.. _operation: 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**: .. program-output:: nodepool-launcher --help :nostderr: To start the nodepool-builder daemon, run **nodepool--builder**: .. program-output:: nodepool-builder --help :nostderr: 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: .. program-output:: nodepool --help :nostderr: The following subcommands deal with nodepool images: dib-image-list ^^^^^^^^^^^^^^ .. program-output:: nodepool dib-image-list --help :nostderr: image-list ^^^^^^^^^^ .. program-output:: nodepool image-list --help :nostderr: image-build ^^^^^^^^^^^ .. program-output:: nodepool image-build --help :nostderr: dib-image-delete ^^^^^^^^^^^^^^^^ .. program-output:: nodepool dib-image-delete --help :nostderr: image-delete ^^^^^^^^^^^^ .. program-output:: nodepool image-delete --help :nostderr: The following subcommands deal with nodepool nodes: list ^^^^ .. program-output:: nodepool list --help :nostderr: delete ^^^^^^ .. program-output:: nodepool delete --help :nostderr: The following subcommands deal with ZooKeeper data management: info ^^^^ .. program-output:: nodepool info --help :nostderr: erase ^^^^^ .. program-output:: nodepool erase --help :nostderr: 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 ^^^^^^^^^^^^^^^^ .. program-output:: nodepool alien-image-list --help :nostderr: Removing a Provider ------------------- Removing a provider from nodepool involves two separate steps: removing from the builder process, and removing from the launcher process. .. warning:: Since the launcher process depends on images being present in the provider, you should follow the process for removing a provider from the launcher before doing the steps to remove it from the builder. Removing from the Launcher ~~~~~~~~~~~~~~~~~~~~~~~~~~ To remove a provider from the launcher, set that provider's ``max-servers`` value to 0 (or any value less than 0). This disables the provider and will instruct the launcher to 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 may remove the provider from launcher configuration file entirely, although leaving it in this state is effectively the same and makes it easy to turn the provider back on. .. note:: There is currently no way to force the launcher to immediately begin deleting any unused instances from a disabled provider. 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. For example, if you want to remove ProviderA from a launcher with a configuration file defined as:: providers: - name: ProviderA region-name: region1 cloud: ProviderA boot-timeout: 120 diskimages: - name: centos - name: fedora pools: - name: main max-servers: 100 labels: - name: centos min-ram: 8192 flavor-name: Performance diskimage: centos key-name: root-key Then you would need to alter the configuration to:: providers: - name: ProviderA region-name: region1 cloud: ProviderA boot-timeout: 120 diskimages: - name: centos - name: fedora pools: - name: main max-servers: 0 labels: - name: centos min-ram: 8192 flavor-name: Performance diskimage: centos key-name: root-key .. note:: The launcher process will automatically notice any changes in its configuration file, so there is no need to restart the service to pick up the change. Removing from the Builder ~~~~~~~~~~~~~~~~~~~~~~~~~ The builder controls image building, uploading, and on-disk cleanup. The builder needs a chance to properly manage these resources for a removed a provider. To do this, you need to first set the ``diskimage`` configuration section for the provider you want to remove to an empty list. .. warning:: Make sure the provider is disabled in the launcher before disabling in the builder. For example, if you want to remove ProviderA from a builder with a configuration file defined as:: providers: - name: ProviderA region-name: region1 diskimages: - name: centos - name: fedora diskimages: - name: centos pause: false elements: - centos-minimal ... env-vars: ... Then you would need to alter the configuration to:: providers: - name: ProviderA region-name: region1 diskimages: [] diskimages: - name: centos pause: false elements: - centos-minimal ... env-vars: ... By keeping the provider defined in the configuration file, but changing the ``diskimages`` to an empty list, you signal the builder to cleanup resources for that provider, including any images already uploaded, any on-disk images, and any image data stored in ZooKeeper. After those resources have been cleaned up, it is safe to remove the provider from the configuration file entirely, if you wish to do so. .. note:: The builder process will automatically notice any changes in its configuration file, so there is no need to restart the service to pick up the change. Web interface ------------- If configured (see :attr:`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. .. http:get:: /image-list The status of uploaded images :query fields: comma-separated list of fields to display :reqheader Accept: ``application/json`` or ``text/*`` :resheader Content-Type: ``application/json`` or ``text/plain`` depending on the :http:header:`Accept` header .. http:get:: /dib-image-list The status of images built by ``diskimage-builder`` :query fields: comma-separated list of fields to display :reqheader Accept: ``application/json`` or ``text/*`` :resheader Content-Type: ``application/json`` or ``text/plain`` depending on the :http:header:`Accept` header .. http:get:: /node-list The status of currently active nodes :query node_id: restrict to a specific node :query fields: comma-separated list of fields to display :reqheader Accept: ``application/json`` or ``text/*`` :resheader Content-Type: ``application/json`` or ``text/plain`` depending on the :http:header:`Accept` header .. http:get:: /request-list Outstanding requests :query fields: comma-separated list of fields to display :reqheader Accept: ``application/json`` or ``text/*`` :resheader Content-Type: ``application/json`` or ``text/plain`` depending on the :http:header:`Accept` header .. http:get:: /label-list All available labels as reported by all launchers :query fields: comma-separated list of fields to display :reqheader Accept: ``application/json`` or ``text/*`` :resheader Content-Type: ``application/json`` or ``text/plain`` depending on the :http:header:`Accept` header .. http:get:: /ready Responds with status code 200 as soon as all configured providers are fully started. During startup it returns 500. This can be used as a readiness probe in a kubernetes based deployment. Monitoring ---------- Nodepool provides monitoring information to statsd. See :ref:`statsd_configuration` to learn how to enable statsd support. Currently, these metrics are supported: Nodepool builder ~~~~~~~~~~~~~~~~ The following metrics are produced by a ``nodepool-builder`` process: .. zuul:stat:: nodepool.dib_image_build...size :type: gauge This stat reports the size of the built image in bytes. ``ext`` is based on the formats of the images created for the build, for example ``qcow2``, ``raw``, ``vhd``, etc. .. zuul:stat:: nodepool.dib_image_build..status.rc :type: gauge Return code of the last DIB run. Zero is successful, non-zero is unsuccessful. .. zuul:stat:: nodepool.dib_image_build..status.duration :type: timer Time the last DIB run for this image build took, in ms .. zuul:stat:: nodepool.dib_image_build..status.last_build :type: gauge The UNIX timestamp of the last time a build for this image returned. This can be useful for presenting a relative time ("X hours ago") in a dashboard. .. zuul:stat:: nodepool.image_update.. :type: counter, timer Number of image uploads to a specific provider in the cloud plus the time in seconds spent to upload the image. Nodepool launcher ~~~~~~~~~~~~~~~~~ The following metrics are produced by a ``nodepool-launcher`` process: .. _nodepool_nodes: .. zuul:stat:: nodepool.nodes. :type: counter Number of nodes in a specific state. state can be: * building * deleting * failed * in-use * ready * used .. zuul:stat:: nodepool.label.