cors

The cors Plugins lets you enable CORS easily.

Attributes

CORS attributes

Name	Type	Required	Default	Description
allow_origins	string	False	"*"	Origins to allow CORS. Use the scheme://host:port format. For example, https://somedomain.com:8081. If you have multiple origins, use a , to list them. If allow_credential is set to false, you can enable CORS for all origins by using *. If allow_credential is set to true, you can forcefully allow CORS on all origins by using ** but it will pose some security issues.
allow_methods	string	False	"*"	Request methods to enable CORS on. For example GET, POST. Use , to add multiple methods. If allow_credential is set to false, you can enable CORS for all methods by using *. If allow_credential is set to true, you can forcefully allow CORS on all methods by using ** but it will pose some security issues.
allow_headers	string	False	"*"	Headers in the request allowed when accessing a cross-origin resource. Use , to add multiple headers. If allow_credential is set to false, you can enable CORS for all request headers by using *. If allow_credential is set to true, you can forcefully allow CORS on all request headers by using ** but it will pose some security issues.
expose_headers	string	False		Headers in the response allowed when accessing a cross-origin resource. Use , to add multiple headers. If allow_credential is set to false, you can enable CORS for all response headers by using *. If not specified, the plugin will not modify the Access-Control-Expose-Headers header. See Access-Control-Expose-Headers - MDN for more details.
max_age	integer	False	5	Maximum time in seconds the result is cached. If the time is within this limit, the browser will check the cached result. Set to -1 to disable caching. Note that the maximum value is browser dependent. See Access-Control-Max-Age for more details.
allow_credential	boolean	False	false	When set to true, allows requests to include credentials like cookies. According to CORS specification, if you set this to true, you cannot use '*' to allow all for the other attributes.
allow_origins_by_regex	array	False	nil	Regex to match origins that allow CORS. For example, [".*\.test.com$"] can match all subdomains of test.com. When set to specified range, only domains in this range will be allowed, no matter what allow_origins is.
allow_origins_by_metadata	array	False	nil	Origins to enable CORS referenced from allow_origins set in the Plugin metadata. For example, if "allow_origins": {"EXAMPLE": "https://example.com"} is set in the Plugin metadata, then ["EXAMPLE"] can be used to allow CORS on the origin https://example.com.

IMPORTANT

1. The allow_credential attribute is sensitive and must be used carefully. If set to true the default value * of the other attributes will be invalid and they should be specified explicitly.
2. When using ** you are vulnerable to security risks like CSRF. Make sure that this meets your security levels before using it.

Resource Timing attributes

Name	Type	Required	Default	Description
timing_allow_origins	string	False	nil	Origin to allow to access the resource timing information. See Timing-Allow-Origin. Use the scheme://host:port format. For example, https://somedomain.com:8081. If you have multiple origins, use a , to list them.
timing_allow_origins_by_regex	array	False	nil	Regex to match with origin for enabling access to the resource timing information. For example, [".*\.test.com"] can match all subdomain of test.com. When set to specified range, only domains in this range will be allowed, no matter what timing_allow_origins is.

note

The Timing-Allow-Origin header is defined in the Resource Timing API, but it is related to the CORS concept.

Suppose you have 2 domains, domain-A.com and domain-B.com. You are on a page on domain-A.com, you have an XHR call to a resource on domain-B.com and you need its timing information. You can allow the browser to show this timing information only if you have cross-origin permissions on domain-B.com. So, you have to set the CORS headers first, then access the domain-B.com URL, and if you set Timing-Allow-Origin, the browser will show the requested timing information.

Metadata

Name	Type	Required	Description
allow_origins	object	False	A map with origin reference and allowed origins. The keys in the map are used in the attribute allow_origins_by_metadata and the value are equivalent to the allow_origins attribute of the Plugin.

Enable Plugin

You can enable the Plugin on a specific Route or Service:

note

You can fetch the admin_key from config.yaml and save to an environment variable with the following command:

admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')

curl http://127.0.0.1:9180/api/stargate/v1/routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "uri": "/hello",
    "plugins": {
        "cors": {}
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:8080": 1
        }
    }
}'

Example usage

After enabling the Plugin, you can make a request to the server and see the CORS headers returned:

curl http://127.0.0.1:9080/hello -v

...
< Server: Stargate web server
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Methods: *
< Access-Control-Allow-Headers: *
< Access-Control-Max-Age: 5
...

Delete Plugin

To remove the cors Plugin, you can delete the corresponding JSON configuration from the Plugin configuration. Stargate will automatically reload and you do not have to restart for this to take effect.

curl http://127.0.0.1:9180/api/stargate/v1/routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
    "uri": "/hello",
    "plugins": {},
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:8080": 1
        }
    }
}'