# LoggerTelegramBackend
[](https://github.com/adriankumpf/logger-telegram-backend/actions)
[](https://hexdocs.pm/logger_telegram_backend)
[](http://hex.pm/packages/logger_telegram_backend)
<!-- MDOC !-->
A logger backend for [Telegram](https://telegram.org/).
## Installation
Add `:logger_telegram_backend` and `:finch` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:logger_telegram_backend, "~> 3.0-rc"},
{:finch, "~> 0.16"},
]
end
```
In your `Application.start/2` callback, add the `LoggerTelegramBackend` backend:
```elixir
@impl true
def start(_type, _args) do
LoggerTelegramBackend)
# ...
end
```
## Configuration
First you need to create a [Telegram Bot](https://core.telegram.org/bots). Follow the [instructions here](https://core.telegram.org/bots#6-botfather) to create one and get the `token` for the bot. You will need to send a message first as bots are not allowed to contact users. Then retrieve your `chat_id` with `$ curl -X GET https://api.telegram.org/botYOUR_TOKEN/getUpdates`.
Then configure the telegram `chat_id` and bot `token`:
```elixir
config :logger, LoggerTelegramBackend,
chat_id: "$chatId",
token: "$botToken"
```
### Options
The available options are:
- `:level` - the level to be logged by this backend (either `:debug`, `:info`, `:warning` or `:error`).
Note that messages are first filtered by the general `:level` configuration for the `:logger` application.
Default: `nil` (all levels are logged)
- `:metadata` - the metadata to be included in the message. Setting `:metadata` to `:all` will get all metadata.
Default: `[:line, :function, :module, :application, :file]`.
- `:metadata_filter` - the metadata which is required in order for a message to be logged.
Default: `nil`
- `:client` - If you need different functionality for the HTTP client, you can define your own module that implements the `LoggerTelegramBackend.HTTPClient` behaviour and set `client` to that module.
Default: `LoggerTelegramBackend.HTTPClient.Finch` (requires `:finch`)
- `:client_pool_opts` - The options passed to configure the pool.
See [Finch.start_link/1](https://hexdocs.pm/finch/Finch.html#start_link/1).
Default: `[]`
- `:client_request_opts` - The options passed on every request.
See [Finch.request/3](https://hexdocs.pm/finch/Finch.html#request/3).
Default: `[]`
### Examples
#### Custom HTTP client
1. Add a module that implements the `LoggerTelegramBackend.HTTPClient` behaviour
2. Pass your client module to the `:client` option:
```elixir
config :logger, LoggerTelegramBackend,
client: MyClient,
# ...
```
##### Hackney Client
A client based on `:hackney` could look like this:
```elixir
defmodule HackneyClient do
@behaviour LoggerTelegramBackend.HTTPClient
@hackney_pool_name :logger_telegram_backend_pool
@impl true
def child_spec do
:hackney_pool.child_spec(@hackney_pool_name, opts)
end
@impl true
def request(method, url, headers, body) do
opts = [{:pool, @hackney_pool_name} :with_body]
case :hackney.request(method, url, headers, body, opts) do
{:ok, _status, _headers, _body} = result -> result
{:error, _reason} = error -> error
end
end
end
```
#### Metadata filter
```elixir
config :logger, LoggerTelegramBackend,
chat_id: "$chatId",
token: "$botToken",
level: :info,
metadata: :all,
metadata_filter: [application: :ui]
```
#### HTTP proxy
```elixir
config :logger, LoggerTelegramBackend,
chat_id: "$chatId",
token: "$botToken",
client_pool_opts: [conn_opts: [{:http, "127.0.0.1", 8888, []}]]
```
See the [Pool Configuration Options](https://hexdocs.pm/finch/Finch.html#start_link/1-pool-configuration-options) for further information.
