bin/vm: Add VM management script

etc/guix/system.scm: Include myself in the "kvm" group so that the QEMU
  commands can be given the "--enable-kvm" flag;
etc/ssh/config: Include the generated SSH config file

1 files changed, 176 insertions, 0 deletions

diff --git a/bin/vm b/bin/vm
new file mode 100755
index 0000000..f4ba093
--- /dev/null
+++ b/bin/vm
@@ -0,0 +1,176 @@
+#!/bin/sh
+set -eu
+
+
+usage() {
+	cat <<-'EOF'
+		Usage:
+		  vm ACTION [OS]
+		  vm -h
+	EOF
+}
+
+help() {
+	cat <<-'EOF'
+
+
+		Options:
+		  -h, --help    show this message
+
+		  ACTION        one of:
+		                - up
+		                - down
+		                - status
+		  OS            the name of the OS to be acted upon
+
+
+		Manage the state of known virtual machines.
+
+		The VM QCOW2 images are stored under
+		$XDG_STATE_HOME/euandreh/qemu/, as "$OS.qcow2" files.  The PIDs
+		of the running images are stored in individual files under
+		$XDG_RUNTIME_DIR/vm-pids/, as "$OS.pid" files.
+
+		It also generates an SSH configuration file to bu `Included`
+		by the main $XDG_CONFIG_HOME/ssh/config file, which contains
+		one alias entry for each VM, so that one can do a combination
+		of `vm up alpine && ssh alpine`.
+
+
+		Examples:
+
+		  Start the VM for Alpine:
+
+		    $ vm up alpine
+
+
+		  Stop the VM for Slackware, which was already down
+
+		    $ vm down slackware
+		    The VM for "slackware" is not running, already.
+
+
+		  List the available VMs, and their current state:
+
+		    $ vm status
+		    alpine:up
+		    slackware:down
+		    freebsd:up
+	EOF
+}
+
+
+for flag in "$@"; do
+	case "$flag" in
+		--)
+			break
+			;;
+		--help)
+			usage
+			help
+			exit
+			;;
+		*)
+			;;
+	esac
+done
+
+while getopts 'h' flag; do
+	case "$flag" in
+		h)
+			usage
+			help
+			exit
+			;;
+		*)
+			usage >&2
+			exit 2
+			;;
+	esac
+done
+shift $((OPTIND - 1))
+
+
+ACTION="${1:-}"
+OS="${2:-}"
+
+eval "$(assert-arg "$ACTION" 'ACTION')"
+
+
+VMS='
+alpine:60022
+'
+
+for vm in $VMS; do
+	NAME="$(echo "$vm" | cut -d: -f1)"
+	PORT="$(echo "$vm" | cut -d: -f2)"
+	cat <<-EOF
+		Host $NAME
+		  HostName localhost
+		  Port $PORT
+
+	EOF
+done > "$XDG_DATA_HOME"/euandreh/vm-ssh.conf
+
+PIDS_DIR="${XDG_RUNTIME_DIR:-${TMPDIR:-/tmp}}/vm-pids"
+PID_F="$PIDS_DIR/$OS.pid"
+mkdir -p "$PIDS_DIR"
+
+
+port_for_os() {
+	_OS="$1"
+	_PORT="$(echo "$VMS" | awk -F: -vOS="$_OS" '$1 == OS { print $2 }')"
+	if [ -z "$_PORT" ]; then
+		printf 'Unknown OS: "%s".\n\n' "$_OS" >&2
+		usage >&2
+		exit 2
+	fi
+	printf '%s' "$_PORT"
+}
+
+case "$ACTION" in
+	status)
+		echo "$VMS" | awk -F: '$0=$1' | while read -r vm; do
+			if [ -e "$PIDS_DIR/$vm.pid" ]; then
+				STATUS=up
+			else
+				STATUS=down
+			fi
+			printf '%s:%s\n' "$vm" "$STATUS"
+		done
+		;;
+	up)
+		eval "$(assert-arg "$OS" 'OS')"
+		PORT="$(port_for_os "$OS")"
+
+		if [ -e "$PID_F" ]; then
+			printf 'The VM for "%s" is already running with PID %s.\n' \
+				"$OS" "$(cat "$PID_F")" >&2
+		else
+			QCOW="$XDG_STATE_HOME"/euandreh/qemu/"$OS".qcow2
+			qemu-system-x86_64 \
+				-m 1G                                           \
+				-nic user,model=virtio,hostfwd=tcp::"$PORT"-:22 \
+				-drive file="$QCOW",media=disk,if=virtio        \
+				-enable-kvm                                     \
+				-nographic 1>/dev/null 2>&1 &
+			printf '%s' $! > "$PID_F.pid"
+		fi
+		;;
+	down)
+		eval "$(assert-arg "$OS" 'OS')"
+		PORT="$(port_for_os "$OS")"
+
+		if [ ! -e "$PID_F" ]; then
+			printf 'The VM for "%s" is not running, already.\n' "$OS" >&2
+		else
+			# shellcheck disable=2064
+			trap "rm -f $PID_F" EXIT
+			kill "$(cat "$PID_F")"
+		fi
+		;;
+	*)
+		printf 'Unrecognized action: "%s".\n\n' "$ACTION" >&2
+		usage >&2
+		exit 2
+esac