9dead00ded
- Moved RST guide to the arch-design folder - Deleted XML files - Updated scripts Change-Id: Id0e38a9cada9dd75cb9c8f3bd2d88ce2f4fd3eac Implements: blueprint archguide-mitaka-rst
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86 lines
3.5 KiB
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====================
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Prescriptive example
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====================
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An online classified advertising company wants to run web applications
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consisting of Tomcat, Nginx and MariaDB in a private cloud. To be able
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to meet policy requirements, the cloud infrastructure will run in their
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own data center. The company has predictable load requirements, but
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requires scaling to cope with nightly increases in demand. Their current
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environment does not have the flexibility to align with their goal of
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running an open source API environment. The current environment consists
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of the following:
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* Between 120 and 140 installations of Nginx and Tomcat, each with 2
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vCPUs and 4 GB of RAM
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* A three-node MariaDB and Galera cluster, each with 4 vCPUs and 8 GB
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RAM
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The company runs hardware load balancers and multiple web applications
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serving their websites, and orchestrates environments using combinations
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of scripts and Puppet. The website generates large amounts of log data
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daily that requires archiving.
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The solution would consist of the following OpenStack components:
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* A firewall, switches and load balancers on the public facing network
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connections.
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* OpenStack Controller service running Image, Identity, Networking,
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combined with support services such as MariaDB and RabbitMQ,
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configured for high availability on at least three controller nodes.
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* OpenStack Compute nodes running the KVM hypervisor.
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* OpenStack Block Storage for use by compute instances, requiring
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persistent storage (such as databases for dynamic sites).
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* OpenStack Object Storage for serving static objects (such as images).
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.. figure:: figures/General_Architecture3.png
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Running up to 140 web instances and the small number of MariaDB
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instances requires 292 vCPUs available, as well as 584 GB RAM. On a
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typical 1U server using dual-socket hex-core Intel CPUs with
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Hyperthreading, and assuming 2:1 CPU overcommit ratio, this would
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require 8 OpenStack Compute nodes.
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The web application instances run from local storage on each of the
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OpenStack Compute nodes. The web application instances are stateless,
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meaning that any of the instances can fail and the application will
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continue to function.
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MariaDB server instances store their data on shared enterprise storage,
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such as NetApp or Solidfire devices. If a MariaDB instance fails,
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storage would be expected to be re-attached to another instance and
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rejoined to the Galera cluster.
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Logs from the web application servers are shipped to OpenStack Object
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Storage for processing and archiving.
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Additional capabilities can be realized by moving static web content to
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be served from OpenStack Object Storage containers, and backing the
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OpenStack Image service with OpenStack Object Storage.
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.. note::
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Increasing OpenStack Object Storage means network bandwidth needs to
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be taken into consideration. Running OpenStack Object Storage with
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network connections offering 10 GbE or better connectivity is
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advised.
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Leveraging Orchestration and Telemetry services is also a potential
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issue when providing auto-scaling, orchestrated web application
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environments. Defining the web applications in a
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:term:`Heat Orchestration Template (HOT)`
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negates the reliance on the current scripted Puppet
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solution.
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OpenStack Networking can be used to control hardware load balancers
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through the use of plug-ins and the Networking API. This allows users to
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control hardware load balance pools and instances as members in these
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pools, but their use in production environments must be carefully
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weighed against current stability.
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