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https://github.com/binocarlos/http-master-proxy
proxy mutable HTTP traffic to an elected master
https://github.com/binocarlos/http-master-proxy
Last synced: 11 days ago
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proxy mutable HTTP traffic to an elected master
- Host: GitHub
- URL: https://github.com/binocarlos/http-master-proxy
- Owner: binocarlos
- Created: 2014-08-05T22:56:39.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2014-08-06T21:49:28.000Z (over 10 years ago)
- Last Synced: 2024-11-03T08:34:15.262Z (17 days ago)
- Language: JavaScript
- Size: 137 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
http-master-proxy
-----------------
proxy mutable HTTP traffic to an elected master
useful if you have a HTTP api where writes must be sent to an elected master but reads can be served from any node in the cluster
## install
```
$ npm install http-master-proxy
```
## usage
Create a [locked](https://github.com/binocarlos/locked) node so we have a consensus on the leader
Then make a function which will proxy POST,PUT and DELETE requests onto the elected master
```js
var http = require("http")
var locked = require("locked")
var masterProxy = require('http-master-proxy')
var serverid = process.env.NODEID
var serveraddress = '127.0.0.1:' + process.env.NODEPORT
// create a locker passing etcd connection details
var locker = locked('127.0.0.1:4001,127.0.0.1:4002')
// create a lock with a value that is the address for our HTTP server
var node = locker({
id:serverid,
path:'/myservice',
value:serveraddress,
ttl:10
})
var proxy = masterProxy(function(){
// return if the current server is the leader
return node.isSelected()
},function(){
// return the address of the current leader
return node.value()
})
var server = http.createServer(proxy(function(req, res){
if(req.url=='/api/v1/leader'){
res.end(node.id() + "\n")
return
}
if(req.method=='GET'){
res.end('get ' + serverid + "\n")
}
else{
res.end('post ' + serverid + "\n")
}
}))
node.start()
server.listen(process.env.NODEPORT)
```
If we ran 3 copies of the server above:
```bash
$ NODEID=node1 NODEPORT=8080 node example.js
$ NODEID=node2 NODEPORT=8081 node example.js
$ NODEID=node3 NODEPORT=8082 node example.js
```
We can see that the server we hit will handle the request:
```bash
$ curl -L http://127.0.0.1:8080/api/v1/blog
get node1
$ curl -L http://127.0.0.1:8081/api/v1/blog
get node2
$ curl -L http://127.0.0.1:8082/api/v1/blog
get node3
```
Lets see which server is currently elected as master:
```bash
$ curl -L http://127.0.0.1:8082/api/v1/leader
node2
```
Then we should expect node2 to handle all POST requests across the whole cluster:
```bash
$ curl -L http://127.0.0.1:8080/api/v1/blog -XPOST -d value=bar
post node2
$ curl -L http://127.0.0.1:8081/api/v1/blog -XPOST -d value=bar
post node2
$ curl -L http://127.0.0.1:8082/api/v1/blog -XPOST -d value=bar
post node2
```
## api
### `var proxy = electedhttp(leaderfn, addressfn)`
Create a proxy function that will proxy POST, PUT and DELETE requests
`leaderfn` is a function that returns a boolean as to whether this node is the current master
`addressfn` is a function that returns the address of the current master
### `var handler = proxy(function handle(req, res){})`
Return a handler function that will be proxied to the master for POST,PUT and DELETE requests
```js
var server = http.createServer(proxy(function(req, res){
// if not GET request then this will be the master
}))
```
## license
MIT