public class PingRequestHandler extends RequestHandlerBase implements SolrCoreAware
This handler is designed to be used as the endpoint for an HTTP Load-Balancer to use when checking the "health" or "up status" of a Solr server.
In its simplest form, the PingRequestHandler should be configured with some defaults indicating a request that should be executed. If the request succeeds, then the PingRequestHandler will respond back with a simple "OK" status. If the request fails, then the PingRequestHandler will respond back with the corresponding HTTP Error code. Clients (such as load balancers) can be configured to poll the PingRequestHandler monitoring for these types of responses (or for a simple connection failure) to know if there is a problem with the Solr server. Note in case isShard=true, PingRequestHandler respond back with what the delegated handler returns (by default it's /select handler).
<requestHandler name="/admin/ping" class="solr.PingRequestHandler">
<lst name="invariants">
<str name="qt">/search</str><!-- handler to delegate to -->
<str name="q">some test query</str>
</lst>
</requestHandler>
A more advanced option available, is to configure the handler with a "healthcheckFile" which can be used to enable/disable the PingRequestHandler.
<requestHandler name="/admin/ping" class="solr.PingRequestHandler">
<!-- relative paths are resolved against the data dir -->
<str name="healthcheckFile">server-enabled.txt</str>
<lst name="invariants">
<str name="qt">/search</str><!-- handler to delegate to -->
<str name="q">some test query</str>
</lst>
</requestHandler>
This health check file feature can be used as a way to indicate to some Load Balancers that the server should be "removed from rotation" for maintenance, or upgrades, or whatever reason you may wish.
The health check file may be created/deleted by any external system, or the PingRequestHandler itself can be used to create/delete the file by specifying an "action" param in a request:
http://.../ping?action=enable
- creates the health check file if it does not already exist
http://.../ping?action=disable
- deletes the health check file if it exists
http://.../ping?action=status
- returns a status code indicating if the healthcheck file exists
("enabled") or not ("disabled")
| Modifier and Type | Class and Description |
|---|---|
protected static class |
PingRequestHandler.ACTIONS |
SolrInfoBean.Category, SolrInfoBean.Group| Modifier and Type | Field and Description |
|---|---|
static String |
HEALTHCHECK_FILE_PARAM |
appends, defaults, httpCaching, initArgs, invariants, solrMetricsContextTYPE| Constructor and Description |
|---|
PingRequestHandler() |
| Modifier and Type | Method and Description |
|---|---|
SolrInfoBean.Category |
getCategory()
Category of this component
|
String |
getDescription()
Simple one or two line description
|
protected void |
handleEnable(boolean enable) |
protected void |
handlePing(SolrQueryRequest req,
SolrQueryResponse rsp) |
void |
handleRequestBody(SolrQueryRequest req,
SolrQueryResponse rsp) |
void |
inform(SolrCore core) |
void |
init(NamedList args)
Initializes the
SolrRequestHandler by creating three SolrParams named. |
boolean |
isPingDisabled()
Returns true if the healthcheck flag-file is enabled but does not exist,
otherwise (no file configured, or file configured and exists)
returns false.
|
Boolean |
registerV2()
Whether this request handler must be made available at the /v2/ path
|
getApis, getInitArgs, getMetricNames, getName, getPluginInfo, getRequestHandler, getSolrMetricsContext, getSolrParamsFromNamedList, getSubHandler, handleRequest, initializeMetrics, setPluginInfoclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitgetMetricRegistry, getMetricsSnapshot, registerMetricNameclose, getUniqueMetricTag, initializeMetricsregisterV1public static final String HEALTHCHECK_FILE_PARAM
public void init(NamedList args)
RequestHandlerBaseSolrRequestHandler by creating three SolrParams named.
| Name | Description |
|---|---|
| defaults | Contains all of the named arguments contained within the list element named "defaults". |
| appends | Contains all of the named arguments contained within the list element named "appends". |
| invariants | Contains all of the named arguments contained within the list element named "invariants". |
Example:
<lst name="defaults"> <str name="echoParams">explicit</str> <str name="qf">text^0.5 features^1.0 name^1.2 sku^1.5 id^10.0</str> <str name="mm">2<-1 5<-2 6<90%</str> <str name="bq">incubationdate_dt:[* TO NOW/DAY-1MONTH]^2.2</str> </lst> <lst name="appends"> <str name="fq">inStock:true</str> </lst> <lst name="invariants"> <str name="facet.field">cat</str> <str name="facet.field">manu_exact</str> <str name="facet.query">price:[* TO 500]</str> <str name="facet.query">price:[500 TO *]</str> </lst>
init in interface SolrRequestHandlerinit in class RequestHandlerBaseargs - The NamedList to initialize fromRequestHandlerBase.handleRequest(org.apache.solr.request.SolrQueryRequest, org.apache.solr.response.SolrQueryResponse),
RequestHandlerBase.handleRequestBody(org.apache.solr.request.SolrQueryRequest, org.apache.solr.response.SolrQueryResponse),
SolrPluginUtils.setDefaults(org.apache.solr.request.SolrQueryRequest, org.apache.solr.common.params.SolrParams, org.apache.solr.common.params.SolrParams, org.apache.solr.common.params.SolrParams),
See also the example solrconfig.xml located in the Solr codebase (example/solr/conf).
public void inform(SolrCore core)
inform in interface SolrCoreAwarepublic boolean isPingDisabled()
public void handleRequestBody(SolrQueryRequest req, SolrQueryResponse rsp) throws Exception
handleRequestBody in class RequestHandlerBaseExceptionprotected void handlePing(SolrQueryRequest req, SolrQueryResponse rsp) throws Exception
Exceptionprotected void handleEnable(boolean enable)
throws SolrException
SolrExceptionpublic String getDescription()
SolrInfoBeangetDescription in interface SolrInfoBeangetDescription in class RequestHandlerBasepublic Boolean registerV2()
ApiSupportregisterV2 in interface ApiSupportpublic SolrInfoBean.Category getCategory()
SolrInfoBeangetCategory in interface SolrInfoBeangetCategory in class RequestHandlerBaseCopyright © 2000-2020 Apache Software Foundation. All Rights Reserved.