---
title: Wagtail & Caching
class: text-center
highlighter: shiki
transition: slide-left
monaco: false
mdc: true
themeConfig:
  primary: '#2e1f5e'
---

# Wagtail & Caching

### Jake Howard{style="color: #e85537;" }

<ul class="list-none! text-sm [&>li]:m-0! mt-1 uppercase">
  <li><em>Senior Systems Engineer</em> @ Torchbox <mdi-fire class="fill-white"/></li>
  <li><em>Security Team</em> & <em>Performance Working Group</em> @ Wagtail <logos-wagtail class="fill-white"/></li>
</ul>

<ul class="list-none! text-xs [&>li]:m-0! mt-3 font-light">
  <li><mdi-earth /> theorangeone.net</li>
  <li><mdi-twitter /> @RealOrangeOne</li>
  <li><mdi-github /> @RealOrangeOne</li>
  <li><mdi-mastodon /> @jake@theorangeone.net</li>
</ul>

---
layout: fact
---

# Disclaimer{style="color: #fd5765;" }

---
layout: cover
---

# What _is_ caching?

---
layout: center
---


# Scale

<style>
@keyframes grow {
  from {

  }

  to {
    font-size: 30rem;
  }
}

h1 {
  animation-name: grow;
  animation-duration: 30s;
  animation-timing-function: linear;
  animation-fill-mode: forwards;
}

</style>

---
layout: cover
---

# <logos-wagtail class="fill-white"/> Caching <em>in Wagtail</em>

---
layout: section
---

## 1:
# Template Fragment Caching

---
layout: image
image: https://d1nvwtjgmbo5v5.cloudfront.net/media/images/Screen_Shot_2015-05-14_at_09.01.5.2e16d0ba.fill-1200x996.png
backgroundSize: cover
---

<style>
.slidev-layout {
  background-position: top center !important;
}
</style>

---
layout: none
---

```html
<div class="one-half--medium one-third--large">
  <div class="card card--link">
    <a href="/developers/springload/made-wagtail/" class="project-image">
      <img src="https://d1nvwtjgmbo5v5.cloudfront.net/media/images/Screen_Shot_2015-05-14_at_09.01.52.2e16d0ba.fill-680x564.png" alt="" title="">
  </a>
  <div class="project__links">
    <a class="project__info" href="/developers/springload/made-wagtail/">
      <span class="u-sr-only">Project info</span>
      <svg class="i i--grey i--hover">
        <use xlink:href="#i-info"></use>
      </svg>
    </a>
    <a class="project__visit" href="http://madewithwagtail.org/" title="Project link" data-analytics="Project|Link click">
      <span class="u-sr-only">Project link</span>
      <svg class="i i--grey i--hover">
        <use xlink:href="#i-visit"></use>
      </svg>
    </a>
  </div>
</div>
<h4 class="project-title">
  Made with Wagtail
</h4>
<p class="project-author">
  <a href="/developers/springload/" title="View the company page of Springload">
    Springload
  </a>
</p>
```

<style>
.slidev-page, .slidev-code-wrapper, .slidev-code {
  height: 100%;
}
</style>


---
layout: cover
background: /website-homepage.png
---

# An example

---
layout: image
image: /website-posts.png
---

---
layout: none
---

````md magic-move
```html
{% load wagtailcore_tags util_tags %}

<article class="media listing-item">
  <div class="columns">
    <figure class="media-left column is-{{ show_listing_images|yesno:'3,1' }} image-column">
      {% if page.list_image_url %}
        <a href="{% pageurl page %}" class="image" title="{{ page.title }}">
          <img src="{{ page.list_image_url }}" alt="{{ page.hero_image_alt }}" loading="lazy" decoding="async" referrerpolicy="no-referrer" />
        </a>
      {% endif %}
    </figure>
    <div class="media-content column">
      <div>
        {% if breadcrumbs %}
          {% include "common/breadcrumbs.html" with parents=page.get_parent_pages %}
        {% endif %}
        <h2 class="title is-3">
          <a href="{% pageurl page %}">{{ page.title }}</a>
        </h2>
        {% include "common/content-details.html" %}
        <p>{{ page.summary }}</p>
      </div>
    </div>
  </div>
</article>
```

```html {all|1|3,27|4-26|all}
{% load wagtailcore_tags wagtail_cache util_tags %}

{% wagtailpagecache FRAGMENT_CACHE_TTL "listing-item" breadcrumbs show_listing_images %}
  <article class="media listing-item">
    <div class="columns">
      <figure class="media-left column is-{{ show_listing_images|yesno:'3,1' }} image-column">
        {% if page.list_image_url %}
          <a href="{% pageurl page %}" class="image" title="{{ page.title }}">
            <img src="{{ page.list_image_url }}" alt="{{ page.hero_image_alt }}" loading="lazy" decoding="async" referrerpolicy="no-referrer" />
          </a>
        {% endif %}
      </figure>
      <div class="media-content column">
        <div>
          {% if breadcrumbs %}
            {% include "common/breadcrumbs.html" with parents=page.get_parent_pages %}
          {% endif %}
          <h2 class="title is-3">
            <a href="{% pageurl page %}">{{ page.title }}</a>
          </h2>
          {% include "common/content-details.html" %}
          <p>{{ page.summary }}</p>
        </div>
      </div>
    </div>
  </article>
{% endwagtailpagecache %}
```
````

<style>
.slidev-page, .slidev-code-wrapper, .slidev-code {
  height: 100%;
}
</style>


---
layout: cover
background: /website-search.png
---

# Duplication

---
layout: center
---

```html {3}
<section class="container">
  {% for page in listing_pages %}
    {% include "common/listing-item.html" %}
  {% endfor %}
</section>
```

<style>
code {
  font-size: 1.5rem !important;
}
</style>

---
layout: image
image: /website-search.png
---

---

# Cache invalidation

<v-click>

```python
>>> BlogPostPage.objects.first().cache_key
```

</v-click>

<v-click>

```python
@property
def cache_key(self) -> str:
    """
    A generic cache key to identify a page in its current state.
    Should the page change, so will the key.

    Customizations to the cache key should be made in :attr:`get_cache_key_components`.
    """
    ...
```

</v-click>

<style>
code {
  font-size: 1rem !important;
}
</style>

---
layout: center
---

# What about Django?

```jinja
{% load cache %}
{% cache 500 sidebar request.user.username %}
    .. sidebar for logged in user ..
{% endcache %}
```
<Transform :scale="1.4">
<v-clicks>

- Current page
- Current site
- Preview
- Cache invalidation

</v-clicks>
</Transform>

<style>
code {
  font-size: 1.5rem !important;
}
</style>

---
layout: section
---

## 2:
# Frontend Caching

---
layout: fact
---

```mermaid
flowchart LR
  U[User]
  CDN{Content<br>Delivery Network}
  W[(Wagtail)]

  U--->CDN
  CDN-..->W
```

---
layout: fact
---

```mermaid
flowchart TD
  U1[🧑‍💻]
  U2[🧑‍💻]
  U3[🧑‍💻]
  U4[🧑‍💻]
  U5[🧑‍💻]
  U6[🧑‍💻]
  U7[🧑‍💻]
  U8[🧑‍💻]
  U9[🧑‍💻]
  U10[🧑‍💻]
  U11[🧑‍💻]
  U12[🧑‍💻]
  U13[🧑‍💻]
  CDN{Content<br>Delivery Network}
  W[(Wagtail)]

  U1--->CDN
  U2--->CDN
  U3--->CDN
  U4--->CDN
  U5--->CDN
  U6--->CDN
  U7--->CDN
  U8--->CDN
  U9--->CDN
  U10--->CDN
  U11--->CDN
  U12--->CDN
  U13--->CDN
  CDN-...->W
```

---
layout: image
image: https://www.cloudflare.com/network-maps/cloudflare-pops-2O04nulSdNrRpJR9fs9OKv.svg
---

Source: Cloudflare

<style>
.slidev-layout {
  background: white;
}

p {
  color: black;
  position: absolute;
  bottom: 0;
  font-size: 0.66rem;
}
</style>

---
layout: cover
background: /wagtail-homepage.png
---

# An example

---
layout: image
image: /map.jpg
transition: fade
---

---
layout: cover
background: /map.jpg
---

# ~XXms

<style>
h1 {
  font-size: 4rem;
}
</style>

---
layout: fact
---

```mermaid
flowchart LR
  U[User]

  subgraph Content Delivery Network
    CDN{Content<br>Delivery Network}
    C[(Cache)]
  end

  W[(Wagtail)]

  U---->CDN
  CDN-.->C
  C---->W
  C-.->CDN
```

---
layout: fact
---

```mermaid
flowchart LR
  U[User]
  A[Admin]

  subgraph Content Delivery Network
    CDN{Content<br>Delivery Network}
    C[(Cache)]
  end

  W[(Wagtail)]

  U---->CDN
  CDN-.->C
  C---->W
  C-.->CDN

  A---->CDN
  CDN---->W
```

---
layout: fact
---

# Content is cached!

```mermaid
flowchart LR
  U1[User]
  U2[User]
  U3[User]

  subgraph Content Delivery Network
    CDN{Content<br>Delivery Network}
    C[(Cache)]
  end

  W[(Wagtail)]

  U1===>CDN
  U2===>CDN
  U3===>CDN
  CDN==>C
  C==>CDN
  C-.....->W
```

---
layout: image
image: /wagtail-homepage-typo.png
---

---
layout: section
---

## Solution:
# Frontend Cache Invalidation
### Wagtail secret sauce <logos-wagtail class="fill-white"/>

---
layout: fact
---

```mermaid
flowchart LR
  U[User]

  subgraph Content Delivery Network
    CDN{Content<br>Delivery Network}
    C[(Cache)]
  end

  W[(Wagtail)]

  U--->CDN
  CDN-->C
  C-->CDN
  C-..->W

  W-.->|Frontend Cache Invalidation|CDN
```

---
layout: center
---

# `settings.py`

### 1.

```python {3}
INSTALLED_APPS = [
    ...
    "wagtail.contrib.frontend_cache"
]
```

#### 2.

```python
WAGTAILFRONTENDCACHE = {
  'cloudflare': {
    'BACKEND': 'wagtail.contrib.frontend_cache.backends.CloudflareBackend',
    'BEARER_TOKEN': os.environ["CF_BEARER_TOKEN"],
    'ZONEID': os.environ["CF_ZONE_ID"],
  },
}
```

#### 3. ???

#### 4. Profit!

<style>
code {
  font-size: 0.9rem !important;
}
</style>

---
layout: fact
---

```mermaid
flowchart LR
  A[Admin]

  subgraph Content Delivery Network
    CDN{Content<br>Delivery Network}
    C[(Cache)]
  end

  W[(Wagtail)]

  A-->|Publish new content to<br><code>/blog/post-1</code>|W

  W-.->|<code>PURGE /blog/post-1</code>|CDN

  CDN-.->C
```

---
layout: cover
background: https://d1nvwtjgmbo5v5.cloudfront.net/media/images/Screen_Shot_2015-05-14_at_09.01.5.2e16d0ba.fill-1200x996.png
---

# Conclusion

---
layout: cover
---

<Transform :scale="1.3">

# Performance means:


- Users are happier <mdi-emoticon-happy />
- Servers are happier <mdi-server-network />
- The planet is happier <mdi-earth class="text-green" />

</Transform>

---
layout: end
---