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Vault-engine scheduler client

State: open/building · Kind: adapter · Audience: system

Summary

Section titled “Summary”
  • A typed Rust client for the vault-engine scheduler: status, run, log and supervision, never a second scheduler.
  • When the engine is silent it builds a degraded status snapshot from task notes and state.json.

Statement

Section titled “Statement”

The crate talks to the vault-engine over HTTP and returns scheduler status with a source of live, fallback or down. When the engine does not answer, it builds a status snapshot from task-note files and state.json and tails logs from disk. Fields only a live engine can know, running and next_due, stay empty in that snapshot. The engine stays the only scheduler. A run request fails when the engine is down and never starts locally. The client also supervises the engine process: it decides whether to attach or start (the host does the spawn), stops with SIGTERM only, and checks pid liveness so no second engine starts.

What it provides

Section titled “What it provides”
  • EngineClient: status, reachable, task_running, run_task and log calls with a 2 s timeout, and the EngineProbe implementation
  • SchedulerStatus and EngineTask DTOs mapped by hand from the engine JSON, shared with the mail, backup and todo experiences
  • File-built fallback snapshot and the live/fallback/down source tri-state
  • Task-note scan with contract validation and after-graph checks, plus schedule labels that describe and never evaluate
  • Log tailing (last 256 KiB) with a line-count clamp
  • Engine supervision: attach-or-start decision, SIGTERM-only stop, pidfile liveness
  • EngineClientPort: the SchedulerPort assembled from the parts above

Underlying implementation

Section titled “Underlying implementation”
  • solutions/determined/crates/determined-engine-client/ is the crate; src/port.rs assembles the client, fallback, scan, logs and supervise modules into SchedulerPort
  • The engine-port feature quarantines scheduler-crossing capabilities behind a compile error (src/engine_port.rs)

Locations

Section titled “Locations”
  • solutions/determined/crates/determined-engine-client/
  • solutions/determined/crates/determined-engine-client/src/client.rs#EngineClient
  • solutions/determined/crates/determined-engine-client/src/fallback.rs#snapshot
  • solutions/determined/crates/determined-engine-client/src/supervise.rs#decide_start
  • solutions/determined/crates/determined-engine-client/src/port.rs#EngineClientPort

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