swarm/dev: add development environment (#14332)

This PR adds a Swarm development environment which can be run in a
Docker container and provides scripts for building binaries and running
Swarm clusters.

swarm/dev/scripts/stop-cluster.sh

@@ -0,0 +1,98 @@
+#!/bin/bash
+#
+# A script to shutdown a dev swarm cluster.
+
+set -e
+
+ROOT="$(cd "$(dirname "$0")/../../.." && pwd)"
+source "${ROOT}/swarm/dev/scripts/util.sh"
+
+DEFAULT_BASE_DIR="${ROOT}/swarm/dev/cluster"
+
+usage() {
+  cat >&2 <<USAGE
+usage: $0 [options]
+
+Shutdown a dev swarm cluster.
+
+OPTIONS:
+  -d, --dir DIR     Base directory [default: ${DEFAULT_BASE_DIR}]
+  -h, --help        Show this message
+USAGE
+}
+
+main() {
+  local base_dir="${DEFAULT_BASE_DIR}"
+
+  parse_args "$@"
+
+  local pid_dir="${base_dir}/pids"
+
+  stop_swarm_nodes
+  stop_node "geth"
+  stop_node "bootnode"
+  delete_network
+}
+
+parse_args() {
+  while true; do
+    case "$1" in
+      -h | --help)
+        usage
+        exit 0
+        ;;
+      -d | --dir)
+        if [[ -z "$2" ]]; then
+          fail "--dir flag requires an argument"
+        fi
+        base_dir="$2"
+        shift 2
+        ;;
+      *)
+        break
+        ;;
+    esac
+  done
+
+  if [[ $# -ne 0 ]]; then
+    usage
+    fail "ERROR: invalid arguments: $@"
+  fi
+}
+
+stop_swarm_nodes() {
+  for name in $(ls "${pid_dir}" | grep -oP 'swarm\d+'); do
+    stop_node "${name}"
+  done
+}
+
+stop_node() {
+  local name=$1
+  local pid_file="${pid_dir}/${name}.pid"
+
+  if [[ -e "${pid_file}" ]]; then
+    info "stopping ${name}"
+    start-stop-daemon \
+      --stop \
+      --pidfile "${pid_file}" \
+      --remove-pidfile \
+      --oknodo \
+      --retry 15
+  fi
+
+  if ip netns list | grep -qF "${name}"; then
+    ip netns delete "${name}"
+  fi
+
+  if ip link show "veth${name}0" &>/dev/null; then
+    ip link delete dev "veth${name}0"
+  fi
+}
+
+delete_network() {
+  if ip link show "swarmbr0" &>/dev/null; then
+    ip link delete dev "swarmbr0"
+  fi
+}
+
+main "$@"