Cache Management

• Default caching policy
• Defining a caching policy.
• Caching content by query string, request headers, or additional custom criteria
• Purging content.

Caching #

Environments and Caching #

Edge and Origin Shield Caching #

• Edge Points-of-Presence (POP): An edge POP handles receives and responds to requests for your content.
• Origin Shield POP: An Origin Shield POP improves cache efficiency, reduces the load on your servers, and reduces network bandwidth. If you have assigned at least one Origin Shield POP to your origin configuration, our edge POPs can funnel cache misses through an Origin Shield POP.

Default Caching Policy #

• An origin server provides cache instructions (aka cache directives).
• A rule defines a caching policy.

Caching a Response #

• Response headers: Define cache directives within response headers. Set these response headers through your web server’s configuration or by defining a rule with header features (e.g., Set Response Headers feature).
• Rules: Define a rule with caching features.

Cache Directives (Response Headers) #

• Cache-Control: private: Prevents our servers from caching the response.
• Cache-Control: no-store: Prevents our servers from caching the response.
• Cache-Control: no-cache: Requires our servers or the client to revalidate cached content.
• Pragma: no-cache: Requires our servers or the client to revalidate cached content.
• Cache-Control: s-maxage: Determines the requested content’s time-to-live (TTL) on our servers. TTL identifies the amount of time that cached content can be served without revalidation.
• Cache-Control: max-age: Determines the requested content’s TTL on the user agent and our servers.
• Expires: Defines an expiration date for the requested content’s TTL. The requested content will be considered stale after the specified date/time.
  If this directive has been assigned an invalid value, including zero, then it will be ignored for the request in question.

• The above directives are ordered according to precedence. Directives that appear higher in the list take precedence over lower ones. In other words, if an asset contains both a Cache-Control and an Expires header, then the Cache-Control header will take precedence.
• Refer to your web server’s documentation to learn how to define response headers.
• You may override a web server’s cache policy by creating a rule or route.

Defining a Caching Policy through Rules #

Defining a Caching Policy through CDN-as-Code #

1router.get('/some/path', {
2  caching: {
3    max_age: '86400s',
4    stale_while_revalidate: '3600s',
5    service_worker_max_age: '3600s',
6    bypass_client_cache: true,
7  },
8  headers: {
9    set_response_headers: {
10      'x-sw-cache-control': 'max-age=3600',
11    },
12  },
13});

Cache Key #

Caching Responses for POST and PUT Requests #

• Rules: Create a rule that sets the Enable Caching for Methods feature to POST, PUT, or both HTTP methods.
• CDN-as-Code:
  JavaScript./routes.js

  Copy

  1router.match('/some/path', {
  2  caching: {
  3      "enable_caching_for_methods": ["POST", "PUT"],
  4    }
  5});

Caching Private Responses #

• Rules: Create a rule that enables the Ignore Origin No Cache feature.
• CDN-as-Code:
  JavaScript

  Copy

  1router.get('/some/path', {
  2  caching: {
  3    ignore_origin_no_cache: [200],
  4  },
  5});

Client Caching #

• Cache directives, such as Cache-Control: max-age and Expires.
• Set Client Max Age feature.

Revalidation #

• The requested content is stale.
• The cached response contains one of the following headers:
  • Last-Modified (preferred)
  • ETag header
  If either response header is not found, then our servers will perform an unconditional GET request to the origin.

Preventing a Response from being Cached #

• Rules: Create a rule that enables the Bypass Cache feature for the desired set of traffic.
• CDN-as-Code:
  JavaScript./routes.js

  Copy

  1new Router()
  2  .get('/random-numbers', {
  3    caching: {
  4      "bypass_cache": true,
  5    },
  6  })

How do I know if a response was served from the cache? #

Caching During Development #

1edgio dev --cache