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m (→‎Accessing DataHub: Added note about case sensitivity of usernames.)
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[[File:Datahub screenshot.png|thumb|468x468px|DataHub User Interface]]
#REDIRECT [[Data Engineering/Systems/DataHub]]
== Overview ==
We run an instance of DataHub which acts as a centralized data catalog, intended to facilitate the following:
* <u>Discovery</u> by potential users of the various data stores operated by WMF.
* <u>Documentation</u> of the data structures, formats, access rights, and other associated details.
* <u>Governance</u> of these data stores, including details of retention, sanitization, recording changes over time.
Currently our DataHub should be considered at an [[:en:Minimum_viable_product|MVP]] stage, so functionality and content may change rapidly as the service develops.
== Accessing DataHub ==
[[File:Location of shell account.png|thumb|Ascertaining your shell login name]]
The URL for the web interface for DataHub is: ''''''
This requires a [[Help:Create a Wikimedia developer account|Wikimedia developer account]] and access is currently limited to members of the <code>wmf</code> or <code>nda</code> LDAP groups.
When logging in, enter your '''shell login name''' and your '''wikitech password''' in order to gain access.
Please note that the username should be entered in '''lower case'''. Please see [[phab:T309382|T309382]] for more information on case-sensitivity in usernames and rights assignment..
If you are in any doubt as to your shell login name you can go to [[Special:Preferences#mw-prefsection-personal|Special:Preferences]] as shown in the following screenshot.
n.b. We intend to use your ''Developer Account username'' in due course, but currently there is [ a bug] preventing this from working.
The DataHub Metadata Service is: '''https://datahub-gms.discovery.wmnet:30443'''
This service is not public facing and it is only available from our private networks. Currently we have not enabled authentication on this interface, although it is planned.
== Related Pages ==
{{Special:PrefixIndex/Analytics/Systems/DataHub/ |stripprefix=1}}
== Service Overview ==
=== DataHub Components ===
The DataHub instance is composed of several components, each built from the same codebase
* a '''metadata server''' (or GMS)
* a '''frontend''' web application
* an '''mce consumer''' (metadata change event)
* an '''mae consumer''' (metadata audit event)
All of these components are stateless and currently run on the [[Kubernetes/Clusters#wikikube (aka eqiad/codfw)|Wikikube]] Kubernetes clusters.
Their containers are built using the [[Deployment pipeline]] and the configuration for this is in the [[gerrit:plugins/gitiles/analytics/datahub/+/refs/heads/wmf/.pipeline/|wmf branch]] of our fork of the datahub repository:
=== Backend Data Tiers ===
The stateful components of the system are:
* a MariaDB database on the [[Analytics/Systems/Cluster/Mysql Meta|analytics-meta]] database
* an Opensearch cluster running on three VMs named <code>datahubsearch100[1-3].eqiad.wmnet</code>
* an instance of Karapace, which acts as a schema registry, running on <code>karapace1001.eqiad.wmnet</code>
* serveral Kafka topics running on the [[Kafka#jumbo (eqiad)|kafka-jumbo]] cluster
Our Opensearch cluster fulfils two roles of:
* a search index
* a graph database
The design document for the DataHub service is [ here] (restricted to WMF staff)
We had previously carried out a [[Data Catalog Application Evaluation]] and subsequently the decision was taken to use DataHub and to implement an MVP deployment.
== Metadata Sources ==
We have several key sources of metadata.
* [[Analytics/Systems/Cluster/Hive|Hive]]
* [[Kafka]]
* [[Analytics/Systems/Druid|Druid]]
* [[Analytics/Systems/Superset|Superset]]
== Ingestion ==
Currently ingestion can be performed by any machine on our private networks, including the [[Analytics/Systems/Clients|stats servers]].
=== Automated Ingestion ===
We are moving to automated and regularly scheduled metadata ingestion using [[Analytics/Systems/Airflow|Airflow]]. Please check back soon for updated documentation on this topic.
=== Manual Ingestion Example ===
The following procedure should help to get started with manual ingestion.
# Select a [[Analytics/Systems/Clients|stats server]] for your use.
# Activate a stacked [[Analytics/Systems/Anaconda|anaconda]] environment.
# Configure the [[HTTP proxy]] servers in your shell
# Install the necessary python modules
# it's very important to install the same version CLI as server that's running,
# otherwise ingestion will not work
pip install 'acryl-datahub[datahub]'~=
datahub version
datahub init
server: https://datahub-gms.discovery.wmnet:30443
Until [ this bug] is fixed, we will also need to use:
export REQUESTS_CA_BUNDLE=/etc/ssl/certs/ca-certificates.crt
Then create a recipe file, install more plugins if required.
datahub ingest -c recipe.yaml
Some examples of recipes, including Hive, Kafka, and Druid are avaiable on [[phab:T299703#7662929|this ticket]]

Latest revision as of 16:31, 2 September 2022