# 🌲 Timber - Great Elixir Logging Made Easy
[](LICENSE.md)
[](https://hex.pm/packages/timber)
[](https://hexdocs.pm/timber/index.html)
[](https://travis-ci.org/timberio/timber-elixir)
Timber for Elixir is a drop in backend for the Elixir `Logger` that
[unobtrusively augments](https://timber.io/docs/concepts/structuring-through-augmentation) your
logs with [rich metadata and context](https://timber.io/docs/concepts/metadata-context-and-events)
making them [easier to search, use, and read](#get-things-done-with-your-logs). It pairs with the
[Timber console](#the-timber-console) to deliver a tailored Elixir logging experience designed to make
you more productive.
1. [**Installation**](#installation)
2. [**Usage** - Simple yet powerful API](#usage)
3. [**Integrations** - Automatic context and metadata for your existing logs](#integrations)
4. [**The Timber Console** - Designed for Elixir developers](#the-timber-console)
5. [**Get things done with your logs**](#get-things-done-with-your-logs)
## Installation
1. Add `timber` as a dependency in `mix.exs`:
```elixir
def deps do
[
{:timber, "~> 3.0.0-alpha.1"},
# ...
]
end
```
2. In your shell, run `mix deps.get`.
3. Now, add the appropriate Mix configuration.
- To send your logs over HTTP (recommended and simplest), follow this example:
```elixir
config :logger,
backends: [Timber.LoggerBackends.HTTP],
utc_log: true
config :timber,
api_key: "TimberAPIKey"
```
- Alternatively, if you'd like logs to be printed out to `STDOUT`, follow this example:
```elixir
config :logger,
backends: [:console],
utc_log: true
config :logger, :console,
format: {Timber.Formatter, :format},
metadata: [:timber_context, :event, :application, :file, :function, :line, :module, :meta]
```
## Usage
### Basic text logging
The Timber library works directly with the standard Elixir
[Logger](https://hexdocs.pm/logger/Logger.html) and installs itself as a
[backend](https://hexdocs.pm/logger/Logger.html#module-backends) during the
setup process. In this way, basic logging is no different than logging without
Timber:
```elixir
Logger.debug("My log statement")
Logger.info("My log statement")
Logger.warn("My log statement")
Logger.error("My log statement")
```
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `error message`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this event's metadata and context](https://timber.io/docs/app/console/view-metadata-and-context)
[...read more in our docs](https://timber.io/docs/languages/elixir/usage/basic-logging)
### Logging events (structured data)
Log structured data without sacrificing readability:
```elixir
event_data = %{customer_id: "xiaus1934", amount: 1900, currency: "USD"}
Logger.info("Payment rejected", event: %{payment_rejected: event_data})
```
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `type:payment_rejected` or `payment_rejected.amount:>100`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this event's data and context](https://timber.io/docs/app/console/view-metadata-and-context)
...[read more in our docs](https://timber.io/docs/languages/elixir/usage/custom-events)
### Setting context
Add shared structured data across your logs:
```elixir
Timber.add_context(build: %{version: "1.0.0"})
Logger.info("My log message")
```
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `job.id:123`
* [View this context when viewing a log's metadata](https://timber.io/docs/app/console/view-metadata-and-context)
...[read more in our docs](https://timber.io/docs/languages/elixir/usage/custom-context)
### Pro-tips 💪
Timings & Metrics
Time code blocks:
```elixir
timer = Timber.start_timer()
# ... code to time ...
Logger.info("Processed background job", event: %{background_job: %{time_ms: timer}})
```
Log generic metrics:
```elixir
Logger.info("Processed background job", event: %{background_job: %{time_ms: 45.6}})
```
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `background_job.time_ms:>500`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this log's metadata in the console](https://timber.io/docs/app/console/view-metadata-and-context)
...[read more in our docs](https://timber.io/docs/languages/elixir/usage/metrics-and-timings)
### Tracking background jobs
*Note: This tip refers to traditional background jobs backed by a queue. For
native Elixir processes we capture the `context.runtime.vm_pid` automatically.
Calls like `spawn/1` and `Task.async/1` will automatially have their `pid`
included in the context.*
For traditional background jobs backed by a queue you'll want to capture relevant
job context. This allows you to segement logs by specific jobs, making it easy to debug and
monitor your job executions. The most important attribute to capture is the `id`:
```elixir
%Timber.Contexts.JobContext{queue_name: "my_queue", id: "abcd1234", attempt: 1}
|> Timber.add_context()
Logger.info("Background job execution started")
# ...
Logger.info("Background job execution completed")
```
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `background_job.time_ms:>500`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this log's metadata in the console](https://timber.io/docs/app/console/view-metadata-and-context)
...[read more in our docs](https://timber.io/docs/languages/elixir/usage/tracking-background-jobs)
### Track communication with external services
We use this trick internally at Timber to track communication with external services.
It logs requests and responses to external services, giving us insight into response times and
failed requests.
Below is a contrived example of submitting an invoice to Stripe.
```elixir
alias Timber.Events.HTTPRequestEvent
alias Timber.Events.HTTPResponseEvent
method = :get
url = "https://api.stripe.com/v1/invoices"
body = "{\"customer\": \"cus_BHhZyYRirFrPkz\"}"
headers = %{}
Logger.info fn ->
event = HTTPRequestEvent.new(direction: "outgoing", service_name: "stripe", method: method, url: url, headers: headers, body: body)
message = HTTPRequestEvent.message(event)
{message, [event: event]}
end
timer = Timber.start_timer()
case :hackney.request(method, url, headers, body, with_body: true) do
{:ok, status, resp_headers, resp_body} ->
Logger.info fn ->
event = HTTPResponseEvent.new(direction: "incoming", service_name: "stripe", status: status, headers: resp_headers, body: resp_body, time_ms: Timber.duration_ms(timer))
message = HTTPResponseEvent.message(event)
{message, [event: event]}
end
{:error, error} ->
message = Exception.message(error)
Logger.error(message, event: error)
{:error, error}
end
```
*Note: Only `method` is required for `HTTPRequestEvent`, and `status` for `HTTPResponseEvent`.
`body`, if logged, will be truncated to `2048` bytes for efficiency reasons. This can be adjusted
with [`Timber.Config.http_body_size_limit/0`](https://hexdocs.pm/timber/Timber.Config.html#http_body_size_limit/0).*
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `background_job.time_ms:>500`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this log's metadata in the console](https://timber.io/docs/app/console/view-metadata-and-context)
...[read more in our docs](https://timber.io/docs/languages/elixir/usage/track-external-service-communication)
### Adding metadata to errors
By default, Timber will capture and structure all of your errors and exceptions, there
is nothing additional you need to do. You'll get the exception `message`, `name`, and `backtrace`.
But, in many cases you need additional context and data. Timber supports additional fields
in your exceptions, simply add fields as you would any other struct.
```elixir
defmodule StripeCommunicationError do
defexception [:message, :customer_id, :card_token, :stripe_response]
end
raise(
StripeCommunicationError,
message: "Bad response #{response} from Stripe!",
customer_id: "xiaus1934",
card_token: "mwe42f64",
stripe_response: response_body
)
```
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `background_job.time_ms:>500`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this log's metadata in the console](https://timber.io/docs/app/console/view-metadata-and-context)
### Sharing context between processes
The `Timber.Context` is local to each process, this is by design as it prevents processes from
conflicting with each other as they maintain their contexts. But many times you'll want to share
context between processes because they are related (such as processes created by `Task` or `Flow`).
In these instances copying the context is easy.
```elixir
current_context = Timber.LocalContext.get()
Task.async fn ->
Timber.LocalContext.put(current_context)
Logger.info("Logs from a separate process")
end
```
`current_context` in the above example is captured in the parent process, and because Elixir's
variable scope is lexical, you can pass the referenced context into the newly created process.
`Timber.LocalContext.put/1` copies that context into the new process dictionary.
* [Search it](https://timber.io/docs/app/console/searching) with queries like: `background_job.time_ms:>500`
* [Alert on it](https://timber.io/docs/app/console/alerts) with threshold based alerts
* [View this log's metadata in the console](https://timber.io/docs/app/console/view-metadata-and-context)
...[read more in our docs](https://timber.io/docs/languages/elixir/usage/sharing-context-between-processes)
## Configuration
Below are a few popular configuration options, for a comprehensive list see [Timber.Config](https://hexdocs.pm/timber/Timber.Config.html#content).
### Capture user context
Capturing `user context` is a powerful feature that allows you to associate logs with users in
your application. This is great for support as you can
[quickly narrow logs to a specific user](https://timber.io/docs/app/console/tail-a-user), making
it easy to identify user reported issues.
#### How to use it
Simply add the `UserContext` immediately after you authenticate the user:
```elixir
%Timber.Contexts.UserContext{id: "my_user_id", name: "John Doe", email: "john@doe.com"}
|> Timber.add_context()
```
All of the `UserContext` attributes are optional, but at least one much be supplied.
## Integrations
Timber provides integrations with popular libraries to easily capture context
and metadata. This automatically upgrades logs produced by these libraries,
making them [easier to search and use](#do-amazing-things-with-your-logs).
* Frameworks & Libraries
* [**Phoenix**](https://timber.io/docs/languages/elixir/integrations/phoenix) via [Timber Phoenix](https://hex.pm/packages/timber_phoenix)
* [**Ecto**](https://timber.io/docs/languages/elixir/integrations/ecto) via [Timber Ecto](https://hex.pm/packages/timber_ecto)
* [**Plug**](https://timber.io/docs/languages/elixir/integrations/plug) via [Timber Plug](https://hex.pm/packages/timber_plug)
* Platforms
* **Exceptions** via [Timber Exceptions](https://hex.pm/packages/timber_excptions)
* [**System / Server**](https://timber.io/docs/languages/elixir/integrations/system)
...more coming soon! Make a request by [opening an issue](https://github.com/timberio/timber-elixir/issues/new)
## Get things done with your logs
Logging features every developer needs:
* [**Powerful searching.** - Find what you need faster.](https://timber.io/docs/app/console/searching)
* [**Live tail users.** - Easily solve customer issues.](https://timber.io/docs/app/console/tail-a-user)
* [**View logs per HTTP request.** - See the full story without the noise.](https://timber.io/docs/app/console/trace-http-requests)
* [**Inspect HTTP request parameters.** - Quickly reproduce issues.](https://timber.io/docs/app/console/inspect-http-requests)
* [**Threshold based alerting.** - Know when things break.](https://timber.io/docs/app/alerts)
...and more! Checkout our [the Timber application docs](https://timber.io/docs/app)
## The Timber Console
[](https://app.timber.io)
[Learn more about our app.](https://timber.io/docs/app)
