It showed up on a self-hosted stand once the CCM fix
in #4917 let the lane past `tenant-and-cluster`.
The step now writes the key with `printf '%s\n'`. If the secret kept its
own newline, the file ends in a blank line, and OpenSSH accepts that.
### Testing
- `hack/proxmox-teardown-contract.bats` gets a case that runs Stage with
a freshly generated key, once without a trailing newline and once with
one, and loads the result with `ssh-keygen -y`. It fails against the old
step on the first form. The whole file passes: 9/9.
- `bats-no-negated-assert`, `bats-strict-setup`, `bats-no-exit-trap`,
`bats-runner-coverage`: 63/63.
- Reproduced by hand on OpenSSH 9.6p1: the same key loads with one or
two trailing newlines and fails with `error in libcrypto` with none.
### Screenshots
Not a UI change.
### Downstream repositories
The diff changes one workflow step and adds a case to an existing bats
file. It moves or renames nothing under `hack/` and changes no make
target or `tags.yaml`.
- [x] No downstream repository is affected by this change
- [ ] [cozystack/website](https://github.com/cozystack/website) -
follow-up:
- [ ]
[cozystack/terraform-provider-cozystack](https://github.com/cozystack/terraform-provider-cozystack)
- follow-up:
- [ ]
[cozystack/ansible-cozystack](https://github.com/cozystack/ansible-cozystack)
- follow-up:
- [ ] [cozystack/ccp](https://github.com/cozystack/ccp) - follow-up:
- [ ] [cozystack/talm](https://github.com/cozystack/talm) - follow-up:
- [ ] [cozystack/cozyhr](https://github.com/cozystack/cozyhr) -
follow-up:
- [ ] [cozystack/cozy-proxy](https://github.com/cozystack/cozy-proxy) -
follow-up:
- [ ]
[cozystack/cozystack-telemetry-server](https://github.com/cozystack/cozystack-telemetry-server)
- follow-up:
- [ ]
[cozystack/external-apps-example](https://github.com/cozystack/external-apps-example)
- follow-up:
- [ ] [cozystack/examples](https://github.com/cozystack/examples) -
follow-up:
- [ ] [cozystack/community](https://github.com/cozystack/community) -
follow-up:
### Release note
```release-note
NONE
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
<!-- coderabbit-ai-generated:v1 -->
## Summary by CodeRabbit
* **Bug Fixes**
* Proxmox workflows now correctly stage SSH keys whether or not the key
ends with a newline.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Aleksei Sviridkin
30fc100e65