SessionStorage
 | This page is currently a draft. More information and discussion about changes to this draft on the talk page. |
Session storage provides application servers with shared access to user session data, making this service critical to site functionality for logged in users. It utilizes Kask, a RESTful opaque key/value storage abstraction on top of Apache Cassandra, deployed in an active/active configuration in both the eqiad and codfw data-centers.
Production Environment
Service endpoints
Discovery
https://sessionstore.discovery.wmnet:8081/sessions/v1
eqiad
https://sessionstore.svc.eqiad.wmnet:8081/sessions/v1
codfw
https://sessionstore.svc.codfw.wmnet:8081/sessions/v1
staging
https://staging.svc.eqiad.wmnet:8081
Prometheus metrics
https://sessionstore.discovery.wmnet:8081/metrics
Readiness
https://sessionstore.discovery.wmnet:8081/healthz
Cassandra
Given the sensitivity of the information stored, a dedicated Cassandra cluster is used.
Common Tasks
Deployment
k8s
Follow the Kubernetes documentation for the sessionstore service.
 | The namespace and Kubernetes service is called "sessionstore" while the Helm chart used is named "kask". |
Deployment-prep
Unlike production, Docker is used to deploy the session storage service in the deployment-prep environment.
In a web browser:
- Visit https://horizon.wikimedia.org
- Select the deployment-prep project
- Select Project → Compute → Instances (in the sidebar)
- Locate and select the deployment-sessionstore04 instance
- Select the Puppet Configuration tab
- Scroll to the bottom of the page, and click edit for Hiera Config (see below)
- Click "Apply Changes"
- Run
sudo run-puppet-agentfrom deployment-sessionstore04
Sample Hiera Config
profile::cassandra::instances:
deployment-sessionstore02.deployment-prep.eqiad1.wikimedia.cloud: {}
profile::docker::engine::declare_service: true
profile::docker::engine::settings: {}
profile::docker::engine::version: 1.12.6-0~debian-jessie
profile::docker::runner::service_defs:
mediawiki-services-kask:
config:
base_uri: /sessions/v1
cassandra:
authentication:
password: cassandra
username: cassandra
hosts:
- deployment-sessionstore02.deployment-prep.eqiad1.wikimedia.cloud
keyspace: sessions
table: values
default_ttl: 86400
listen_address: 0.0.0.0
listen_port: 8080
openapi_spec: /go/src/gerrit.wikimedia.org/r/mediawiki/services/kask/openapi.yaml
service_name: sessions
namespace: wikimedia
override_cmd: ./kask --config /etc/mediawiki-services-kask/config.yaml
port: 8080
version: v1.0.10
| The contents of mediawiki-services-config.config are written verbatim to the container as /etc/mediawiki-services-kask/config.yaml (the Kask configuration file) |
| Use mediawiki-services-kask.version to specify the Kask Docker image tag. Use mediawiki-services-kask.port to assign the port Kask will listen on. |
Pool and Depool
| FIXME: Stub. |