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open-consul/website/source/api/health.html.md
Paul Banks 5b0d4db6bc Support Agent Caching for Service Discovery Results (#4541) 
* Add cache types for catalog/services and health/services and basic test that caching works

* Support non-blocking cache types with Cache-Control semantics.

* Update API docs to include caching info for every endpoint.

* Comment updates per PR feedback.

* Add note on caching to the 10,000 foot view on the architecture page to make the new data path more clear.

* Document prepared query staleness quirk and force all background requests to AllowStale so we can spread service discovery load across servers.
2018-10-10 16:55:34 +01:00

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layout page_title sidebar_current description
api Health - HTTP API api-health The /health endpoints query health-related information for services and checks in Consul.

Health HTTP Endpoint

The /health endpoints query health-related information. They are provided separately from the /catalog endpoints since users may prefer not to use the optional health checking mechanisms. Additionally, some of the query results from the health endpoints are filtered while the catalog endpoints provide the raw entries.

List Checks for Node

This endpoint returns the checks specific to the node provided on the path.

Method Path Produces
GET /health/node/:node application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries Consistency Modes Agent Caching ACL Required
YES all none node:read,service:read

Parameters

  • node (string: <required>) - Specifies the name or ID of the node to query. This is specified as part of the URL

  • dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/health/node/my-node

Sample Response

[
  {
    "ID": "40e4a748-2192-161a-0510-9bf59fe950b5",
    "Node": "foobar",
    "CheckID": "serfHealth",
    "Name": "Serf Health Status",
    "Status": "passing",
    "Notes": "",
    "Output": "",
    "ServiceID": "",
    "ServiceName": "",
    "ServiceTags": []
  },
  {
    "ID": "40e4a748-2192-161a-0510-9bf59fe950b5",
    "Node": "foobar",
    "CheckID": "service:redis",
    "Name": "Service 'redis' check",
    "Status": "passing",
    "Notes": "",
    "Output": "",
    "ServiceID": "redis",
    "ServiceName": "redis",
    "ServiceTags": ["primary"]
  }
]

List Checks for Service

This endpoint returns the checks associated with the service provided on the path.

Method Path Produces
GET /health/checks/:service application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries Consistency Modes Agent Caching ACL Required
YES all none node:read,service:read

Parameters

  • service (string: <required>) - Specifies the service to list checks for. This is provided as part of the URL.

  • dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter.

  • near (string: "") - Specifies a node name to sort the node list in ascending order based on the estimated round trip time from that node. Passing ?near=_agent will use the agent's node for the sort. This is specified as part of the URL as a query parameter.

  • node-meta (string: "") - Specifies a desired node metadata key/value pair of the form key:value. This parameter can be specified multiple times, and will filter the results to nodes with the specified key/value pairs. This is specified as part of the URL as a query parameter.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/health/checks/my-service

Sample Response

[
  {
    "Node": "foobar",
    "CheckID": "service:redis",
    "Name": "Service 'redis' check",
    "Status": "passing",
    "Notes": "",
    "Output": "",
    "ServiceID": "redis",
    "ServiceName": "redis",
	"ServiceTags": ["primary"]
  }
]

List Nodes for Service

This endpoint returns the nodes providing the service indicated on the path. Users can also build in support for dynamic load balancing and other features by incorporating the use of health checks.

Method Path Produces
GET /health/service/:service application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries Consistency Modes Agent Caching ACL Required
YES all background refresh node:read,service:read

Parameters

  • service (string: <required>) - Specifies the service to list services for. This is provided as part of the URL.

  • dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter.

  • near (string: "") - Specifies a node name to sort the node list in ascending order based on the estimated round trip time from that node. Passing ?near=_agent will use the agent's node for the sort. This is specified as part of the URL as a query parameter.

  • tag (string: "") - Specifies the tag to filter the list. This is specifies as part of the URL as a query parameter.

  • node-meta (string: "") - Specifies a desired node metadata key/value pair of the form key:value. This parameter can be specified multiple times, and will filter the results to nodes with the specified key/value pairs. This is specified as part of the URL as a query parameter.

  • passing (bool: false) - Specifies that the server should return only nodes with all checks in the passing state. This can be used to avoid additional filtering on the client side.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/health/service/my-service

Sample Response

[
  {
    "Node": {
      "ID": "40e4a748-2192-161a-0510-9bf59fe950b5",
      "Node": "foobar",
      "Address": "10.1.10.12",
      "Datacenter": "dc1",
      "TaggedAddresses": {
        "lan": "10.1.10.12",
        "wan": "10.1.10.12"
      },
      "Meta": {
        "instance_type": "t2.medium"
      }
    },
    "Service": {
      "ID": "redis",
      "Service": "redis",
      "Tags": ["primary"],
      "Address": "10.1.10.12",
      "Meta": {
        "redis_version": "4.0"
      },
      "Port": 8000
    },
    "Checks": [
      {
        "Node": "foobar",
        "CheckID": "service:redis",
        "Name": "Service 'redis' check",
        "Status": "passing",
        "Notes": "",
        "Output": "",
        "ServiceID": "redis",
        "ServiceName": "redis",
		"ServiceTags": ["primary"]
      },
      {
        "Node": "foobar",
        "CheckID": "serfHealth",
        "Name": "Serf Health Status",
        "Status": "passing",
        "Notes": "",
        "Output": "",
        "ServiceID": "",
        "ServiceName": "",
        "ServiceTags": []
      }
    ]
  }
]

List Nodes for Connect-capable Service

This endpoint returns the nodes providing a Connect-capable service in a given datacenter. This will include both proxies and native integrations. A service may register both Connect-capable and incapable services at the same time, so this endpoint may be used to filter only the Connect-capable endpoints.

Method Path Produces
GET /health/connect/:service application/json

Parameters and response format are the same as /health/service/:service.

List Checks in State

This endpoint returns the checks in the state provided on the path.

Method Path Produces
GET /health/state/:state application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries Consistency Modes Agent Caching ACL Required
YES all none node:read,service:read

Parameters

  • state (string: <required>) - Specifies the state to query. Supported states are any, passing, warning, or critical. The any state is a wildcard that can be used to return all checks.

  • dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter.

  • near (string: "") - Specifies a node name to sort the node list in ascending order based on the estimated round trip time from that node. Passing ?near=_agent will use the agent's node for the sort. This is specified as part of the URL as a query parameter.

  • node-meta (string: "") - Specifies a desired node metadata key/value pair of the form key:value. This parameter can be specified multiple times, and will filter the results to nodes with the specified key/value pairs. This is specified as part of the URL as a query parameter.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/health/state/passing

Sample Response

[
  {
    "Node": "foobar",
    "CheckID": "serfHealth",
    "Name": "Serf Health Status",
    "Status": "passing",
    "Notes": "",
    "Output": "",
    "ServiceID": "",
    "ServiceName": "",
    "ServiceTags": []
  },
  {
    "Node": "foobar",
    "CheckID": "service:redis",
    "Name": "Service 'redis' check",
    "Status": "passing",
    "Notes": "",
    "Output": "",
    "ServiceID": "redis",
    "ServiceName": "redis",
	  "ServiceTags": ["primary"]
  }
]