caddy cache

This is a simple caching plugin for caddy server

Notice: Although this plugin works with static content it is not advised. Static content will not see great benefits. It should be used when there are slow responses, for example when using caddy as a proxy to a slow backend.

Build

Notice: Build requires Go 1.12 or higher.

To use it you need to compile your own version of caddy with this plugin. First fetch the code

• export GO111MODULE=on
• go get -u github.com/caddyserver/caddy/...
• go get -u github.com/nicolasazrak/caddy-cache/...

Then update the file in $GOPATH/src/github.com/caddyserver/caddy/caddy/caddymain/run.go and import _ "github.com/nicolasazrak/caddy-cache".

And finally build caddy with:

• cd $GOPATH/src/github.com/caddyserver/caddy/caddy
• ./build.bash

This will produce the caddy binary in that same folder. For more information about how plugins work read this doc.

Usage

Example minimal usage in Caddyfile

caddy.test {
    proxy / yourserver:5000
    cache
}

This will store in cache responses that specifically have a Cache-control, Expires or Last-Modified header set.

For more advanced usages you can use the following parameters:

• match_path: Paths to cache. For example match_path /assets will cache all successful responses for requests that start with /assets and are not marked as private.
• match_header: Matches responses that have the selected headers. For example match_header Content-Type image/png image/jpg will cache all successful responses that with content type image/png OR image/jpg. Note that if more than one is specified, anyone that matches will make the response cacheable.
• path: Path where to store the cached responses. By default it will use the operating system temp folder.
• default_max_age: Max-age to use for matched responses that do not have an explicit expiration. (Default: 5 minutes)
• status_header: Sets a header to add to the response indicating the status. It will respond with: skip, miss or hit. (Default: X-Cache-Status)
• cache_key: Configures the cache key using Placeholders, it supports any of the request placeholders. (Default: {method} {host}{path}?{query})

caddy.test {
    proxy / yourserver:5000
    cache {
        match_path /assets
        match_header Content-Type image/jpg image/png
        status_header X-Cache-Status
        default_max_age 15m
        path /tmp/caddy-cache
    }
}

Logs

Caddy-cache adds a {cache_status} placeholder that can be used in logs.

Benchmarks

Benchmark files are in benchmark folder. Tests were run on my Lenovo G480 with Intel i3 3220 and 8gb of ram.

• First test: Download sherlock.txt (608 Kb) file from the root (caddy.test3), a proxy to root server (caddy.test2) and a proxy to root server with cache (caddy.test).

  wrk -c 400 -d 30s --latency -t 4 http://caddy.test:2015/sherlock.txt

  	Req/s	Throughput	99th Latency
  proxy + cache	4548.03	2.64 GB/s	561.39 ms
  proxy	1043.61	619.65 MB/s	1.00 s
  root	3668.14	2.13 GB/s	612.39 ms

• Second test: Download montecristo.txt (2,6 Mb) file from the root (caddy.test3), a proxy to root server (caddy.test2) and a proxy to root server with cache (caddy.test).

  wrk -c 400 -d 30s --latency -t 4 http://caddy.test:2015/montecristo.txt

  	Req/s	Throughput	99th Latency
  proxy + cache	1199.81	3.01 GB/s	1.65 s
  proxy	473.14	1.20 GB/s	1.81 s
  root	1064.44	2.66 GB/s	1.71 s

• Third test: Download pg31674.txt (41 Kb) a root server (caddy.test5) with gzip and a proxy to root server with cache (caddy.test4).

  wrk -c 50 -d 30s --latency -H 'Accept-Encoding: gzip' -t 4 http://caddy.test4:2015/pg31674.txt

  	Req/s	Throughput	99th Latency
  proxy + cache	16547.84	242.05 MB/s	22.48ms
  root	792.08	11.60 MB/s	109.98ms

Todo list

• [x] Support vary header
• [x] Add header with cache status
• [x] Stream responses while fetching them from upstream
• [x] Locking concurrent requests to the same path
• [x] File disk storage for larger objects
• [x] Add a configuration to not use query params in cache key (via cache_key directive)
• [ ] Purge cache entries #1
• [ ] Serve stale content if proxy is down
• [ ] Punch hole cache
• [ ] Do conditional requests to revalidate data
• [ ] Max entries size