add option to disable the full page cache

Author: syphar

src/cdn.rs

@@ -401,6 +401,11 @@ pub(crate) fn queue_crate_invalidation(
     config: &Config,
     name: &str,
 ) -> Result<()> {
+    if !config.full_page_cache {
+        info!("full page cache disabled, skipping queueing invalidation");
+        return Ok(());
+    }
+
     let mut add = |distribution_id: &str, path_patterns: &[&str]| -> Result<()> {
         for pattern in path_patterns {
             debug!(distribution_id, pattern, "enqueueing web CDN invalidation");

src/config.rs

@@ -77,6 +77,11 @@ pub struct Config {
     // generate just that directive. Values are in seconds.
     pub(crate) cache_control_stale_while_revalidate: Option<u32>,
 
+    // Activate full page caching.
+    // When disabled, we still cache static assets.
+    // This only affects pages that depend on invalidations to work.
+    pub(crate) full_page_cache: bool,
+
     pub(crate) cdn_backend: CdnKind,
 
     // CloudFront distribution ID for the web server.
@@ -174,6 +179,8 @@ impl Config {
                 "CACHE_CONTROL_STALE_WHILE_REVALIDATE",
             )?,
 
+            full_page_cache: env("DOCSRS_FULL_PAGE_CACHE", true)?,
+
             cdn_backend: env("DOCSRS_CDN_BACKEND", CdnKind::Dummy)?,
 
             cloudfront_distribution_id_web: maybe_env("CLOUDFRONT_DISTRIBUTION_ID_WEB")?,

src/utils/daemon.rs

@@ -109,6 +109,11 @@ pub fn start_background_cdn_invalidator(context: &dyn Context) -> Result<(), Err
         return Ok(());
     }
 
+    if !config.full_page_cache {
+        info!("full page cache disabled, skipping background cdn invalidation");
+        return Ok(());
+    }
+
     cron("cdn invalidator", Duration::from_secs(60), move || {
         let mut conn = pool.get()?;
         if let Some(distribution_id) = config.cloudfront_distribution_id_web.as_ref() {

src/web/cache.rs

@@ -48,16 +48,26 @@ impl CachePolicy {
             CachePolicy::NoStoreMustRevalidate => Some(NO_STORE_MUST_REVALIDATE.clone()),
             CachePolicy::ForeverInCdnAndBrowser => Some(FOREVER_IN_CDN_AND_BROWSER.clone()),
             CachePolicy::ForeverInCdn => {
-                // A missing `max-age` or `s-maxage` in the Cache-Control header will lead to
-                // CloudFront using the default TTL, while the browser not seeing any caching header.
-                // This means we can have the CDN caching the documentation while just
-                // issuing a purge after a build.
-                // https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html#ExpirationDownloadDist
-                None
+                if config.full_page_cache {
+                    // A missing `max-age` or `s-maxage` in the Cache-Control header will lead to
+                    // CloudFront using the default TTL, while the browser not seeing any caching header.
+                    // This means we can have the CDN caching the documentation while just
+                    // issuing a purge after a build.
+                    // https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html#ExpirationDownloadDist
+                    None
+                } else {
+                    Some(NO_CACHING.clone())
+                }
+            }
+            CachePolicy::ForeverInCdnAndStaleInBrowser => {
+                if config.full_page_cache {
+                    config
+                        .cache_control_stale_while_revalidate
+                        .map(|seconds| format!("stale-while-revalidate={seconds}").parse().unwrap())
+                } else {
+                    Some(NO_CACHING.clone())
+                }
             }
-            CachePolicy::ForeverInCdnAndStaleInBrowser => config
-                .cache_control_stale_while_revalidate
-                .map(|seconds| format!("stale-while-revalidate={seconds}").parse().unwrap()),
         }
     }
 }
@@ -129,6 +139,7 @@ mod tests {
             Ok(())
         });
     }
+
     #[test]
     fn render_stale_with_config() {
         wrapper(|env| {
@@ -145,4 +156,36 @@ mod tests {
             Ok(())
         });
     }
+
+    #[test]
+    fn render_forever_in_cdn_disabled() {
+        wrapper(|env| {
+            env.override_config(|config| {
+                config.full_page_cache = false;
+            });
+
+            assert_eq!(
+                CachePolicy::ForeverInCdn.render(&env.config()).unwrap(),
+                "max-age=0"
+            );
+            Ok(())
+        });
+    }
+
+    #[test]
+    fn render_forever_in_cdn_or_stale_disabled() {
+        wrapper(|env| {
+            env.override_config(|config| {
+                config.full_page_cache = false;
+            });
+
+            assert_eq!(
+                CachePolicy::ForeverInCdnAndStaleInBrowser
+                    .render(&env.config())
+                    .unwrap(),
+                "max-age=0"
+            );
+            Ok(())
+        });
+    }
 }