# New Relic's Elixir Agent
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The Open-Source Elixir Agent allows you to monitor your `Elixir` applications with New Relic. It helps you track transactions, distributed traces and other parts of your application's behavior and provides an overview of underlying [BEAM activity](https://github.com/newrelic/elixir_agent/wiki/BEAM-stats-page).
[View the Documentation](https://hexdocs.pm/new_relic_agent)
### Support Statement
New Relic has open-sourced this project to enable monitoring of `Elixir` applications. This project is provided AS-IS WITHOUT WARRANTY OR SUPPORT, although you can report issues and contribute to the project here on GitHub.
### Contributing
We'd love to get your contributions to improve the elixir agent! Keep in mind when you submit your pull request, you'll need to sign the CLA via the click-through using CLA-Assistant. If you'd like to execute our corporate CLA, or if you have any questions, please drop us an email at [open-source@newrelic.com](mailto:open-source@newrelic.com).
## Installation
Install the [Hex package](https://hex.pm/packages/new_relic_agent)
Requirements:
* Erlang/OTP 22
* Elixir 1.9
```elixir
defp deps do
[
{:new_relic_agent, "~> 1.0"}
]
end
```
## Configuration
You need to set a few required configuration keys so we can authenticate properly.
#### Via Application config
```elixir
config :new_relic_agent,
app_name: "My App",
license_key: "license_key"
```
#### Via Environment variables
You can also configure these attributes via `ENV` vars, which helps keep secrets out of source code.
* `NEW_RELIC_APP_NAME`
* `NEW_RELIC_LICENSE_KEY`
#### HTTP Client Settings
httpc client settings can be overridden if needed. For example, the HTTP connect timeout can be increased which can help alleviate errors related to timeouts connecting to New Relic:
```elixir
config :new_relic_agent,
app_name: "My App",
license_key: "license_key",
httpc_request_options: [connect_timeout: 5000]
```
#### For Elixir 1.15 and higher
Due to changes in the Elixir 1.15 Logger, additional logger configuration is needed for NewRelic to capture all errors. Update your logger configuration by setting `handle_sasl_reports` to `true` and adding `NewRelic.ErrorLogger` to your logger backends.
```elixir
config :logger,
handle_sasl_reports: true,
backends: [:console, NewRelic.ErrorLogger]
```
## Telemetry-based Instrumentation
Some common Elixir packages are auto-instrumented via [`telemetry`](https://github.com/beam-telemetry/telemetry)
* [`Plug`](https://github.com/elixir-plug/plug): See [NewRelic.Telemetry.Plug](https://hexdocs.pm/new_relic_agent/NewRelic.Telemetry.Plug.html) for details.
* [`Phoenix`](https://github.com/phoenixframework/phoenix): See [NewRelic.Telemetry.Phoenix](https://hexdocs.pm/new_relic_agent/NewRelic.Telemetry.Phoenix.html) for details.
* [`Ecto`](https://github.com/elixir-ecto/ecto): See [NewRelic.Telemetry.Ecto](https://hexdocs.pm/new_relic_agent/NewRelic.Telemetry.Ecto.html) for details.
* [`Redix`](https://github.com/whatyouhide/redix): See [NewRelic.Telemetry.Redix](https://hexdocs.pm/new_relic_agent/NewRelic.Telemetry.Redix.html) for details.
## Agent Features
There are a few agent features that can be enabled via configuration. Please see the documentation for more information.
* [Logs In Context](https://hexdocs.pm/new_relic_agent/NewRelic.Config.html#feature/1-logs-in-context)
* [Infinite Tracing](https://hexdocs.pm/new_relic_agent/NewRelic.Config.html#feature/1-infinite-tracing)
* [Security Controls](https://hexdocs.pm/new_relic_agent/NewRelic.Config.html#feature?/1-security)
## Manual Instrumentation
#### Transactions
The `Plug` and `Phoenix` instrumentation automatically report a Transaction for each request.
These Transactions will follow across any process spawned and linked (ex: `Task.async`), but will _not_ follow a process that isn't linked (ex: `Task.Supervisor.async_nolink`).
To manually connect a Transaction to an unlinked process, you can use `NewRelic.get_transaction` and `NewRelic.connect_to_transaction`. See the docs for those functions for further details.
```elixir
tx = NewRelic.get_transaction()
spawn(fn ->
NewRelic.connect_to_transaction(tx)
# ...
end)
```
If you are using a `Task` to spawn work, you can use the pre-instrumented `NewRelic.Instrumented.Task` convienince module to make this easier. Just `alias` it in your module and all your Tasks will be instrumented. You may also use the functions directly.
```elixir
alias NewRelic.Instrumented.Task
Task.Supervisor.async_nolink(MyTaskSupervisor, fn ->
# This process wil be automatically connected to the Transaction...
end)
```
#### Function Tracing
`NewRelic.Tracer` enables detailed Function tracing. Annotate a function and it'll show up as a span in Transaction Traces / Distributed Traces, and we'll collect aggregate stats about it. Install it by adding `use NewRelic.Tracer` to any module, and annotating any function with an `@trace` module attribute
```elixir
defmodule MyModule do
use NewRelic.Tracer
@trace :work
def work do
# Will report as `MyModule.work/0`
end
end
```
#### Distributed Tracing
Requests to other services can be traced with the combination of an additional outgoing header and an `:external` tracer.
```elixir
defmodule MyExternalService do
use NewRelic.Tracer
@trace {:request, category: :external}
def request(method, url, headers) do
NewRelic.set_span(:http, url: url, method: method, component: "HttpClient")
headers = headers ++ NewRelic.distributed_trace_headers(:http)
HttpClient.request(method, url, headers)
end
end
```
#### Pre-Instrumented Modules
`NewRelic.Instrumented.Mix.Task` To enable the Agent and record an Other Transaction during a `Mix.Task`, simply `use NewRelic.Instrumented.Mix.Task`. This will ensure the agent is properly started, records a Transaction, and is shut down.
```elixir
defmodule Mix.Tasks.Example do
use Mix.Task
use NewRelic.Instrumented.Mix.Task
def run(args) do
# ...
end
end
```
`NewRelic.Instrumented.HTTPoison` Automatically wraps HTTP calls in a span, and adds an outbound header to track the request as part of a Distributed Trace.
```elixir
alias NewRelic.Instrumented.HTTPoison
HTTPoison.get("http://www.example.com")
```
#### Other Transactions
You may start an "Other" Transaction for non-HTTP related work. This could used be while consuming from a message queue, for example.
To start an Other Transaction:
```elixir
NewRelic.start_transaction(category, name)
```
And to stop the Transaction within the same process:
```elixir
NewRelic.stop_transaction()
```
#### Adapters
There are a few adapters which leverage this agent to provide library / framework specific instrumentation. Note that these will eventually be replaced with `telemetry` based instrumentation.
* `Absinthe` https://github.com/binaryseed/new_relic_absinthe
#### Disabling
If you want to disable the agent, you can do it in two different ways:
* Application config: `config :new_relic_agent, license_key: nil`
* Environment variables: `NEW_RELIC_HARVEST_ENABLED=false`
