Presto and the data.world Collector
Introduction
Note
The latest version of the Collector is 2.128. To view the release notes for this version and all previous versions, please go here.
The data.world Collector harvests metadata from your source system. Please read over the data.world Collector FAQ to familiarize yourself with the Collector.
Prerequisites
You must have a ddw-catalogs (or other) dataset set up to hold your catalog files when you are done running the collector.
The machine running the catalog collector should have connectivity to the internet or access to the source instance. It is recommended to have a minimum of 8GB memory and a 2Ghz processor.
Docker must be installed. For more information see https://docs.docker.com/get-docker/.
The user defined to run the data.world Collector must have read access to all resources being cataloged.
The computer running the data.world Collector needs a Java Runtime Environment. OpenJDK 17 is supported and available here.
Permissions
The account used to authenticate needs to read the information schema of the databases about which it is collecting metadata. It does not need read access to the data within the tables.
What is cataloged
The information cataloged by the collector includes:
Ways to run the data.world Collector
There are a few different ways to run the data.world Collector--any of which can be combined with an automation strategy to keep your catalog up to date:
Create a configuration file (config.yml) - This option stores all the information needed to catalog your data sources. It is an especially valuable option if you have multiple data sources to catalog as you don't need to run multiple scripts or CLI commands separately.
Run the collector though a CLI - Repeat runs of the collector requires you to re-enter the command for each run.
Note
This section walks you through the process of running the collector using CLI.
Writing the data.world Collector command
The easiest way to create your Collector command is to:
Copy the following example command
Edit it for your organization and data source
Open a terminal window in any Unix environment that uses a Bash shell and paste your command into it.
The example command includes the minimal parameters required to run the collector (described below)--your instance may require more. A description of all the available parameters is available in this article. Edit the command by adding any other parameters you wish to use, and by replacing the values for all your parameters with your information as appropriate. Parameters required by the Collector are in bold.
Important
Do not forget to replace x.y in datadotworld/dwcc:x.y with the version of the Collector you want to use (e.g., datadotworld/dwcc:2.113).
Basic parameters
Each collector has parameters that are required, parameters that are recommended, and parameters that are completely optional. Required parameters must be present for the command to run. Recommended parameters are either:
parameters that exist in pairs, and one or the other must be present for the command to run (e.g.,
--agentand--base)parameters that we recommend to improve your experience running the command in some way
Together, the required and recommended parameters make up the Basic parameters for each collector. The Basic parameters for this collector are:
Docker and the data.world Collector
Detailed information about the Docker portion of the command can be found here. When you run the command, run will attempt to find the image locally, and if it doesn't find it, it will go to Dockerhub and download it automatically:
Handling custom certificates
If the target data instance has a custom SSL certificate, we recommend extending our Docker image and installing the custom cert like this (where ./ca.der is the name and location of the cert file).
Dockerfile:
FROM datadotworld/dwcc:<collector_version>
ADD ./ca.der ca.der
RUN keytool -importcert -alias startssl -cacerts -storepass changeit -noprompt -file ca.derImportant
Do not forget to replace <collector_version> in datadotworld/dwcc:<collector_version> with the version of the Collector you want to use (for example, datadotworld/dwcc:2.126).
Then, in the directory with that Dockerfile:
docker build -t dwcc-cert .
Note
The command needs to be all lower case, and there must be a dot (.) supplied to reference the current directory.
Finally, change the docker run command to use dwcc-cert instead of dwcc. Here is an example command for cataloging Tableau with a custom SSL certificate:
docker run -it --rm --mount type=bind,source=/tmp,target=/dwcc-output \ --mount type=bind,source=/tmp,target=/app/log dwcc-cert \ catalog-tableau --tableau-api-base-url <baseUrl> \ --tableau-password <password> --tableau-username <username> \ -a <account> -n <catalogName> -o "/dwcc-output"
Collector runtime and troubleshooting
The catalog collector may run in several seconds to many minutes depending on the size and complexity of the system being crawled. If the catalog collector runs without issues, you should see no output on the terminal, but a new file that matching *.dwec.ttl should be in the directory you specified for the output. If there was an issue connecting or running the catalog collector, there will be either a stack trace or a *.log file. Both of those can be sent to support to investigate if the errors are not clear. A list of common issues and problems encountered when running the collectors is available here.
Upload the .ttl file generated from running the Collector
When the data.world Collector runs successfully, it creates a .ttl file in the directory you specified as the dwcc-output directory. The automatically-generated file name is databaseName.catalogName.dwec.ttl. You can rename the file or leave the default, and then upload it to your ddw-catalogs dataset (or wherever you store your catalogs).
Caution
If there is already a .ttl catalog file with the same name in your ddw-catalogs dataset, when you add the new one it will overwrite the existing one.
Automating updates to your metadata catalog
Keep your metadata catalog up to date using cron, your Docker container, or your automation tool of choice to run the catalog collector on a regular basis. Considerations for how often to schedule include:
Frequency of changes to the schema
Business criticality of up-to-date data
For organizations with schemas that change often and where surfacing the latest data is business critical, daily may be appropriate. For those with schemas that do not change often and which are less critical, weekly or even monthly may make sense. Consult your data.world representative for more tailored recommendations on how best to optimize your catalog collector processes.