feat: ability to have s-maxage cache control headers (#80)

* added a serverExpiresIn header

* added missing comma in specifying cache-control options

* use triple =, not double =, to follow standards

* added tests for s-maxage being added to cache control

* improved description of serverExpiresIn and but removed it from the example of the object definition, since it's an advanced feature

* check for undefined before converting privacy to lowercase to avoid errors

* removed superfluous info from Readme

Author: Julie Goldberg

Readme.md

@@ -106,13 +106,14 @@ fastify.listen(3000, (err) => {
 for a *cache-response-directive* as defined by RFC 2616.
 + `expiresIn` (Default: `undefined`): a value, in seconds, for the *max-age* the
 resource may be cached. When this is set, and `privacy` is not set to `no-cache`,
-then `', max-age=<value>'` will be appended to the `cache-control` header.
+then `', max-age=<value>'` will be appended to the `cache-control` header. 
 + `cache` (Default: `abstract-cache.memclient`): an [abstract-cache][acache]
 protocol compliant cache object. Note: the plugin requires a cache instance to
 properly support the ETag mechanism. Therefore, if a falsy value is supplied
 the default will be used.
 + `cacheSegment` (Default: `'fastify-caching'`): segment identifier to use when
 communicating with the cache.
++ `serverExpiresIn` (Default: `undefined`): a value, in seconds, for the length of time the resource is fresh and may be held in a shared cache (e.g. a CDN). Shared caches will ignore max-age when this is specified, though browsers will continue to use max-age. Should be used with expiresIn, not in place of it. When this is set, and `privacy` is set to `public`,  then `', s-maxage=<value>'` will be appended to the `cache-control` header.  
 
 [acache]: https://www.npmjs.com/package/abstract-cache
 

plugin.js

@@ -8,6 +8,7 @@ const abstractCache = require('abstract-cache')
 
 const defaultOptions = {
   expiresIn: undefined,
+  serverExpiresIn: undefined,
   privacy: undefined,
   cache: undefined,
   cacheSegment: 'fastify-caching'
@@ -69,6 +70,10 @@ function fastifyCachingPlugin (instance, options, next) {
       value = `${_options.privacy}, max-age=${_options.expiresIn}`
     }
 
+    if (_options.privacy !== undefined && _options.privacy.toLowerCase() === 'public' && _options.serverExpiresIn) {
+      value += `, s-maxage=${_options.serverExpiresIn}`
+    }
+
     instance.addHook('onRequest', (req, res, next) => {
       res.header('Cache-control', value)
       next()

test/headers.test.js

@@ -108,6 +108,80 @@ test('sets private with max-age header', (t) => {
   })
 })
 
+test('sets public with max-age and s-maxage header', (t) => {
+  t.plan(2)
+  const instance = fastify()
+  const opts = {
+    privacy: plugin.privacy.PUBLIC,
+    expiresIn: 300,
+    serverExpiresIn: 12345
+  }
+  instance.register(plugin, opts)
+  instance.get('/', (req, reply) => {
+    reply.send({ hello: 'world' })
+  })
+  instance.listen(0, (err) => {
+    if (err) t.threw(err)
+    instance.server.unref()
+    const portNum = instance.server.address().port
+    const address = `http://127.0.0.1:${portNum}`
+
+    http.get(address, (res) => {
+      t.ok(res.headers['cache-control'])
+      t.equal(res.headers['cache-control'], 'public, max-age=300, s-maxage=12345')
+    }).on('error', (err) => t.threw(err))
+  })
+})
+
+test('only sets max-age and ignores s-maxage with private header', (t) => {
+  t.plan(2)
+  const instance = fastify()
+  const opts = {
+    privacy: plugin.privacy.PRIVATE,
+    expiresIn: 300,
+    serverExpiresIn: 12345
+  }
+  instance.register(plugin, opts)
+  instance.get('/', (req, reply) => {
+    reply.send({ hello: 'world' })
+  })
+  instance.listen(0, (err) => {
+    if (err) t.threw(err)
+    instance.server.unref()
+    const portNum = instance.server.address().port
+    const address = `http://127.0.0.1:${portNum}`
+
+    http.get(address, (res) => {
+      t.ok(res.headers['cache-control'])
+      t.equal(res.headers['cache-control'], 'private, max-age=300')
+    }).on('error', (err) => t.threw(err))
+  })
+})
+
+test('s-maxage is optional with public header', (t) => {
+  t.plan(2)
+  const instance = fastify()
+  const opts = {
+    privacy: plugin.privacy.PUBLIC,
+    expiresIn: 300
+  }
+  instance.register(plugin, opts)
+  instance.get('/', (req, reply) => {
+    reply.send({ hello: 'world' })
+  })
+  instance.listen(0, (err) => {
+    if (err) t.threw(err)
+    instance.server.unref()
+    const portNum = instance.server.address().port
+    const address = `http://127.0.0.1:${portNum}`
+
+    http.get(address, (res) => {
+      t.ok(res.headers['cache-control'])
+      t.equal(res.headers['cache-control'], 'public, max-age=300')
+    }).on('error', (err) => t.threw(err))
+  })
+})
+
 test('sets no-store with max-age header', (t) => {
   t.plan(2)
   const instance = fastify()