74486d86fb
The spread iterator can panic when processing an evaluation, resulting in an unrecoverable state in the cluster. Whenever a panicked server restarts and quorum is restored, the next server to dequeue the evaluation will panic. To trigger this state: * The job must have `max_parallel = 0` and a `canary >= 1`. * The job must not have a `spread` block. * The job must have a previous version. * The previous version must have a `spread` block and at least one failed allocation. In this scenario, the desired changes include `(place 1+) (stop 1+), (ignore n) (canary 1)`. Before the scheduler can place the canary allocation, it tries to find out which allocations can be stopped. This passes back through the stack so that we can determine previous-node penalties, etc. We call `SetJob` on the stack with the previous version of the job, which will include assessing the `spread` block (even though the results are unused). The task group spread info state from that pass through the spread iterator is not reset when we call `SetJob` again. When the new job version iterates over the `groupPropertySets`, it will get an empty `spreadAttributeMap`, resulting in an unexpected nil pointer dereference. This changeset resets the spread iterator internal state when setting the job, logging with a bypass around the bug in case we hit similar cases, and a test that panics the scheduler without the patch. |
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README.md
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://nomadproject.io
- Tutorials: HashiCorp Learn
- Forum: Discuss
- Mailing List: Google Groups
- Gitter: hashicorp-nomad
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 Learn: 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 Learn: Nomad Reference Architecture for recommended practices and a reference architecture for production deployments.
Documentation
Full, comprehensive documentation is available on the Nomad website: https://www.nomadproject.io/docs
Guides are available on HashiCorp Learn.
Contributing
See the contributing directory for more developer documentation.