- Hands-On Enterprise Java Microservices with Eclipse MicroProfile
- Cesar Saavedra Heiko W. Rupp Jeff Mesnil Pavol Loffay Antoine Sabot Durand Scott Stark
- 272字
- 2021-06-24 12:56:25
The Health Check protocol and wire format
The MP-HC specification defines the requirement to support the HTTP GET requests against a logical /health REST endpoint that may return any one of the following codes to represent the endpoint's status:
- 200: It is up and healthy.
- 500: It is unhealthy due to an unknown error.
- 503: It is down and not ready to respond to requests.
Note that many cloud environments simply look at the request return code as either success or failure, so the differentiation between a 500 and 503 code may not be distinguishable.
The payload of a /health request must be a JSON object that matches the schema given in the following (for more information on the JSON schema syntax see http://jsonschema.net/#/).
Following is the JSON schema for MicroProfile Health Check responses:
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"outcome": {
"type": "string"
},
"checks": {
"type": "array",
"items": {
"type": "object",
"properties": {
"name": {
"type": "string"
},
"state": {
"type": "string"
},
"data": {
"type": "object",
"properties": {
"key": {
"type": "string"
},
"value": {
"type": "string|boolean|int"
}
}
}
},
"required": [
"name",
"state"
]
}
}
},
"required": [
"outcome",
"checks"
]
}
So, an MP-HC response consists of a JSON object that contains a status property of the string type and a checks property of the array of objects type. The checks array object type consists of a required name and status string, along with an optional data object that contains optional key and value pairs. In the next section, we will see how a microservice specifies a health check response.