open-consul/website/source/docs/agent/http/health.html.markdown

---
layout: "docs"
page_title: "Health Checks (HTTP)"
sidebar_current: "docs-agent-http-health"
description: >
  The Health endpoints are used to query health-related information.
---

# Health HTTP Endpoint

The Health endpoints are used to query health-related information. They are provided separately
from the Catalog 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.

The following endpoints are supported:

* [`/v1/health/node/<node>`](#health_node): Returns the health info of a node
* [`/v1/health/checks/<service>`](#health_checks): Returns the checks of a service
* [`/v1/health/service/<service>`](#health_service): Returns the nodes and health info of a service
* [`/v1/health/state/<state>`](#health_state): Returns the checks in a given state

All of the health endpoints support blocking queries and all consistency modes.

### <a name="health_node"></a> /v1/health/node/\<node\>

This endpoint is hit with a `GET` and returns the checks specific to the node
provided on the path. By default, the datacenter of the agent is queried;
however, the `dc` can be provided using the `?dc=` query parameter.

It returns a JSON body like this:

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

In this case, we can see there is a system level check (that is, a check with
no associated `ServiceID`) as well as a service check for Redis. The `serfHealth` check
is special in that it is automatically present on every node. When a node
joins the Consul cluster, it is part of a distributed failure detection
provided by Serf. If a node fails, it is detected and the status is automatically
changed to `critical`.

This endpoint supports blocking queries and all consistency modes.

### <a name="health_checks"></a> /v1/health/checks/\<service\>

This endpoint is hit with a `GET` and returns the checks associated with
the service provided on the path. By default, the datacenter of the agent is queried;
however, the `dc` can be provided using the `?dc=` query parameter.

Adding the optional `?near=` parameter with a node name will 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.

In Consul 0.7.3 and later, the optional `?node-meta=` parameter can be
provided with 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
health checks on nodes with the specified key/value pair(s).

It returns a JSON body like this:

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

This endpoint supports blocking queries and all consistency modes.

### <a name="health_service"></a> /v1/health/service/\<service\>

This endpoint is hit with a `GET` and returns the nodes providing
the service indicated on the path. By default, the datacenter of the agent is queried;
however, the `dc` can be provided using the `?dc=` query parameter.

Adding the optional `?near=` parameter with a node name will 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.

By default, all nodes matching the service are returned. The list can be filtered
by tag using the `?tag=` query parameter.

Providing the `?passing` query parameter, added in Consul 0.2, will
filter results to only nodes with all checks in the `passing` state.
This can be used to avoid extra filtering logic on the client side.

In Consul 0.7.3 and later, the optional `?node-meta=` parameter can be
provided with 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 pair(s).

This endpoint is very similar to the `/v1/catalog/service` endpoint; however, this
endpoint automatically returns the status of the associated health check
as well as any system level health checks. This allows a client to avoid
sending traffic to nodes that are failing health tests or reporting warnings.

Users can also build in support for dynamic load balancing and other features
by incorporating the use of health checks.

It returns a JSON body like this:

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

This endpoint supports blocking queries and all consistency modes.

### <a name="health_state"></a> /v1/health/state/\<state\>

This endpoint is hit with a `GET` and returns the checks in the
state provided on the path. By default, the datacenter of the agent is queried;
however, the `dc` can be provided using the `?dc=` query parameter.

Adding the optional `?near=` parameter with a node name will 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.

In Consul 0.7.3 and later, the optional `?node-meta=` parameter can be
provided with 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
health checks on nodes with the specified key/value pair(s).

The supported states are `any`, `passing`, `warning`, or `critical`.
The `any` state is a wildcard that can be used to return all checks.

It returns a JSON body like this:

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

This endpoint supports blocking queries and all consistency modes.