2781717ad6
The BinPackIter accounted for node reservations twice when scoring nodes which could bias scores toward nodes with reservations. Pseudo-code for previous algorithm: ``` proposed = reservedResources + sum(allocsResources) available = nodeResources - reservedResources score = 1 - (proposed / available) ``` The node's reserved resources are added to the total resources used by allocations, and then the node's reserved resources are later substracted from the node's overall resources. The new algorithm is: ``` proposed = sum(allocResources) available = nodeResources - reservedResources score = 1 - (proposed / available) ``` The node's reserved resources are no longer added to the total resources used by allocations. My guess as to how this bug happened is that the resource utilization variable (`util`) is calculated and returned by the `AllocsFit` function which needs to take reserved resources into account as a basic feasibility check. To avoid re-calculating alloc resource usage (because there may be a large number of allocs), we reused `util` in the `ScoreFit` function. `ScoreFit` properly accounts for reserved resources by subtracting them from the node's overall resources. However since `util` _also_ took reserved resources into account the score would be incorrect. Prior to the fix the added test output: ``` Node: reserved Score: 1.0000 Node: reserved2 Score: 1.0000 Node: no-reserved Score: 0.9741 ``` The scores being 1.0 for *both* nodes with reserved resources is a good hint something is wrong as they should receive different scores. Upon further inspection the double accounting of reserved resources caused their scores to be >1.0 and clamped. After the fix the added test outputs: ``` Node: no-reserved Score: 0.9741 Node: reserved Score: 0.9480 Node: reserved2 Score: 0.8717 ```
Nomad 
Overview
Nomad is an easy-to-use, flexible, and performant workload orchestrator that deploys:
Nomad enables developers to use declarative infrastructure-as-code for deploying their applications (jobs). Nomad uses bin packing to efficiently schedule jobs and optimize for resource utilization. Nomad is supported on macOS, Windows, and Linux.
Nomad is widely adopted and used in production by PagerDuty, Target, Citadel, Trivago, SAP, Pandora, Roblox, eBay, Deluxe Entertainment, and more.
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Deploy Containers and Legacy Applications: Nomad’s flexibility as an orchestrator enables an organization to run containers, legacy, and batch applications together on the same infrastructure. Nomad brings core orchestration benefits to legacy applications without needing to containerize via pluggable task drivers.
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Simple & Reliable: Nomad runs as a single 75MB binary and is entirely self contained - combining resource management and scheduling into a single system. Nomad does not require any external services for storage or coordination. Nomad automatically handles application, node, and driver failures. Nomad is distributed and resilient, using leader election and state replication to provide high availability in the event of failures.
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Device Plugins & GPU Support: Nomad offers built-in support for GPU workloads such as machine learning (ML) and artificial intelligence (AI). Nomad uses device plugins to automatically detect and utilize resources from hardware devices such as GPU, FPGAs, and TPUs.
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Federation for Multi-Region, Multi-Cloud: Nomad was designed to support infrastructure at a global scale. Nomad supports federation out-of-the-box and can deploy jobs across multiple regions and clouds.
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Proven Scalability: Nomad is optimistically concurrent, which increases throughput and reduces latency for workloads. Nomad has been proven to scale to clusters of 10K+ nodes in real-world production environments.
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HashiCorp Ecosystem: Nomad integrates seamlessly with Terraform, Consul, Vault for provisioning, service discovery, and secrets management.
Getting Started
Get started with Nomad quickly in a sandbox environment on the public cloud or on your computer.
- Local
- AWS
- Azure
These methods are not meant for production.
Documentation & Guides
- Installing Nomad for Production
- Advanced Job Scheduling on Nomad with Affinities
- Increasing Nomad Fault Tolerance with Spread
- Load Balancing on Nomad with Fabio & Consul
- Deploying Stateful Workloads via Portworx
- Running Apache Spark on Nomad
- Integrating Vault with Nomad for Secrets Management
- Securing Nomad with TLS
- Continuous Deployment with Nomad and Terraform
- Auto-bootstrapping a Nomad Cluster
Documentation is available on the Nomad website here.
Resources
- Website
- Mailing List
- Gitter
- Webinars
- Community Calls
Who Uses Nomad
- CircleCI
- Citadel
- Deluxe Entertainment
- Jet.com (Walmart)
- PagerDuty
- Pandora
- SAP Ariba
- SeatGeek
- Spaceflight Industries
- SpotInst
- Target
- Trivago
- Roblox
- Oscar Health
- eBay
- Joyent
- Dutch National Police
- N26
- Elsevier
- Graymeta
- NIH NCBI
- Q2Ebanking
- imgix
- Region Syddanmark
...and more!
Contributing to Nomad
If you wish to contribute to Nomad, you will need Go installed on your machine (version 1.14.1+ is required, and gcc-go is not supported).
See the contributing directory for more developer documentation.
Developing with Vagrant There is an included Vagrantfile that can help bootstrap the process. The created virtual machine is based off of Ubuntu 16, and installs several of the base libraries that can be used by Nomad.
To use this virtual machine, checkout Nomad and run vagrant up from the root
of the repository:
$ git clone https://github.com/hashicorp/nomad.git
$ cd nomad
$ vagrant up
The virtual machine will launch, and a provisioning script will install the needed dependencies.
Developing locally
For local dev first make sure Go is properly installed, including setting up a
GOPATH. After setting up Go, clone this
repository into $GOPATH/src/github.com/hashicorp/nomad. Then you can
download the required build tools such as vet, cover, godep etc by bootstrapping
your environment.
$ make bootstrap
...
Nomad creates many file handles for communicating with tasks, log handlers, etc.
In some development environments, particularly macOS, the default number of file
descriptors is too small to run Nomad's test suite. You should set
ulimit -n 1024 or higher in your shell. This setting is scoped to your current
shell and doesn't affect other running shells or future shells.
Afterwards type make test. This will run the tests. If this exits with exit status 0,
then everything is working!
$ make test
...
To compile a development version of Nomad, run make dev. This will put the
Nomad binary in the bin and $GOPATH/bin folders:
$ make dev
Optionally run Consul to enable service discovery and health checks:
$ sudo consul agent -dev
And finally start the nomad agent:
$ sudo bin/nomad agent -dev
If the Nomad UI is desired in the development version, run make dev-ui. This will build the UI from source and compile it into the dev binary.
$ make dev-ui
...
$ bin/nomad
...
To compile protobuf files, installing protoc is required: See
https://github.com/google/protobuf for more information.
Note: Building the Nomad UI from source requires Node, Yarn, and Ember CLI. These tools are already in the Vagrant VM. Read the UI README for more info.
To cross-compile Nomad, run make prerelease and make release.
This will generate all the static assets, compile Nomad for multiple
platforms and place the resulting binaries into the ./pkg directory:
$ make prerelease
$ make release
...
$ ls ./pkg
...