PuppetDB 4.0: Query structure

Included in Puppet Enterprise 2016.1. A newer version is available; see the version menu above for details.

Summary

PuppetDB’s query API can retrieve data objects from PuppetDB for use in other applications. For example, the PuppetDB-termini for Puppet masters use this API to collect exported resources.

The query API is implemented as HTTP URLs on the PuppetDB server. By default, it can only be accessed over the network via host-verified HTTPS; see the jetty settings if you need to access the API over unencrypted HTTP.

Query structure

A query consists of an HTTP GET request to an endpoint URL which may or may not contain:

  • A query URL parameter, whose value is a query string.
  • Other URL parameters, to configure paging or other behavior.

That is, most queries will look like a GET request to a URL that resembles the following:

https://puppetdb:8081/pdb/query/v4/<ENDPOINT>?query=<QUERY STRING>

Alternatively, you can provide the entity context instead of using the <ENDPOINT> suffix with the following:

https://puppetdb:8081/pdb/query/v4?query=<QUERY STRING>

Consult the root endpoint documentation for more details.

API URLs

API URLs generally look like this:

https://<SERVER>:<PORT>/pdb/query/<API VERSION>/<ENDPOINT>?<PARAMETER>=<VALUE>&<PARAMETER>=<VALUE>

For example: https://puppetdb:8081/pdb/query/v4/resources?limit=50&offset=50.

API version

After the /pdb/query/ prefix, the first part of an API URL is the API version, written in the v4 format. This section describes version 4 of the API, so every URL will begin with /pdb/query/v4.

Entity endpoints

After the version, URLs are organized into a number of endpoints that express the entity you wish to query for.

Conceptually, an entity endpoint represents a PuppetDB entity. Each version of the PuppetDB API defines a set number of endpoints.

See the entities documentation for a list of the available endpoints. Each endpoint may have additional sub-endpoints under it; these are generally just shortcuts for the most common types of query, so that you can write terser and simpler query strings.

URL parameters

Finally, the URL may include some URL parameters. Some endpoints require certain parameters; for others they’re optional or disallowed. Each endpoint’s page lists the parameters it accepts, and most endpoints also support the paging parameters.

A group of parameters begins with a question mark (?). Each parameter is formatted as <PARAMETER>=<VALUE>, and additional parameters are separated by ampersands (&). All parameter values must be URL-encoded.

query

The most common URL parameter is query, which lets you define the set of results returned by most endpoints.

There are two query languages available in PuppetDB, consult the documentation for each for more details.

  • AST query language: a JSON based query language.
  • [Puppet query language (experimental)][pql]: a new query language designed for human users to simplify querying over the legacy AST language.

A complete query string describes a comparison operation. When submitting a query, PuppetDB will check every possible result from the endpoint to see if it matches the comparison from the query string, and will only return those objects that match.

Note: Only the root endpoint supports PQL.

Paging

The next most common URL parameters are the paging parameters.

Most PuppetDB query endpoints support paged results via a set of shared URL parameters. For more information, please see the documentation on paging.

Query responses

All queries return data with a content type of application/json. Each endpoint’s page describes the format of its return data.

Tutorial and tips

For a walkthrough on constructing queries, see the query tutorial page. For quick tips on using curl to make ad hoc queries, see the curl tips page.

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