Healthie.NET.Temporal 4.1.4

Healthie.NET.Temporal

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Schedules pulse checks with Temporal, so the schedule lives in the cluster rather than in the process.

Installation

dotnet add package Healthie.NET.Temporal

Usage

using Healthie.Scheduling.Temporal;
using Temporalio.Extensions.Hosting;

builder.Services.AddSingleton<ITemporalClient>(await TemporalClient.ConnectAsync(new("localhost:7233")));

builder.Services
    .AddHealthie(typeof(Program).Assembly)
    .AddHealthieTemporal(options => options.TaskQueue = "healthie");

// A worker must be listening on the same queue, or the schedules fire and nothing runs.
builder.Services
    .AddHostedTemporalWorker("healthie")
    .AddScopedActivities<PulseCheckerActivities>()
    .AddWorkflow<PulseCheckerWorkflow>();

The Temporal client is yours to create: its address, namespace, TLS and API key are your decisions, and a library that picked them would be picking which cluster your workflows run on.

What it buys, and what it costs

Buys: the schedule survives a restart and a redeploy, each occurrence is handed to exactly one worker however many replicas are running, and every run has a history somebody can look at.

Costs: a Temporal cluster. If you do not already run one, this is the wrong trade — Healthie.NET.Hangfire gives you the same survives-a-restart, runs-once-across-replicas properties against a database you probably already have, and the built-in timer needs nothing at all.

The SDK also carries a native Rust core, so it is a large dependency: it adds a few hundred megabytes to a build output. Worth knowing before adding it to something small.

Details

Schedules are named healthie-<checker name>, so they are recognisable in the Temporal UI and cannot collide with your own.

Overlap policy is Skip. A checker already refuses to run on top of itself, so buffering would queue occurrences that each return immediately — and a check that is late is worth less than the next one, which is current.

Cron expressions use Healthie.NET's standard Unix form: five fields, or six with leading seconds. Temporal uses seven fields when seconds are present because its sixth field is a year, so the adapter appends a wildcard year to Healthie.NET's six-field form. Fixed periods become interval specs, which Temporal counts from an epoch rather than from creation time, so replicas agree on when a schedule fires. Temporal's one-second minimum is validated before an existing schedule is replaced.

The workflow does nothing but call an activity — workflow code must be deterministic, and a pulse check is not — and the activity is given the checker's name, because a schedule outlives the process that created it and a checker does not survive being serialized.

Testing

The mapping from a schedule to a Temporal specification is unit-tested. Everything else needs a running cluster, so it is not exercised in the default test suite — that suite deliberately requires no infrastructure. Run it against a dev server (temporal server start-dev) when changing this package.