* To describe working configurations of OpenStack (which code branches work together? what do config files look like for those branches?)
* To make it easier for developers to dive into OpenStack so that they can productively contribute without having to understand every part of the system at once
IMPORTANT: Be sure to carefully read `stack.sh` and any other scripts you execute before you run them, as they install software and may alter your networking configuration. We strongly recommend that you run `stack.sh` in a clean and disposable vm when you are first getting started.
The devstack master branch generally points to trunk versions of OpenStack components. For older, stable versions, look for branches named stable/[release] in the DevStack repo. For example, you can do the following to create a diablo OpenStack cloud:
You can also pick specific OpenStack project releases by setting the appropriate `*_BRANCH` variables in `localrc` (look in `stackrc` for the default set). Usually just before a release there will be milestone-proposed branches that need to be tested::
Installing in a dedicated disposable vm is safer than installing on your dev machine! Plus you can pick one of the supported Linux distros for your VM. To start a dev cloud run the following NOT AS ROOT (see below for more):
DevStack runs rampant over the system it runs on, installing things and uninstalling other things. Running this on a system you care about is a recipe for disappointment, or worse. Alas, we're all in the virtualization business here, so run it in a VM. And take advantage of the snapshot capabilities of your hypervisor of choice to reduce testing cycle times. You might even save enough time to write one more feature before the next feature freeze...
``stack.sh`` needs to have root access for a lot of tasks, but it also needs to have not-root permissions for most of its work and for all of the OpenStack services. So ``stack.sh`` specifically does not run if you are root. This is a recent change (Oct 2013) from the previous behaviour of automatically creating a ``stack`` user. Automatically creating a user account is not always the right response to running as root, so that bit is now an explicit step using ``tools/create-stack-user.sh``. Run that (as root!) if you do not want to just use your normal login here, which works perfectly fine.
You can override environment variables used in `stack.sh` by creating file name `localrc`. It is likely that you will need to do this to tweak your networking configuration should you need to access your cloud from a different host.
Apache web server is enabled for wsgi services by setting `APACHE_ENABLED_SERVICES` in your localrc. But remember to enable these services at first as above.
devstack supports adding specific Neutron configuration flags to the service, Open vSwitch plugin and LinuxBridge plugin configuration files. To make use of this feature, the following variables are defined and can be configured in your `localrc` file:
devstack also supports configuring the Neutron ML2 plugin. The ML2 plugin can run with the OVS, LinuxBridge, or Hyper-V agents on compute hosts. A simple way to configure the ml2 plugin is shown below:
# VLAN configuration
Q_PLUGIN=ml2
ENABLE_TENANT_VLANS=True
# GRE tunnel configuration
Q_PLUGIN=ml2
ENABLE_TENANT_TUNNELS=True
# VXLAN tunnel configuration
Q_PLUGIN=ml2
Q_ML2_TENANT_NETWORK_TYPE=vxlan
The above will default in devstack to using the OVS on each compute host. To change this, set the `Q_AGENT` variable to the agent you want to run (e.g. linuxbridge).
Q_AGENT This specifies which agent to run with the ML2 Plugin (either `openvswitch` or `linuxbridge`).
Q_ML2_PLUGIN_MECHANISM_DRIVERS The ML2 MechanismDrivers to load. The default is none. Note, ML2 will work with the OVS and LinuxBridge agents by default.
Q_ML2_PLUGIN_TYPE_DRIVERS The ML2 TypeDrivers to load. Defaults to all available TypeDrivers.
Q_ML2_PLUGIN_GRE_TYPE_OPTIONS GRE TypeDriver options. Defaults to none.
Q_ML2_PLUGIN_VXLAN_TYPE_OPTIONS VXLAN TypeDriver options. Defaults to none.
Q_ML2_PLUGIN_VLAN_TYPE_OPTIONS VLAN TypeDriver options. Defaults to none.
Q_AGENT_EXTRA_AGENT_OPTS Extra configuration options to pass to the OVS or LinuxBridge Agent.
DevStack has a hook mechanism to call out to a dispatch script at specific points in the execution if `stack.sh`, `unstack.sh` and `clean.sh`. This allows higher-level projects, especially those that the lower level projects have no dependency on, to be added to DevStack without modifying the scripts. Tempest is built this way as an example of how to structure the dispatch script, see `extras.d/80-tempest.sh`. See `extras.d/README.md` for more information.
You likely want to change your `localrc` to run a scheduler that will balance VMs across hosts:
SCHEDULER=nova.scheduler.simple.SimpleScheduler
You can then run many compute nodes, each of which should have a `stackrc` which includes the following, with the IP address of the above controller node:
Be aware that there are some features currently missing in cells, one notable one being security groups. The exercises have been patched to disable functionality not supported by cells.
Historically DevStack has used ``localrc`` to contain all local configuration and customizations. More and more of the configuration variables available for DevStack are passed-through to the individual project configuration files. The old mechanism for this required specific code for each file and did not scale well. This is handled now by a master local configuration file.
# local.conf
The new config file ``local.conf`` is an extended-INI format that introduces a new meta-section header that provides some additional information such as a phase name and destination config filename:
[[ <phase> | <filename> ]]
where <phase> is one of a set of phase names defined by ``stack.sh`` and <filename> is the project config filename. The filename is eval'ed in the stack.sh context so all environment variables are available and may be used. Using the project config file variables in the header is strongly suggested (see example of NOVA_CONF below). If the path of the config file does not exist it is skipped.
The defined phases are:
* local - extracts ``localrc`` from ``local.conf`` before ``stackrc`` is sourced
* post-config - runs after the layer 2 services are configured and before they are started
* extra - runs after services are started and before any files in ``extra.d`` are executes
The file is processed strictly in sequence; meta-sections may be specified more than once but if any settings are duplicated the last to appear in the file will be used.
[[post-config|$NOVA_CONF]]
[DEFAULT]
use_syslog = True
[osapi_v3]
enabled = False
A specific meta-section ``local:localrc`` is used to provide a default localrc file. This allows all custom settings for DevStack to be contained in a single file. ``localrc`` is not overwritten if it exists to preserve compatability.
[[local|localrc]]
FIXED_RANGE=10.254.1.0/24
ADMIN_PASSWORD=speciale
LOGFILE=$DEST/logs/stack.sh.log
Note that ``Q_PLUGIN_CONF_FILE`` is unique in that it is assumed to _NOT_ start with a ``/`` (slash) character. A slash will need to be added: