Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/rvarago/mini-balancer
A toy and mini load balancer
https://github.com/rvarago/mini-balancer
Last synced: 1 day ago
JSON representation
A toy and mini load balancer
- Host: GitHub
- URL: https://github.com/rvarago/mini-balancer
- Owner: rvarago
- License: mit
- Created: 2021-05-01T13:54:14.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2021-07-27T17:19:53.000Z (over 3 years ago)
- Last Synced: 2023-03-05T07:41:53.576Z (almost 2 years ago)
- Language: Rust
- Size: 33.2 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# mini-balancer
A toy and mini load-balancer.
## Disclaimer
> This is just a toy project of mine, only meant to serve as something fun for me to build with Rust. I do not intend to maintain nor make it production-ready at all.
## Description
`mini-balancer` is a simple connection-based, transport-level, TCP-only, mini load-balancer, where a *frontend* listens for TCP connections and then forwards them to one of the *backends*.
As an example, one may have more than one instance of a given application offering a TCP server to many clients and wants to distribute connections among such instances.
## Balancing Algorithms
The only balancing algorithm implemented thus far is a simplified round-robin, where a frontend receives incoming connection and then forwards them to a given sequence of `n` backends `(b_1, ..., b_n)` in a cyclical manner, such that:
* the first connection `c_1` goes to `b_1`,
* ...
* the nth connection `c_n` goes to `b_n`,
* the (n+1)th connection `c_n+1` goes again to `b_1` and so the process forever repeats.
## Configuration Schema
An informal description of the [TOML](https://github.com/toml-lang/toml) configuration schema is as follows:
```toml
[frontend]
bind_on = ""
[[frontend.backend]]
forward_to = ""
```
## Examples
### Balancing Connections Between Two Backends
Let's consider we have two instances of an application listening for connections on `127.0.0.1:8080` and `127.0.0.1:9090`, and we want to have a single end-point on `127.0.0.1:7070` where all connections will be received and then distributed among our instances.
For simplicity, let's simulate our instances as echo servers with `socat`:
```sh
λ socat -v tcp-l:8080,fork exec:'/bin/cat'
```
```sh
λ socat -v tcp-l:9090,fork exec:'/bin/cat'
```
Assuming we have saved the following configuration file as `mini-balancer.local.toml`:
```toml
[frontend]
bind_on = "127.0.0.1:7070"
[[frontend.backend]]
forward_to = "127.0.0.1:8080"
[[frontend.backend]]
forward_to = "127.0.0.1:9090"
```
We can then start `mini-balancer` as:
```sh
λ mini-balancer -v -c mini-balancer.local.toml
```
To simulate a client, we once again rely on `socat` to send a message as:
```sh
λ echo "first connection" | socat tcp:127.0.0.1:7070 -
```
```sh
λ echo "second connection" | socat tcp:127.0.0.1:7070 -
```
The first connection should go to the first backend, whereas the second connection should go to the second backend. The logs should look like as follows:
```sh
May 08 14:18:45.305 INFO frontend{local_address=127.0.0.1:7070}: mini_balancer::balancing::frontend: listening for connections
May 08 14:19:01.488 INFO handle_connection{peer_address=127.0.0.1:49438}: mini_balancer::balancing::frontend: serving connection
May 08 14:19:01.488 INFO handle_connection{peer_address=127.0.0.1:49438}:through{target_address=127.0.0.1:8080}: mini_balancer::balancing::middleware::client: opened client connection
May 08 14:19:01.490 INFO handle_connection{peer_address=127.0.0.1:49438}: mini_balancer::balancing::frontend: served connection
May 08 14:19:13.622 INFO handle_connection{peer_address=127.0.0.1:49444}: mini_balancer::balancing::frontend: serving connection
May 08 14:19:13.623 INFO handle_connection{peer_address=127.0.0.1:49444}:through{target_address=127.0.0.3:9090}: mini_balancer::balancing::middleware::client: opened client connection
May 08 14:19:13.627 INFO handle_connection{peer_address=127.0.0.1:49444}: mini_balancer::balancing::frontend: served connection
```
Lastly, if we open a third connection, it should again go to the first backend.
## Instructions
* Minimum Supported Rust Version (MSRV): `1.51.0`.
## Linting
```sh
cargo clippy
```
## Building
```sh
cargo build
```
## Testing
```sh
cargo test
```