# LoggerTelegramBackend
[](https://github.com/adriankumpf/logger-telegram-backend/actions)
[](https://hexdocs.pm/logger_telegram_backend)
[](http://hex.pm/packages/logger_telegram_backend)
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A logger backend for [Telegram](https://telegram.org/).
## Installation
Add `:logger_telegram_backend` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:logger_telegram_backend, "~> 2.0"},
{:hackney, "~> 1.17"}, # optional, but recommended adapter
]
end
```
## Configuration
First of all 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. Since bots are not allowed to contact users, you need to send a message first. Afterwards, retrieve your `chat_id` with `$ curl -X GET https://api.telegram.org/botYOUR_TOKEN/getUpdates`.
Then add `LoggerTelegramBackend` to the `:backends` configuration, configure the telegram `chat_id` and bot `token`:
```elixir
config :logger, backends: [LoggerTelegramBackend, :console]
config :logger, :telegram,
chat_id: "$chatId",
token: "$botToken"
```
The logger configuration is read at runtime from the application environment so that you can provide it via [distillerys](https://github.com/bitwalker/distillery) dynamic configuration with environment variables.
### Options
The following options are available:
- `:level` - the level to be logged by this backend (either `:debug`,
`:info`, `:warn` or `:error`). Note that messages are filtered by the general `:level` configuration for the `:logger` application first. If not explicitly configured all levels are logged.
- `:metadata` - the metadata to be included in the telegram message. Defaults to `[:line, :function, :module, :application, :file]`. Setting `:metadata` to `:all` gets all metadata.
- `:metadata_filter` - the metadata which is required in order for a message to be logged. Example: `metadata_filter: [application: :ui]`.
- `:proxy` - connect via an HTTP tunnel or a socks5 proxy. See the [hackney docs](https://github.com/benoitc/hackney#proxy-a-connection) for further information. (Only available with the default hackney adapter).
- `:adapter` - the [Tesla adapter](https://hexdoks.pm/tesla/readme.html) for the Telegram client (default: `{Tesla.Adapter.Hackney, pool: :logger_telegram_backend}`)
#### Examples
##### With Metadata Filter
```elixir
config :logger, :telegram,
chat_id: "$chatId",
token: "$botToken",
level: :info,
metadata: :all
metadata_filter: [application: :ui]
```
##### With Finch Adapter
```elixir
config :logger, :telegram,
chat_id: "$chatId",
token: "$botToken",
adapter: {Tesla.Adapter.Finch, name: MyFinch}
```
Note: You'll need to add Finch instead of hackney to your list of dependencies:
```elixir
{:finch, "~> 0.6"}
```
##### With Proxy
```elixir
config :logger, :telegram,
chat_id: "$chatId",
token: "$botToken",
proxy: "socks5://127.0.0.1:9050"
```
### Multiple logger handlers
Like the [LoggerFileBackend](https://github.com/onkel-dirtus/logger_file_backend) multiple logger handlers may be configured, each with different `:chat_id`s, `:level`s etc. Each handler has to be configured as a separate logger backend:
```elixir
config :logger,
backends: [
{LoggerTelegramBackend, :telegram_filter},
{LoggerTelegramBackend, :telegram_level},
:console
]
config :logger, :telegram_filter,
chat_id: "$chatId",
token: "$botToken",
metadata_filter: [application: :ui],
metadata: [:line, :function, :module, :pid]
config :logger, :telegram_level,
chat_id: "$chatId",
token: "$botToken",
level: :warn
```
