--- layout: api page_title: HTTP API description: |- Consul exposes a RESTful HTTP API to control almost every aspect of the Consul agent. --- # HTTP API Structure The main interface to Consul is a RESTful HTTP API. The API can perform basic CRUD operations on nodes, services, checks, configuration, and more. ## Authentication When authentication is enabled, a Consul token should be provided to API requests using the `X-Consul-Token` header or with the Bearer scheme in the authorization header. This reduces the probability of the token accidentally getting logged or exposed. When using authentication, clients should communicate via TLS. If no token is provided for an HTTP request then Consul will use the default ACL token if it has been configured. If no default ACL token was configured then the anonymous token will be used. Below is an example using `curl` with `X-Consul-Token`. ```shell-session $ curl \ --header "X-Consul-Token: " \ http://127.0.0.1:8500/v1/agent/members ``` Below is an example using `curl` with a [RFC6750](https://tools.ietf.org/html/rfc6750) Bearer token. ```shell-session $ curl \ --header "Authorization: Bearer " \ http://127.0.0.1:8500/v1/agent/members ``` **Security Note:** Though you could pass the token through the `?token=` query parameter, this method is highly discouraged because the token can show up in access logs as part of the URL. The `?token=` query parameter is deprecated and will be removed in a future Consul version. To learn more about the ACL system read the [documentation](/consul/docs/security/acl). ## Version Prefix Unless indicated otherwise, all API routes are prefixed with `/v1/`. ## Formatted JSON Output By default, the output of all HTTP API requests is minimized JSON. If the client passes `pretty` on the query string, formatted JSON will be returned. ## HTTP Methods Consul's API aims to be RESTful, although there are some exceptions. The API responds to the standard HTTP verbs GET, PUT, and DELETE. Each API method will clearly document the verb(s) it responds to and the generated response. The same path with different verbs may trigger different behavior. For example: ```text PUT /v1/kv/foo GET /v1/kv/foo ``` Even though these share a path, the `PUT` operation creates a new key whereas the `GET` operation reads an existing key. Here is the same example using `curl`: ```shell-session $ curl \ --request PUT \ --data 'hello consul' \ http://127.0.0.1:8500/v1/kv/foo ``` ## URL-Encoded Resource Names Some Consul HTTP API endpoints accept resource names in URL path or query parameters. To pass a resource name containing URL-invalid characters, such as `/` or ` `, URL-encode the resource name into the URL. However, we generally recommend using resource names that don't require URL-encoding. Depending on the validation that Consul applies to a resource name, Consul may still reject a request if it considers the resource name invalid for that endpoint. And even if Consul considers the resource name valid, it may degrade other functionality, such as failed [DNS lookups](/consul/docs/services/discovery/dns-overview) for nodes or services with names containing invalid DNS characters. This HTTP API capability also allows the [CLI to accept arguments with URL-invalid characters](/consul/commands#arguments-with-url-invalid-characters). ### Invalid Characters The linefeed character (`%0a`) will cause a request to be rejected even if it is URL-encoded. ## Translated Addresses Consul 0.7 added the ability to translate addresses in HTTP response based on the configuration setting for [`translate_wan_addrs`](/consul/docs/agent/config/config-files#translate_wan_addrs). In order to allow clients to know if address translation is in effect, the `X-Consul-Translate-Addresses` header will be added if translation is enabled, and will have a value of `true`. If translation is not enabled then this header will not be present. ## Default ACL Policy All API responses for Consul versions after 1.9 will include an HTTP response header `X-Consul-Default-ACL-Policy` set to either "allow" or "deny" which mirrors the current value of the agent's [`acl.default_policy`](/consul/docs/agent/config/config-files#acl_default_policy) option. This is also the default [intention](/consul/docs/connect/intentions) enforcement action if no intention matches. This is returned even if ACLs are disabled. ## Results Filtered by ACLs As of Consul 1.11, most list endpoints support an `X-Consul-Results-Filtered-By-ACLs` HTTP response header. This indicates that the response contains a partial subset of results, because some have been filtered out by ACL policies. In order to limit information leakage, this header is only present for requests authenticated by a valid ACL token. The following example uses `curl` to view the `X-Consul-Results-Filtered-By-ACLs` response header. ```shell-session $ curl \ --header "X-Consul-Token: " \ --include \ http://127.0.0.1:8500/v1/catalog/services HTTP/1.1 200 OK Content-Type: application/json ... X-Consul-Default-Acl-Policy: deny X-Consul-Results-Filtered-By-Acls: true { "redis": [], "postgresql": ["primary", "secondary"] } ``` ## UUID Format UUID-format identifiers generated by the Consul API use the [hashicorp/go-uuid](https://github.com/hashicorp/go-uuid) library. These UUID-format strings are generated using high quality, purely random bytes. It is not intended to be RFC compliant, merely to use a well-understood string representation of a 128-bit value. ## CORS HTTP Response Headers As of Consul 1.18, Consul adds an HTTP header `Access-Control-Expose-Headers: x-consul-default-acl-policy` to all responses in order to support linking self-managed Enterprise clusters to HCP Consul Central.