Multi-Node Lab¶
Here is OpenStack in a realistic test configuration with multiple physical servers.
Prerequisites Linux & Network¶
Minimal Install¶
You need to have a system with a fresh install of Linux. You can download the Minimal CD for Ubuntu releases since DevStack will download & install all the additional dependencies. The netinstall ISO is available for Fedora and CentOS/RHEL.
Install a couple of packages to bootstrap configuration:
apt-get install -y git sudo || yum install -y git sudo
Network Configuration¶
The first iteration of the lab uses OpenStack’s FlatDHCP network controller so only a single network will be required. It should be on its own subnet without DHCP; the host IPs and floating IP pool(s) will come out of this block. This example uses the following:
- Gateway: 192.168.42.1
- Physical nodes: 192.168.42.11-192.168.42.99
- Floating IPs: 192.168.42.128-192.168.42.254
Configure each node with a static IP. For Ubuntu edit
/etc/network/interfaces:
auto eth0
iface eth0 inet static
address 192.168.42.11
netmask 255.255.255.0
gateway 192.168.42.1
For Fedora and CentOS/RHEL edit
/etc/sysconfig/network-scripts/ifcfg-eth0:
BOOTPROTO=static
IPADDR=192.168.42.11
NETMASK=255.255.255.0
GATEWAY=192.168.42.1
Installation shake and bake¶
Add the DevStack User¶
OpenStack runs as a non-root user that has sudo access to root. There is
nothing special about the name, we’ll use stack here. Every node
must use the same name and preferably uid. If you created a user during
the OS install you can use it and give it sudo privileges below.
Otherwise create the stack user:
groupadd stack
useradd -g stack -s /bin/bash -d /opt/stack -m stack
This user will be making many changes to your system during installation and operation so it needs to have sudo privileges to root without a password:
echo "stack ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
From here on use the stack user. Logout and login as the
stack user.
Set Up Ssh¶
Set up the stack user on each node with an ssh key for access:
mkdir ~/.ssh; chmod 700 ~/.ssh
echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCyYjfgyPazTvGpd8OaAvtU2utL8W6gWC4JdRS1J95GhNNfQd657yO6s1AH5KYQWktcE6FO/xNUC2reEXSGC7ezy+sGO1kj9Limv5vrvNHvF1+wts0Cmyx61D2nQw35/Qz8BvpdJANL7VwP/cFI/p3yhvx2lsnjFE3hN8xRB2LtLUopUSVdBwACOVUmH2G+2BWMJDjVINd2DPqRIA4Zhy09KJ3O1Joabr0XpQL0yt/I9x8BVHdAx6l9U0tMg9dj5+tAjZvMAFfye3PJcYwwsfJoFxC8w/SLtqlFX7Ehw++8RtvomvuipLdmWCy+T9hIkl+gHYE4cS3OIqXH7f49jdJf jesse@spacey.local" > ~/.ssh/authorized_keys
Download DevStack¶
Grab the latest version of DevStack:
git clone https://git.openstack.org/openstack-dev/devstack
cd devstack
Up to this point all of the steps apply to each node in the cluster. From here on there are some differences between the cluster controller (aka ‘head node’) and the compute nodes.
Configure Cluster Controller¶
The cluster controller runs all OpenStack services. Configure the
cluster controller’s DevStack in local.conf:
[[local|localrc]]
HOST_IP=192.168.42.11
FLAT_INTERFACE=eth0
FIXED_RANGE=10.4.128.0/20
FIXED_NETWORK_SIZE=4096
FLOATING_RANGE=192.168.42.128/25
MULTI_HOST=1
LOGFILE=/opt/stack/logs/stack.sh.log
ADMIN_PASSWORD=labstack
DATABASE_PASSWORD=supersecret
RABBIT_PASSWORD=supersecret
SERVICE_PASSWORD=supersecret
In the multi-node configuration the first 10 or so IPs in the private
subnet are usually reserved. Add this to local.sh to have it run
after every stack.sh run:
for i in `seq 2 10`; do /opt/stack/nova/bin/nova-manage fixed reserve 10.4.128.$i; done
Fire up OpenStack:
./stack.sh
A stream of activity ensues. When complete you will see a summary of
stack.sh‘s work, including the relevant URLs, accounts and passwords
to poke at your shiny new OpenStack. The most recent log file is
available in stack.sh.log.
Configure Compute Nodes¶
The compute nodes only run the OpenStack worker services. For additional
machines, create a local.conf with:
[[local|localrc]]
HOST_IP=192.168.42.12 # change this per compute node
FLAT_INTERFACE=eth0
FIXED_RANGE=10.4.128.0/20
FIXED_NETWORK_SIZE=4096
FLOATING_RANGE=192.168.42.128/25
MULTI_HOST=1
LOGFILE=/opt/stack/logs/stack.sh.log
ADMIN_PASSWORD=labstack
DATABASE_PASSWORD=supersecret
RABBIT_PASSWORD=supersecret
SERVICE_PASSWORD=supersecret
DATABASE_TYPE=mysql
SERVICE_HOST=192.168.42.11
MYSQL_HOST=$SERVICE_HOST
RABBIT_HOST=$SERVICE_HOST
GLANCE_HOSTPORT=$SERVICE_HOST:9292
ENABLED_SERVICES=n-cpu,n-net,n-api-meta,c-vol,placement-client
NOVA_VNC_ENABLED=True
NOVNCPROXY_URL="http://$SERVICE_HOST:6080/vnc_auto.html"
VNCSERVER_LISTEN=$HOST_IP
VNCSERVER_PROXYCLIENT_ADDRESS=$VNCSERVER_LISTEN
Note: the n-api-meta service is a version of the api server
that only serves the metadata service. It’s needed because the
computes created won’t have a routing path to the metadata service on
the controller.
Fire up OpenStack:
./stack.sh
A stream of activity ensues. When complete you will see a summary of
stack.sh‘s work, including the relevant URLs, accounts and passwords
to poke at your shiny new OpenStack. The most recent log file is
available in stack.sh.log.
Cleaning Up After DevStack¶
Shutting down OpenStack is now as simple as running the included
unstack.sh script:
./unstack.sh
A more aggressive cleanup can be performed using clean.sh. It
removes certain troublesome packages and attempts to leave the system in
a state where changing the database or queue manager can be reliably
performed.
./clean.sh
Sometimes running instances are not cleaned up. DevStack attempts to do this when it runs but there are times it needs to still be done by hand:
sudo rm -rf /etc/libvirt/qemu/inst*
sudo virsh list | grep inst | awk '{print $1}' | xargs -n1 virsh destroy
Options pimp your stack¶
Additional Users¶
DevStack creates two OpenStack users (admin and demo) and two
projects (also admin and demo). admin is exactly what it
sounds like, a privileged administrative account that is a member of
both the admin and demo projects. demo is a normal user
account that is only a member of the demo project. Creating
additional OpenStack users can be done through the dashboard, sometimes
it is easier to do them in bulk from a script, especially since they get
blown away every time stack.sh runs. The following steps are ripe
for scripting:
# Get admin creds
. openrc admin admin
# List existing projects
openstack project list
# List existing users
openstack user list
# Add a user and project
NAME=bob
PASSWORD=BigSecret
PROJECT=$NAME
openstack project create $PROJECT
openstack user create $NAME --password=$PASSWORD --project $PROJECT
openstack role add Member --user $NAME --project $PROJECT
# The Member role is created by stack.sh
# openstack role assignment list
Swift¶
Swift, OpenStack Object Storage, requires a significant amount of resources
and is disabled by default in DevStack. The support in DevStack is geared
toward a minimal installation but can be used for testing. To implement a
true multi-node test of swift, additional steps will be required. Enabling it is as
simple as enabling the swift service in local.conf:
enable_service s-proxy s-object s-container s-account
Swift, OpenStack Object Storage, will put its data files in SWIFT_DATA_DIR (default
/opt/stack/data/swift). The size of the data ‘partition’ created
(really a loop-mounted file) is set by SWIFT_LOOPBACK_DISK_SIZE. The
Swift config files are located in SWIFT_CONF_DIR (default
/etc/swift). All of these settings can be overridden in (wait for
it...) local.conf.
Volumes¶
DevStack will automatically use an existing LVM volume group named
stack-volumes to store cloud-created volumes. If stack-volumes
doesn’t exist, DevStack will set up a 10Gb loop-mounted file to contain
it. This obviously limits the number and size of volumes that can be
created inside OpenStack. The size can be overridden by setting
VOLUME_BACKING_FILE_SIZE in local.conf.
stack-volumes can be pre-created on any physical volume supported by
Linux’s LVM. The name of the volume group can be changed by setting
VOLUME_GROUP_NAME in localrc. stack.sh deletes all logical
volumes in VOLUME_GROUP_NAME that begin with VOLUME_NAME_PREFIX as
part of cleaning up from previous runs. It is recommended to not use the
root volume group as VOLUME_GROUP_NAME.
The details of creating the volume group depends on the server hardware involved but looks something like this:
pvcreate /dev/sdc
vgcreate stack-volumes /dev/sdc
Syslog¶
DevStack is capable of using rsyslog to aggregate logging across the
cluster. It is off by default; to turn it on set SYSLOG=True in
local.conf. SYSLOG_HOST defaults to HOST_IP; on the compute
nodes it must be set to the IP of the cluster controller to send syslog
output there. In the example above, add this to the compute node
local.conf:
SYSLOG_HOST=192.168.42.11
Using Alternate Repositories/Branches¶
The git repositories for all of the OpenStack services are defined in
stackrc. Since this file is a part of the DevStack package changes
to it will probably be overwritten as updates are applied. Every setting
in stackrc can be redefined in local.conf.
To change the repository or branch that a particular OpenStack service
is created from, simply change the value of *_REPO or *_BRANCH
corresponding to that service.
After making changes to the repository or branch, if RECLONE is not
set in localrc it may be necessary to remove the corresponding
directory from /opt/stack to force git to re-clone the repository.
For example, to pull nova, OpenStack Compute, from a proposed release candidate in the primary nova repository:
NOVA_BRANCH=rc-proposed
To pull glance, OpenStack Image service, from an experimental fork:
GLANCE_BRANCH=try-something-big
GLANCE_REPO=https://github.com/mcuser/glance.git
Notes stuff you might need to know¶
Reset the Bridge¶
How to reset the bridge configuration:
sudo brctl delif br100 eth0.926
sudo ip link set dev br100 down
sudo brctl delbr br100
Set MySQL Password¶
If you forgot to set the root password you can do this:
mysqladmin -u root -pnova password 'supersecret'
Live Migration¶
In order for live migration to work with the default live migration URI:
[libvirt]
live_migration_uri = qemu+ssh://stack@%s/system
SSH keys need to be exchanged between each compute node:
The SOURCE root user’s public RSA key (likely in /root/.ssh/id_rsa.pub) needs to be in the DESTINATION stack user’s authorized_keys file (~stack/.ssh/authorized_keys). This can be accomplished by manually copying the contents from the file on the SOURCE to the DESTINATION. If you have a password configured for the stack user, then you can use the following command to accomplish the same thing:
ssh-copy-id -i /root/.ssh/id_rsa.pub stack@DESTINATION
The DESTINATION host’s public ECDSA key (/etc/ssh/ssh_host_ecdsa_key.pub) needs to be in the SOURCE root user’s known_hosts file (/root/.ssh/known_hosts). This can be accomplished by running the following on the SOURCE machine (hostname must be used):
ssh-keyscan -H DEST_HOSTNAME | sudo tee -a /root/.ssh/known_hosts
Verify that login via ssh works without a password:
ssh -i /root/.ssh/id_rsa.pub stack@DESTINATION
In essence, this means that every compute node’s root user’s public RSA key must exist in every other compute node’s stack user’s authorized_keys file and every compute node’s public ECDSA key needs to be in every other compute node’s root user’s known_hosts file. Please note that if the root or stack user does not have a SSH key, one can be generated using:
ssh-keygen -t rsa
The above steps are necessary because libvirtd runs as root when the live_migration_uri uses the “qemu:///system” family of URIs. For more information, see the libvirt documentation.