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When an allocation fails it triggers an evaluation. The evaluation is processed and the scheduler sees it needs to reschedule, which triggers a follow-up eval. The follow-up eval creates a plan to `(stop 1) (place 1)`. The replacement alloc has a `RescheduleTracker` (or gets its `RescheduleTracker` updated). But in the case where the follow-up eval can't place all allocs (there aren't enough resources), it can create a partial plan to `(stop 1) (place 0)`. It then creates a blocked eval. The plan applier stops the failed alloc. Then when the blocked eval is processed, the job is missing an allocation, so the scheduler creates a new allocation. This allocation is _not_ a replacement from the perspective of the scheduler, so it's not handed off a `RescheduleTracker`. This changeset fixes this by annotating the reschedule tracker whenever the scheduler can't place a replacement allocation. We check this annotation for allocations that have the `stop` desired status when filtering out allocations to pass to the reschedule tracker. I've also included tests that cover this case and expands coverage of the relevant area of the code. Fixes: https://github.com/hashicorp/nomad/issues/12147 Fixes: https://github.com/hashicorp/nomad/issues/17072
Nomad
Nomad is a simple and flexible workload orchestrator to deploy and manage containers (docker, podman), non-containerized applications (executable, Java), and virtual machines (qemu) across on-prem and clouds at scale.
Nomad is supported on Linux, Windows, and macOS. A commercial version of Nomad, Nomad Enterprise, is also available.
- Website: https://developer.hashicorp.com/nomad
- Tutorials: HashiCorp Developer
- Forum: Discuss
Nomad provides several key features:
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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 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 applications 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.
Quick Start
Testing
See Developer: Getting Started for instructions on setting up a local Nomad cluster for non-production use.
Optionally, find Terraform manifests for bringing up a development Nomad cluster on a public cloud in the terraform directory.
Production
See Developer: Nomad Reference Architecture for recommended practices and a reference architecture for production deployments.
Documentation
Full, comprehensive documentation is available on the Nomad website: https://developer.hashicorp.com/nomad/docs
Guides are available on HashiCorp Developer.
Roadmap
A timeline of major features expected for the next release or two can be found in the Public Roadmap.
This roadmap is a best guess at any given point, and both release dates and projects in each release are subject to change. Do not take any of these items as commitments, especially ones later than one major release away.
Contributing
See the contributing directory for more developer documentation.