[THREESCALE-586] Default credentials policy

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Ability to modify query parameters in the URL rewriting policy [PR #724](https://github.com/3scale/apicast/pull/724)
 - 3scale referrer policy [PR #728](https://github.com/3scale/apicast/pull/728)
 - Liquid templating support in the rate-limit policy [PR #719](https://github.com/3scale/apicast/pull/719)
+- Default credentials policy [PR #741](https://github.com/3scale/apicast/pull/741), [THREESCALE-586](https://issues.jboss.org/browse/THREESCALE-586)
 
 ### Changed
 

gateway/src/apicast/policy/default_credentials/apicast-policy.json

@@ -0,0 +1,69 @@
+{
+  "$schema": "http://apicast.io/policy-v1/schema#manifest#",
+  "name": "Default credentials",
+  "summary": "Provides default credentials for unauthenticated requests",
+  "description":
+    ["This policy allows to expose a service without authentication. ",
+     "It can be useful, for example, for legacy apps that cannot be adapted to ",
+     "send the auth params. ",
+     "When the credentials are not provided in the request, this policy ",
+     "provides the default ones configured. ",
+     "An app_id + app_key or a user_key should be configured."],
+  "version": "builtin",
+  "configuration": {
+    "type":"object",
+    "properties":{
+      "auth_type":{
+        "type":"string",
+        "enum":[
+          "user_key",
+          "app_id_and_app_key"
+        ],
+        "default":"user_key"
+      }
+    },
+    "required":[
+      "auth_type"
+    ],
+    "dependencies":{
+      "auth_type":{
+        "oneOf":[
+          {
+            "properties":{
+              "auth_type":{
+                "enum":[
+                  "user_key"
+                ]
+              },
+              "user_key":{
+                "type":"string"
+              }
+            },
+            "required":[
+              "user_key"
+            ]
+          },
+          {
+            "properties":{
+              "auth_type":{
+                "enum":[
+                  "app_id_and_app_key"
+                ]
+              },
+              "app_id":{
+                "type":"string"
+              },
+              "app_key":{
+                "type":"string"
+              }
+            },
+            "required":[
+              "app_id",
+              "app_key"
+            ]
+          }
+        ]
+      }
+    }
+  }
+}

gateway/src/apicast/policy/default_credentials/default_credentials.lua

@@ -0,0 +1,102 @@
+--- Default credentials policy
+
+local tostring = tostring
+
+local policy = require('apicast.policy')
+local _M = policy.new('Default credentials policy')
+
+local new = _M.new
+
+function _M.new(config)
+  local self = new(config)
+
+  if config then
+    self.default_credentials = {
+      user_key = config.user_key,
+      app_id = config.app_id,
+      app_key = config.app_key
+    }
+  else
+    self.default_credentials = {}
+  end
+
+  return self
+end
+
+local function creds_missing(service)
+  local service_creds = service:extract_credentials()
+  if not service_creds then return true end
+
+  local backend_version = tostring(service.backend_version)
+
+  if backend_version == '1' then
+    return service_creds.user_key == nil
+  elseif backend_version == '2' then
+    return service_creds.app_id == nil and service_creds.app_key == nil
+  end
+end
+
+local function provide_creds_for_version_1(service, default_creds)
+  if default_creds.user_key then
+    -- follows same format as Service.extract_credentials()
+    service.extracted_credentials = {
+      default_creds.user_key,
+      user_key = default_creds.user_key
+    }
+
+    ngx.log(ngx.DEBUG, 'Provided default creds for request')
+  else
+    ngx.log(ngx.WARN, 'No default user key configured')
+  end
+end
+
+local function provide_creds_for_version_2(service, default_creds)
+  if default_creds.app_id and default_creds.app_key then
+    -- follows same format as Service.extract_credentials()
+    service.extracted_credentials = {
+      default_creds.app_id,
+      default_creds.app_key,
+      app_id = default_creds.app_id,
+      app_key = default_creds.app_key
+    }
+
+    ngx.log(ngx.DEBUG, 'Provided default creds for request')
+  else
+    ngx.log(ngx.WARN, 'No default app_id + app_key configured')
+  end
+end
+
+local creds_provider = {
+  ["1"] = provide_creds_for_version_1,
+  ["2"] = provide_creds_for_version_2
+}
+
+local function backend_version_is_supported(backend_version)
+  return creds_provider[backend_version] ~= nil
+end
+
+local function provide_creds(service, default_creds)
+  local backend_version = tostring(service.backend_version)
+  creds_provider[backend_version](service, default_creds)
+end
+
+function _M:rewrite(context)
+  local service = context.service
+
+  if not service then
+    ngx.log(ngx.ERR, 'No service in the context')
+    return
+  end
+
+  local backend_version = tostring(service.backend_version)
+  if not backend_version_is_supported(backend_version) then
+    ngx.log(ngx.ERR, 'Incompatible backend version: ', backend_version)
+    return
+  end
+
+  if creds_missing(service) then
+    provide_creds(service, self.default_credentials)
+  end
+end
+
+return _M

gateway/src/apicast/policy/default_credentials/init.lua

@@ -0,0 +1 @@
+return require('default_credentials')

gateway/src/apicast/proxy.lua

@@ -225,7 +225,13 @@ function _M:rewrite(service, context)
 
   ngx.var.secret_token = service.secret_token
 
-  local credentials, err = service:extract_credentials()
+  -- Another policy might have already extracted the creds.
+  local credentials = service.extracted_credentials
+
+  local err
+  if not credentials then
+    credentials, err = service:extract_credentials()
+  end
 
   if not credentials then
     ngx.log(ngx.WARN, "cannot get credentials: ", err or 'unknown error')