This page is currently a draft.
More information and discussion about changes to this draft on the talk page.
FIXME: This document needs expansion
RESTBase is an API proxy serving the REST API at
/api/rest_v1/. It uses Cassandra as a storage backend.
It is currently running on hosts with the
Deployment and config changes
RESTBase is deployed by Scap.
What to check after a deploy
Deploys to do not always go according to plan, and regressions are not always obvious. Here is a list of things you should check after each deploy:
- Does the API documentation still load? Consider exercising some of the endpoints from the UI (perhaps by requesting an html render).
- Check error logs in logstash.
- Have a look at the metrics in Grafana. Have latencies increased, or error rates jumped? Is memory utilization consistent with expectations? What about storage (op rates, exceptions, etc)?
- Consider making an edit to a page using Visual Editor.
- Take a look at some recent Visual Editor-performed changes (French Wikipedia works great for this, as they use VE by default). Do the diffs looks reasonable?
- Keep a close eye on
#wikimedia-operations, if someone spots a problem, they're likely to raise the issue there.
Be sure to log all actions ahead of time in
#wikimedia-operations. Don't be shy about including details.
Adding a new RESTBase host
Before following these instructions, ensure you follow the provisioning documentation for a new Cassandra node.
- Add hosts to the deployment list in the Restbase deploy repo
- If there have been changes to the restbase service since you applied the correct roles to the host (the latest deployed version should be pulled via Puppet during the first puppet runs), deploy restbase to the hosts: from deployment.eqiad.wmnet,
git pulland then
scap deploy -f -l restbaseNNNN.DC.wmnet "First deploy to restbaseNNNN"
- Add the hosts to conftool-data
- If the hosts are healthy in Icinga at this point and if you feel it is safe as regards deployment timing and so on, pool the hosts:
sudo confctl select name=restbaseNNNN.DC.wmnet set/pooled=yes:weight=10
- Verify that the hosts have been added and are healthy via the pybal API
Renewing expired certificates
Every now and again Cassandra certificates will come close to expiry (for example: SSL WARNING - Certificate restbase2016-a valid until 2020-11-29 09:26:14 +0000 (expires in 53 days)). Certificates need to be deleted and recreated in the Puppet secrets directory - See the Cassandra documentation for details.
In production, the
instance-data path is usually a RAID array. It is used for hints, commitlogs and caches - all vital to the stable operation of the Cassandra instances. Under unusual circumstances (a large rebalancing, an instance behaving erroneously etc) this mount can fill up quickly and space will sometimes be required to back out of this condition. For this reason, we set a lower threshold for disk free on this path than for other disks.
To temporarily switch to local logging for debugging, you can change the config.yaml log stanza like this:
logging: name: restbase streams: # level can be trace, debug, info, warn, error - level: info path: /tmp/debug.log
Alternatively, you can log to stdout by commenting out the streams sub-object. This is useful for debugging startup failures like this:
cd /srv/deployment/restbase/deploy/ sudo -u restbase node restbase/server.js -c /etc/restbase/config.yaml -n 0
-n 0 parameter avoids forking off any workers, which reduces log noise. Instead, a single worker is started up right in the master process.
Analytics and metrics
Hive query for action API & rest API traffic:
use wmf; SELECT SUM(IF (uri_path LIKE '/api/rest_v1/%', 1, 0)) as count_rest, SUM(IF (uri_path LIKE '/w/api.php%', 1, 0)) as count_action FROM wmf.webrequest WHERE webrequest_source = 'text' AND year = 2017 AND month = 9 AND (uri_path LIKE '/api/rest_v1/%' OR uri_path LIKE '/w/api.php%');