consul/website/source/docs/agent/http/catalog.html.markdown

layout	page_title	sidebar_current	description
docs	Catalog (HTTP)	docs-agent-http-catalog	The Catalog is the endpoint used to register and deregister nodes, services, and checks. It also provides query endpoints.

Catalog HTTP Endpoint

The Catalog is the endpoint used to register and deregister nodes, services, and checks. It also provides query endpoints.

The following endpoints are supported:

• /v1/catalog/register : Registers a new node, service, or check
• /v1/catalog/deregister : Deregisters a node, service, or check
• /v1/catalog/datacenters : Lists known datacenters
• /v1/catalog/nodes : Lists nodes in a given DC
• /v1/catalog/services : Lists services in a given DC
• /v1/catalog/service/<service> : Lists the nodes in a given service
• /v1/catalog/node/<node> : Lists the services provided by a node

The nodes and services endpoints support blocking queries and tunable consistency modes.

/v1/catalog/register

The register endpoint is a low-level mechanism for registering or updating entries in the catalog. It is usually preferable to instead use the agent endpoints for registration as they are simpler and perform anti-entropy.

The register endpoint expects a JSON request body to be PUT. The request body must look something like:

{
  "Datacenter": "dc1",
  "Node": "foobar",
  "Address": "192.168.10.10",
  "TaggedAddresses": {
    "lan": "192.168.10.10",
    "wan": "10.0.10.10"
  },
  "NodeMeta": {
    "somekey": "somevalue"
  },
  "Service": {
    "ID": "redis1",
    "Service": "redis",
    "Tags": [
      "primary",
      "v1"
    ],
    "Address": "127.0.0.1",
    "Port": 8000
  },
  "Check": {
    "Node": "foobar",
    "CheckID": "service:redis1",
    "Name": "Redis health check",
    "Notes": "Script based health check",
    "Status": "passing",
    "ServiceID": "redis1"
  }
}

The behavior of the endpoint depends on what keys are provided. The endpoint requires Node and Address to be provided while Datacenter will be defaulted to match that of the agent. If only those are provided, the endpoint will register the node with the catalog. TaggedAddresses can be used in conjunction with the translate_wan_addrs configuration option and the wan address. The lan address was added in Consul 0.7 to help find the LAN address if address translation is enabled.

The Meta block was added in Consul 0.7.3 to enable associating arbitrary metadata key/value pairs with a node for filtering purposes. For more information on node metadata, see the node meta section of the configuration page.

If the Service key is provided, the service will also be registered. If ID is not provided, it will be defaulted to the value of the Service.Service property. Only one service with a given ID may be present per node. The service Tags, Address, and Port fields are all optional.

If the Check key is provided, a health check will also be registered. The register API manipulates the health check entry in the Catalog, but it does not setup the script, TTL, or HTTP check to monitor the node's health. To truly enable a new health check, the check must either be provided in agent configuration or set via the agent endpoint.

The CheckID can be omitted and will default to the value of Name. As with Service.ID, the CheckID must be unique on this node. Notes is an opaque field that is meant to hold human-readable text. If a ServiceID is provided that matches the ID of a service on that node, the check is treated as a service level health check, instead of a node level health check. The Status must be one of passing, warning, or critical.

Multiple checks can be provided by replacing Check with Checks and sending an array of Check objects.

It is important to note that Check does not have to be provided with Service and vice versa. A catalog entry can have either, neither, or both.

An optional ACL token may be provided to perform the registration by including a WriteRequest block in the query payload, like this:

{
  "WriteRequest": {
    "Token": "foo"
  }
}

If the API call succeeds, a 200 status code is returned.

/v1/catalog/deregister

The deregister endpoint is a low-level mechanism for directly removing entries from the Catalog. It is usually preferable to instead use the agent endpoints for deregistration as they are simpler and perform anti-entropy.

The deregister endpoint expects a JSON request body to be PUT. The request body must look like one of the following:

{
  "Datacenter": "dc1",
  "Node": "foobar",
}

{
  "Datacenter": "dc1",
  "Node": "foobar",
  "CheckID": "service:redis1"
}

{
  "Datacenter": "dc1",
  "Node": "foobar",
  "ServiceID": "redis1",
}

The behavior of the endpoint depends on what keys are provided. The endpoint requires Node to be provided while Datacenter will be defaulted to match that of the agent. If only Node is provided, the node and all associated services and checks are deleted. If CheckID is provided, only that check is removed. If ServiceID is provided, the service and its associated health check (if any) are removed.

An optional ACL token may be provided to perform the deregister action by adding a WriteRequest block to the payload, like this:

{
  "WriteRequest": {
    "Token": "foo"
  }
}

If the API call succeeds a 200 status code is returned.

/v1/catalog/datacenters

This endpoint is hit with a GET and is used to return all the datacenters that are known by the Consul server.

The datacenters will be sorted in ascending order based on the estimated median round trip time from the server to the servers in that datacenter.

It returns a JSON body like this:

["dc1", "dc2"]

This endpoint does not require a cluster leader and will succeed even during an availability outage. Therefore, it can be used as a simple check to see if any Consul servers are routable.

/v1/catalog/nodes

This endpoint is hit with a GET and returns the nodes registered in a given DC. 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 will filter the results to nodes with that pair present.

It returns a JSON body like this:

[
  {
    "Node": "baz",
    "Address": "10.1.10.11",
    "TaggedAddresses": {
      "lan": "10.1.10.11",
      "wan": "10.1.10.11"
    },
    "Meta": {
      "instance_type": "t2.medium"
    }
  },
  {
    "Node": "foobar",
    "Address": "10.1.10.12",
    "TaggedAddresses": {
      "lan": "10.1.10.11",
      "wan": "10.1.10.12"
    },
    "Meta": {
      "instance_type": "t2.large"
    }
  }
]

This endpoint supports blocking queries and all consistency modes.

/v1/catalog/services

This endpoint is hit with a GET and returns the services registered in a given DC. By default, the datacenter of the agent is queried; however, the dc can be provided using the ?dc= query parameter.

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 will filter the results to services with that pair present.

It returns a JSON body like this:

{
  "consul": [],
  "redis": [],
  "postgresql": [
    "primary",
    "secondary"
  ]
}

The keys are the service names, and the array values provide all known tags for a given service.

This endpoint supports blocking queries and all consistency modes.

/v1/catalog/service/<service>

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

The service being queried must be provided on the path. By default all nodes in that service are returned. However, the list can be filtered by tag using the ?tag= 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.

It returns a JSON body like this:

[
  {
    "Address": "192.168.10.10",
    "TaggedAddresses": {
      "lan": "192.168.10.10",
      "wan": "10.0.10.10"
    },
    "Meta": {
      "instance_type": "t2.medium"
    }
    "CreateIndex": 51,
    "ModifyIndex": 51,
    "Node": "foobar",
    "ServiceAddress": "172.17.0.3",
    "ServiceEnableTagOverride": false,
    "ServiceID": "32a2a47f7992:nodea:5000",
    "ServiceName": "foobar",
    "ServicePort": 5000,
    "ServiceTags": [
      "tacos"
    ]
  }
]

This endpoint supports blocking queries and all consistency modes.

The returned fields are as follows:

• Address: IP address of the Consul node on which the service is registered
• TaggedAddresses: List of explicit LAN and WAN IP addresses for the agent
• Meta: Added in Consul 0.7.3, a list of user-defined metadata key/value pairs for the node
• CreateIndex: Internal index value representing when the service was created
• ModifyIndex: Last index that modified the service
• Node: Node name of the Consul node on which the service is registered
• ServiceAddress: IP address of the service host — if empty, node address should be used
• ServiceEnableTagOverride: Whether service tags can be overridden on this service
• ServiceID: A unique service instance identifier
• ServiceName: Name of the service
• ServicePort: Port number of the service
• ServiceTags: List of tags for the service

/v1/catalog/node/<node>

This endpoint is hit with a GET and returns the node's registered services. By default, the datacenter of the agent is queried; however, the dc can be provided using the ?dc= query parameter. The node being queried must be provided on the path.

It returns a JSON body like this:

{
  "Node": {
    "Node": "foobar",
    "Address": "10.1.10.12",
    "TaggedAddresses": {
      "lan": "10.1.10.12",
      "wan": "10.1.10.12"
    },
    "Meta": {
      "instance_type": "t2.medium"
    }
  },
  "Services": {
    "consul": {
      "ID": "consul",
      "Service": "consul",
      "Tags": null,
      "Port": 8300
    },
    "redis": {
      "ID": "redis",
      "Service": "redis",
      "Tags": [
        "v1"
      ],
      "Port": 8000
    }
  }
}

This endpoint supports blocking queries and all consistency modes.