# OpenTelemetryDecorator
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A function decorator for OpenTelemetry traces.
## Usage
The event name can be any string.
defmodule MyApp.Worker do
use OpenTelemetryDecorator
@decorate trace("my_app.worker.do_work")
def do_work(arg1, arg2) do
...doing work
do_more_work(arg1)
end
@decorate trace("MyApp::Worker::do_work")
def do_more_work(arg1) do
...doing more work
end
end
We use `OpenTelemetry.Tracer.current_span_ctx()` to automatically link new spans to the current trace (if it exists and is in the same process). So the above example will link the `do_work` and `do_more_work` spans for you by default.
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", [: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", [: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", [[:arg1, :count], [:arg2, :count], :total])
def do_work(arg1, arg2) do
total = arg1.count + arg2.count
{:ok, total}
end
end
## Installation
Add `open_telemetry_decorator` to your list of dependencies in `mix.exs` and do a `mix deps.get`:
```elixir
def deps do
[
{:open_telemetry_decorator, "~> 0.1.0"}
]
end
```
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## Development
`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 dependencies
* `mix compile --warnings-as-errors` for a stricter compile
* `mix coveralls.html` to check for test coverage
* `mix credo` to suggest more idiomatic style for your code
* `mix dialyzer` to find problems typing might reveal… albeit *slowly*
* `mix docs` to generate documentation