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feat(redis): opt-in persistent connections via REDIS_PERSISTENT - #173
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Each php-fpm request opens a new TLS connection per redis connection it uses, and the TLS handshakes saturate the Valkey CPU during token bursts. With REDIS_PERSISTENT=true every redis connection keeps one persistent socket per worker, under its own persistent id. The connections share host:port, so a shared id would let one connection's SELECT switch the database of another within the same request. Defaults to off. Signed-off-by: smarcet <smarcet@gmail.com>
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📝 WalkthroughWalkthroughThe Redis configuration now supports optional persistent connections. When ChangesRedis persistence configuration
Priority: ⬇️ Low Estimated code review effort: 2 (Simple) | ~5 minutes Change: Feature Merge Risk: 🔵 Low · up to The new setting is off by default, so merging does not change current behavior. Before enabling it on any environment that uses the phpredis client, add a separate Pre-merge checks |
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The title clearly and concisely describes the main change: adding opt-in persistent Redis connections controlled by REDIS_PERSISTENT. |
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Inline comments:
Review comments at @config/database.php:
- Line 119: Update the Redis connection entries’ persistent configuration so
Predis retains its existing string IDs, while PhpRedis uses persistent=true and
a distinct persistent_id for each connection. Apply this to every affected
connection entry, including the default connection.
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config/database.php
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…onnection Laravel's PhpRedisConnector reads 'persistent' only as a flag and takes the socket id from 'persistent_id'. predis ignores the key. Signed-off-by: smarcet <smarcet@gmail.com>
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📘 OpenAPI / Swagger preview ➡️ https://OpenStackweb.github.io/openstackid/openapi/pr-173/ This page is automatically updated on each push to this PR. |
* feat(redis): opt-in persistent connections via REDIS_PERSISTENT Each php-fpm request opens a new TLS connection per redis connection it uses, and the TLS handshakes saturate the Valkey CPU during token bursts. With REDIS_PERSISTENT=true every redis connection keeps one persistent socket per worker, under its own persistent id. The connections share host:port, so a shared id would let one connection's SELECT switch the database of another within the same request. Defaults to off. Signed-off-by: smarcet <smarcet@gmail.com> * fix(redis): set persistent_id so phpredis also keeps one socket per connection Laravel's PhpRedisConnector reads 'persistent' only as a flag and takes the socket id from 'persistent_id'. predis ignores the key. Signed-off-by: smarcet <smarcet@gmail.com> --------- Signed-off-by: smarcet <smarcet@gmail.com>
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ref: https://app.clickup.com/t/86bcemtn3
Summary
Every php-fpm request opens a new TLS connection to Valkey for each redis connection it uses (predis, no persistence; 5 named connections: default, cache, session, worker, doctrine_cache). In prod that is about 3 new TLS connections per IDP request. During the 2026-10-09 17:55 UTC burst (about 880 IDP requests in 30 s), Valkey took about 104 new connections/s and the host reached 44.5% CPU on 2 vCPU, while the Valkey process itself used at most 0.08 cores: the CPU goes into TLS handshakes, not commands.
This adds an opt-in
REDIS_PERSISTENTflag. When true, each redis connection keeps one persistent socket per php-fpm worker, so later requests reuse the TLS session and only resend AUTH and SELECT.Each connection gets its own persistent id (
openstackid_<name>). The connections share host:port, and with a shared id PHP hands the same socket to all of them within a request: one connection's SELECT then switches the database of the others.Default is off; nothing changes until the env var is set.
Verification
Throwaway Redis with TLS, predis v2.2.2 from this repo's vendor, PHP 8.3 CLI, 200 simulated requests that each write through a db0 connection and a db1 connection:
php -l config/database.phppasses.Rollout
Enable on stage first (separate argocd-apps PR), run the login, 2FA, OTP, logout, refresh and introspection flows, and compare
rate(redis_total_connections_received)and Valkey CPU under a burst before and after.Risks
pm.max_requestsrecycles workers.maxclients.Summary by CodeRabbit