@fresh8/copacetic
v5.0.0
Published
A package to help your service check the health of its dependencies.
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Copacetic
A package to help your service check the health of its dependencies.
Requirements
Node v6.4.0 and above
Installation
npm install @fresh8/copacetic --save
Quick Start - Javascript
const Copacetic = require('@fresh8/copacetic')
const level = require('@fresh8/copacetic').dependencyLevel
const copacetic = Copacetic()
// Register a dependency
copacetic.registerDependency({
name: 'My-Dependency',
url: 'https://my-Dependency.io',
// Defaults to SOFT
level: level.HARD
})
// Check its health
copacetic
.check({
name: 'My-Dependency',
retries: 2
})
.on('healthy', (Dependency) => {
/**
* { name: 'My-Dependency',
* healthy: true/false,
* lastChecked: Date,
* level: 'SOFT'
* }
*/
})
.on('unhealthy', (Dependency) => {
// Handle degraded state...
})
// in promise mode
copacetic.eventEmitterMode = false
copacetic
.check({ name: 'my-web-service' })
.then((res) => {
console.log(`${res.name} is healthy!`)
})
.catch((err) => {
console.log(err)
})
Quick Start - Typescript
import * as Copacetic from '@fresh8/copacetic'
const copacetic = Copacetic('my-service')
const myDependencyOverHttp : Copacetic.DependencyOptions = {
name: 'my-web-service',
url: 'http://example.com'
}
copacetic.registerDependency(myDependencyOverHttp)
instance
.check({ name: 'my-web-service' })
.on('healthy', (res: Copacetic.Health) => {
// do something with your healthy dependency :)
})
.on('unhealthy', (res: Copacetic.Health) => {
// handle degraded state
})
// in promise mode
copacetic.eventEmitterMode = false
async function waitForWebService () {
try {
const res = await instance
.check<Copacetic.Health>({ name: 'my-web-service' })
console.log(`${res.name} is healthy!`)
} catch (err) {
console.log(err)
}
}
Quick Start - cluster mode
const Copacetic = require('@fresh8/copacetic')
const level = require('@fresh8/copacetic').dependencyLevel
const copacetic = Copacetic("A name", false)
Copacetic.cluster.attach(copacetic)
if (process.worker) {
//register your usual dependencies like databases
//use the line below to have the worker ask the master process a full health report
copacetic.checkCluster() //`checkCluster` is only defined if the process is a worker and if you called `attach()`
.then(console.log)
} else {
copacetic.checkAll()
.then(() => {
console.log(copacetic.healthReport) //Contains health information as reported by the workers
})
}
Classes
Typedefs
Copacetic ⇐ EventEmitter
Kind: global class
Extends: EventEmitter
- Copacetic ⇐ EventEmitter
- new Copacetic([name])
- .isHealthy ⇒ Boolean
- .healthInfo ⇒ Array.<DependencyHealth>
- .healthReport ⇒ HealthReport
- .getDependency(dependency) ⇒ Dependency
- .isDependencyRegistered(dependency) ⇒ Boolean
- .registerDependency(opts) ⇒ Copacetic
- .deregisterDependency(name) ⇒ Copacetic
- .pollAll([interval], [parallel], [schedule]) ⇒ Copacetic
- .poll([name], [dependencies], [interval], [parallel], [schedule]) ⇒ Copacetic
- .stop()
- .checkAll([parallel]) ⇒ Copacetic
- .check([name], [dependencies], [retries], [parallel]) ⇒ Copacetic
- .waitFor(opts)
- ._checkOne(name, maxDelay) ⇒ Promise
- ._checkMany(dependencies, parallel) ⇒ Promise
new Copacetic([name])
| Param | Type | Default | Description | | --- | --- | --- | --- | | [name] | String | '' | The name of your service |
copacetic.isHealthy ⇒ Boolean
Kind: instance property of Copacetic
Returns: Boolean - Copacetic is healthy when all hard dependencies are healthy
copacetic.healthInfo ⇒ Array.<DependencyHealth>
Kind: instance property of Copacetic
Returns: Array.<DependencyHealth> - Health information on all dependencies
copacetic.healthReport ⇒ HealthReport
Kind: instance property of Copacetic
Returns: HealthReport - A full report of health information and dependencies
copacetic.getDependency(dependency) ⇒ Dependency
Kind: instance method of Copacetic
| Param | Type | | --- | --- | | dependency | Dependency | String |
copacetic.isDependencyRegistered(dependency) ⇒ Boolean
Kind: instance method of Copacetic
Returns: Boolean - Whether the dependency has been registered
| Param | Type | | --- | --- | | dependency | Dependency | String |
copacetic.registerDependency(opts) ⇒ Copacetic
Adds a dependency to a Copacetic instance
Kind: instance method of Copacetic
| Param | Type | Description | | --- | --- | --- | | opts | Object | The configuration for a dependency |
copacetic.deregisterDependency(name) ⇒ Copacetic
Removes a dependency from a Copacetic instance
Kind: instance method of Copacetic
| Param | Type | Description | | --- | --- | --- | | name | String | The name used to identify a dependency |
copacetic.pollAll([interval], [parallel], [schedule]) ⇒ Copacetic
Polls the health of all registered dependencies
Kind: instance method of Copacetic
| Param | Type | Default | | --- | --- | --- | | [interval] | String | '5 seconds' | | [parallel] | Boolean | true | | [schedule] | String | 'start' |
copacetic.poll([name], [dependencies], [interval], [parallel], [schedule]) ⇒ Copacetic
Polls the health of a set of dependencies
Kind: instance method of Copacetic
Emits: Copacetic#event:health
| Param | Type | Default | Description | | --- | --- | --- | --- | | [name] | String | | The identifier of a single dependency to be checked | | [dependencies] | Array.<Object> | | An explicit set of dependencies to be polled | | [interval] | String | '5 seconds' | | | [parallel] | Boolean | true | Kick of health checks in parallel or series | | [schedule] | String | 'start' | Schedule the next check to start (interval - ms) | ms |
Example
copacetic.poll({
dependencies: [
{ name: 'my-dep' },
{ name: 'my-other-dep', retries: 2, maxDelay: '2 seconds' }
],
schedule: 'end',
interval: '1 minute 30 seconds'
})
.on('health', (serviceHealth, stop) => {
// Do something with the result
// [{ name: String, health: Boolean, level: HARD/SOFT, lastCheck: Date }]
// stop polling
stop()
})
Example
copacetic.poll({ name: 'my-dependency' })
.on('health', () => { ... Do something })
copacetic.stop()
stops polling registered dependencies
Kind: instance method of Copacetic
copacetic.checkAll([parallel]) ⇒ Copacetic
Checks the health of all registered dependencies
Kind: instance method of Copacetic
| Param | Type | Default | Description | | --- | --- | --- | --- | | [parallel] | Boolean | true | Kick of health checks in parallel or series |
copacetic.check([name], [dependencies], [retries], [parallel]) ⇒ Copacetic
Checks the health of a set, or single dependency
Kind: instance method of Copacetic
Emits: Copacetic#event:health, Copacetic#event:healthy, Copacetic#event:unhealthy
| Param | Type | Default | Description | | --- | --- | --- | --- | | [name] | String | | The identifier of a single dependency to be checked | | [dependencies] | Array.<Object> | | An explicit set of dependencies to be checked | | [retries] | Integer | 1 | How many times should a dependency be checked, until it is deemed unhealthy | | [parallel] | Boolean | true | Kick of health checks in parallel or series |
Example
copacetic.check({ name: 'my-dependency' })
Example
copacetic.check({ name: 'my-dependency', retries: 5 })
.on('healthy', serviceHealth => { ... Do stuff })
.on('unhealthy', serviceHealth => { ... Handle degraded state })
Example
copacetic.check({ dependencies: [
{ name: 'my-dep' },
{ name: 'my-other-dep', retries: 2, maxDelay: '1 second' }
] })
.on('health', (servicesHealth) => {
// Do something with the result
// [{ name: String, health: Boolean, level: HARD/SOFT, lastCheck: Date }]
})
Example
copacetic.check({ name: 'my-dependency' })
.then((health) => { ... Do Stuff })
.catch((err) => { ... Handle degraded state })
copacetic.waitFor(opts)
Convenience method that waits for a single, or set of dependencies to become healthy. Calling this means copacetic will keep re-checking indefinitely until the dependency(s) become healthy. If you want more control, use .check().
Kind: instance method of Copacetic
| Param | Type | Description | | --- | --- | --- | | opts | Object | options accepted by check() |
Example
// wait indefinitely
copacetic.waitFor({ name: 'my-dependency'})
.on('healthy', serviceHealth => { ... Do stuff })
Example
// give up after 5 tries
copacetic.waitFor({ name: 'my-dependency', retries: 5})
.on('healthy', serviceHealth => { ... Do stuff })
copacetic._checkOne(name, maxDelay) ⇒ Promise
Kind: instance method of Copacetic
| Param | Type | Description | | --- | --- | --- | | name | String | The name used to identify a dependency | | maxDelay | Integer | The maximum interval of time to wait when retrying |
copacetic._checkMany(dependencies, parallel) ⇒ Promise
Checks an array of dependencies in parallel or sequantially
Kind: instance method of Copacetic
| Param | Type | | --- | --- | | dependencies | Array.<Dependency> | | parallel | Boolean |
HealthReport : Object
The full health report including isHealthy and dependencies
Kind: global typedef
Properties
| Name | Type | Description | | --- | --- | --- | | isHealthy | Boolean | The result of isHealthy | | Name | String | | | dependencies | Array.<DependencyHealth> | The result of healthInfo |