https://github.com/smallnest/glean
hotfix for go applications via plugin, supports Linux and MacOS
https://github.com/smallnest/glean
hot-reload hotfix hotfix-update plugin plugins
Last synced: 29 days ago
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hotfix for go applications via plugin, supports Linux and MacOS
- Host: GitHub
- URL: https://github.com/smallnest/glean
- Owner: smallnest
- License: apache-2.0
- Created: 2017-09-08T09:27:56.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2018-02-28T03:28:11.000Z (about 7 years ago)
- Last Synced: 2025-03-19T06:51:24.687Z (about 1 month ago)
- Topics: hot-reload, hotfix, hotfix-update, plugin, plugins
- Language: Go
- Homepage:
- Size: 30.3 KB
- Stars: 135
- Watchers: 7
- Forks: 6
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Glean
*A go plugin framework that can reload variables and functions from plugins automatically.*
[](https://opensource.org/licenses/Apache-2.0) [](http://godoc.org/github.com/smallnest/glean) [](https://travis-ci.org/smallnest/glean) [](https://goreportcard.com/report/github.com/smallnest/glean)
## Installation
```sh
go get -u github.com/smallnest/glean
```
## Feature
- load symbol and you don't worry about errors
- load/reload exported variables and funtions from plugins
- watch plugins' changes and reload pointer of variables and function in applications
**Notice** glean only can reload functions or variables that can be addresses.
## Examples
see [Examples](https://github.com/smallnest/glean/tree/master/_example)
Let's look the httpserver example to learn how to use glean.
### httpserver
httpserver is a very very simple http server.
A simple http server is just like this:
```go
var FooHandler = func(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, "Hello, world")
}
http.Handle("/foo", fooHandler)
log.Fatal(http.ListenAndServe(":9988", nil))
```
Our goal is to replace fooHandler with latest code dynamically (hot fix).
```go
var FooHandler = func(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, "Hello, gp")
}
```
No need to restart this server.
**step1:** build the two plugin
enter `_example/httpserver/plugins/plugin1` and `_example/httpserver/plugins/plugin2`, and run the `build.sh` to generate the so file.
Currently plugin supports linux and MacOS.
**step2:** modify the server implementation
```go
package main
import (
"log"
"net/http"
"github.com/smallnest/glean"
)
func main() {
g := glean.New("plugin.json")
err := g.LoadConfig()
if err != nil {
panic(err)
}
var fooHandler func(w http.ResponseWriter, r *http.Request)
err = g.ReloadAndWatch("FooHandlerID", &fooHandler)
if err != nil {
panic(err)
}
http.HandleFunc("/foo", WarpFuncPtr(&fooHandler))
log.Fatal(http.ListenAndServe(":9988", nil))
}
func WarpFuncPtr(fn *func(w http.ResponseWriter, r *http.Request)) func(w http.ResponseWriter, r *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
(*fn)(w, r)
}
}
```
Firstly create the Glean instance and load config from given file.
And then use `ReloadAndWatch` to load fooHandler and begin to watch its changes.
At last use WarpFuncPtr to wrap fooHandler as a HandleFunc.
Run `go run main.go` to start this server, use a browser to visit "http://locakhost:9988/foo" and you will see `hello world`
Change the config file `plugin.json` and replace `"file": "plugins/plugin1/plugin1.so"` with :
```
"file": "plugins/plugin2/plugin2.so",
```
Browser the prior location and you will see `hello gp`.