feat: Add support for proxying font URLs

frontend/src/lib/constants.tsx

@@ -164,6 +164,7 @@ export const FEATURE_FLAGS = {
     SURVEY_NPS_RESULTS: 'survey-nps-results', // owner: @liyiy
     // owner: #team-monitoring
     SESSION_RECORDING_ALLOW_V1_SNAPSHOTS: 'session-recording-allow-v1-snapshots',
+    SESSION_REPLAY_CORS_PROXY: 'session-replay-cors-proxy', // owner: #team-monitoring
     HOGQL_INSIGHTS: 'hogql-insights', // owner: @mariusandra
     WEBHOOKS_DENYLIST: 'webhooks-denylist', // owner: #team-pipeline
 } as const

frontend/src/scenes/session-recordings/player/rrweb/__snapshots__/index.test.ts.snap

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`CorsPlugin should replace font urls in links 1`] = `"https://replay.ph-proxy.com/proxy?url=https://app.posthog.com/fonts/my-font.woff2?t=1234"`;
+
+exports[`CorsPlugin should replace font urls in links 2`] = `"https://replay.ph-proxy.com/proxy?url=https://app.posthog.com/fonts/my-font.ttf"`;
+
+exports[`CorsPlugin should replace font urls in stylesheets 1`] = `"@font-face { font-display: fallback; font-family: "Roboto Condensed"; font-weight: 400; font-style: normal; src: url("https://replay.ph-proxy.com/proxy?url=https://posthog.com/assets/fonts/roboto/roboto_condensed_reg-webfont.woff2?11012022") format("woff2"), url("https://replay.ph-proxy.com/proxy?url=https://posthog.com/assets/fonts/roboto/roboto_condensed_reg-webfont.woff?11012022")"`;
+
+exports[`CorsPlugin should replace font urls in stylesheets 2`] = `"url("https://replay.ph-proxy.com/proxy?url=https://app.posthog.com/fonts/my-font.woff2")"`;

frontend/src/scenes/session-recordings/player/rrweb/index.test.ts

@@ -0,0 +1,24 @@
+import { CorsPlugin } from '.'
+
+describe('CorsPlugin', () => {
+    it.each([
+        `@font-face { font-display: fallback; font-family: "Roboto Condensed"; font-weight: 400; font-style: normal; src: url("https://posthog.com/assets/fonts/roboto/roboto_condensed_reg-webfont.woff2?11012022") format("woff2"), url("https://posthog.com/assets/fonts/roboto/roboto_condensed_reg-webfont.woff?11012022")`,
+        `url("https://app.posthog.com/fonts/my-font.woff2")`,
+    ])('should replace font urls in stylesheets', (content: string) => {
+        expect(CorsPlugin._replaceFontCssUrls(content)).toMatchSnapshot()
+    })
+
+    it.each(['https://app.posthog.com/fonts/my-font.woff2?t=1234', 'https://app.posthog.com/fonts/my-font.ttf'])(
+        'should replace font urls in links',
+        (content: string) => {
+            expect(CorsPlugin._replaceFontUrl(content)).toMatchSnapshot()
+        }
+    )
+
+    it.each(['https://app.posthog.com/my-image.jpeg'])(
+        'should not replace non-font urls in links',
+        (content: string) => {
+            expect(CorsPlugin._replaceFontUrl(content)).toEqual(content)
+        }
+    )
+})

frontend/src/scenes/session-recordings/player/rrweb/index.ts

@@ -0,0 +1,38 @@
+import { ReplayPlugin, playerConfig } from 'rrweb/typings/types'
+
+const PROXY_URL = 'https://replay.ph-proxy.com' as const
+
+export const CorsPlugin: ReplayPlugin & {
+    _replaceFontCssUrls: (value: string) => string
+    _replaceFontUrl: (value: string) => string
+} = {
+    _replaceFontCssUrls: (value: string): string => {
+        return value.replace(
+            /url\("(https:\/\/\S*(?:.eot|.woff2|.ttf|.woff)\S*)"\)/gi,
+            `url("${PROXY_URL}/proxy?url=$1")`
+        )
+    },
+
+    _replaceFontUrl: (value: string): string => {
+        return value.replace(/^(https:\/\/\S*(?:.eot|.woff2|.ttf|.woff)\S*)$/i, `${PROXY_URL}/proxy?url=$1`)
+    },
+
+    onBuild: (node) => {
+        if (node.nodeName === 'STYLE') {
+            const styleElement = node as HTMLStyleElement
+            styleElement.innerText = CorsPlugin._replaceFontCssUrls(styleElement.innerText)
+        }
+
+        if (node.nodeName === 'LINK') {
+            const linkElement = node as HTMLLinkElement
+            linkElement.href = CorsPlugin._replaceFontUrl(linkElement.href)
+        }
+    },
+}
+
+export const COMMON_REPLAYER_CONFIG: Partial<playerConfig> = {
+    triggerFocus: false,
+    insertStyleRules: [
+        `.ph-no-capture {   background-image: url("data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMTYiIGhlaWdodD0iMTYiIHZpZXdCb3g9IjAgMCAxNiAxNiIgZmlsbD0ibm9uZSIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4KPHJlY3Qgd2lkdGg9IjE2IiBoZWlnaHQ9IjE2IiBmaWxsPSJibGFjayIvPgo8cGF0aCBkPSJNOCAwSDE2TDAgMTZWOEw4IDBaIiBmaWxsPSIjMkQyRDJEIi8+CjxwYXRoIGQ9Ik0xNiA4VjE2SDhMMTYgOFoiIGZpbGw9IiMyRDJEMkQiLz4KPC9zdmc+Cg=="); }`,
+    ],
+}

frontend/src/scenes/session-recordings/player/sessionRecordingPlayerLogic.ts

@@ -31,7 +31,12 @@ import { SessionRecordingPlayerExplorerProps } from './view-explorer/SessionReco
 import { createExportedSessionRecording } from '../file-playback/sessionRecordingFilePlaybackLogic'
 import { RefObject } from 'react'
 import posthog from 'posthog-js'
+import { COMMON_REPLAYER_CONFIG, CorsPlugin } from './rrweb'
 import { now } from 'lib/dayjs'
+import { ReplayPlugin } from 'rrweb/typings/types'
+import { preflightLogic } from 'scenes/PreflightCheck/preflightLogic'
+import { featureFlagLogic } from 'lib/logic/featureFlagLogic'
+import { FEATURE_FLAGS } from 'lib/constants'
 
 export const PLAYBACK_SPEEDS = [0.5, 1, 2, 3, 4, 8, 16]
 export const ONE_FRAME_MS = 100 // We don't really have frames but this feels granular enough
@@ -102,6 +107,10 @@ export const sessionRecordingPlayerLogic = kea<sessionRecordingPlayerLogicType>(
             ['speed', 'skipInactivitySetting'],
             userLogic,
             ['hasAvailableFeature'],
+            preflightLogic,
+            ['preflight'],
+            featureFlagLogic,
+            ['featureFlags'],
         ],
         actions: [
             sessionRecordingDataLogic(props),
@@ -471,16 +480,24 @@ export const sessionRecordingPlayerLogic = kea<sessionRecordingPlayerLogicType>(
                 return
             }
 
+            const plugins: ReplayPlugin[] = []
+
+            // We don't want non-cloud products to talk to our proxy as it likely won't work, but we _do_ want local testing to work
+            if (
+                values.featureFlags[FEATURE_FLAGS.SESSION_REPLAY_CORS_PROXY] &&
+                (values.preflight?.cloud || window.location.hostname === 'localhost')
+            ) {
+                plugins.push(CorsPlugin)
+            }
+
             const replayer = new Replayer(values.sessionPlayerData.snapshotsByWindowId[windowId], {
                 root: values.rootFrame,
-                triggerFocus: false,
-                insertStyleRules: [
-                    `.ph-no-capture {   background-image: url("data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMTYiIGhlaWdodD0iMTYiIHZpZXdCb3g9IjAgMCAxNiAxNiIgZmlsbD0ibm9uZSIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4KPHJlY3Qgd2lkdGg9IjE2IiBoZWlnaHQ9IjE2IiBmaWxsPSJibGFjayIvPgo8cGF0aCBkPSJNOCAwSDE2TDAgMTZWOEw4IDBaIiBmaWxsPSIjMkQyRDJEIi8+CjxwYXRoIGQ9Ik0xNiA4VjE2SDhMMTYgOFoiIGZpbGw9IiMyRDJEMkQiLz4KPC9zdmc+Cg=="); }`,
-                ],
+                ...COMMON_REPLAYER_CONFIG,
                 // these two settings are attempts to improve performance of running two Replayers at once
                 // the main player and a preview player
                 mouseTail: props.mode !== SessionRecordingPlayerMode.Preview,
                 useVirtualDom: false,
+                plugins,
             })
 
             actions.setPlayer({ replayer, windowId })