Adding Tags to a Request

You can use tagging to supply extra context on errors and performance incidents. Tagging can help to add information that is not already part of a request, such as the session data, headers, environment data, or parameters. Tags can also be used to filter on samples within an incident to find all errors for a specific user or slow pages for a particular locale.

You can set tags wherever the current transaction or span is accessible. We recommend calling it before your application code runs in a request, such as a callback. You can see what tags apply to a sample on the Error and Performance incident page.

Using Link Templates it's possible to add links to your application with tag data, such as the admin panel for the signed-in user. You can see this in practice in the below screenshot, with the Link 1 and Link 2 tags.

Ruby

With the AppSignal for Ruby gem, use the Appsignal.add_tags helper methods to add tags to error and performance samples. On Ruby gem version 3 and older, use the Appsignal.set_tags helper.

You can use Appsignal.add_tags wherever an active transaction is accessible, we recommend calling it before your application code runs in the request, such as in a before_action using Rails.

before_action do
  Appsignal.add_tags(
    :user_id => current_user.id,
    :stripe_customer_id => stripe_customer_id,
    :locale => I18n.locale,
    :default_locale => I18n.default_locale
  )
end

Limitations

Tags that do not meet these limitations are dropped without warning.

• The tag key must be a String or Symbol.
• The tagged value must be a String, Symbol, Integer or Boolean (true/false).
  • Boolean values are supported in Ruby gem 3.11 and newer.
• The length of the tag value must be less than 256 characters.
• Nested hash values are not supported for tags, please use custom data instead.

# Unsupported: hash value type is not supported
Appsignal.add_tags(
  :i18n => {
    :locale => I18n.locale,
    :default_locale => I18n.default_locale
  }
)

Elixir

Use the Appsignal.Span.set_sample_data function to supply extra context on errors and performance samples. Use the "tags" sample key for the function to add tags to the span.

Appsignal.Span.set_sample_data(
  Appsignal.Tracer.root_span,
  "tags",
  %{
    locale: "en",
    user_id: user_id,
    stripe_customer_id: stripe_customer_id,
    locale: locale,
    default_locale: default_locale
  }
)

Last call is leading

The set_sample_data helper can be called multiple times, but only the last value will be retained. When the code is run below:

Appsignal.Span.set_sample_data(Appsignal.Tracer.root_span, "tags", %{locale: "en"})
Appsignal.Span.set_sample_data(Appsignal.Tracer.root_span, "tags", %{user: "bob"})
Appsignal.Span.set_sample_data(Appsignal.Tracer.root_span, "tags", %{locale: "de"})

it will result in the following tags being stored:

%{
  locale: "de"
}

Setting sample data on a span

To add sample data to a span as soon as it's created, add a custom_on_create_fun:

defmodule MyApp.Appsignal do
  def custom_on_create_fun(_span) do
    Appsignal.Span.set_sample_data(Appsignal.Tracer.root_span, "tags", %{"locale": "en"})
  end
end

Then, add it to your app's configuration:

# config/config.exs
config :appsignal, custom_on_create_fun: &MyApp.Appsignal.custom_on_create_fun/1

The custom_on_create_fun requires AppSignal for Elixir version 2.8.3 or higher.

Limitations

Tags that do not meet these limitations are dropped without warning.

• The tag key must be a String or Atom.
• The tagged value must be a String, Atom or Integer.
• The length of the tag value must be less than 256 characters.
• Nested map values are not supported for tags, please use custom data instead.

# Unsupported: map value type is not supported
Appsignal.Span.set_sample_data(
  Appsignal.Tracer.root_span,
  "tags",
  %{
    i18n: %{
      locale: "en_GB",
      default_locale: "en_US"
    }
  }
)

Node.js

Import the setTag helper function to add tags to spans for errors and performance samples.

import { setTag } from "@appsignal/nodejs";
 
setTag("user_id", user_id);
setTag("stripe_customer_id", stripe_customer_id);
setTag("locale", locale);
setTag("default_locale", default_locale);

Limitations

Tags that do not meet these limitations are dropped without warning.

• The tag key must be a String.
• The tagged value must be a String, Number or Boolean.
• The length of the tag value must be less than 256 characters.
• Nested object values are not supported for tags, please use the setCustomData helper function instead.

const tracer = appsignal.tracer();
const span = tracer.currentSpan();
 
# Unsupported: object value type is not supported
span.set("i18n", { locale: "en_GB", default_locale: "en_US" });

Python

Import the set_tag helper method to add tags to spans for errors and performance samples.

from appsignal import set_tag
 
set_tag("user_id", user_id)
set_tag("stripe_customer_id", stripe_customer_id)
set_tag("locale", locale)
set_tag("default_locale", default_locale)

Limitations

Tags that do not meet these limitations are dropped without warning.

• The tag key must be a String.
• The tagged value must be a String, Integer, Float or Boolean.
• The length of the tag value must be less than 256 characters.
• Nested object values are not supported for tags, please use the set_custom_data helper function instead.