Operation¶
Nodepool has two components which run as daemons. The
nodepool-builder
daemon is responsible for building diskimages and
uploading them to providers, and the nodepool-launcher
daemon is
responsible for launching and deleting nodes.
Both daemons frequently re-read their configuration file after starting to support adding or removing new images and providers, or otherwise altering the configuration.
These daemons communicate with each other via a Zookeeper database. You must run Zookeeper and at least one of each of these daemons to have a functioning Nodepool installation.
Nodepool-builder¶
The nodepool-builder
daemon builds and uploads images to
providers. It may be run on the same or a separate host as the main
nodepool daemon. Multiple instances of nodepool-builder
may be
run on the same or separate hosts in order to speed up image builds
across many machines, or supply high-availability or redundancy.
However, since nodepool-builder
allows specification of the number
of both build and upload threads, it is usually not advantageous to
run more than a single instance on one machine. Note that while
diskimage-builder (which is responsible for building the underlying
images) generally supports executing multiple builds on a single
machine simultaneously, some of the elements it uses may not. To be
safe, it is recommended to run a single instance of
nodepool-builder
on a machine, and configure that instance to run
only a single build thread (the default).
Nodepool-launcher¶
The main nodepool daemon is named nodepool-launcher
and is
responsible for managing cloud instances launched from the images
created and uploaded by nodepool-builder
.
When a new image is created and uploaded, nodepool-launcher
will
immediately start using it when launching nodes (Nodepool always uses
the most recent image for a given provider in the ready
state).
Nodepool will delete images if they are not the most recent or second
most recent ready
images. In other words, Nodepool will always
make sure that in addition to the current image, it keeps the previous
image around. This way if you find that a newly created image is
problematic, you may simply delete it and Nodepool will revert to
using the previous image.
Daemon usage¶
To start the main Nodepool daemon, run nodepool-launcher:
usage: nodepool-launcher [-h] [-l LOGCONFIG] [--version] [-p PIDFILE] [-d]
[-c CONFIG] [-s SECURE] [--no-webapp]
Node pool.
optional arguments:
-h, --help show this help message and exit
-l LOGCONFIG path to log config file
--version show program's version number and exit
-p PIDFILE path to pid file
-d do not run as a daemon
-c CONFIG path to config file
-s SECURE path to secure file
--no-webapp
To start the nodepool-builder daemon, run nodepool–builder:
usage: nodepool-builder [-h] [-l LOGCONFIG] [--version] [-p PIDFILE] [-d]
[-c CONFIG] [-s SECURE]
[--build-workers BUILD_WORKERS]
[--upload-workers UPLOAD_WORKERS] [--fake]
NodePool Image Builder.
optional arguments:
-h, --help show this help message and exit
-l LOGCONFIG path to log config file
--version show program's version number and exit
-p PIDFILE path to pid file
-d do not run as a daemon
-c CONFIG path to config file
-s SECURE path to secure config file
--build-workers BUILD_WORKERS
number of build workers
--upload-workers UPLOAD_WORKERS
number of upload workers
--fake Do not actually run diskimage-builder (used for
testing)
To stop a daemon, send SIGINT to the process.
When yappi (Yet Another Python Profiler) is available, additional functions’ and threads’ stats are emitted as well. The first SIGUSR2 will enable yappi, on the second SIGUSR2 it dumps the information collected, resets all yappi state and stops profiling. This is to minimize the impact of yappi on a running system.
Metadata¶
When Nodepool creates instances, it will assign the following nova metadata:
- groups
- A comma separated list containing the name of the image and the name of the provider. This may be used by the Ansible OpenStack inventory plugin.
- nodepool_image_name
- The name of the image as a string.
- nodepool_provider_name
- The name of the provider as a string.
- nodepool_node_id
- The nodepool id of the node as an integer.
Common Management Tasks¶
In the course of running a Nodepool service you will find that there are some common operations that will be performed. Like the services themselves these are split into two groups, image management and instance management.
Image Management¶
Before Nodepool can launch any cloud instances it must have images to boot
off of. nodepool dib-image-list
will show you which images are available
locally on disk. These images on disk are then uploaded to clouds,
nodepool image-list
will show you what images are bootable in your
various clouds.
If you need to force a new image to be built to pick up a new feature more
quickly than the normal rebuild cycle (which defaults to 24 hours) you can
manually trigger a rebuild. Using nodepool image-build
you can tell
Nodepool to begin a new image build now. Note that depending on work that
the nodepool-builder is already performing this may queue the build. Check
nodepool dib-image-list
to see the current state of the builds. Once
the image is built it is automatically uploaded to all of the clouds
configured to use that image.
At times you may need to stop using an existing image because it is broken.
Your two major options here are to build a new image to replace the existing
image or to delete the existing image and have Nodepool fall back on using
the previous image. Rebuilding and uploading can be slow so typically the
best option is to simply nodepool image-delete
the most recent image
which will cause Nodepool to fallback on using the previous image. Howevever,
if you do this without “pausing” the image it will be immediately reuploaded.
You will want to pause the image if you need to further investigate why
the image is not being built correctly. If you know the image will be built
correctly you can simple delete the built image and remove it from all clouds
which will cause it to be rebuilt using nodepool dib-image-delete
.
Command Line Tools¶
Usage¶
The general options that apply to all subcommands are:
usage: nodepool [-h] [-l LOGCONFIG] [--version] [-c CONFIG] [-s SECURE]
[--debug]
{list,image-list,dib-image-list,image-build,alien-image-list,delete,image-delete,dib-image-delete,config-validate,request-list,info,erase}
...
Node pool.
optional arguments:
-h, --help show this help message and exit
-l LOGCONFIG path to log config file
--version show program's version number and exit
-c CONFIG path to config file
-s SECURE path to secure file
--debug show DEBUG level logging
commands:
valid commands
{list,image-list,dib-image-list,image-build,alien-image-list,delete,image-delete,dib-image-delete,config-validate,request-list,info,erase}
additional help
list list nodes
image-list list images from providers
dib-image-list list images built with diskimage-builder
image-build build image using diskimage-builder
alien-image-list list images not accounted for by nodepool
delete place a node in the DELETE state
image-delete delete an image
dib-image-delete Delete a dib built image from disk along with all
cloud uploads of this image
config-validate Validate configuration file
request-list list the current node requests
info Show provider data from zookeeper
erase Erase provider data from zookeeper
The following subcommands deal with nodepool images:
dib-image-list¶
usage: nodepool dib-image-list [-h]
optional arguments:
-h, --help show this help message and exit
image-list¶
usage: nodepool image-list [-h]
optional arguments:
-h, --help show this help message and exit
image-build¶
usage: nodepool image-build [-h] image
positional arguments:
image image name
optional arguments:
-h, --help show this help message and exit
dib-image-delete¶
usage: nodepool dib-image-delete [-h] id
positional arguments:
id dib image id
optional arguments:
-h, --help show this help message and exit
image-delete¶
usage: nodepool image-delete [-h] --provider PROVIDER --image IMAGE
--upload-id UPLOAD_ID --build-id BUILD_ID
optional arguments:
-h, --help show this help message and exit
--provider PROVIDER provider name
--image IMAGE image name
--upload-id UPLOAD_ID
image upload id
--build-id BUILD_ID image build id
The following subcommands deal with nodepool nodes:
list¶
usage: nodepool list [-h] [--detail]
optional arguments:
-h, --help show this help message and exit
--detail Output detailed node info
delete¶
usage: nodepool delete [-h] [--now] id
positional arguments:
id node id
optional arguments:
-h, --help show this help message and exit
--now delete the node in the foreground
The following subcommands deal with ZooKeeper data management:
info¶
usage: nodepool info [-h] PROVIDER
positional arguments:
PROVIDER Provider name
optional arguments:
-h, --help show this help message and exit
erase¶
usage: nodepool erase [-h] [--force] PROVIDER
positional arguments:
PROVIDER Provider name
optional arguments:
-h, --help show this help message and exit
--force Bypass the warning prompt
If Nodepool’s database gets out of sync with reality, the following commands can help identify compute instances or images that are unknown to Nodepool:
alien-image-list¶
usage: nodepool alien-image-list [-h] [provider]
positional arguments:
provider provider name
optional arguments:
-h, --help show this help message and exit
Removing a Provider¶
To remove a provider, remove all of the images from that provider`s configuration (and remove all instances of that provider from any labels) and set that provider’s max-servers to -1. This will instruct Nodepool to delete any images uploaded to that provider, not upload any new ones, and stop booting new nodes on the provider. You can then let the nodes go through their normal lifecycle. Once all nodes have been deleted you remove the config from nodepool for that provider entirely (though leaving it in this state is effectively the same and makes it easy to turn the provider back on).
If urgency is required you can delete the nodes directly instead of waiting for them to go through their normal lifecycle but the effect is the same.
Web interface¶
If configured (see webapp-conf
), a nodepool-launcher
instance can provide a range of end-points that can provide
information in text and json
format. Note if there are multiple
launchers, all will provide the same information.
-
GET
/image-list
¶ The status of uploaded images
Query Parameters: - fields – comma-separated list of fields to display
Request Headers: - Accept –
application/json
ortext/*
Response Headers: - Content-Type –
application/json
ortext/plain
depending on the Accept header
-
GET
/dib-image-list
¶ The status of images built by
diskimage-builder
Query Parameters: - fields – comma-separated list of fields to display
Request Headers: - Accept –
application/json
ortext/*
Response Headers: - Content-Type –
application/json
ortext/plain
depending on the Accept header
-
GET
/node-list
¶ The status of currently active nodes
Query Parameters: - node_id – restrict to a specific node
- fields – comma-separated list of fields to display
Request Headers: - Accept –
application/json
ortext/*
Response Headers: - Content-Type –
application/json
ortext/plain
depending on the Accept header
-
GET
/request-list
¶ Outstanding requests
Query Parameters: - fields – comma-separated list of fields to display
Request Headers: - Accept –
application/json
ortext/*
Response Headers: - Content-Type –
application/json
ortext/plain
depending on the Accept header
-
GET
/label-list
¶ All available labels as reported by all launchers
Query Parameters: - fields – comma-separated list of fields to display
Request Headers: - Accept –
application/json
ortext/*
Response Headers: - Content-Type –
application/json
ortext/plain
depending on the Accept header
Monitoring¶
Nodepool provides monitoring information to statsd. See Statsd and Graphite to learn how to enable statsd support. Currently, these metrics are supported:
Nodepool builder¶
-
nodepool.dib_image_build.<diskimage_name>.<ext>.size
(gauge)¶ This stat reports the size of the built image in bytes.
-
nodepool.image_update.<image name>.<provider name>
(counter, timer)¶ Number of image uploads to a specific provider in the cloud plus the time in seconds spent to upload the image.
-
nodepool.builder.dib_image_build.<diskimage_name>.<ext>.rc
(gauge)¶ Return code of the DIB.
-
nodepool.builder.dib_image_build.<diskimage_name>.<ext>.duration
(timer)¶ Time the DIB run took.
Nodepool launcher¶
-
nodepool.provider.<provider>.max_servers
(gauge)¶ Current setting of the max-server configuration parameter for the respective provider.
-
nodepool.nodes.<state>
(counter)¶ Number of nodes in a specific state.
state can be:
- building
- deleting
- failed
- in-use
- ready
- used
-
nodepool.provider.<provider>.nodes.<state>
(gauge)¶ Number of nodes per provider that are in one specific state. See nodepool.nodes for a list of possible states.
-
nodepool.label.<label>.nodes.<state>
(counter)¶ Number of nodes with a specific label in a specific state. See nodepool.nodes for a list of possible states.
-
nodepool.task.<provider>.<task>
(counter, timer)¶ Number of tasks executed per provider plus the duration of the task execution.
-
nodepool.launch.<result>
(counter, timer)¶ Number of launches, categorized by the launch result plus the duration of the launch.
result can be:
- ready: launch was successful
- error.zksession: Zookeeper session was lost
- error.quota: Quota of the provider was reached
- error.unknown: Some other error during launch
-
nodepool.launch.provider.<provider>.<az>.<result>
(counter, timer)¶ Number of launches per provider per availability zone, categorized by the launch result plus duration of the launch.
See nodepool.launch for a list of possible results.
-
nodepool.launch.image.<image>.<result>
(counter, timer)¶ Number of launches per image, categorized by the launch result plus duration of the launch.
See nodepool.launch for a list of possible results.
-
nodepool.launch.requestor.<requestor>.<result>
(counter, timer)¶ Number of launches per requestor, categorized by the launch result plus the duration of the launch.
See nodepool.launch for a list of possible results.
OpenStack API stats¶
Low level details on the timing of OpenStack API calls will be logged
by the API task manager. These calls are logged under
nodepool.task.<provider>.<api-call>
. The API call name is of the
generic format <endpoint><method><operation>
transformed into a
CamelCase value with no deliminators; for example the
compute.GET.servers
call becomes ComputeGetServers
and
compute.POST.os-volumes_boot
becomes ComputePostOsVolumesBoot
.
Since these calls reflect the internal operations of the
openstacksdk
, the exact keys logged may vary across providers and
releases.