1[[http-meta-data]] 2=== HTTP Meta Data 3 4By default, the client sends some meta data about the HTTP connection using 5custom headers. 6 7You can disable or enable it using the following methods: 8 9 10==== Elastic Meta Header 11 12The client sends a `x-elastic-client-meta` header by default. 13This header is used to collect meta data about the versions of the components 14used by the client. For instance, a value of `x-elastic-client-meta` can be 15`es=7.14.0-s,php=7.4.11,t=7.14.0-s,a=0,cu=7.68.0`, where each value is the 16version of `es=Elasticsearch`, `t` is the transport version (same of client), 17`a` is asyncronouts (`0=false` by default) and `cu=cURL`. 18 19If you would like to disable it you can use the `setElasticMetaHeader()` 20method, as follows: 21 22[source,php] 23---- 24$client = Elasticsearch\ClientBuilder::create() 25 ->setElasticMetaHeader(false) 26 ->build(); 27---- 28 29==== Include port number in Host header 30 31This is a special setting for the client that enables the port in the 32Host header. This setting has been introduced to prevent issues with 33HTTP proxy layers (see issue https://github.com/elastic/elasticsearch-php/issues/993[#993]). 34 35By default the port number is not included in the Host header. 36If you want you can enable it using the `includePortInHostHeader()` function, 37as follows: 38 39[source,php] 40---- 41$client = Elasticsearch\ClientBuilder::create() 42 ->includePortInHostHeader(true) 43 ->build(); 44---- 45 46==== Send the API compatibility layer 47 48Starting from version 7.13, {es} supports a compatibility header in 49`Content-Type` and `Accept`. The PHP client can be configured to emit the following HTTP headers: 50 51[source] 52---- 53Content-Type: application/vnd.elasticsearch+json; compatible-with=7 54Accept: application/vnd.elasticsearch+json; compatible-with=7 55---- 56 57which signals to {es} that the client is requesting 7.x version of request and response 58bodies. This allows upgrading from 7.x to 8.x version of Elasticsearch without upgrading 59everything at once. {es} should be upgraded first after the compatibility header is 60configured and clients should be upgraded second. 61 62To enable this compatibility header, you need to create an `ELASTIC_CLIENT_APIVERSIONING` 63environment variable and set it to `true` or `1`, before the `Client` class initialization. 64 65In PHP you can set this environment variable as follows: 66 67[source,php] 68---- 69putenv("ELASTIC_CLIENT_APIVERSIONING=true"); 70---- 71