4a93691064
Since Amazon provides NTP servers within their network, this should be far superior to using the default NTP pools; and since the service is provided by Amazon there's very little risk in enabling it by default. (If someone is able to compromise Amazon's NTP servers and exploit them to attack EC2 instances, they would almost certainly be able to compromise EC2 instances even without ntpd running...) MFC after: 1 week Relnotes: EC2 instances now keep their clocks synchronized using the Amazon Time Sync Service (aka. NTP).
108 lines
4.6 KiB
Bash
108 lines
4.6 KiB
Bash
#!/bin/sh
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#
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# $FreeBSD$
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#
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# Packages to install into the image we're creating. This is a deliberately
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# minimalist set, providing only the packages necessary to bootstrap further
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# package installation as specified via EC2 user-data.
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export VM_EXTRA_PACKAGES="ec2-scripts firstboot-freebsd-update firstboot-pkgs dual-dhclient amazon-ssm-agent"
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# Set to a list of third-party software to enable in rc.conf(5).
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export VM_RC_LIST="ec2_configinit ec2_fetchkey ec2_ephemeralswap ec2_loghostkey firstboot_freebsd_update firstboot_pkgs ntpd"
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# Build with a 3 GB UFS partition; the growfs rc.d script will expand
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# the partition to fill the root disk after the EC2 instance is launched.
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# Note that if this is set to <N>G, we will end up with an <N+1> GB disk
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# image since VMSIZE is the size of the UFS partition, not the disk which
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# it resides within.
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export VMSIZE=3072M
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# No swap space; the ec2_ephemeralswap rc.d script will allocate swap
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# space on EC2 ephemeral disks. (If they exist -- the T2 low-cost instances
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# and the C4 compute-optimized instances don't have ephemeral disks. But
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# it would be silly to bloat the image and increase costs for every instance
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# just for those two families, especially since instances ranging in size
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# from 1 GB of RAM to 60 GB of RAM would need different sizes of swap space
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# anyway.)
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export NOSWAP=YES
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vm_extra_pre_umount() {
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# The firstboot_pkgs rc.d script will download the repository
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# catalogue and install or update pkg when the instance first
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# launches, so these files would just be replaced anyway; removing
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# them from the image allows it to boot faster.
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chroot ${DESTDIR} env ASSUME_ALWAYS_YES=yes \
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/usr/sbin/pkg delete -f -y pkg
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rm ${DESTDIR}/var/db/pkg/repo-*.sqlite
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# The size of the EC2 root disk can be configured at instance launch
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# time; expand our filesystem to fill the disk.
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echo 'growfs_enable="YES"' >> ${DESTDIR}/etc/rc.conf
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# EC2 instances use DHCP to get their network configuration. IPv6
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# requires accept_rtadv.
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echo 'ifconfig_DEFAULT="SYNCDHCP accept_rtadv"' >> ${DESTDIR}/etc/rc.conf
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# Unless the system has been configured via EC2 user-data, the user
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# will need to SSH in to do anything.
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echo 'sshd_enable="YES"' >> ${DESTDIR}/etc/rc.conf
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# The AWS CLI tools are generally useful, and small enough that they
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# will download quickly; but users will often override this setting
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# via EC2 user-data.
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echo 'firstboot_pkgs_list="awscli"' >> ${DESTDIR}/etc/rc.conf
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# Enable IPv6 on all interfaces, and use DHCP on both IPv4 and IPv6.
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echo 'ipv6_activate_all_interfaces="YES"' >> ${DESTDIR}/etc/rc.conf
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echo 'dhclient_program="/usr/local/sbin/dual-dhclient"' >> ${DESTDIR}/etc/rc.conf
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# The EC2 console is output-only, so while printing a backtrace can
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# be useful, there's no point dropping into a debugger or waiting
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# for a keypress.
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echo 'debug.trace_on_panic=1' >> ${DESTDIR}/etc/sysctl.conf
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echo 'debug.debugger_on_panic=0' >> ${DESTDIR}/etc/sysctl.conf
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echo 'kern.panic_reboot_wait_time=0' >> ${DESTDIR}/etc/sysctl.conf
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# The console is not interactive, so we might as well boot quickly.
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echo 'autoboot_delay="-1"' >> ${DESTDIR}/boot/loader.conf
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echo 'beastie_disable="YES"' >> ${DESTDIR}/boot/loader.conf
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# EC2 has two consoles: An emulated serial port ("system log"),
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# which has been present since 2006; and a VGA console ("instance
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# screenshot") which was introduced in 2016.
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echo 'boot_multicons="YES"' >> ${DESTDIR}/boot/loader.conf
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# Some older EC2 hardware used a version of Xen with a bug in its
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# emulated serial port. It is not clear if EC2 still has any such
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# nodes, but apply the workaround just in case.
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echo 'hw.broken_txfifo="1"' >> ${DESTDIR}/boot/loader.conf
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# Load the kernel module for the Amazon "Elastic Network Adapter"
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echo 'if_ena_load="YES"' >> ${DESTDIR}/boot/loader.conf
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# Disable ChallengeResponseAuthentication according to EC2
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# requirements.
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sed -i '' -e \
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's/^#ChallengeResponseAuthentication yes/ChallengeResponseAuthentication no/' \
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${DESTDIR}/etc/ssh/sshd_config
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# Use the NTP service provided by Amazon
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sed -i '' -e 's/^pool/#pool/' \
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-e 's/^#server.*/server 169.254.169.123 iburst/' \
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${DESTDIR}/etc/ntp.conf
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# The first time the AMI boots, the installed "first boot" scripts
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# should be allowed to run:
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# * ec2_configinit (download and process EC2 user-data)
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# * ec2_fetchkey (arrange for SSH using the EC2-provided public key)
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# * growfs (expand the filesystem to fill the provided disk)
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# * firstboot_freebsd_update (install critical updates)
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# * firstboot_pkgs (install packages)
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touch ${DESTDIR}/firstboot
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rm -f ${DESTDIR}/etc/resolv.conf
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return 0
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}
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