fix(remote): abort the bootstrap when the installer cannot be fetched

[tas50]

The defect

The generated script opens with set -e and then runs:

curl -L 'https://omnitruck.cinc.sh/install.sh' | sudo bash -s --

A pipeline reports only the exit status of its last command, so set -e sees bash's status, not curl's. A 404, a DNS failure, or a TLS error is silently swallowed — bash cheerfully executes an empty or error-page input and exits 0 — and the script marches on to:

sudo cinc-client -j /etc/cinc/first-boot.json

which is not installed. The operator gets a confusing downstream failure instead of the real one, and cinc node bootstrap reports it against a host that is now half-configured.

The fix

Download to a temp file and run that, so a failed fetch is a failed command that set -e acts on:

set -e
CINC_INSTALLER="$(mktemp)"
trap 'rm -f "$CINC_INSTALLER"' EXIT
curl -fsSL 'https://omnitruck.cinc.sh/install.sh' -o "$CINC_INSTALLER"
sudo bash "$CINC_INSTALLER" -v '18'

• -f so an HTTP error is a failure rather than an error page saved and executed as the "installer".
• -sS to keep the progress meter out of the SSH output while preserving real error messages.
• trap so the file is removed even when a later step fails.

set -o pipefail would also fix it, but it is not POSIX and the script runs under whatever login shell the target happens to have — dash, notably, does not support it.

bash -s -- becomes bash "$CINC_INSTALLER": -s means "read the script from stdin", which no longer applies, and the -- would otherwise be passed to the installer as $1.

The trust assumption is unchanged. The target still executes whatever the bootstrap URL serves; this only makes a failure to fetch it visible.

Tests

• TestBootstrapCommandStopsWhenTheInstallerCannotBeFetched — no pipe into a shell, curl uses -f, set -e retained.
• TestBootstrapCommandCleansUpTheInstaller — the temp file is trapped for removal.
• TestBootstrapCommandBuildsCincClientScript and TestNodeBootstrapDryRunCommand both pinned the old curl line and are updated.

go test ./..., go vet ./..., and gofmt -l . are clean.