diff --git a/.drone.star b/.drone.star
new file mode 100644
index 0000000..841b438
--- /dev/null
+++ b/.drone.star
@@ -0,0 +1,41 @@
+# 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++ CXXSTD=03,11,14 ADDR Job 0", "g++", packages="g++-multilib", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14', 'ADDRMD': '32,64', 'DRONE_JOB_UUID': 'b6589fc6ab'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++ CXXSTD=03,11,14 ADDR Job 1", "g++", packages="", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14', 'ADDRMD': '32,64', 'DRONE_JOB_UUID': '356a192b79'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++ CXXSTD=03,11,14 Job 2", "g++", packages="", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14', 'DRONE_JOB_UUID': 'da4b9237ba'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++ CXXSTD=03,11,14 ADDR Job 3", "g++", packages="", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++', 'CXXSTD': '03,11,14', 'ADDRMD': '32,64', 'DRONE_JOB_UUID': '77de68daec'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.4 CXXSTD=98,0x Job 4", "g++", packages="g++-4.4", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.4', 'CXXSTD': '98,0x', 'DRONE_JOB_UUID': '1b64538924'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=gcc COMPILER=g++-4.6 CXXSTD=03,0x Job 5", "g++", packages="g++-4.6", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-4.6', 'CXXSTD': '03,0x', 'DRONE_JOB_UUID': 'ac3478d69a'}, globalenv=globalenv),
+  linux_cxx("UBSAN=1 TOOLSET=gcc COMPILER=g++-10 CXXSTD=03 Job 6", "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': 'c1dfd96eea'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=/usr/bin/clang++ CXXST Job 7", "/usr/bin/clang++", packages="clang-3.3", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'clang', 'COMPILER': '/usr/bin/clang++', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': '902ba3cda1'}, globalenv=globalenv),
+  linux_cxx("TOOLSET=clang COMPILER=/usr/bin/clang++ CXXST Job 8", "/usr/bin/clang++", packages="clang-3.4", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1404:1", environment={'TOOLSET': 'clang', 'COMPILER': '/usr/bin/clang++', 'CXXSTD': '03,11', 'DRONE_JOB_UUID': 'fe5dbbcea5'}, globalenv=globalenv),
+  linux_cxx("UBSAN=1 TOOLSET=clang COMPILER=clang++-11 CXX Job 9", "clang++-11", packages="clang-11", llvm_os="xenial", llvm_ver="11", buildtype="boost", buildscript="drone", image=linuxglobalimage, environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++-11', 'CXXSTD': '03,11,14,17,20', 'UBSAN_OPTIONS': 'print_stacktrace=1', 'DRONE_JOB_UUID': '0ade7c2cf9'}, globalenv=globalenv),
+  linux_cxx("UBSAN=1 TOOLSET=clang COMPILER=clang++-libc++ Job 10", "clang++-libc++", packages="libc++-dev", buildtype="boost", buildscript="drone", image="cppalliance/droneubuntu1804:1", environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++-libc++', 'CXXSTD': '03,11,14,17,2a', 'UBSAN_OPTIONS': 'print_stacktrace=1', 'DRONE_JOB_UUID': 'b1d5781111'}, globalenv=globalenv),
+  osx_cxx("TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 12", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="7.3", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z', 'ADDRMD': '32,64', 'DRONE_JOB_UUID': '7b52009b64'}, globalenv=globalenv),
+  osx_cxx("TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 13", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="8.3", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z', 'ADDRMD': '32,64', 'DRONE_JOB_UUID': 'bd307a3ec3'}, globalenv=globalenv),
+  osx_cxx("TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 14", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="9.4", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z', 'ADDRMD': '32,64', 'DRONE_JOB_UUID': 'fa35e19212'}, globalenv=globalenv),
+  osx_cxx("TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 15", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="10.1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': 'f1abd67035'}, globalenv=globalenv),
+  osx_cxx("TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 16", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="11.3", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z', 'DRONE_JOB_UUID': '1574bddb75'}, globalenv=globalenv),
+  osx_cxx("UBSAN=1 TOOLSET=clang COMPILER=clang++ CXXSTD Job 17", "clang++", packages="", buildtype="boost", buildscript="drone", xcode_version="12.2", environment={'UBSAN': '1', 'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '03,11,14,1z', 'UBSAN_OPTIONS': 'print_stacktrace=1', 'DRONE_JOB_UUID': '0716d9708d'}, globalenv=globalenv),
+  linux_cxx("CMAKE=1 Job 18", "g++", packages="", buildtype="aa8f93b806-b342e8ae9b", buildscript="drone", image=linuxglobalimage, environment={'CMAKE': '1', 'DRONE_JOB_UUID': '9e6a55b6b4'}, globalenv=globalenv),
+  linux_cxx("CMAKE=1 BUILD_SHARED_LIBS=ON Job 19", "g++", packages="", buildtype="aa8f93b806-0b4c708508", buildscript="drone", image=linuxglobalimage, environment={'CMAKE': '1', 'BUILD_SHARED_LIBS': 'ON', 'DRONE_JOB_UUID': 'b3f0c7f6bb'}, globalenv=globalenv),
+  linux_cxx("CMAKE_SUBDIR_TEST=1 Job 20", "g++", packages="", buildtype="5e4a4d0f23-fda7c76df5", buildscript="drone", image=linuxglobalimage, environment={'CMAKE_SUBDIR_TEST': '1', 'DRONE_JOB_UUID': '91032ad7bb'}, globalenv=globalenv),
+  linux_cxx("CMAKE_INSTALL=1 Job 21", "g++", packages="", buildtype="aa8f93b806-e569545176", buildscript="drone", image=linuxglobalimage, environment={'CMAKE_INSTALL': '1', 'DRONE_JOB_UUID': '472b07b9fc'}, 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 0000000..69a67e0
--- /dev/null
+++ b/.drone/drone.sh
@@ -0,0 +1,118 @@
+#!/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'
+
+BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $TRAVIS_BUILD_DIR/* libs/system
+python tools/boostdep/depinst/depinst.py system
+./bootstrap.sh
+./b2 headers
+
+echo '==================================> SCRIPT'
+
+echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+./b2 -j3 libs/system/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${ADDRMD:+address-model=$ADDRMD} ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
+
+elif [ "$DRONE_JOB_BUILDTYPE" == "aa8f93b806-b342e8ae9b" ]; then
+
+echo '==================================> INSTALL'
+
+BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $TRAVIS_BUILD_DIR/* libs/system
+python tools/boostdep/depinst/depinst.py system
+./bootstrap.sh
+./b2 headers
+
+echo '==================================> SCRIPT'
+
+mkdir __build__ && cd __build__
+cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=system -DBUILD_TESTING=ON ..
+ctest --output-on-failure -R boost_system
+
+elif [ "$DRONE_JOB_BUILDTYPE" == "aa8f93b806-0b4c708508" ]; then
+
+echo '==================================> INSTALL'
+
+BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $TRAVIS_BUILD_DIR/* libs/system
+python tools/boostdep/depinst/depinst.py system
+./bootstrap.sh
+./b2 headers
+
+echo '==================================> SCRIPT'
+
+mkdir __build__ && cd __build__
+cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBUILD_SHARED_LIBS=ON -DBOOST_INCLUDE_LIBRARIES=system -DBUILD_TESTING=ON ..
+ctest --output-on-failure -R boost_system
+
+elif [ "$DRONE_JOB_BUILDTYPE" == "5e4a4d0f23-fda7c76df5" ]; then
+
+echo '==================================> INSTALL'
+
+BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+git clone -b $BOOST_BRANCH https://github.com/boostorg/assert.git ../assert
+git clone -b $BOOST_BRANCH https://github.com/boostorg/config.git ../config
+git clone -b $BOOST_BRANCH https://github.com/boostorg/core.git ../core
+git clone -b $BOOST_BRANCH https://github.com/boostorg/predef.git ../predef
+git clone -b $BOOST_BRANCH https://github.com/boostorg/winapi.git ../winapi
+
+echo '==================================> SCRIPT'
+
+cd test/cmake_subdir_test && mkdir __build__ && cd __build__
+cmake ..
+cmake --build .
+cmake --build . --target check
+
+elif [ "$DRONE_JOB_BUILDTYPE" == "aa8f93b806-e569545176" ]; then
+
+echo '==================================> INSTALL'
+
+BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+cd ..
+git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+cd boost-root
+git submodule update --init tools/boostdep
+cp -r $TRAVIS_BUILD_DIR/* libs/system
+python tools/boostdep/depinst/depinst.py system
+./bootstrap.sh
+./b2 headers
+
+echo '==================================> SCRIPT'
+
+pip install --user cmake
+mkdir __build__ && cd __build__
+cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES="system;core" -DBUILD_TESTING=OFF -DCMAKE_INSTALL_PREFIX=~/.local ..
+cmake --build . --target install
+cd ../libs/system/test/cmake_install_test && mkdir __build__ && cd __build__
+cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+cmake --build .
+cmake --build . --target check
+
+fi