Cache

Sweety provides two caching mechanisms: FastCGI response cache (PHP) and proxy response cache (HTTP upstream).

FastCGI Cache

Equivalent to Nginx fastcgi_cache, caches PHP-FPM responses.

[sites.fastcgi.cache]
path               = "/tmp/sweety-fcgi-cache"  # Disk cache directory (omit for memory-only)
max_entries        = 1000                       # Max memory cache entries (default 1000)
ttl                = 60                         # Cache TTL (seconds, default 60)
cacheable_statuses = [200, 301, 302]            # Cacheable status codes
cacheable_methods  = ["GET", "HEAD"]            # Cacheable methods

# Skip cache when these request headers are present (no read, no write)
bypass_headers = []

# Ignore these response headers' effect on cache decisions
# WordPress sends Cache-Control: no-store and Set-Cookie, configure this to cache anyway
ignore_headers = ["Cache-Control", "Set-Cookie"]

WordPress Recommended Cache Config

[sites.fastcgi.cache]
max_entries    = 2000
ttl            = 300           # Cache for 5 minutes
ignore_headers = ["Cache-Control", "Set-Cookie"]

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Proxy Cache (proxy_cache)

Equivalent to Nginx proxy_cache, caches HTTP upstream responses.

[sites.proxy_cache]
path               = "/tmp/sweety-proxy-cache"
max_entries        = 1000
ttl                = 60
cacheable_statuses = [200, 301, 302]
cacheable_methods  = ["GET", "HEAD"]
bypass_headers     = ["Authorization", "Cookie"]
ignore_headers     = []

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Static File Cache

Static files are cached automatically. Three-tier cache:

Tier	Condition	Description
Content cache	File ≤ 64KB	Full content in memory with pre-compressed gzip/brotli/zstd variants
fd cache	File > 64KB	Caches file descriptor + stat metadata, avoids repeated open
sendfile(2)	Linux/macOS H1 non-TLS	Kernel zero-copy transfer

Configuration ([global])

[global]
open_file_cache_max      = 200000  # Max cached entries (default 200000)
open_file_cache_inactive = 60      # Inactivity eviction timeout (seconds, default 60)
open_file_cache_total_mb = 512     # Content cache memory limit (MB, default 512)

Behavior

• min_uses = 2: Files are cached only after 2 accesses to prevent cache pollution
• inotify real-time eviction: File changes evict the cache entry immediately
• Pre-compression: First cache write generates gzip/brotli/zstd variants automatically
• ETag / Last-Modified: Returns 304 Not Modified on cache hit
• Range requests: Memory-cached files are sliced directly, zero disk I/O

For CDN / multi-site deployments, increase open_file_cache_max and open_file_cache_total_mb.

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Cache Field Reference

Field	Default	Description
path	None	Disk cache directory, omit for memory-only
max_entries	1000	Max cached responses in memory
ttl	60	Cache TTL (seconds)
cacheable_statuses	[200, 301, 302]	Which status codes can be cached
cacheable_methods	["GET", "HEAD"]	Which HTTP methods can be cached
bypass_headers	[]	Skip cache when these request headers are present
ignore_headers	[]	Ignore these response headers that would block caching

bypass_headers vs ignore_headers

	bypass_headers	ignore_headers
Check timing	On request arrival	On response return
Effect	Request header present → skip cache read & write	Response header present → still write to cache
Typical use	Authorization (don't cache logged-in users)	Cache-Control: no-store (force-cache WordPress)

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Per-Location Cache Rules

[[sites.locations.cache_rules]] sets Cache-Control response headers by file extension:

[[sites.locations]]
path    = "/"
handler = "static"

[[sites.locations.cache_rules]]
pattern       = "\\.(js|css|woff2?)$"
cache_control = "public, max-age=2592000, immutable"

[[sites.locations.cache_rules]]
pattern       = "\\.(png|jpg|gif|webp|ico)$"
cache_control = "public, max-age=2592000"

[[sites.locations.cache_rules]]
pattern       = "\\.html$"
cache_control = "public, max-age=3600"

You can also override cache_control at the location level:

[[sites.locations]]
path          = "^~ /static/"
handler       = "static"
cache_control = "public, max-age=86400"