# TeslaHTTPCache
HTTP caching middleware for Tesla
## Installation
```elixir
def deps do
[
{:tesla_http_cache, "~> 0.1.0"}
]
end
```
You need to setup a cache store as well for production use.
[http_cache_store_native](https://github.com/tanguilp/http_cache_store_native) is such a
store.
## Configuration
Options of this middleware are options of the [http_cache](https://hexdocs.pm/http_cache)
library, By default, the following options are set:
- `:type`: `:private`
- `:auto_accept_encoding`: `true`
- `:auto_compress`: `true`
The `:store` option must be set when configuring the middleware.
## Examples
Notice the `age` response header after the first request.
```elixir
iex> client = Tesla.client([{TeslaHTTPCache, store: :http_cache_store_process}])
%Tesla.Client{
adapter: nil,
fun: nil,
post: [],
pre: [{TeslaHTTPCache, :call, [[store: :http_cache_store_process]]}]
}
iex> Tesla.get!(client, "http://perdu.com")
%Tesla.Env{
__client__: %Tesla.Client{
adapter: nil,
fun: nil,
post: [],
pre: [{TeslaHTTPCache, :call, [[store: :http_cache_store_process]]}]
},
__module__: Tesla,
body: "<html><head><title>Vous Etes Perdu ?</title></head><body><h1>Perdu sur l'Internet ?</h1><h2>Pas de panique, on va vous aider</h2><strong><pre> * <----- vous êtes ici</pre></strong></body></html>\n",
headers: [
{"cache-control", "max-age=600"},
{"date", "Wed, 29 Jun 2022 12:23:18 GMT"},
{"accept-ranges", "bytes"},
{"etag", "\"cc-5344555136fe9\""},
{"server", "Apache"},
{"vary", "Accept-Encoding,User-Agent"},
{"content-type", "text/html"},
{"expires", "Wed, 29 Jun 2022 12:33:18 GMT"},
{"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
{"content-length", "204"}
],
method: :get,
opts: [],
query: [],
status: 200,
url: "http://perdu.com"
}
iex> Tesla.get!(client, "http://perdu.com")
%Tesla.Env{
__client__: %Tesla.Client{
adapter: nil,
fun: nil,
post: [],
pre: [{TeslaHTTPCache, :call, [[store: :http_cache_store_process]]}]
},
__module__: Tesla,
body: "<html><head><title>Vous Etes Perdu ?</title></head><body><h1>Perdu sur l'Internet ?</h1><h2>Pas de panique, on va vous aider</h2><strong><pre> * <----- vous êtes ici</pre></strong></body></html>\n",
headers: [
{"cache-control", "max-age=600"},
{"date", "Wed, 29 Jun 2022 12:23:18 GMT"},
{"accept-ranges", "bytes"},
{"etag", "\"cc-5344555136fe9\""},
{"server", "Apache"},
{"vary", "Accept-Encoding,User-Agent"},
{"content-type", "text/html"},
{"expires", "Wed, 29 Jun 2022 12:33:18 GMT"},
{"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
{"content-length", "204"},
{"age", "4"}
],
method: :get,
opts: [],
query: [],
status: 200,
url: "http://perdu.com"
}
iex> Tesla.get!(client, "http://perdu.com", headers: [{"range", "bytes=12-43"}])
%Tesla.Env{
__client__: %Tesla.Client{
adapter: nil,
fun: nil,
post: [],
pre: [{TeslaHTTPCache, :call, [[store: :http_cache_store_process]]}]
},
__module__: Tesla,
body: "<title>Vous Etes Perdu ?</title>",
headers: [
{"cache-control", "max-age=600"},
{"date", "Wed, 29 Jun 2022 12:23:18 GMT"},
{"accept-ranges", "bytes"},
{"etag", "\"cc-5344555136fe9\""},
{"server", "Apache"},
{"vary", "Accept-Encoding,User-Agent"},
{"content-type", "text/html"},
{"expires", "Wed, 29 Jun 2022 12:33:18 GMT"},
{"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
{"content-range", "bytes 12-43/204"},
{"content-length", "32"},
{"age", "125"}
],
method: :get,
opts: [],
query: [],
status: 206,
url: "http://perdu.com"
}
iex> Tesla.get!(client, "http://perdu.com", headers: [{"cache-control", "no-cache"}])
%Tesla.Env{
__client__: %Tesla.Client{
adapter: nil,
fun: nil,
post: [],
pre: [{TeslaHTTPCache, :call, [[store: :http_cache_store_process]]}]
},
__module__: Tesla,
body: "<html><head><title>Vous Etes Perdu ?</title></head><body><h1>Perdu sur l'Internet ?</h1><h2>Pas de panique, on va vous aider</h2><strong><pre> * <----- vous êtes ici</pre></strong></body></html>\n",
headers: [
{"accept-ranges", "bytes"},
{"content-type", "text/html"},
{"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
{"content-length", "204"},
{"age", "1"},
{"cache-control", "max-age=600"},
{"connection", "Keep-Alive"},
{"date", "Wed, 29 Jun 2022 12:28:10 GMT"},
{"etag", "\"cc-5344555136fe9\""},
{"server", "Apache"},
{"vary", "User-Agent,Accept-Encoding"},
{"expires", "Wed, 29 Jun 2022 12:38:10 GMT"},
{"keep-alive", "timeout=5, max=98"}
],
method: :get,
opts: [],
query: [],
status: 200,
url: "http://perdu.com"
}
```
## Telemetry events
The following events are emitted:
- `[:tesla_http_cache, :hit]` when a response is returned from the cache
- measurements: none
- metadata:
- `:freshness`: one of
- `:fresh`: a fresh response was returned
- `:stale`: a stale response was returned
- `:revalidated`: the response was successfully revalidated and returned
- `[:tesla_http_cache, :miss]` in case of cache miss
- measurements: none
- metadata: none
