Add integration for offline support

Offline events are cached in the browser with localforage.

Author: davidmyersdev

packages/browser/package.json

@@ -17,8 +17,10 @@
   },
   "dependencies": {
     "@sentry/core": "5.20.1",
+    "@sentry/minimal": "5.20.1",
     "@sentry/types": "5.20.1",
     "@sentry/utils": "5.20.1",
+    "localforage": "^1.8.1",
     "tslib": "^1.9.3"
   },
   "devDependencies": {

packages/browser/src/integrations/index.ts

@@ -3,3 +3,4 @@ export { TryCatch } from './trycatch';
 export { Breadcrumbs } from './breadcrumbs';
 export { LinkedErrors } from './linkederrors';
 export { UserAgent } from './useragent';
+export { Offline } from './offline';

packages/browser/src/integrations/offline.ts

@@ -0,0 +1,100 @@
+import { addGlobalEventProcessor, getCurrentHub } from '@sentry/core';
+import { captureEvent } from '@sentry/minimal';
+import { Event, Integration } from '@sentry/types';
+import { getGlobalObject, uuid4 } from '@sentry/utils';
+// @ts-ignore
+import localforage = require('localforage');
+
+/**
+ * cache offline errors and send when connected
+ */
+export class Offline implements Integration {
+  /**
+   * @inheritDoc
+   */
+  public static id: string = 'Offline';
+
+  /**
+   * @inheritDoc
+   */
+  public readonly name: string = Offline.id;
+
+  /**
+   * event cache
+   */
+  public offlineEventStore: LocalForage;
+
+  /**
+   * @inheritDoc
+   */
+  public constructor() {
+    this.offlineEventStore = localforage.createInstance({
+      name: 'sentry/offlineEventStore',
+    });
+
+    getGlobalObject<Window>().addEventListener('online', () => {
+      this._sendEvents().catch(() => {
+        // todo: handle localforage error
+      });
+    });
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public setupOnce(): void {
+    addGlobalEventProcessor(async (event: Event) => {
+      if (getCurrentHub().getIntegration(Offline)) {
+        const global = getGlobalObject<Window>();
+
+        // cache if we are positively offline
+        if ('navigator' in global && 'onLine' in global.navigator && !global.navigator.onLine) {
+          try {
+            await this._cacheEvent(event);
+          } catch (error) {
+            // todo: handle localforage error
+          }
+
+          // return null on success or failure, because being offline will still result in an error
+          return null;
+        }
+      }
+
+      return event;
+    });
+  }
+
+  /**
+   * cache an event to send later
+   * @param event an event
+   */
+  private async _cacheEvent(event: Event): Promise<Event> {
+    return this.offlineEventStore.setItem(uuid4(), event);
+  }
+
+  /**
+   * purge event from cache
+   */
+  private async _purgeEvent(cacheKey: string): Promise<void> {
+    return this.offlineEventStore.removeItem(cacheKey);
+  }
+
+  /**
+   * send all events
+   */
+  private async _sendEvents(): Promise<void> {
+    return this.offlineEventStore.iterate((event: any, cacheKey: string, _index: number) => {
+      try {
+        const newEventId = captureEvent(event);
+
+        if (newEventId) {
+          this._purgeEvent(cacheKey)
+            .then(_ => _)
+            .catch(_ => _);
+        }
+      } catch (error) {
+        // handle JSON.parse error
+      }
+    });
+  }
+}

yarn.lock

@@ -1939,11 +1939,32 @@ [email protected]:
   resolved "https://registry.yarnpkg.com/after/-/after-0.8.2.tgz#fedb394f9f0e02aa9768e702bda23b505fae7e1f"
   integrity sha1-/ts5T58OAqqXaOcCvaI7UF+ufh8=
 
-agent-base@4, agent-base@5, agent-base@6, agent-base@^4.3.0, agent-base@~4.2.1:
+agent-base@4, agent-base@^4.3.0:
+  version "4.3.0"
+  resolved "https://registry.yarnpkg.com/agent-base/-/agent-base-4.3.0.tgz#8165f01c436009bccad0b1d122f05ed770efc6ee"
+  integrity sha512-salcGninV0nPrwpGNn4VTXBb1SOuXQBiqbrNXoeizJsHrsL6ERFM2Ne3JUSBWRE6aeNJI2ROP/WEEIDUiDe3cg==
+  dependencies:
+    es6-promisify "^5.0.0"
+
+agent-base@5:
   version "5.1.1"
   resolved "https://registry.yarnpkg.com/agent-base/-/agent-base-5.1.1.tgz#e8fb3f242959db44d63be665db7a8e739537a32c"
   integrity sha512-TMeqbNl2fMW0nMjTEPOwe3J/PRFP4vqeoNuQMG0HlMrtm5QxKqdvAkZ1pRBQ/ulIyDD5Yq0nJ7YbdD8ey0TO3g==
 
+agent-base@6:
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/agent-base/-/agent-base-6.0.1.tgz#808007e4e5867decb0ab6ab2f928fbdb5a596db4"
+  integrity sha512-01q25QQDwLSsyfhrKbn8yuur+JNw0H+0Y4JiGIKd3z9aYk/w/2kxD/Upc+t2ZBBSUNff50VjPsSW2YxM8QYKVg==
+  dependencies:
+    debug "4"
+
+agent-base@~4.2.1:
+  version "4.2.1"
+  resolved "https://registry.yarnpkg.com/agent-base/-/agent-base-4.2.1.tgz#d89e5999f797875674c07d87f260fc41e83e8ca9"
+  integrity sha512-JVwXMr9nHYTUXsBFKUqhJwvlcYU/blreOEUkhNR2eXZIvwd+c+o5V4MgDPKWnMS/56awN3TRzIP+KoPn+roQtg==
+  dependencies:
+    es6-promisify "^5.0.0"
+
 agentkeepalive@^3.4.1:
   version "3.5.2"
   resolved "https://registry.yarnpkg.com/agentkeepalive/-/agentkeepalive-3.5.2.tgz#a113924dd3fa24a0bc3b78108c450c2abee00f67"
@@ -5114,6 +5135,18 @@ es6-object-assign@^1.1.0:
   resolved "https://registry.yarnpkg.com/es6-object-assign/-/es6-object-assign-1.1.0.tgz#c2c3582656247c39ea107cb1e6652b6f9f24523c"
   integrity sha1-wsNYJlYkfDnqEHyx5mUrb58kUjw=
 
+es6-promise@^4.0.3:
+  version "4.2.8"
+  resolved "https://registry.yarnpkg.com/es6-promise/-/es6-promise-4.2.8.tgz#4eb21594c972bc40553d276e510539143db53e0a"
+  integrity sha512-HJDGx5daxeIvxdBxvG2cb9g4tEvwIk3i8+nhX0yGrYmZUzbkdg8QbDevheDB8gd0//uPj4c1EQua8Q+MViT0/w==
+
+es6-promisify@^5.0.0:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/es6-promisify/-/es6-promisify-5.0.0.tgz#5109d62f3e56ea967c4b63505aef08291c8a5203"
+  integrity sha1-UQnWLz5W6pZ8S2NQWu8IKRyKUgM=
+  dependencies:
+    es6-promise "^4.0.3"
+
 escalade@^3.0.1:
   version "3.0.2"
   resolved "https://registry.yarnpkg.com/escalade/-/escalade-3.0.2.tgz#6a580d70edb87880f22b4c91d0d56078df6962c4"
@@ -6528,6 +6561,11 @@ ignore@^5.1.4:
   resolved "https://registry.yarnpkg.com/ignore/-/ignore-5.1.8.tgz#f150a8b50a34289b33e22f5889abd4d8016f0e57"
   integrity sha512-BMpfD7PpiETpBl/A6S498BaIJ6Y/ABT93ETbby2fP00v4EbvPBXWEoaR1UBPKs3iR53pJY7EtZk5KACI57i1Uw==
 
+immediate@~3.0.5:
+  version "3.0.6"
+  resolved "https://registry.yarnpkg.com/immediate/-/immediate-3.0.6.tgz#9db1dbd0faf8de6fbe0f5dd5e56bb606280de69b"
+  integrity sha1-nbHb0Pr43m++D13V5Wu2BigN5ps=
+
 import-fresh@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/import-fresh/-/import-fresh-2.0.0.tgz#d81355c15612d386c61f9ddd3922d4304822a546"
@@ -8106,6 +8144,13 @@ libnpmpublish@^1.1.1:
     semver "^5.5.1"
     ssri "^6.0.1"
 
+[email protected]:
+  version "3.1.1"
+  resolved "https://registry.yarnpkg.com/lie/-/lie-3.1.1.tgz#9a436b2cc7746ca59de7a41fa469b3efb76bd87e"
+  integrity sha1-mkNrLMd0bKWd56QfpGmz77dr2H4=
+  dependencies:
+    immediate "~3.0.5"
+
 lines-and-columns@^1.1.6:
   version "1.1.6"
   resolved "https://registry.yarnpkg.com/lines-and-columns/-/lines-and-columns-1.1.6.tgz#1c00c743b433cd0a4e80758f7b64a57440d9ff00"
@@ -8155,6 +8200,13 @@ loader-utils@^2.0.0:
     emojis-list "^3.0.0"
     json5 "^2.1.2"
 
+localforage@^1.8.1:
+  version "1.8.1"
+  resolved "https://registry.yarnpkg.com/localforage/-/localforage-1.8.1.tgz#f6c0a24b41ab33b10e4dc84342dd696f6f3e3433"
+  integrity sha512-azSSJJfc7h4bVpi0PGi+SmLQKJl2/8NErI+LhJsrORNikMZnhaQ7rv9fHj+ofwgSHrKRlsDCL/639a6nECIKuQ==
+  dependencies:
+    lie "3.1.1"
+
 locate-path@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/locate-path/-/locate-path-2.0.0.tgz#2b568b265eec944c6d9c0de9c3dbbbca0354cd8e"