TeslaHTTPCache

HTTP caching middleware for Tesla

Installation

def deps do
  [
    {:http_cache, "~> 0.3.1"}
    {:tesla_http_cache, "~> 0.3.0"}
  ]
end

Responses have to be stored in a separate store backend (this library does not come with one), such as:

http_cache_store_memory: responses are stored in memory (ETS)
http_cache_store_disk: responses are stored on disk. An application using the sendfile system call (such as plug_http_cache) may benefit from the kernel's memory caching automatically

Both are cluster-aware.

Configuration

Options of this middleware are options of the 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.

iex> client = Tesla.client([{TeslaHTTPCache, %{store: :http_cache_store_process}}])
%Tesla.Client{
  fun: nil,
  pre: [{TeslaHTTPCache, :call, [%{store: :http_cache_store_process}]}],
  post: [],
  adapter: nil
}
iex> Tesla.get!(client, "http://perdu.com")
%Tesla.Env{
  method: :get,
  url: "http://perdu.com",
  query: [],
  headers: [
    {"cache-control", "max-age=600"},
    {"date", "Sat, 22 Apr 2023 14:15:11 GMT"},
    {"etag", "W/\"cc-5344555136fe9-gzip\""},
    {"server", "cloudflare"},
    {"vary", "Accept-Encoding,User-Agent"},
    {"content-type", "text/html"},
    {"expires", "Sat, 22 Apr 2023 14:25:11 GMT"},
    {"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
    {"cf-cache-status", "DYNAMIC"},
    {"report-to",
     "{\"endpoints\":[{\"url\":\"https:\\/\\/a.nel.cloudflare.com\\/report\\/v3?s=OW%2BJhOzTmxq4FGquM7w7bvkDLoryGQY9elB6ajNGx6Wgw0%2BjJechCF9vurIyh1V8rJ%2F0O6KL%2B36xUILE8SICSy1o0O1%2FrR2lx0XHgsN0ZWhBXsWf81OnlHM6ITw%3D\"}],\"group\":\"cf-nel\",\"max_age\":604800}"},
    {"nel",
     "{\"success_fraction\":0,\"report_to\":\"cf-nel\",\"max_age\":604800}"},
    {"cf-ray", "7bbe7a35ea419bc2-FRA"},
    {"alt-svc", "h3=\":443\"; ma=86400, h3-29=\":443\"; ma=86400"},
    {"content-length", "204"}
  ],
  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 &ecirc;tes ici</pre></strong></body></html>\n",
  status: 200,
  opts: [],
  __module__: Tesla,
  __client__: %Tesla.Client{
    fun: nil,
    pre: [{TeslaHTTPCache, :call, [%{store: :http_cache_store_process}]}],
    post: [],
    adapter: nil
  }
}
iex> Tesla.get!(client, "http://perdu.com")
%Tesla.Env{
  method: :get,
  url: "http://perdu.com",
  query: [],
  headers: [
    {"cache-control", "max-age=600"},
    {"date", "Sat, 22 Apr 2023 14:15:11 GMT"},
    {"etag", "W/\"cc-5344555136fe9-gzip\""},
    {"server", "cloudflare"},
    {"vary", "Accept-Encoding,User-Agent"},
    {"content-type", "text/html"},
    {"expires", "Sat, 22 Apr 2023 14:25:11 GMT"},
    {"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
    {"cf-cache-status", "DYNAMIC"},
    {"report-to",
     "{\"endpoints\":[{\"url\":\"https:\\/\\/a.nel.cloudflare.com\\/report\\/v3?s=OW%2BJhOzTmxq4FGquM7w7bvkDLoryGQY9elB6ajNGx6Wgw0%2BjJechCF9vurIyh1V8rJ%2F0O6KL%2B36xUILE8SICSy1o0O1%2FrR2lx0XHgsN0ZWhBXsWf81OnlHM6ITw%3D\"}],\"group\":\"cf-nel\",\"max_age\":604800}"},
    {"nel",
     "{\"success_fraction\":0,\"report_to\":\"cf-nel\",\"max_age\":604800}"},
    {"cf-ray", "7bbe7a35ea419bc2-FRA"},
    {"alt-svc", "h3=\":443\"; ma=86400, h3-29=\":443\"; ma=86400"},
    {"content-length", "204"},
    {"age", "8"}
  ],
  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 &ecirc;tes ici</pre></strong></body></html>\n",
  status: 200,
  opts: [],
  __module__: Tesla,
  __client__: %Tesla.Client{
    fun: nil,
    pre: [{TeslaHTTPCache, :call, [%{store: :http_cache_store_process}]}],
    post: [],
    adapter: nil
  }
}
iex> Tesla.get!(client, "http://perdu.com", headers: [{"range", "bytes=12-43"}])
%Tesla.Env{
  method: :get,
  url: "http://perdu.com",
  query: [],
  headers: [
    {"cache-control", "max-age=600"},
    {"date", "Sat, 22 Apr 2023 14:15:11 GMT"},
    {"etag", "W/\"cc-5344555136fe9-gzip\""},
    {"server", "cloudflare"},
    {"vary", "Accept-Encoding,User-Agent"},
    {"content-type", "text/html"},
    {"expires", "Sat, 22 Apr 2023 14:25:11 GMT"},
    {"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
    {"cf-cache-status", "DYNAMIC"},
    {"report-to",
     "{\"endpoints\":[{\"url\":\"https:\\/\\/a.nel.cloudflare.com\\/report\\/v3?s=OW%2BJhOzTmxq4FGquM7w7bvkDLoryGQY9elB6ajNGx6Wgw0%2BjJechCF9vurIyh1V8rJ%2F0O6KL%2B36xUILE8SICSy1o0O1%2FrR2lx0XHgsN0ZWhBXsWf81OnlHM6ITw%3D\"}],\"group\":\"cf-nel\",\"max_age\":604800}"},
    {"nel",
     "{\"success_fraction\":0,\"report_to\":\"cf-nel\",\"max_age\":604800}"},
    {"cf-ray", "7bbe7a35ea419bc2-FRA"},
    {"alt-svc", "h3=\":443\"; ma=86400, h3-29=\":443\"; ma=86400"},
    {"content-range", "bytes 12-43/204"},
    {"content-length", "32"},
    {"age", "22"}
  ],
  body: "<title>Vous Etes Perdu ?</title>",
  status: 206,
  opts: [],
  __module__: Tesla,
  __client__: %Tesla.Client{
    fun: nil,
    pre: [{TeslaHTTPCache, :call, [%{store: :http_cache_store_process}]}],
    post: [],
    adapter: nil
  }
}
iex> Tesla.get!(client, "http://perdu.com", headers: [{"cache-control", "no-cache"}])
%Tesla.Env{
  method: :get,
  url: "http://perdu.com",
  query: [],
  headers: [
    {"cache-control", "max-age=600"},
    {"date", "Sat, 22 Apr 2023 14:15:46 GMT"},
    {"etag", "W/\"cc-5344555136fe9-gzip\""},
    {"server", "cloudflare"},
    {"vary", "Accept-Encoding,User-Agent"},
    {"content-type", "text/html"},
    {"expires", "Sat, 22 Apr 2023 14:25:46 GMT"},
    {"last-modified", "Thu, 02 Jun 2016 06:01:08 GMT"},
    {"cf-cache-status", "DYNAMIC"},
    {"report-to",
     "{\"endpoints\":[{\"url\":\"https:\\/\\/a.nel.cloudflare.com\\/report\\/v3?s=3gbcT%2Bp7OxvokGPjTitRoTA9KyQOcbn6z1EG5jp2%2Frvg%2FqA%2Bi0CZgDK0O7VNSB6c5UIPsilr%2BMysTPCgi8ocxYYCsMhc82q4e7EP4nAI5zYYuJhmMGFXTeSjWMI%3D\"}],\"group\":\"cf-nel\",\"max_age\":604800}"},
    {"nel",
     "{\"success_fraction\":0,\"report_to\":\"cf-nel\",\"max_age\":604800}"},
    {"cf-ray", "7bbe7b10f8619bc2-FRA"},
    {"alt-svc", "h3=\":443\"; ma=86400, h3-29=\":443\"; ma=86400"},
    {"content-length", "204"}
  ],
  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 &ecirc;tes ici</pre></strong></body></html>\n",
  status: 200,
  opts: [],
  __module__: Tesla,
  __client__: %Tesla.Client{
    fun: nil,
    pre: [{TeslaHTTPCache, :call, [%{store: :http_cache_store_process}]}],
    post: [],
    adapter: nil
  }
}

Middleware order

http_cache only caches iodata bodies. As a consequence, beware of not decoding the body before caching. For instance, do not:

defp client(token) do
  Tesla.client([
    Tesla.Middleware.Logger,
    {Tesla.Middleware.BearerAuth, token: token},
    {TeslaHTTPCache, %{store: :http_cache_store_memory}},
    Tesla.Middleware.JSON # <- WRONG!!!
  ])
end

as the JSON will be decoded before caching, and the body wil be a map (not cacheable). Instead do:

defp client(token) do
  Tesla.client([
    Tesla.Middleware.Logger,
    {Tesla.Middleware.BearerAuth, token: token},
    Tesla.Middleware.JSON,
    {TeslaHTTPCache, %{store: :http_cache_store_memory}}
  ])
end

Response will be cached first then decoded.

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

Name		Name	Last commit message	Last commit date
Latest commit History 24 Commits
lib		lib
test		test
.formatter.exs		.formatter.exs
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
mix.exs		mix.exs
mix.lock		mix.lock

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TeslaHTTPCache

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