CORS implementation within API Self-hosted

This article is intended for users wanting to configure CORS (Cross-origin resource sharing) support to their API Self-hosted instance.

To enable CORS support you will need to add a series of variables and values to your environment field within your docker-compose.yml file (or similar). For reference, you can find our full guide on docker-compose.yml file configuration here. 

Note: CORS is only supported in API Self-Hosted version 2.3.1 and above. 

Firstly let's look at an example docker-compose.yml file, with all the CORS settings added. 

version: '3.5'
  services:
    apish:
      environment:
        DRAFTABLE_APISH_DJANGO: |-
          draftable:
            django:
              enable_cors: True #enables CORS on the Draftable Self Hosted instance
              cors:
                allowed_origins: [] # List of allowed origins 
                allowed_origin_regexes: [] # List of regular expressions matching allowed origins 
                allow_all_origins: True # Allow CORS requests from any origin
    image: draftable/apish:latest
    ports:
      - 80:80/tcp # HTTP
      - 0.0.0.0:8443:443/tcp # HTTPS
    volumes:
      - draftable_volumne:/srv/draftable
      - /sys/fs/cgroup:/sys/fs/cgroup
volumes:
  draftable_volume:

There are multiple variables that are added to this yaml configuration. See below for an explanation of each variable and its purpose.  

• DRAFTABLE_APISH_DJANGO: |-: This is a new environment variable exposed to the Docker container and DRAFTABLE_APISH_DJANGO: |-It is required for CORS support. This is different and should not be confused with DRAFTABLE_APISH_NGINX: |-, and you can remove DRAFTABLE_APISH_NGINX: |- if no other configuration is being used inside that environment variable.
• enable_cors:: This variable which is seated under the django: key sets whether CORS is enabled or not on the instance. If set to true CORS will be enabled on that instance. 
• allowed_origins:: This variable which is seated under the cors: key allows you to provide a list of the allowed origins for CORS. The correct formatting for this field is: 

allowed_origins:
  - my.domain.com
  - some.other.domain.com

• allowed_origin_regexes:: This variable which is seated under the cors: key allows you to list the regular expressions matching the allowed origins
• allow_all_origins:: This variable which is seated under the cors: key allows you to turn on CORS requests from any origin. This is the equivalent of using * as a wildcard and needs to be set to True for this effect.  

Of the fields added under DRAFTABLE_APISH_DJANGO: |- you only need to add one of those fields for configuration to function. This allow_all_originsfield is obviously the easiest (it defaults to False), as it just allows requests from anywhere. A more secure configuration is one of the first two options being allowed_origins: and allowed_origin_regexes:.