finish writing gentoo_nspawn_container_on_Digital_Ocean.md

gentoo_nspawn_container_on_Digital_Ocean.md

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-## Install a Gentoo nspawn Container on Ubuntu 17.04 on Digital Ocean.
+## Install a Gentoo nspawn Container on Ubuntu 17.04 on Digital Ocean.
+
+Spin up an Ubuntu 17.04 droplet, because nspawn containers are slightly
+more difficult with Ubuntu 16.04. Install systemd-container.
+
+```bash
+apt install systemd-container
+```
+
+After installing systemd-container you will discover a new directory,
+/var/lib/machines, and you can create a directory there for a new container.
+You'll need a systemd stage3 tarball for gentoo and you can get those from the
+[Gentoo Website](http://distfiles.gentoo.org/releases/amd64/autobuilds/current-stage3-amd64-systemd/)  
+
+After checking the hash you can extract it to your new folder
+
+```bash
+cd /var/lib/machines/gentoocontainer/
+tar xvjpf /path/to/stage3-*.tar.bz2 --xattrs --numeric-owner
+cd ../
+```
+
+Start the container so you can create a root password
+
+```bash
+systemd-nspawn -D gentoocontainer
+passwd
+logout
+```
+
+Because of how Digital Ocean sets up networking, if you want to subnet
+the container, start systemd-network (systemd-resolved is probably already running).
+And optionally it's also pretty straightforward to create a /usr/portage directory
+on the host operating system, and then bind that directory to the container.
+
+```bash
+# start the container and login as root
+systemd-nspawn -b -D gentoocontainer
+# to subnet the container
+# start systemd-networkd on host
+# and add -n flag
+systemctl start systemd-networkd
+systemd-nspawn -b -D gentoocontainer -n
+# to bind /usr/portage
+# create /usr/portage on host
+mkdir /usr/portage
+# and add the --bind option
+systemd-nspawn -b -D gentoocontainer -n --bind=/usr/portage
+```
+
+You should have a root command line on the container, and there really are only
+two further things to consider: the container probably inherits timezone
+from the host, but not locale. And your MAKEOPTS="-j<some number>", some things
+seem to not compile if your MAKEOPTS j number is more than the number of
+cores on the host.  
+
+Your systemd-nspawn command will open up one root console, but if you use
+a multi-plexer like byobu you can run additional sessions with machinectl
+commands
+
+```bash
+# also works with new users in the container which you might create
+machinectl shell root@gentoocontainer
+# and then to get the whole environment call bash
+bash
+# to power down the container
+poweroff
+```