Wikifeeds
Wikifeeds is an API service served via API Gateway. The functionality provided by this was previously part of Mobile content services (MCS).
Contacts
The service is maintained by the Content Transform Team, who can be reached on Slack in #content-transformers.
Primary contacts:
- Yiannis Giannelos (
nemo-yiannis) - Mateus Santos (
mateusbs17)
In case there is a need of an emergency deployment or rollback, serviceops team should be able to handle it (irc: #wikimedia-operations, #wikimedia-serviceops).
Overview
Repository
Wikifeeds is a node.js webservice supporting the Explore feeds in the official Wikipedia Android and iOS apps.
It creates content that is served via the public REST API feed content endpoints (served by API Gateway):
- /api/rest_v1/feed/featured/{yyyy}/{mm}/{dd}
- /api/rest_v1/feed/announcements
- /api/rest_v1/feed/onthisday/{type}/{mm}/{dd}
- /api/rest_v1/page/random/{format}
See docs on the English Wikipedia: https://en.wikipedia.org/api/rest_v1/#/Feed and https://en.wikipedia.org/api/rest_v1/#/Page%20content/get_page_random__format_.
Technology
Wikifeeds is split off from the main mobileapps/mobile content service. As such it is a nodejs service. It's a service-runner compatible service based on the Node.js service template.
The service is deployed on the WMF services kubernetes cluster using helm. This means that the service is packaged as a docker image. The docker image is built by the Deployment pipeline.
Deployment
The images that are used in production can be found on the WMF docker registry. New images are built, after code is merged to the master branch, automatically by the deployment pipeline.
The production clusters are managed using kubernetes and helm. These are also used for a staging instance as well. The configuration for these can be found in the operations/deployment-charts repo. Details for applying those adjustments to the production clusters can be found at Kubernetes deployments docs.
Internal endpoints
After each deployment its useful to test wikifeeds in its internal endpoints before it gets served to public traffic. For example on staging (from the deployment node):
- GET featured feeds responses
curl -v https://staging.svc.eqiad.wmnet:4101/en.wikipedia.org/v1/aggregated/featured/2023/09/29
- GET announcements
curl -v https://staging.svc.eqiad.wmnet:4101/en.wikipedia.org/v1/announcements
For production endpoints the hostnames for the internal service endpoints are:
- https://wikifeeds.svc.codfw.wmnet:4101
- https://wikifeeds.svc.eqiad.wmnet:4101
Architecture
In a nutshell, the service gathers information about featured content from the templates used to display it on various Wikipedias, and provides it in a standard, structured format.
- For /feed/featured/{yyyy}/{mm}/{dd}:
- /page/featured/{yyyy}/{mm}/{dd}
- /media/image/featured/{yyyy}/{mm}/{dd}
- /page/most-read/{yyyy}/{mm}/{dd}
- /page/news
- /feed/onthisday/selected/{mm}/{dd}
- For /feed/onthisday/all/{mm}{dd}:
- /feed/onthisday/births/{mm}/{dd}
- /feed/onthisday/deaths/{mm}/{dd}
- /feed/onthisday/events/{mm}/{dd}
- /feed/onthisday/holidays/{mm}/{dd}
- /feed/onthisday/selected/{mm}/{dd}
The service also provides a /feed/announcements endpoint that is used to provide content of special announcements for things like campaigns and fundraising. The content of these announcements is currently defined entirely within the service code.
The service also provides a /page/random/title endpoint. API Gateway exposes this as /page/random/{format}. {format} can be something like title, summary, html. So a client can get either just the title or the associated page content.
Metrics
The service reports response times via the metrics API provided by service-runner (as is the standard behavior of services based on the Node.js service template).
Service level indicators/objectives (SLIs/SLOs)
| SLI: Traffic | |
|---|---|
| Endpoint | SLO: Requests per second |
| /page/random | 25 ≤ RPS ≤ 100 |
| All others | 1 ≤ RPS ≤ 10 |
| SLI: Latency | |
|---|---|
| Endpoint | SLO: Max latency (p50) |
| /feed/onthisday/events | 500ms |
| /media/image/featured | 250ms |
| /page/most-read | 200ms |
| All others | 100ms |
| SLI: Server errors (5xx) | |
|---|---|
| Endpoint | SLO: Max 5xx error rate |
| All endpoints | 1/1000 |
Table patterns from [1].