Add Request Headers

By default, the AppSignal integrations track request HTTP headers for web applications in supported libraries. You can set custom request headers on a transaction or span. Modifying the request headers will overwrite the data set by the AppSignal instrumentations. All request headers are filtered by our integrations before being sent to our servers.

🔐 Do not send Personal Identifiable Information (PII) to AppSignal. Filter PII (e.g., names, emails) and use an ID, hash, or pseudonymized identifier instead.

Use Link Templates to link them back in your app.

See the table below for a list of accepted value types for request headers.

Language	Accepted header name	Accepted header value
Ruby	String	String
Elixir	String	String
Node.js	String	String
Python	String	String
Go	String	String, String slice
Java	String	String, String array
PHP	String	String, String array

The below code sample shows how to set custom request headers:

# Call `add_headers` multiple times to set more headers
Appsignal.add_headers("REQUEST_METHOD" => "GET", "REQUEST_PATH" => "/some-path")
Appsignal.add_headers("PATH_INFO" => "/a-path")
Appsignal.add_headers("PATH_INFO" => "/some-path")
# Headers:
# {
#   "REQUEST_METHOD" => "GET",
#   "REQUEST_PATH" => "/some-path",
#   "PATH_INFO" => "/some-path"
# }

Appsignal.Span.set_sample_data(
  Appsignal.Tracer.root_span,
  "environment",
  %{
    "request_method" => "GET",
    "path_info" => "/some-path"
  }
)

import { setHeader } from "@appsignal/nodejs";

setHeader("request_method", "GET");
setHeader("path_info", "/some-path");

from appsignal import set_header

set_header("request_method", "GET");
set_header("path_info", "/some-path");

// Additional setup is required to first fetch or create a new span
span.SetAttributes(attribute.StringSlice("http.request.header.content-type", []string{"application/json"}))
span.SetAttributes(attribute.StringSlice("http.request.header.custom-header"), []string{"abc", "def"})

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.common.AttributeKey;
import java.util.Arrays;

// Additional setup is required to first fetch or create a new span
Span span = Span.current();

// Set single header values
span.setAttribute("http.request.header.request-method", "GET");
span.setAttribute("http.request.header.path-info", "/some-path");
span.setAttribute("http.request.header.content-type", "application/json");

// Set header with multiple values (array)
span.setAttribute(
    AttributeKey.stringArrayKey("http.request.header.custom-header"),
    Arrays.asList("value1", "value2")
);

<?php
use Appsignal\Appsignal;

// Set single header values
Appsignal::addHeaders([
    'request-method' => 'GET',
    'path-info' => '/some-path',
    'content-type' => 'application/json',
]);

// Set header with multiple values (array)
Appsignal::addHeaders([
    'custom-header' => ['value1', 'value2'],
]);

For certain languages, additional setup is required. Please follow the instructions for these languages:

Go
Java

Limitations

Only the last value for a request header is stored if the application sets a request header multiple times. For Elixir, if the helper is called multiple times, only the last set of request headers (environment) is stored.

Getting started

Guides

Limitations

​Limitations

Limitations