A function decorator for OpenTelemetry traces.
Add open_telemetry_decorator
to your list of dependencies in mix.exs
. We include the opentelemetry_api
package, but you'll need to add opentelemetry
yourself in order to report spans and traces.
def deps do
[
{:open_telemetry_decorator, "~> 1.0.0-rc.3"},
{:opentelemetry, "~> 1.0.0-rc.3"}
]
end
Then follow the directions for the exporter of your choice to send traces to to zipkin, honeycomb, etc.
https://github.com/garthk/opentelemetry_honeycomb
https://github.com/opentelemetry-beam/opentelemetry_zipkin
Add use OpenTelemetryDecorator
to the module, and decorate any methods you want to trace with @decorate trace("span name")
.
The trace
decorator will automatically wrap the decorated function in an opentelemetry span with the provided name.
defmodule MyApp.Worker do
use OpenTelemetryDecorator
@decorate trace("worker.do_work")
def do_work(arg1, arg2) do
...doing work
end
end
The trace
decorator allows you to specify an includes
option which gives you more flexibility with what you can include in the span attributes. Omitting the includes
option with trace
means no attributes will be added to the span.
defmodule MyApp.Worker do
use OpenTelemetryDecorator
@decorate trace("worker.do_work", include: [:arg1, :arg2])
def do_work(arg1, arg2) do
...doing work
end
end
The decorator uses a macro to insert code into your function at compile time to wrap the body in a new span and link it to the currently active span. In the example above, the do_work
method would become something like this:
def do_work(arg1, arg2) do
require OpenTelemetry.Span
require OpenTelemetry.Tracer
parent_ctx = OpenTelemetry.Tracer.current_span_ctx()
OpenTelemetry.Tracer.with_span "my_app.worker.do_work", %{parent: parent_ctx} do
...doing work
OpenTelemetry.Span.set_attributes(arg1: arg1, arg2: arg2)
end
end
You can provide span attributes by specifying a list of variable names as atoms.
This list can include...
Any variables (in the top level closure) available when the function exits:
defmodule MyApp.Math do
use OpenTelemetryDecorator
@decorate trace("my_app.math.add", include: [:a, :b, :sum])
def add(a, b) do
sum = a + b
{:ok, thing1}
end
end
The result of the function by including the atom :result
:
defmodule MyApp.Math do
use OpenTelemetryDecorator
@decorate trace("my_app.math.add", include: [:result])
def add(a, b) do
sum = a + b
{:ok, thing1}
end
end
Map/struct properties using nested lists of atoms:
defmodule MyApp.Worker do
use OpenTelemetryDecorator
@decorate trace("my_app.worker.do_work", include: [[:arg1, :count], [:arg2, :count], :total])
def do_work(arg1, arg2) do
total = arg1.count + arg2.count
{:ok, total}
end
end
make check
before you commit! If you'd prefer to do it manually:
mix do deps.get, deps.unlock --unused, deps.clean --unused
if you change dependenciesmix compile --warnings-as-errors
for a stricter compilemix coveralls.html
to check for test coveragemix credo
to suggest more idiomatic style for your codemix dialyzer
to find problems typing might reveal… albeit slowlymix docs
to generate documentation