34a268d8dc
Two-layer structure: Sources (raw notes) + Wiki (compile output) Four domains: Dev (40), Venture (3), Homelab (23), Reference (0) Includes CLAUDE.md spec, index pages at all levels, compile log Co-Authored-By: Lovebug <lovebug@herbylab.dev>
142 lines
3.7 KiB
Markdown
142 lines
3.7 KiB
Markdown
---
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created: 2026-04-15
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path: Sources/Homelab
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project: wp-cron-supercronic-deploy
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status: completed
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tags:
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- pbs
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- wordpress
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- traefik
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- docker
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- cron
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type: session-notes
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updated: 2026-04-15
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---
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# WP-Cron → Supercronic Sidecar Deployment
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Session notes captured retroactively from March 7 work, before the n8n
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email pipeline was in place.
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## Problem
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Uptime Kuma status checks were triggering WordPress's built-in WP-Cron on
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every HTTP request, causing cron jobs to fire unpredictably on page load
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instead of on a proper schedule. Added unnecessary load and made cron
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behavior non-deterministic.
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## Solution
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Three-part fix:
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1. **Disable WP-Cron on page load** via `wp-config.php`
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2. **Block external access to `wp-cron.php`** at the Traefik middleware
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layer
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3. **Deploy a Supercronic sidecar container** that calls wp-cron on a real
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schedule via the internal Docker network
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## Implementation
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### 1. wp-config.php
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```php
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define('ALTERNATE_WP_CRON', false);
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define('DISABLE_WP_CRON', true);
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```
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`wp-config.php` is bind-mounted from the host so Ansible can manage it:
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```yaml
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volumes:
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- wordpress_data:/var/www/html
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- ./wp-config.php:/var/www/html/wp-config.php
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```
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To pull a fresh copy out of a running container:
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```bash
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docker cp wordpress:/var/www/html/wp-config.php
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/opt/docker/wordpress/wp-config.php
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```
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### 2. Traefik middleware — block external `wp-cron.php`
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```jinja
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- traefik.http.routers.wordpress.middlewares=www-redirect,block-wpcron
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- traefik.http.middlewares.block-wpcron.redirectregex.regex=^/wp-cron\.php.*
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- traefik.http.middlewares.block-wpcron.redirectregex.replacement=/
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```
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The router definition must include `block-wpcron` in the middlewares chain
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or Traefik silently does not apply it.
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Verify:
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```bash
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curl -Lv https://plantbasedsoutherner.com/wp-cron.php 2>&1 | grep -E
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"HTTP|Location"
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# Expected: HTTP/2 302 + Location: https://plantbasedsoutherner.com
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```
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### 3. Supercronic sidecar
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Project structure:
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```
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/opt/docker/wpcron/
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Dockerfile
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crontab
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docker-compose.yml
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```
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`crontab` (set to every minute — Wordfence and Jetpack schedule events at
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this frequency):
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```
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* * * * * curl -s http://wordpress/wp-cron.php?doing_wp_cron
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```
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`Dockerfile`:
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```dockerfile
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FROM alpine:latest
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ARG SUPERCRONIC_VERSION=v0.2.29
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ARG SUPERCRONIC_ARCH=amd64
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RUN wget -q
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https://github.com/aptible/supercronic/releases/download/${SUPERCRONIC_VERSION}/supercronic-linux-${SUPERCRONIC_ARCH}
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\
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-O /usr/local/bin/supercronic && \
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chmod +x /usr/local/bin/supercronic && \
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apk add --no-cache curl
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COPY crontab /etc/crontab
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CMD ["/usr/local/bin/supercronic", "/etc/crontab"]
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```
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The sidecar lives in its own compose project. To reach the WordPress
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container, the wpcron compose file declares the WordPress network as
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`external: true`.
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## Bonus Fix — Redis Auth on Production
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Discovered during the deploy that the production WordPress container was
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missing the Redis password env var. Env vars had been moved to an `.env`
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file on staging but the change never made it back to production. Fixed and
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now part of the standard env handoff between environments.
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## Key Learnings
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- **Traefik `redirectregex` matches path only**, not the full URL — design
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regex accordingly
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- **`depends_on` only works within the same Docker Compose project** — for
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cross-project dependencies, declare the network as `external: true`
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- **`docker compose up -d --force-recreate `** is the right
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command to pick up compose file changes (not `restart`, which reuses the
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old config)
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- **Cron interval matters:** Plugins like Wordfence and Jetpack schedule
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per-minute events, so a 5-minute cron will leave them perpetually behind.
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Every minute is the right default for this stack.
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## Status
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Deployed to staging then promoted to production. Running cleanly since.
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...sent from Jenny & Travis |