org.hawkular.agent.prometheus

Class PrometheusScraper

java.lang.Object

org.hawkular.agent.prometheus.PrometheusScraper

public class PrometheusScraper
extends Object

Given a Prometheus protocol endpoint, this will scrape the Prometheus data it finds there. scrape() is typically the API most consumers will want to use. Given a URL or file, this is able to give you all the metric data found there, regardless of the format of the data.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	PrometheusScraper.OpenConnectionDetails

Constructor Summary

Constructors

Constructor and Description
PrometheusScraper(File file, PrometheusDataFormat dataFormat) Scrape data from the given file.
PrometheusScraper(String host, int port, String context)
PrometheusScraper(URL url)
PrometheusScraper(URL url, PrometheusDataFormat dataFormat) This constructor allows you to explicitly indicate what data format is expected.

Method Summary

Modifier and Type	Method and Description
protected String	getBinaryFormatContentType() This is the content type of the supported Prometheus binary format.
protected String	getTextFormatContentType() This is the content type of the supported Prometheus text format.
protected PrometheusScraper.OpenConnectionDetails	openConnection(URL endpointUrl) This provides a hook for subclasses to be able to connect to the Prometheus endpoint and tell us what the content type is and to give us the actual stream to the data.
List<MetricFamily>	scrape() This will collect all metric data from the endpoint and return the entire list of all metric families found there.
void	scrape(PrometheusMetricsWalker walker)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PrometheusScraper

public PrometheusScraper(String host,
                         int port,
                         String context)
                  throws MalformedURLException

Throws:

MalformedURLException

PrometheusScraper

public PrometheusScraper(URL url)

PrometheusScraper

public PrometheusScraper(URL url,
                         PrometheusDataFormat dataFormat)

This constructor allows you to explicitly indicate what data format is expected. If the URL cannot provide a content type, this data format will determine what data format will be assumed. If the URL does provide a content type, the given data format is ignored. This is useful if you are providing a URL that actually refers to a file in which case the URL connection will not be able to provide a content type.

Parameters:

url - the URL where the Prometheus metric data is found

dataFormat - the data format of the metric data found at the URL, or null if the URL endpoint can provide it for us via content negotiation.

See Also:

#PrometheusScraperUrl(File, PrometheusDataFormat)

PrometheusScraper

public PrometheusScraper(File file,
                         PrometheusDataFormat dataFormat)

Scrape data from the given file. The data format will indicate if it is binary protocol buffer data or text data ("text/plain").

Parameters:

file - the file to scrape

dataFormat - the format of the metric data in the file.

Method Detail

scrape

public List<MetricFamily> scrape()
                          throws IOException

This will collect all metric data from the endpoint and return the entire list of all metric families found there.

Returns:

all metric data found at the endpoint

Throws:

IOException - if failed to scrape data

scrape

public void scrape(PrometheusMetricsWalker walker)
            throws IOException

Throws:

IOException

getBinaryFormatContentType

protected String getBinaryFormatContentType()

This is the content type of the supported Prometheus binary format. This can be used in the Accept header when making the HTTP request to the Prometheus endpoint.

Returns:

binary format content type

getTextFormatContentType

protected String getTextFormatContentType()

This is the content type of the supported Prometheus text format. This can be used in the Accept header when making the HTTP request to the Prometheus endpoint.

Returns:

text format content type

openConnection

protected PrometheusScraper.OpenConnectionDetails openConnection(URL endpointUrl)
                                                          throws IOException

This provides a hook for subclasses to be able to connect to the Prometheus endpoint and tell us what the content type is and to give us the actual stream to the data. This is useful in case callers need to connect securely to the Prometheus endpoint. Subclasses need to open the secure connection with their specific secure credentials and other security details and return the input stream to the data (as well as its content type). If subclasses return a null content type in the returned object the data format passed to this object's constructor will be assumed as the data format in the input stream. The default implementation is to simply open an unsecured connection to the URL.

Parameters:

url - the Prometheus endpoint

Returns:

connection details for the Prometheus endpoint

Throws:

IOException - if the connection could not be opened