Healthie.NET.LeaderElection
4.1.1
Prefix Reserved
dotnet add package Healthie.NET.LeaderElection --version 4.1.1
NuGet\Install-Package Healthie.NET.LeaderElection -Version 4.1.1
<PackageReference Include="Healthie.NET.LeaderElection" Version="4.1.1" />
<PackageVersion Include="Healthie.NET.LeaderElection" Version="4.1.1" />
<PackageReference Include="Healthie.NET.LeaderElection" />
paket add Healthie.NET.LeaderElection --version 4.1.1
#r "nuget: Healthie.NET.LeaderElection, 4.1.1"
#:package Healthie.NET.LeaderElection@4.1.1
#addin nuget:?package=Healthie.NET.LeaderElection&version=4.1.1
#tool nuget:?package=Healthie.NET.LeaderElection&version=4.1.1
Healthie.NET.LeaderElection
Deprecated as of 4.1.0
Leader election now ships in Healthie.NET, the core package. Call
AddHealthieLeaderElection()there and drop this reference — running the checks on one replica at a time works exactly as it does here.Nothing breaks if you keep it. This package is still published, as an assembly of type forwards, so an application referencing it keeps compiling and running untouched. It carried no third-party dependency, so keeping it separate cost you an install and saved you nothing. It will not gain features.
▶ Live demo — board.healthie-dotnet.dev — a read-only Healthie.NET dashboard watching real status pages (Anthropic, OpenAI, GitHub, Cloudflare, and more), built from these packages. Full documentation at healthie-dotnet.dev.
Runs pulse checks on one replica at a time.
The problem it solves
Without it, every replica runs every check. Three replicas mean:
- a database asked three times whether it is healthy, on every interval
- three sets of results racing to write the same state document, two of them wasted
- one outage paging somebody three times
None of that is visible from a dashboard, which is what makes it worth fixing before it matters.
Installation
dotnet add package Healthie.NET.LeaderElection
Usage
using Healthie.LeaderElection;
builder.Services
.AddHealthie(typeof(Program).Assembly)
.AddHealthieLeaderElection(); // after the scheduler it should wrap
builder.Services.AddSingleton<ILeaseProvider, YourSharedLeaseProvider>();
Call it after the scheduler. It decorates whatever IPulseScheduler is registered at that point, so unlike every other AddHealthie* in this library it is not order-independent. Calling it first throws with an explanation rather than silently wrapping the built-in timer when you meant Quartz.
It works with every scheduler — the built-in timer, Quartz, Hangfire, Coravel, Temporal — because it wraps rather than replaces.
You need a shared lease provider
The default keeps leases in memory, which makes every replica the leader of itself and leaves the problem exactly where it was. It exists so the feature can be switched on and tested without standing anything up.
Implement ILeaseProvider against something your replicas share — a table with a conditional update, a Redis SET NX, a blob lease. It is two methods:
Task<bool> TryAcquireAsync(string leaseName, string holderId, TimeSpan duration, CancellationToken ct);
Task ReleaseAsync(string leaseName, string holderId, CancellationToken ct);
Acquire and renew are one operation on purpose — take it if nobody holds it, if it has expired, or if it is already mine. Separating them invites a renew that succeeds against a lease somebody else now holds.
Failover
A lease expires rather than being handed over, because the failure worth designing for is the replica that stops without saying anything — killed, redeployed, partitioned away. Another replica takes over once the lease lapses, without needing its cooperation.
LeaseDuration (30s default) is therefore how long checks pause when a leader dies abruptly. RenewInterval (10s) is comfortably shorter, so a single slow round trip does not move leadership for no reason.
If the lease store becomes unreachable, the replica stands down. It can no longer prove it leads, and two leaders is the state this exists to prevent.
| Product | Versions Compatible and additional computed target framework versions. |
|---|---|
| .NET | net8.0 is compatible. net8.0-android was computed. net8.0-browser was computed. net8.0-ios was computed. net8.0-maccatalyst was computed. net8.0-macos was computed. net8.0-tvos was computed. net8.0-windows was computed. net9.0 was computed. net9.0-android was computed. net9.0-browser was computed. net9.0-ios was computed. net9.0-maccatalyst was computed. net9.0-macos was computed. net9.0-tvos was computed. net9.0-windows was computed. net10.0 is compatible. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed. |
-
net10.0
- Healthie.NET.DependencyInjection (>= 4.1.1)
-
net8.0
- Healthie.NET.DependencyInjection (>= 4.1.1)
NuGet packages
This package is not used by any NuGet packages.
GitHub repositories
This package is not used by any popular GitHub repositories.
### Fixed
- **The dashboard cropped its own rows on anything narrower than a laptop.** The row and its column
header share one track definition, and two rules overrode it: a read-only board drops the controls
column, and a narrow viewport folds the row down to three. Written as separate rule sets they
fought on specificity, and `.hpm-list--readonly .hpm-row` outranks a `.hpm-row` inside a media
query -- so on a read-only board the fold never applied at any width. Every row was drawn with
five tracks demanding 556px inside a 342px phone: 214px of columns clipped off the right, the name
squeezed to its 160px minimum to make room for columns that were not visible anyway, and no
scrollbar to reach them, because the overflow was clipped rather than scrolled. The definition is
now a single custom property on the list, which is the one element both variants already sit on,
so the fold cannot be outranked.
- **The last column was clipped on an ordinary 1280 laptop, read-only or not.** The detail panel
moved below the list at 1100px, but a full row needs a 706px column and the list only reaches that
at 1402px of viewport -- so between those two the three columns fitted the window while the middle
one no longer fitted a row. That threshold is now 1400px, calibrated on the editable board, which
is the wider of the two and the default.
- **Group and tag chips were sliced down the middle on a phone.** They sit on the row's sub-line,
which truncates with `text-overflow: ellipsis` -- and that ellipsizes text, not an inline-flex
pill, so a chip was cut mid-shape instead. The folded row has vertical room the wide one does not,
so the line now wraps there, exactly as it already does on a card.
- **Cards lost their rate, sparkline and last-checked time on a phone.** The three cells were hidden
for every layout below 820px, but only the row layout was short of width; a card stacks them into
areas down its own length, where they fit. They are now hidden for the row layout alone.
### Changed
- **The packages point at [healthie-dotnet.dev](https://healthie-dotnet.dev/).** `PackageProjectUrl`
is the landing site rather than the repository, because NuGet renders it as the package's "Project
website" and a reader who clicks it wants documentation and the live board, not a source tree.
`RepositoryUrl` still points at GitHub, so Source Link and NuGet's own source link are unaffected.
Every package README now links the documentation site alongside the live demo, which moved to
[board.healthie-dotnet.dev](https://board.healthie-dotnet.dev/).
- **Releases carry build provenance.** The release workflow attests which workflow, at which commit,
produced each package, so `gh attestation verify <package>.nupkg --repo ivanvyd/Healthie.NET`
proves a download came from this repository. The SBOM already said what went into a package; this
says who built it, which is the half a tampered build would otherwise be free to restate.
- The repository README leads with a screenshot rather than a 10MB animation, and `Healthie.NET.Redis`
gained the header every other package README already had.
Full changelog: https://github.com/ivanvyd/Healthie.NET/blob/v4.1.1/CHANGELOG.md