14892e3943
* allow serviceData to override cacheSeconds with a longer value * prevent [endpoint] json cacheSeconds property exceeding service default * allow ShieldsRuntimeError to specify a cacheSeconds property By default error responses use the cacheLength of the service class throwing the error. This allows error to tell the handling layer the maxAge that should be set on the error badge response. * add customExceptions param This 1. allows us to specify custom properties to pass to the exception constructor if we throw any of the standard got errors e.g: `ETIMEDOUT`, `ECONNRESET`, etc 2. uses a custom `cacheSeconds` property (if set on the exception) to set the response maxAge * customExceptions --> systemErrors * errorMessages --> httpErrors
112 lines
3.2 KiB
JavaScript
112 lines
3.2 KiB
JavaScript
import assert from 'assert'
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import Joi from 'joi'
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import coalesce from './coalesce.js'
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const serverStartTimeGMTString = new Date().toGMTString()
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const serverStartTimestamp = Date.now()
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const isOptionalNonNegativeInteger = Joi.number().integer().min(0)
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const queryParamSchema = Joi.object({
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cacheSeconds: isOptionalNonNegativeInteger,
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maxAge: isOptionalNonNegativeInteger,
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})
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.oxor('cacheSeconds', 'maxAge')
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.unknown(true)
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.required()
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function overrideCacheLengthFromQueryParams(queryParams) {
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try {
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const {
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cacheSeconds: overrideCacheLength,
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maxAge: legacyOverrideCacheLength,
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} = Joi.attempt(queryParams, queryParamSchema)
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return coalesce(overrideCacheLength, legacyOverrideCacheLength)
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} catch (e) {
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return undefined
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}
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}
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function coalesceCacheLength({
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cacheHeaderConfig,
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serviceDefaultCacheLengthSeconds,
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serviceOverrideCacheLengthSeconds,
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queryParams,
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}) {
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const { defaultCacheLengthSeconds } = cacheHeaderConfig
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// The config returns a number so this should never happen. But this logic
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// would be completely broken if it did.
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assert(defaultCacheLengthSeconds !== undefined)
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const cacheLength = coalesce(
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serviceOverrideCacheLengthSeconds,
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serviceDefaultCacheLengthSeconds,
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defaultCacheLengthSeconds
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)
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// Overrides can apply _more_ caching, but not less. Query param overriding
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// can request more overriding than service override, but not less.
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const candidateOverrides = [
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overrideCacheLengthFromQueryParams(queryParams),
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].filter(x => x !== undefined)
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return Math.max(cacheLength, ...candidateOverrides)
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}
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function setHeadersForCacheLength(res, cacheLengthSeconds) {
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const now = new Date()
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const nowGMTString = now.toGMTString()
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// Send both Cache-Control max-age and Expires in case the client implements
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// HTTP/1.0 but not HTTP/1.1.
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let cacheControl, expires
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if (cacheLengthSeconds === 0) {
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// Prevent as much downstream caching as possible.
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cacheControl = 'no-cache, no-store, must-revalidate'
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expires = nowGMTString
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} else {
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cacheControl = `max-age=${cacheLengthSeconds}, s-maxage=${cacheLengthSeconds}`
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expires = new Date(now.getTime() + cacheLengthSeconds * 1000).toGMTString()
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}
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res.setHeader('Date', nowGMTString)
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res.setHeader('Cache-Control', cacheControl)
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res.setHeader('Expires', expires)
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}
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function setCacheHeaders({
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cacheHeaderConfig,
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serviceDefaultCacheLengthSeconds,
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serviceOverrideCacheLengthSeconds,
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queryParams,
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res,
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}) {
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const cacheLengthSeconds = coalesceCacheLength({
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cacheHeaderConfig,
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serviceDefaultCacheLengthSeconds,
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serviceOverrideCacheLengthSeconds,
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queryParams,
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})
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setHeadersForCacheLength(res, cacheLengthSeconds)
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}
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const staticCacheControlHeader = `max-age=${24 * 3600}, s-maxage=${24 * 3600}` // 1 day.
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function setCacheHeadersForStaticResource(res) {
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res.setHeader('Cache-Control', staticCacheControlHeader)
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res.setHeader('Last-Modified', serverStartTimeGMTString)
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}
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function serverHasBeenUpSinceResourceCached(req) {
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return (
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serverStartTimestamp <= new Date(req.headers['if-modified-since']).getTime()
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)
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}
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export {
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coalesceCacheLength,
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setCacheHeaders,
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setHeadersForCacheLength,
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setCacheHeadersForStaticResource,
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serverHasBeenUpSinceResourceCached,
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}
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