[](https://hex.pm/packages/libcluster_etcd)
# LibclusterEtcd
Etcd strategy for libcluster. It utilisez Etcd v2 API.
## Installation
The package can be installed by adding `libcluster_etcd` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:libcluster_etcd, "~> 1.1.0"}
]
end
```
## Configuration
Minimal configuration is list of etcd nodes ```etcd_nodes``` and directory name ```directory```:
```elixir
config :libcluster,
topologies: [
etcd: [
strategy: LibclusterEtcd.Strategy,
config: [
etcd_nodes: ["http://10.0.0.1:2379", "http://10.0.0.2:2379"],
directory: "cluster"
]
]
]
```
In addition to that you can control polling interval, ttl of the keys and ttl refresh interval, ```httpc``` options:
```elixir
config :libcluster,
topologies: [
etcd: [
strategy: LibclusterEtcd.Strategy,
config: [
etcd_nodes: ["http://10.0.0.1:2379", "http://10.0.0.2:2379"],
directory: "cluster",
ttl: 10_000,
ttl_refresh_interval: 5_000,
polling_interval: 5_000
]
]
]
```
| Parameter | Required? | Default Value | Description | |
|:--------------------:|:---------:|:-----------------------------------------------------------------------------------:|:-----------------------------------------------------------------------:|---|
| etcd_nodes | Yes | | List of etcd nodes | |
| directory | Yes | | Etcd directory to store cluster nodes registrations | |
| ttl | No | 10_000 | Node's registration ttl in ms. Uses etcd ttl to keep key alive. | |
| ttl_refresh_interval | No | 5_000 | How often to refresh ttl of a key, ms. Should be less than ```ttl```. | |
| polling_interval | No | 5_000 | How often to scan ```directory``` and connect and disconnect nodes, ms. | |
| http_opts | No | [ timeout: 10_000, connect_timeout: 2_000, autoredirect: false, relaxed: true ] | ```httpc``` options used for each request to etcd. | |
| | | | | |
```ttl```, ```ttl_refresh_interval```, ```timeout``` and ```connect_timeout``` should be carefully chosen. If ```connect_timeout``` is greater or equal to ```ttl``` then most likely etcd key will expire before it will be renewed if etcd client tries to connect to a dead node.
