diff --git a/.drone.star b/.drone.star
new file mode 100644
index 000000000..3381a1ecf
--- /dev/null
+++ b/.drone.star
@@ -0,0 +1,48 @@
+# Use, modification, and distribution are
+# subject to the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE.txt)
+#
+# Copyright Rene Rivera 2020.
+
+# For Drone CI we use the Starlark scripting language to reduce duplication.
+# As the yaml syntax for Drone CI is rather limited.
+#
+#
+globalenv={}
+linuxglobalimage="cppalliance/droneubuntu1604:1"
+windowsglobalimage="cppalliance/dronevs2019"
+
+def main(ctx):
+  return [
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.4 CXXSTD=98 Job 0", "g++", packages="g++-4.4", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.4', 'CXXSTD': '98', 'DRONE_JOB_UUID': 'b6589fc6ab'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.6 CXXSTD=03,0x Job 1", "g++", packages="g++-4.6", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.6', 'CXXSTD': '03,0x', 'DRONE_JOB_UUID': '356a192b79'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.7 CXXSTD=03,11 Job 2", "g++-4.7", packages="g++-4.7", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.7', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': 'da4b9237ba'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=03,11 Job 3", "g++-4.8", packages="g++-4.8", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.8', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': '77de68daec'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.9 CXXSTD=03,11 Job 4", "g++-4.9", packages="g++-4.9", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.9', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': '1b64538924'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-5 CXXSTD=03,11,14,1z Job 5", "g++-5", packages="g++-5", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-5', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': 'ac3478d69a'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-6 CXXSTD=03,11,14,1z Job 6", "g++-6", packages="g++-6", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-6', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': 'c1dfd96eea'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-7 CXXSTD=03,11,14,17 Job 7", "g++-7", packages="g++-7", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-7', 'CXXSTD': '03,11,14,17', 'DRONE_JOB_UUID': '902ba3cda1'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-8 CXXSTD=03,11,14,17 Job 8", "g++-8", packages="g++-8", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-8', 'CXXSTD': '03,11,14,17,2a', 'DRONE_JOB_UUID': 'fe5dbbcea5'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-9 CXXSTD=03,11,14,17 Job 9", "g++-9", packages="g++-9", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-9', 'CXXSTD': '03,11,14,17,2a', 'DRONE_JOB_UUID': '0ade7c2cf9'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-10 CXXSTD=03,11,14,1 Job 10", "g++-10", packages="g++-10", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-10', 'CXXSTD': '03,11,14,17,20', 'DRONE_JOB_UUID': 'b1d5781111'}, globalenv=globalenv),
+  linux_cxx("UBSAN=1 TOOLSET=gcc COMPILER=g++-10 CXXSTD=03 Job 11", "g++-10", packages="g++-10", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1804:1", environment={'UBSAN': '1', 'TOOLSET': 'gcc', 'COMPILER': 'g++-10', 'CXXSTD': '03,11,14,17,20', 'UBSAN_OPTIONS': 'print_stacktrace=1', 'LINKFLAGS': '-fuse-ld=gold', 'DRONE_JOB_UUID': '17ba079149'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-3.5 CXXSTD=03, Job 12", "clang++-3.5", packages="clang-3.5 libstdc++-4.9-dev", llvm_os="trusty", llvm_ver="3.5", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-3.5', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': '7b52009b64'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=03, Job 13", "clang++-3.6", packages="clang-3.6 libstdc++-5-dev", llvm_os="trusty", llvm_ver="3.6", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-3.6', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': 'bd307a3ec3'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=03, Job 14", "clang++-3.7", packages="clang-3.7 libstdc++-5-dev", llvm_os="trusty", llvm_ver="3.7", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-3.7', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': 'fa35e19212'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=03, Job 15", "clang++-3.8", packages="clang-3.8 libstdc++-6-dev", llvm_os="xenial", llvm_ver="3.8", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-3.8', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': 'f1abd67035'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=03, Job 16", "clang++-3.9", packages="clang-3.9 libstdc++-6-dev", llvm_os="xenial", llvm_ver="3.9", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-3.9', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': '1574bddb75'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-4.0 CXXSTD=03, Job 17", "clang++-4.0", packages="clang-4.0 libstdc++-6-dev", llvm_os="xenial", llvm_ver="4.0", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-4.0', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': '0716d9708d'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-5.0 CXXSTD=03, Job 18", "clang++-5.0", packages="clang-5.0 libstdc++-7-dev", llvm_os="xenial", llvm_ver="5.0", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-5.0', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': '9e6a55b6b4'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=03, Job 19", "clang++-6.0", packages="clang-6.0 libstdc++-8-dev", llvm_os="xenial", llvm_ver="6.0", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-6.0', 'CXXSTD': '03,11,14,17,2a', 'DRONE_JOB_UUID': 'b3f0c7f6bb'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-7 CXXSTD=03,11 Job 20", "clang++-7", packages="clang-7 libstdc++-8-dev", llvm_os="xenial", llvm_ver="7", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-7', 'CXXSTD': '03,11,14,17,2a', 'DRONE_JOB_UUID': '91032ad7bb'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-8 CXXSTD=03,11 Job 21", "clang++-8", packages="clang-8 libstdc++-8-dev", llvm_os="xenial", llvm_ver="8", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-8', 'CXXSTD': '03,11,14,17,2a', 'DRONE_JOB_UUID': '472b07b9fc'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-9 CXXSTD=03,11 Job 22", "clang++-9", packages="clang-9 libstdc++-9-dev", llvm_os="xenial", llvm_ver="9", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-9', 'CXXSTD': '03,11,14,17,2a', 'DRONE_JOB_UUID': '12c6fc06c9'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-10 CXXSTD=03,1 Job 23", "clang++-10", packages="clang-10 libstdc++-9-dev", llvm_os="xenial", llvm_ver="10", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-10', 'CXXSTD': '03,11,14,17,20', 'DRONE_JOB_UUID': 'd435a6cdd7'}, globalenv=globalenv),
+  linux_cxx("UBSAN=1 TOOLSET=clang COMPILER=clang++-10 CXX Job 24", "clang++-10", packages="clang-10 libstdc++-9-dev", llvm_os="xenial", llvm_ver="10", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++-10', 'CXXSTD': '03,11,14,17,20', 'UBSAN_OPTIONS': 'print_stacktrace=1', 'DRONE_JOB_UUID': '4d134bc072'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=clang++-10 CXXSTD=03,1 Job 25", "clang++-10", packages="clang-10 libc++-10-dev libc++abi-10-dev", llvm_os="xenial", llvm_ver="10", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'CXXFLAGS': '-stdlib=libc++', 'LINKFLAGS': '-stdlib=libc++', 'TOOLSET': 'clang', 'COMPILER': 'clang++-10', 'CXXSTD': '03,11,14,17,20', 'DRONE_JOB_UUID': 'f6e1126ced'}, globalenv=globalenv),
+  linux_cxx("UBSAN=1 TOOLSET=clang COMPILER=clang++-10 CXX Job 26", "clang++-10", packages="clang-10 libc++-10-dev libc++abi-10-dev", llvm_os="xenial", llvm_ver="10", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1604:1", environment={'CXXFLAGS': '-stdlib=libc++', 'LINKFLAGS': '-stdlib=libc++', 'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++-10', 'CXXSTD': '03,11,14,17,20', 'UBSAN_OPTIONS': 'print_stacktrace=1', 'DRONE_JOB_UUID': '887309d048'}, globalenv=globalenv),
+  osx_cxx("TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 27", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="11.2", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,17', 'DRONE_JOB_UUID': 'bc33ea4e26'}, globalenv=globalenv),
+    ]
+
+# from https://github.com/boostorg/boost-ci
+load("@boost_ci//ci/drone/:functions.star", "linux_cxx","windows_cxx","osx_cxx","freebsd_cxx")
diff --git a/.drone/drone.sh b/.drone/drone.sh
new file mode 100755
index 000000000..e71d19014
--- /dev/null
+++ b/.drone/drone.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+
+# Copyright 2020 Rene Rivera, Sam Darwin
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE.txt or copy at http://boost.org/LICENSE_1_0.txt)
+
+set -e
+export TRAVIS_BUILD_DIR=$(pwd)
+export DRONE_BUILD_DIR=$(pwd)
+export TRAVIS_BRANCH=$DRONE_BRANCH
+export VCS_COMMIT_ID=$DRONE_COMMIT
+export GIT_COMMIT=$DRONE_COMMIT
+export REPO_NAME=$DRONE_REPO
+export PATH=~/.local/bin:/usr/local/bin:$PATH
+
+if [ "$DRONE_JOB_BUILDTYPE" == "boost" ]; then
+
+echo '==================================> INSTALL'
+
+GIT_FETCH_JOBS=8
+BOOST_BRANCH=develop
+if [ "$TRAVIS_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule init tools/build
+git submodule init tools/boostdep
+git submodule init tools/boost_install
+git submodule init libs/headers
+git submodule init libs/config
+git submodule update --jobs $GIT_FETCH_JOBS
+cp -r $TRAVIS_BUILD_DIR/* libs/iterator
+python tools/boostdep/depinst/depinst.py --git_args "--jobs $GIT_FETCH_JOBS" iterator
+./bootstrap.sh
+./b2 headers
+
+echo '==================================> SCRIPT'
+
+echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+BUILD_JOBS=`(nproc || sysctl -n hw.ncpu) 2> /dev/null`
+./b2 -j $BUILD_JOBS libs/iterator/test toolset=$TOOLSET cxxstd=$CXXSTD ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on visibility=global} ${CXXFLAGS:+cxxflags="$CXXFLAGS"} ${LINKFLAGS:+linkflags="$LINKFLAGS"}
+
+fi