#!/usr/bin/env bash
# author: joe.zheng
# version: 24.08.12

set -e

SELF="$(basename $0)"
SELF_VERSION="$(sed -n '1,4s/# version: \(.*\)/\1/p' $0)"

SUDO=""
if [[ $(id -u) != "0" ]]; then
  SUDO="sudo"
fi

DIR_ROOT="${DIR_ROOT:-$(dirname $0)/registry}"
SVC_PORT="${SVC_PORT:-5000}"  # port number

function usage() {
  cat <<EOF
Usage: $SELF [command] [args]
  Docker registry as a pull-through cache with security control

  The default configuraion is very restricted, customize to meet your needs

Commands:
  start  initialize and start the registry
  stop   stop the registry

Environment variables:
  DRY_RUN:  print out information only if it is "y"
  DIR_ROOT: the folder for $SELF, default: $DIR_ROOT
  SVC_PORT: port number to listen: default: $SVC_PORT

Examples:

  1. Start registry
    $SELF start

  2. Stop registry
    $SELF stop

Version: $SELF_VERSION
EOF
}

function msg {
  echo "> $@"
}

function err {
  echo "> $@" >&2
}

if [[ -z "$1" || "$1" == "-h" ]]; then
  usage && exit
else
  cmd="$1"
  shift
fi

DIR_DATA="$DIR_ROOT/data"
msg "generate folder: $DIR_ROOT"
[[ $DRY_RUN != 'y' ]] && mkdir -p $DIR_ROOT $DIR_DATA

if [[ "$cmd" == "start" ]]; then
  for n in docker-compose.yml proxy.conf registry.env; do
    f="$DIR_ROOT/$n"
    msg "generating $f"
    if [[ -f $f ]]; then
      msg "already exists, skip"
    else
      if [[ $DRY_RUN != 'y' ]]; then
        if [[ $n == "docker-compose.yml" ]]; then
          cat <<EOF > $f
version: "3"

services:
    nginx:
      image: "nginx:1.23.4-alpine"
      ports:
        - $SVC_PORT:5000
      depends_on:
        - registry
      volumes:
        - ./proxy.conf:/etc/nginx/nginx.conf:ro

    registry:
      image: registry:2
      env_file:
        - registry.env
      volumes:
        - ./data:/var/lib/registry
EOF
        elif [[ $n == "proxy.conf" ]]; then
          cat <<EOF > $f
user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;

events {
    worker_connections  1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '\$remote_addr - \$remote_user [\$time_local] "\$request" '
                      '\$status \$body_bytes_sent "$http_referer" '
                      '"\$http_user_agent" "\$http_x_forwarded_for"';
    access_log  /var/log/nginx/access.log  main;

    sendfile           on;
    keepalive_timeout  65;

    limit_conn_zone \$binary_remote_addr zone=addr:10m;
    limit_req_zone  \$binary_remote_addr zone=one:10m rate=1r/s;

    server {
        listen       5000;
        server_name  localhost;

        # default security control, very restricted!
        limit_conn addr 3;
        limit_req  zone=one burst=20;
        limit_rate 200k;

        location / {
            proxy_pass http://registry:5000;
            proxy_set_header  Host              \$http_host;   # required for docker client's sake
            proxy_set_header  X-Real-IP         \$remote_addr; # pass on real client's IP
            proxy_set_header  X-Forwarded-For   \$proxy_add_x_forwarded_for;
            proxy_set_header  X-Forwarded-Proto \$scheme;
        }
    }
}
EOF
        elif [[ $n == "registry.env" ]]; then
          cat <<EOF > $f
REGISTRY_PROXY_REMOTEURL="https://registry-1.docker.io"
REGISTRY_PROXY_TTL=2
REGISTRY_STORAGE_DELETE_ENABLED="true"
EOF
        fi
      fi
      msg "$f is generated"
    fi
  done

  msg "start registry"
  [[ $DRY_RUN != 'y' ]] && (cd $DIR_ROOT && docker compose up -d)
elif [[ "$cmd" == "stop" ]]; then
  msg "stop registry"
  [[ $DRY_RUN != 'y' ]] && (cd $DIR_ROOT && docker compose down)
else
  err "not supported cmd: $cmd"
  exit 1
fi

msg "done"