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Set headers on every answer

The answers of the orders API should all carry some headers and lose others, whatever the backend sends. response-rewrite changes the answer on its way back to the client. This guide sets Cache-Control to no-store on every answer of orders-api, so that browsers and proxies keep no copy, and removes the Server header. At the end, your backend stays as it is, and the client gets its answers with the headers you chose.

Before you start​

  • This guide starts from orders-api as Route requests to a backend leaves it, with no other plugin. A plugin from another guide that this page does not name can change the answers below; remove it first or work on a copy of the route.
  • The requests below call /orders/42.
  • The host name of your gateway. In the console it is the first part of the Address line on a route's Overview tab, api.example.com in this page's examples; replace it in every request below.
  • The headers to set and to remove, and the value of each header you set.
  • The Editor or Environment administrator role in this environment.

Steps​

1. Choose response-rewrite​

Open orders-api under Routes, select its Plugins tab, then Add plugin at the top right of the tab. Open the Transformation category, or type response-rewrite in the search box. Select response-rewrite, then Configure.

2. Choose the three lists​

Under Headers, choose Add, set and remove. It shows three lists: headers to append, headers to write over and headers to drop.

3. Set one header and remove another​

Under Set, select Add Set. The new row has two boxes, the header's name and its value. Under Remove, type a value and press Enter for each.

FieldValueWhy
SetCache-Control in the first box, no-store in the secondEvery answer carries it, whatever the backend sent.
RemoveServerThe gateway adds this header to answers itself. Listed here, it is gone from the answer.

Leave Add empty, and leave the fields for the status and the body as they are. An empty field leaves that part of the answer as the backend sent it.

4. Add the plugin​

Select Add plugin at the bottom of the panel. The tab now lists response-rewrite, and the plugin is saved like this:

The Add response-rewrite panel with the Server header removed from every answer.
response-rewrite · as the console saves it
{
  "headers": {
    "set": {
      "Cache-Control": "no-store"
    },
    "remove": [
      "Server"
    ]
  }
}

Check it​

Send a request to the route and read the headers of the answer.

curl
curl -i -L 'https://<gateway host>/orders/42'

Among the response headers your curl prints, Cache-Control: no-store is there, and no Server header is.

The caching header
Every answer carries Cache-Control: no-store, whatever the backend sent.

Set the same headers on every route​

A plugin on a route changes the answers of that route only. To change the answers of every route of the environment, put response-rewrite with the same settings on a global rule. Its plugins run on every route in the environment. Apply a plugin to every request creates the rule and adds plugins to it.

What to know​

  • The other choice under Headers, One value per header, writes every header with the value given there, replacing what the answer carries.
  • Add is a list like Remove, not two boxes like Set. Each entry is one value, the header's name, a colon and its value, with no second colon. An entry without the colon is refused when you save.
  • response-rewrite changes what the client gets, not what the backend receives. To change the request on its way to the backend, see Rewrite the path your backend sees.
  • The plugin can also replace the status and the body of the answer. The reference lists those fields.
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