PingTower State Elevator

Turns a stream of raw pings into server status: failure and latency thresholds → UP / DOWN.

Stack: C#, .NET 10, RabbitMQ, Redis.

Role in the system

A single failed ping is not an outage. state-elevator keeps a small state machine per server, applies the user's thresholds to every incoming ping and emits an event only when the status actually changes. Everything downstream — the live dashboard, email and Telegram alerts — reacts to those events.

flowchart LR
  API[api] -->|server.target.*| S((state-elevator))
  PS[ping-service] -->|server.ping.recorded| S
  S -->|server.status.changed| API2[api]
  S --- R[(Redis<br>config + state)]

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Features

• Failure threshold — the status flips to DOWN after failureThreshold consecutive failures (default 1); any success resets the counter and sets UP.
• Latency threshold — a successful ping slower than latencyThresholdMs counts as a failure.
• Change-only events — server.status.changed is published only on a transition (UNKNOWN → UP, UP → DOWN, …), never on every ping.
• Self-cleaning state — runtime state lives in Redis with a TTL of 3 × intervalSec, so forgotten servers expire on their own; inactive or deleted servers are dropped immediately.
• Safe consumption — manual acks; malformed messages are rejected, transient errors are requeued.

Contracts

Direction	Channel	Name	Payload
In	queue ← serverEventsExchange	q.state-elevator.server-events (server.target.*)	server + ping settings → config snapshot
In	queue ← pingEventsExchange	q.state-elevator.ping-events (server.ping.recorded)	ping result
Out	exchange statusEventsExchange	server.status.changed	{ "server_id", "status": "UP" | "DOWN" }
Storage	Redis (db 1)	state-elevator:server-config:{id}, state-elevator:server-state:{id}	thresholds; status + consecutive failures

Full message schemas: infra/rabbitmq/asyncapi.yaml.

Quick start

Whole stack — via infra (all repos cloned side by side):

make -C infra up

This service only (broker and Redis already running from infra):

cp .env.example .env
docker compose up -d --build

Local development:

dotnet run --project src/StateElevatorWorker
dotnet test src/src.sln

Structure

state-elevator/
└── src/
    ├── Domain/                # store and publisher abstractions
    ├── Application/           # StateEvaluation — the status state machine, DTOs, settings
    ├── Infrastructure/        # Redis repository, RabbitMQ status publisher
    ├── StateElevatorWorker/   # hosted worker: consumers for server and ping events
    └── tests/                 # unit and integration tests