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/run.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+#
+# A script to build and run the Swarm development environment using Docker.
+
+set -e
+
+ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+
+# DEFAULT_NAME is the default name for the Docker image and container
+DEFAULT_NAME="swarm-dev"
+
+usage() {
+  cat >&2 <<USAGE
+usage: $0 [options]
+
+Build and run the Swarm development environment.
+
+Depends on Docker being installed locally.
+
+OPTIONS:
+  -n, --name NAME          Docker image and container name [default: ${DEFAULT_NAME}]
+  -d, --docker-args ARGS   Custom args to pass to 'docker run' (e.g. '-p 8000:8000' to expose a port)
+  -h, --help               Show this message
+USAGE
+}
+
+main() {
+  local name="${DEFAULT_NAME}"
+  local docker_args=""
+  parse_args "$@"
+  build_image
+  run_image
+}
+
+parse_args() {
+  while true; do
+    case "$1" in
+      -h | --help)
+        usage
+        exit 0
+        ;;
+      -n | --name)
+        if [[ -z "$2" ]]; then
+          echo "ERROR: --name flag requires an argument" >&2
+          exit 1
+        fi
+        name="$2"
+        shift 2
+        ;;
+      -d | --docker-args)
+        if [[ -z "$2" ]]; then
+          echo "ERROR: --docker-args flag requires an argument" >&2
+          exit 1
+        fi
+        docker_args="$2"
+        shift 2
+        ;;
+      *)
+        break
+        ;;
+    esac
+  done
+
+  if [[ $# -ne 0 ]]; then
+    usage
+    echo "ERROR: invalid arguments" >&2
+    exit 1
+  fi
+}
+
+build_image() {
+  docker build --tag "${name}" "${ROOT}/swarm/dev"
+}
+
+run_image() {
+  exec docker run \
+    --privileged \
+    --interactive \
+    --tty \
+    --rm \
+    --hostname "${name}" \
+    --name     "${name}" \
+    --volume   "${ROOT}:/go/src/github.com/ethereum/go-ethereum" \
+    --volume   "/var/run/docker.sock:/var/run/docker.sock" \
+    ${docker_args} \
+    "${name}" \
+    /bin/bash
+}
+
+main "$@"