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AppSignal collects headers for HTTP requests by default for supported frameworks. This data may help track down errors or performance issues that were caused by request header data a client is sending. In compliance with GDPR, AppSignal collects a minimal amount of headers by default. To comply with GDPR rules, collecting no user identifiable data, AppSignal collects a very limited amount of headers by default. To further limit the collection of header data, you can configure which headers AppSignal collects.
Read more about request header filtering and what types of headers to set up filtering for in our Request Header Collection documentation.
🔐 Do not send Personal Identifiable Information (PII) to AppSignal. Filter PII (e.g., names, emails) and use an ID, hash, or pseudonymized identifier instead.

For HIPAA-covered entities, more info on signing a Business Associate Agreement (BAA) is available in our Business Add-Ons documentation.

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Configure Headers

An application’s session data can be filtered by configuring keys in an allowlist. This allowlist system will filter out all the session data keys not in this list. AppSignal does not collect the name or value of headers filtered out by your allowlist.

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Example

For example, an application with this AppSignal config: 
request_headers: ["Request-Method"]
Will only send the Request-Method header to AppSignal.com. This guide will show you how to configure your application’s request header filtering allowlist based on what language your application uses:

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Ruby

AppSignal automatically stores the configured request headers in the Ruby integration for Rails apps and other frameworks. It has a built-in list of request headers to collect by default that you can customize with the request_headers config option. To configure which request headers to collect for each request, add the following configuration to your config/appsignal.yml file in the environment group where you want it to apply. The request_headers 
Appsignal.configure do |config|
  config.request_headers += ["ADDITONAL_CUSTOM_HEADER", "EXTRA_HEADER"]
end

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Elixir

AppSignal automatically stores the configured request headers for Phoenix apps and other frameworks in the Elixir integration. It has a built-in list of request headers collected by default which you can customize using the request_headers config option. To configure which request headers to collect for each request, add the following configuration to your config/appsignal.exs file in the environment group where you want it to apply. The request_headers value is a list of strings. 
config :appsignal, :config,
  request_headers: ~w(
    path-info request-method request-uri server-name server-port server-protocol
  ) # Example list of headers

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Node.js

In the Node.js integration, AppSignal automatically stores the configured request headers for Express apps and other frameworks. It has a built-in list of request headers to collect by default that you can customize with the requestHeaders config option. To configure which request headers to collect for each request, add the following configuration to your AppSignal client instance creation. The requestHeaders value is an array of strings. 
const { Appsignal } = require("@appsignal/nodejs");

new Appsignal({
  requestHeaders: ["accept", "cache-control", "content-length", "range"],
});

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Python

In the Python integration, if an app sets request headers, AppSignal will automatically collect the configured request headers. It has a built-in list of request headers to collect by default that you can customize with the request_headers config option. To configure which request headers to collect for each request, add the following configuration to your AppSignal client instance creation. The request_headers value is a list of strings. 
from appsignal import Appsignal

appsignal = Appsignal(
    # Other config
    request_headers: ["accept", "cache-control", "content-length", "range"],
)

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Go

If an app records request headers, AppSignal will automatically filter the configured request headers. It has a built-in list of request headers to collect by default that you can customize with the request_headers config option. See the Go configuration page for more information on how to configure OpenTelemetry for Go apps. To configure which request headers to collect for each request, add the following configuration to your AppSignal client instance creation. The request_headers value is a slice of strings. 
res := resource.NewWithAttributes(
	// Only send these specific headers
	attribute.StringSlice("appsignal.config.request_headers", []string{"accept", "request_method", "content_length"}),

	// Do not send any headers
	attribute.StringSlice("appsignal.config.request_headers", []string{}),
)

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Java

In the Java integration, if an app sets request headers, AppSignal will automatically collect the configured request headers. It has a built-in list of request headers to collect by default that you can customize with the request_headers config option. To configure which request headers to collect for each request, add the following configuration. The request_headers value is an array of strings. 
function encode() {
  echo -n "$@" | sed 's/,/%2C/g'
}

export OTEL_RESOURCE_ATTRIBUTES="\
  appsignal.config.request_headers=$(encode "accept,cache-control,content-length,range"),\
  ..."

# Do not send any headers
export OTEL_RESOURCE_ATTRIBUTES="\
  appsignal.config.request_headers=,\
  ..."

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PHP

In the PHP integration, if an app sets request headers, AppSignal will automatically collect the configured request headers. It has a built-in list of request headers to collect by default that you can customize with the request_headers config option. To configure which request headers to collect for each request, add the following configuration. The request_headers value is an array of strings. 
return [
    // Send selected headers
    'request_headers' => ['accept', 'cache-control', 'content-length', 'range'],

    // Do not send any headers
    'request_headers' => [],

    // ... other options
];