Guest Access and Hosts

Connect to Linux guests, run scripts, read logs, and publish SSH or hosts entries.

This reference covers Barn 1.2.0. Option tables distinguish options also available in 1.1.0 from additions in 1.2.0; see the version baseline. All commands inherit the global options.

barn ssh

barn ssh [flags] [node] [-- command...]

Open an interactive SSH session on the selected prepared node, defaulting to the prepared control node (or first prepared node). Remote commands require --; arguments after it are joined for the remote shell like ordinary ssh. Put Barn options before the separator. Node selectors are resolved node names, not IP addresses, aliases, or groups.

A remote command returns its exit status unchanged. Structured interactive SSH sends session output to stderr and the final report to stdout. See SSH argument rules.

No local options beyond --help; global presentation options still apply.

barn ssh
barn ssh meta
barn ssh meta -- 'df -h /data; id'

barn exec

barn exec [flags] [node] -- command...

Run one remote command on the selected prepared node, with the same default-node selection as ssh. -- and a non-empty first command argument are required. Separate arguments preserve spaces, quotes, and later empty values. Use sh -c for pipelines, redirection, or variable expansion; a single command string is also accepted as compatibility shell shorthand.

Text mode forwards the child output and exit status. Structured output includes success, exit_code, stdout, and stderr. A nonzero remote exit is passed through, so inspect that result before interpreting the number as a Barn error class.

Aliases: ex.

No local options beyond --help; global presentation options still apply.

barn exec meta -- hostname
barn exec meta -- printf '<%s>\n' 'a b' ''
barn --json exec meta -- sh -c 'echo out; exit 17'

barn logs

barn logs [node] [flags]

Read the selected node’s serial console or QEMU diagnostic log, defaulting to the prepared control/first node. --source events selects the deployment-wide bounded event log and takes no node argument; it can be read before deployment state exists. Following logs emits a stream rather than one final document. -f means follow here, not inventory. QEMU argv is hidden unless verbose output is enabled.

Aliases: l.

barn logs meta
barn logs meta --source qemu
barn logs --source events --follow
barn --json logs meta --follow

barn provision

barn provision [node...] [flags]

Stream a local Bash script over the verified deployment SSH connection to selected running nodes, or all nodes if no names are supplied. The script is not left behind as a guest file; its digest is recorded for auditing. It does not create or start VMs.

--script is required. The default concurrency is 1 and the timeout is one hour for the operation. Unlike development lifecycle concurrency, --parallel 0 is invalid. --sudo uses noninteractive guest sudo -n; ensure the guest user has the required permission. Review per-node output and failures in structured mode.

barn provision --script ./check.sh meta
barn provision --script ./bootstrap.sh --sudo --parallel 2 --timeout 30m

barn ssh-config

barn ssh-config [node...] [flags]

Print the Linux deployment’s OpenSSH fragment. --install writes a fragment and one Include in ~/.ssh/config; printing and installation accept node selectors. --remove removes only the named Barn fragment, needs no deployment state, and takes no nodes. Install and remove are mutually exclusive.

The default prefix is barn and its fragment is ~/.ssh/barn_config. Normal lifecycle commands maintain the default fragment automatically. If the user’s SSH configuration cannot be safely edited, Barn reports the manual Include instruction; direct barn ssh remains usable.

Aliases: sc.

barn ssh-config
barn ssh-config --install meta
barn ssh-config --install --name lab
barn ssh-config --remove --name lab

barn hosts install

barn hosts install [flags]

Publish applied node names and aliases in the Barn-owned block of the host’s /etc/hosts, using the digest-matched privileged helper. On a terminal it shows the change and asks before applying; in noninteractive or structured mode it only previews unless --yes is passed. An unchanged block requires no privilege. This file is not automatically published by up.

Barn 1.2.0 adds -f pigsty.yml, publishing inventory nodes plus all.vars.vm_hosts before VM creation. It replaces the whole Barn block, so a later call without -f drops inventory-only service names. See local service names.

Aliases: i.

barn hosts install --json
barn hosts install --yes

barn hosts uninstall

barn hosts uninstall [flags]

Remove only the Barn-owned /etc/hosts block while retaining other entries. It needs no inventory or deployment state. Terminal mode displays a plan and asks; noninteractive/structured mode previews unless --yes is supplied. Removing the block does not delete VMs or change guest DNS configuration.

Aliases: u.

barn hosts uninstall --json
barn hosts uninstall --yes

Implementation

command_root.go · command_access.go · main.go

The version baseline identifies the released source and the changes since 1.1.0.