I recently upgraded one of my homelab servers to FreeBSD 14-CURRENT, and I updated my Ansible scripts to build up some needed Jails for various services. I have never relied on iocage, exjail, or the like and have instead typically built my jails from source. With the latest FreeBSD -CURRENT a make installworld / make distribution into the new jail DESTDIR created a 1.3GB installation. This is a large surface area for running just a single service such as nginx, and so I visited the src.conf build options to get the base system of each jail down to 85MB.
The largest parts of the default 14-CURRENT userland install is by far /usr/lib/debug at 724MB. Clang/LLVM/LLDB is another large chunk. The full src.conf to build a base userland without many unneeded bits is included below:
WITHOUT_ACCT=true WITHOUT_ACPI=true WITHOUT_APM=true WITHOUT_ATM=true WITHOUT_AUTOFS=true WITHOUT_BHYVE=true WITHOUT_BLUETOOTH=true WITHOUT_BOOT=true WITHOUT_BOOTPARAMD=true WITHOUT_BOOTPD=true WITHOUT_BSDINSTALL=true WITHOUT_BSNMP=true WITHOUT_CLANG=true WITHOUT_CXGBETOOL=true WITHOUT_DEBUG_FILES=true WITHOUT_DTRACE=true WITHOUT_EFI=true WITHOUT_EXAMPLES=true WITHOUT_FINGER=true WITHOUT_FLOPPY=true WITHOUT_FREEBSD_UPDATE=true WITHOUT_FTP=true WITHOUT_GAMES=true #WITHOUT_GH_BC=true WITHOUT_GNU_DIFF=true WITHOUT_HAST=true WITHOUT_HTML=true WITHOUT_HYPERV=true WITHOUT_INCLUDES=true WITHOUT_INSTALLLIB=true WITHOUT_IPFILTER=true WITHOUT_IPFW=true WITHOUT_ISCSI=true WITHOUT_JAIL=true WITHOUT_LEGACY_CONSOLE=true WITHOUT_LIB32=true WITHOUT_LLDB=true WITHOUT_LOCALES=true WITHOUT_LPR=true WITHOUT_MAN=true WITHOUT_MANCOMPRESS=true WITHOUT_MLX5TOOL=true WITHOUT_NDIS=true WITHOUT_NETCAT=true WITHOUT_NIS=true WITHOUT_NLS=true WITHOUT_NTP=true WITHOUT_OFED=ture WITHOUT_OPENMP=true WITHOUT_PF=true WITHOUT_PMC=true WITHOUT_PPP=true WITHOUT_RADIUS_SUPPORT=true WITHOUT_RBOOTD=true WITHOUT_RESCUE=true WITHOUT_ROUTED=true WITHOUT_SENDMAIL=true WITHOUT_SHAREDOCS=true WITHOUT_SYSCONS=true WITHOUT_TALK=true WITHOUT_TESTS=true WITHOUT_UNBOUND=true WITHOUT_USB=true WITHOUT_VT=true WITHOUT_WIRELESS=true WITHOUT_ZFS=true
Note that WITHOUT_GH_BC is broken for installworld in -CURRENT at present, so I've commented it out. nginx, isc-dhcpd, and other packages I install my jails add about 40MB each, and so I'm pretty happy with an 85MB base system for each jail.
FreeBSD has a long history of projects to provide a minimal system for embedded devices and other use cases, such as PicoBSD (deprecated -- FreeBSD 3 on a single floppy!), NanoBSD, mfsBSD, and more. Please see these projects for more robust techniques to further minimize. This post is meant purely to see how small I can get an installed jail userland from the output of a default make buildworld by just setting build variables with make installworld.
