書名： Hands-On Enterprise Java Microservices with Eclipse MicroProfile
作者名： Cesar Saavedra Heiko W. Rupp Jeff Mesnil Pavol Loffay Antoine Sabot Durand Scott Stark
本章字數： 272字
更新時間： 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.

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Hands-On Enterprise Java Microservices with Eclipse MicroProfile

The Health Check protocol and wire format