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.

Go

In a Go app, to add an AppSignal tag to a span on a trace, first fetch the active span or create a new span as described on our Go custom instrumentation page.

Then, set an attribute on the span using the attribute helper that matches the type of the tag value, see also the tag limitations below.

The span attribute name has the following format: appsignal.tag.<tag name>. Replace <tag name> with the name of the tag.

// Example format
span.SetAttributes(attribute.String("appsignal.tag.<tag_name>", "string"))
 
// Supported types
span.SetAttributes(attribute.String("appsignal.tag.my_tag_string", "tag value"))
span.SetAttributes(attribute.StringSlice("appsignal.tag.my_tag_int64", []string{"abc", "def"}))
span.SetAttributes(attribute.Bool("appsignal.tag.my_tag_bool_true", true))
span.SetAttributes(attribute.Bool("appsignal.tag.my_tag_bool_false", false))
span.SetAttributes(attribute.BoolSlice("appsignal.tag.my_tag_bool_slice", []bool{true, false}))
span.SetAttributes(attribute.Float64("appsignal.tag.my_tag_float64", 12.34))
span.SetAttributes(attribute.Float64Slice("appsignal.tag.my_tag_float64_slice", []float64{12.34, 56.78}))
span.SetAttributes(attribute.Int("appsignal.tag.my_tag_int", 1234))
span.SetAttributes(attribute.IntSlice("appsignal.tag.my_tag_int", []int{1234, 5678}))
span.SetAttributes(attribute.Int64("appsignal.tag.my_tag_int64", 1234))
span.SetAttributes(attribute.Int64Slice("appsignal.tag.my_tag_int64_slice", []int64{1234, 5678}))

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, Boolean, or a slice of those types.
• The length of the tag value must be less than 256 characters.
• Nested object values (maps) are not supported for tags.