Build-up your own NetBSD AMI

Fetch and build NetBSD

EC2 does not provide direct access to console. As a consequence, we cannot rely on it for installation, especially via sysinst(8) . We must therefore build and install NetBSD in a separate directory, and configure it manually, before upload.

This tutorial assumes that you will build the system under /mnt/ec2.

/!\Please note that you will need the makefs(8) tool later in the process, so you can build a file system image that can be uploaded to Amazon EC2. You are therefore advised to perform the installation directly under a living NetBSD system, or in case your are not, to fetch the src tree to build the toolchain, which will contain the nbmakefs utility.

Details regarding on how you can fetch src are given in the NetBSD's guide. Here are the basic commands you should type to build and install NetBSD under /mnt/ec2:

cd /usr/
# grab a recent src.tgz file (use curl(1), ftp(1), wget(1), ...)
ftp -a 'http://ftp.netbsd.org/pub/NetBSD/NetBSD-current/tar_files/src.tar.gz'
# Decompress
tar -xzpf src.tar.gz
cd src
# the following commands will build tools, distribution and kernel
./build.sh -O ../obj -T ../tools -m amd64 tools
./build.sh -O ../obj -T ../tools -D ../dest -R ../release -m amd64 -U distribution
./build.sh -O ../obj -T ../tools -m amd64 kernel=XEN3_DOMU
# install distribution in /mnt/ec2
su root ./build.sh -O ../obj -T ../tools -D ../dest -R ../release -U -V INSTALLSETS="base etc" install=/mnt/ec2

Configuration of your NetBSD EC2 tree

/!\This part assumes that you have a non-configured NetBSD system extracted under /mnt/ec2; that is, it should have not been modified through sysinst(8) , nor by you.

Under /mnt/ec2, edit the files to add (or modify) these lines:

etc/rc.conf

rc_configured=YES

ec2_init=YES
sshd=YES # for remote shell access to instance

etc/ssh/sshd_config

# Allows root to login via authentication keys
PermitRootLogin without-password

This file is needed if you want to login via the EC2 SSH key pair created previously:

etc/rc.d/ec2_init

#!/bin/sh
#
# PROVIDE: ec2_init
# REQUIRE: NETWORKING
# BEFORE:  LOGIN

$_rc_subr_loaded . /etc/rc.subr

name="ec2_init"
rcvar=${name}
start_cmd="ec2_init"
stop_cmd=":"

METADATA_URL="http://169.254.169.254/latest/meta-data/"
SSH_KEY_URL="public-keys/0/openssh-key"
HOSTNAME_URL="hostname"

SSH_KEY_FILE="/root/.ssh/authorized_keys"

ec2_init()
{
        (
        umask 022
        # fetch the key pair from Amazon Web Services
        EC2_SSH_KEY=$(ftp -o - "${METADATA_URL}${SSH_KEY_URL}")

        if [ -n "$EC2_SSH_KEY" ]; then
                # A key pair is associated with this instance, add it
                # to root 'authorized_keys' file
                mkdir -p $(dirname "$SSH_KEY_FILE")
                touch "$SSH_KEY_FILE"
                cd $(dirname "$SSH_KEY_FILE")

                grep -q "$EC2_SSH_KEY" "$SSH_KEY_FILE"
                if [ $? -ne 0 ]; then
                        echo "Setting EC2 SSH key pair: ${EC2_SSH_KEY##* }"
                        echo "$EC2_SSH_KEY" >> "$SSH_KEY_FILE"
                fi
        fi

        # set hostname
        HOSTNAME=$(ftp -o - "${METADATA_URL}${HOSTNAME_URL}")
        echo "Setting EC2 hostname: ${HOSTNAME}"
        echo "$HOSTNAME" > /etc/myname
        hostname "$HOSTNAME"
        )
}

load_rc_config $name
run_rc_command "$1"

Create various files and directories:

cd /mnt/ec2
# Add proc and kern directories
mkdir grub kern proc
# EC2 network configuration, via DHCP
echo "dhcp" > etc/ifconfig.xennet0
# Basic fstab entries
cat > etc/fstab << EOF
/dev/xbd1a /        ffs    rw 1 1
/dev/xbd0a /grub    ext2fs rw 2 2
kernfs     /kern    kernfs rw
ptyfs      /dev/pts ptyfs  rw
procfs     /proc    procfs rw
EOF
# EC2 startup script (if you installed it)
if [ -f etc/rc.d/ec2_init ]; then
    chmod 555 etc/rc.d/ec2_init
fi

You can then proceed to modifying the system living under /mnt/ec2, so it can fit your needs (adding custom binaries, packages, etc). When done, build the NetBSD-AMI.img.gz ffs image, via makefs(8) , or nbmakefs, from the toolchain:

$ makefs -t ffs -B le -s 256m -N /mnt/ec2/etc/ -o density=32k /tmp/NetBSD-AMI.img /mnt/ec2/ 
Calculated size of `NetBSD-AMI.img': 268435456 bytes, 7345 inodes
Extent size set to 8192
NetBSD-AMI.img: 256.0MB (524288 sectors) block size 8192, fragment size 1024
        using 5 cylinder groups of 53.88MB, 6896 blks, 1728 inodes.
super-block backups (for fsck -b #) at:
     32, 110368, 220704, 331040, 441376,
Populating `NetBSD-AMI.img'
Image `NetBSD-AMI.img' complete
$ gzip -9n NetBSD-AMI.img

Upload NetBSD to EC2

We must now upload our NetBSD system to EC2. For that, we will have to create a minimalist EC2 instance, to which we will copy our files to construct our snapshots. We will use an Amazon Linux AMI instance.

EC2 being localized in geographical regions, you have to carefully choose the AMI identifier you want to use there. This depends on where you want to execute your instance. Amazon Linux AMI IDs are listed on the main page of the project, by regions. Choose ones backed by EBS.

The examples listed here assume that the instances run in US East, within the c zone (e.g. us-east-1c). To have a list of EC2 regions, you can use the command ec2-describe-regions, and ec2-describe-availability-zones for availability zones.

Create an Amazon Linux instance

Creating an instance is straightforward. Amazon provides different types of instances, with varying levels of billing and reliability. We will use a micro instance; its pricing is almost free.

$ ec2-run-instances ami-74f0061d -t t1.micro -z us-east-1c -k $EC2_SSH_KEYNAME
RESERVATION     r-1ab61377      983624114127    default
INSTANCE        i-5babe737      ami-74f0061d                    pending <your_ssh_key_pair_name>  0               t1.micro        2011-02-17T23:15:04+0000        us-east-1c      aki-427d952b                    monitoring-disabled                                     ebs                                     paravirtual     xen     

Use the instance identifier i-XXXXXXX to query the instance state via ec2-describe-instances. It will take some time to launch:

$ sleep 5 && ec2-describe-instances i-5babe737 | grep running
$ sleep 5 && ec2-describe-instances i-5babe737 | grep running
INSTANCE        i-5babe737      ami-74f0061d    ec2-67-202-24-108.compute-1.amazonaws.com       ip-10-99-86-193.ec2.internal    running <your_ssh_key_pair_name>  0               t1.micro        2011-02-17T23:22:37+0000        us-east-1c      aki-427d952b                    monitoring-disabled     67.202.24.108   10.99.86.193                    ebs

Create and attach your NetBSD volumes

We will have to create and attach two EBS volumes:

  1. one to contain the Grub menu.lst config file, as well as the NetBSD kernel.
  2. the other one will contain the root file-system.
ec2-create-volume -s 1 -z us-east-1c # 1GiB -- will be used for Grub and kernel
VOLUME  vol-24f88d4c    1               us-east-1c      creating        2011-02-18T00:06:21+0000
ec2-create-volume -s 5 -z us-east-1c # 5GiB -- will contain the root file-system
VOLUME  vol-36f88d5e    5               us-east-1c      creating        2011-02-18T00:06:32+0000
*** Wait until both volumes are marked as "available" ***
ec2-describe-volumes vol-24f88d4c vol-36f88d5e
VOLUME  vol-36f88d5e    5               us-east-1c      available       2011-02-18T00:06:32+0000
VOLUME  vol-24f88d4c    1               us-east-1c      available       2011-02-18T00:06:21+0000
# Attach them under /dev/sdf and /dev/sdg respectively
ec2-attach-volume vol-36f88d5e -i i-5babe737 -d "/dev/sdf" # root file-system
ATTACHMENT      vol-36f88d5e    i-5babe737      /dev/sdf        attaching       2011-02-18T00:13:53+0000
ec2-attach-volume vol-24f88d4c -i i-5babe737 -d "/dev/sdg" # Grub and kernel
ATTACHMENT      vol-24f88d4c    i-5babe737      /dev/sdg        attaching       2011-02-18T00:14:02+0000
*** Wait until both volumes are "attached" ***
ec2-describe-volumes vol-24f88d4c vol-36f88d5e
VOLUME  vol-36f88d5e    5               us-east-1c      in-use  2011-02-18T00:06:32+0000
ATTACHMENT      vol-36f88d5e    i-5babe737      /dev/sdf        attached        2011-02-18T00:14:00+0000
VOLUME  vol-24f88d4c    1               us-east-1c      in-use  2011-02-18T00:06:21+0000
ATTACHMENT      vol-24f88d4c    i-5babe737      /dev/sdg        attached        2011-02-18T00:14:10+0000

Snapshots!

Before we can connect to our brand new instance, we have to allow connections on SSH port (22) through the AWS EC2 firewall:

$ ec2-authorize default -p 22 --region us-east-1
GROUP           default 
PERMISSION              default ALLOWS  tcp     22      22      FROM    CIDR    0.0.0.0/0

We can now upload the kernel and the NetBSD disk image created earlier, NetBSD-AMI.img.gz, to our instance host:

# Upload kernel to Linux AMI
rsync -aPv -e "ssh -i $EC2_SSH_KEY" /usr/obj/sys/arch/amd64/compile/XEN3_DOMU/netbsd \
        ec2-user@ec2-67-202-24-108.compute-1.amazonaws.com:
# Upload disk image
rsync -aPv -e "ssh -i $EC2_SSH_KEY" NetBSD-AMI.img.gz \
        ec2-user@ec2-67-202-24-108.compute-1.amazonaws.com:

Then, log in to the instance, via its name. We will format and mount the Grub partition, create the menu.lst file, then copy files to their respective partitions.

$ ec2-describe-instances i-5babe737
INSTANCE        i-5babe737      ami-74f0061d    ec2-67-202-24-108.compute-1.amazonaws.com       ip-10-99-86-193.ec2.internal    running <your_ssh_key_pair_name>  0               t1.micro        2011-02-17T23:22:37+0000        us-east-1c      aki-427d952b                    monitoring-disabled     67.202.24.108   10.99.86.193                    ebs
$ ssh -i "$EC2_SSH_KEY" ec2-user@ec2-67-202-24-108.compute-1.amazonaws.com
[...]
[ec2-user@ip-10-99-86-193 ~]$ sudo su
[root@ip-10-99-86-193 ec2-user]# mkdir /mnt/grub
[root@ip-10-99-86-193 ec2-user]# mkfs.ext2 /dev/sdg
[...]
[root@ip-10-99-86-193 ec2-user]# mount /dev/sdg /mnt/grub/
[root@ip-10-99-86-193 ec2-user]# mkdir -p /mnt/grub/boot/grub/
[root@ip-10-99-86-193 ec2-user]# cat > /mnt/grub/boot/grub/menu.lst << EOF
default=0
timeout=0
hiddenmenu

title NetBSD AMI
root (hd0)
kernel /boot/netbsd root=xbd1
EOF
[root@ip-10-99-86-193 ec2-user]# mv netbsd /mnt/grub/boot/
[root@ip-10-99-86-193 ec2-user]# umount /dev/sdg
[root@ip-10-99-86-193 ec2-user]# gunzip < NetBSD-AMI.img.gz | dd of=/dev/sdf bs=32k
[root@ip-10-99-86-193 ec2-user]# sync

Shutdown the Linux instance

We now have to detach volumes, snapshot them, then we shutdown the Linux instance.

# ec2-detach-volume vol-36f88d5e
ATTACHMENT      vol-36f88d5e    i-5babe737      /dev/sdf        detaching       2011-02-18T00:14:00+0000
# ec2-detach-volume vol-24f88d4c
ATTACHMENT      vol-24f88d4c    i-5babe737      /dev/sdg        detaching       2011-02-18T00:14:10+0000
# ec2-create-snapshot vol-36f88d5e
SNAPSHOT        snap-deef2bb2   vol-36f88d5e    pending 2011-02-18T01:17:59+0000                983624114127    5
# ec2-create-snapshot vol-24f88d4c
SNAPSHOT        snap-8aef2be6   vol-24f88d4c    pending 2011-02-18T01:18:10+0000                983624114127    1
# ec2-terminate-instances i-5babe737
INSTANCE        i-5babe737      running shutting-down

Playing with your first NetBSD instance

Create your first NetBSD AMI

An AMI requires multiples components to be registered: the snapshots IDs we made in the previous chapter, as well as a specific AKI: the one that can chain-load Xenified kernels through PyGrub.

/!\ AKIs are entitled to the same conditions as AMIs: their IDs are region-specific. So choose one carefully, or you will not be able to launch your NetBSD instance later!

The list of AKIs that suits our situation can be obtained with the following command:

# Obtain all kernel images (AKI) for region US East, for which manifest location contains pv-grub (for PyGrub)
# ec2-describe-images -a --region=us-east-1 -F image-type=kernel -F manifest-location=*pv-grub*
IMAGE   aki-407d9529    ec2-public-images/pv-grub-hd0-V1.01-i386.gz.manifest.xml        amazon  available       public          i386    kernel                          instance-store  paravirtual     xen
IMAGE   aki-427d952b    ec2-public-images/pv-grub-hd0-V1.01-x86_64.gz.manifest.xml      amazon  available       public          x86_64  kernel                          instance-store  paravirtual     xen
IMAGE   aki-4c7d9525    ec2-public-images/pv-grub-hd00-V1.01-i386.gz.manifest.xml       amazon  available       public          i386    kernel                          instance-store  paravirtual     xen
IMAGE   aki-4e7d9527    ec2-public-images/pv-grub-hd00-V1.01-x86_64.gz.manifest.xml     amazon  available       public          x86_64  kernel                          instance-store  paravirtual     xen

Pick the one with the correct architecture (x86_64 here). hd0 are for AMIs where the snapshot contains no partition (where the volume is itself the whole partition), while hd00 are for snapshots partitioned in a classical way (via MBR). Choose hd0 AKIs. In this case, that will be aki-427d952b.

We can proceed to the creation of our AMI, with:

  1. /dev/sda1 as Grub partition (/dev/sdg, snapshot snap-8aef2be6 of volume vol-24f88d4c)
  2. /dev/sda2 as root file-system (/dev/sdf, snapshot snap-deef2bb2 of volume vol-36f88d5e)
$ ec2-register -a x86_64 --kernel aki-427d952b --region us-east-1 \
    -b "/dev/sda1=snap-8aef2be6" -b "/dev/sda2=snap-deef2bb2" -n "NetBSD-x86_64-current" \
    -d "<add your own description here>
IMAGE   ami-74d0231d

Launch your first instance

You can now start your own NetBSD instance, via:

$ ec2-run-instances ami-74d0231d -t t1.micro -z us-east-1c -k $EC2_SSH_KEYNAME
RESERVATION     r-08218465      983624114127    default
INSTANCE        i-953d72f9      ami-74d0231d                    pending         0               t1.micro        2011-02-18T02:05:46+0000        us-east-1c      aki-4e7d9527                    monitoring-disabled
*** Wait a few minutes, micro instances take time to start ***
# Query console output for your new instance
$ ec2-get-console-output i-953d72f9
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 5.99.45 (XEN3_DOMU) #9: Wed Feb 16 21:14:49 CET 2011
[...]
NetBSD/amd64 (ip-10-112-58-223.ec2.internal) (console)

login: 

Connect to your NetBSD instance

Connection is similar to the one you used for the Amazon Linux instance, except that you login as "root" instead of "ec2-user":

$ ec2-describe-instances i-953d72f9
RESERVATION     r-da8021b7      983624114127    default
INSTANCE        i-953d72f9      ami-74d0231d    ec2-50-16-3-55.compute-1.amazonaws.com  ip-10-112-58-223.ec2.internal   running <your_ssh_key_pair_name>  0               t1.micro        2011-02-19T04:01:03+0000        us-east-1c      aki-427d952b                    monitoring-disabled     50.16.3.55      10.112.58.223                   ebs                                     paravirtual     xen     
BLOCKDEVICE     /dev/sda1       vol-ec3c4a84    2011-02-19T04:01:31.000Z        
BLOCKDEVICE     /dev/sda2       vol-ee3c4a86    2011-02-19T04:01:31.000Z        
$ ssh -i "$EC2_SSH_KEY" root@ec2-50-16-3-55.compute-1.amazonaws.com
The authenticity of host 'ec2-50-16-3-55.compute-1.amazonaws.com (50.16.3.55)' can't be established.
[...]
Thank you for helping us test and improve NetBSD.

Terminal type is xterm.
We recommend that you create a non-root account and use su(1) for root access.
ip-10-112-58-223# uname -a
NetBSD ip-10-112-58-223.ec2.internal 5.99.45 NetBSD 5.99.45 (XEN3_DOMU) #9: Wed Feb 16 21:14:49 CET 2011  jym@paris:/home/jym/cvs/obj/sys/arch/amd64/compile/XEN3_DOMU amd64
ip-10-112-58-223# 

Done!

And now?

Well, you got a NetBSD instance that is in almost every part similar to what a NetBSD domU can be. You can use this domU to host Internet services, run a database, extend your build farm, or use it as a sandbox. The AMI being built around snapshots, you can play and break your instance in every way you want; just restart one anew if you need to. Don't forget that Amazon will charge acccordingly :)

Remember, you can query information regarding your AWS account through misc/ec2-api-tools package. It is quite easy to use these tools for scripting; for a more elaborate, graphical interface, use the Amazon Management Console.

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