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Go Health Check
An easy to use, extensible health check library for Go applications.
Table of Contents
- Example
- Motivation
- Inspiration
- Installation
- API
- Testing
- Implementing custom checkers
- Implemented health check indicators
- LICENSE
Example
package main
import (
"net/http"
"database/sql"
"time"
"github.com/dimiro1/health"
"github.com/dimiro1/health/url"
"github.com/dimiro1/health/db"
"github.com/dimiro1/health/redis"
_ "github.com/go-sql-driver/mysql"
)
func main() {
database, _ := sql.Open("mysql", "/")
mysql := db.NewMySQLChecker(database)
timeout := 5 * time.Second
companies := health.NewCompositeChecker()
companies.AddChecker("Microsoft", url.NewChecker("https://www.microsoft.com/"))
companies.AddChecker("Oracle", url.NewChecker("https://www.oracle.com/"))
companies.AddChecker("Google", url.NewChecker("https://www.google.com/"))
handler := health.NewHandler()
handler.AddChecker("Go", url.NewCheckerWithTimeout("https://golang.org/", timeout))
handler.AddChecker("Big Companies", companies)
handler.AddChecker("MySQL", mysql)
handler.AddChecker("Redis", redis.NewChecker("tcp", ":6379"))
http.Handle("/health/", handler)
http.ListenAndServe(":8080", nil)
}
$ curl localhost:8080/health/
If everything is ok the server must respond with HTTP Status 200 OK and have following json in the body.
{
"Big Companies": {
"Google": {
"code": 200,
"status": "UP"
},
"Microsoft": {
"code": 200,
"status": "UP"
},
"Oracle": {
"code": 200,
"status": "UP"
},
"status": "UP"
},
"Go": {
"code": 200,
"status": "UP"
},
"MySQL": {
"status": "UP",
"version": "10.1.9-MariaDB"
},
"Redis": {
"status": "UP",
"version": "3.0.5"
},
"status": "UP"
}
The server responds with HTTP Status 503 Service Unavailable if the ckeck is Down and the json response could be something like this.
{
"Big Companies": {
"Google": {
"code": 200,
"status": "UP"
},
"Microsoft": {
"code": 200,
"status": "UP"
},
"Oracle": {
"code": 200,
"status": "UP"
},
"status": "UP"
},
"Go": {
"code": 200,
"status": "UP"
},
"MySQL": {
"status": "DOWN",
"error": "Error 1044: Access denied for user ''@'localhost' to database 'invalid-database'",
},
"Redis": {
"status": "UP",
"version": "3.0.5"
},
"status": "DOWN"
}
Motivation
It is very important to verify the status of your system, not only the system itself, but all its dependencies, If your system is not Up you can easily know what is the cause of the problem only looking the health check.
Also it serves as a kind of basic integration test between the systems.
Inspiration
I took a lot of ideas from the spring framework.
Installation
This package is a go getable package.
$ go get github.com/dimiro1/health
API
The API is stable and I do not have any plans to break compatibility, but I recommend you to vendor this dependency in your project, as it is a good practice.
Testing
You have to install the test dependencies.
$ go get gopkg.in/DATA-DOG/go-sqlmock.v1
$ go get github.com/rafaeljusto/redigomock
or you can go get this package with the -t flag
go get -t github.com/dimiro1/health
Implementing custom checkers
The key interface is health.Checker, you only have to implement a type that satisfies that interface.
type Checker interface {
Check() Health
}
Here is an example of Disk Space usage (unix only).
package main
import (
"syscall"
"os"
)
type DiskSpaceChecker struct {
Dir string
Threshold uint64
}
func NewDiskSpaceChecker(dir string, threshold uint64) DiskSpaceChecker {
return DiskSpaceChecker{Dir: dir, Threshold: threshold}
}
func (d DiskSpaceChecker) Check() health.Health {
health := health.NewHealth()
var stat syscall.Statfs_t
wd, err := os.Getwd()
if err != nil {
health.Down().AddInfo("error", err.Error()) // Why the check is Down
return health
}
syscall.Statfs(wd, &stat)
diskFreeInBytes := stat.Bavail * uint64(stat.Bsize)
if diskFreeInBytes < d.Threshold {
health.Down()
} else {
health.Up()
}
health.
AddInfo("free", diskFreeInBytes).
AddInfo("threshold", d.Threshold)
return health
}
Important
The status key in the json has priority over a status key added by a Checker, so if some checker adds a status key to the json, it will not be rendered
Implemented health check indicators
| Health | Description | Package |
|---|---|---|
| url.Checker | Check the connection with some URL | https://github.com/dimiro1/health/tree/master/url |
| db.Checker | Check the connection with the database | https://github.com/dimiro1/health/tree/master/db |
| redis.Checker | Check the connection with the redis | https://github.com/dimiro1/health/tree/master/redis |
LICENSE
The MIT License (MIT)
Copyright (c) 2016 Claudemiro
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
