l4proxy: add active HTTP health checks#423
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The active health checker only performed a raw TCP dial, so it could not distinguish application-level state behind an open port. Add optional HTTP probing to ActiveHealthChecks: - uri: request path; when set, the check does an HTTP GET - expect_status: healthy status, or a class (e.g. 2 => any 2xx); default 200 - https: probe over TLS - tls_skip_verify: skip cert verification for HTTPS probes Caddyfile equivalents: health_uri, health_status, health_https, health_tls_skip_verify. When uri is unset the check remains a raw TCP dial, so existing behavior is unchanged. This lets a layer4 proxy follow a primary-election endpoint such as Patroni's /primary, which returns 200 only on the elected leader. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This was referenced Jun 1, 2026
- Remove dead error-handling around setHealthy (it never returns an error), bringing doActiveHTTPHealthCheck to 100% statement coverage. - Document health_uri / health_status / health_https / health_tls_skip_verify in docs/handlers/proxy.md. - Add a caddyfile_adapt integration test for the HTTP health check options. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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What
Adds an optional HTTP mode to the layer4 proxy's active health checks. Today the active health check only performs a raw TCP dial, so it can tell whether a port is open but nothing about the application-level state behind it.
New
ActiveHealthChecksfields (JSON):uri— request path; when set, the check performs an HTTPGETinstead of a TCP dialexpect_status— healthy status code, or a class (e.g.2matches any 2xx); default200https— perform the check over TLStls_skip_verify— skip TLS verification (useful with self-signed certs)Caddyfile equivalents:
health_uri,health_status(accepts200or2xx),health_https,health_tls_skip_verify.When
uriis unset the check stays a raw TCP dial, so existing behavior is unchanged.Why
It lets a layer4 proxy follow an application-level signal instead of mere port-liveness. For example, Patroni (PostgreSQL HA) exposes
/primary, which returns200only on the elected leader; with this change the proxy can route to whichever upstream is currently primary and follow failover automatically — something the TCP-only check cannot do, since every node accepts TCP connections regardless of role.Tests
Added
healthchecks_test.go: healthy/unhealthy by status, status-class match, HTTPS (self-signed), connection-refused, invalid-URI, and Caddyfile parsing (happy + error paths).go test ./modules/l4proxy/passes;gofmtandgo vetare clean.