[THREESCALE-1524][config] add support to filter services by public URL.

This commit adds the option to filter services based on the endpoint.
This commit expose a new config flag using the env variable
`APICAST_SERVICES_FILTER_BY_URL`, services filter happens on
`configuration.filter_services`.

Signed-off-by: Eloy Coto <eloy.coto@gmail.com>

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 
 - Ability to configure client certificate chain depth [PR #1006](https://github.com/3scale/APIcast/pull/1006)
+- You can filter services by endpoint name using Regexp [PR #1022](https://github.com/3scale/APIcast/pull/1022) [THREESCALE-1524](https://issues.jboss.org/browse/THREESCALE-1524)
 
 ### Fixed
 

doc/parameters.md

@@ -186,6 +186,30 @@ before the client is throttled by adding latency.
 When set to _true_, APIcast will log the response code of the response returned by the API backend in 3scale. In some plans this information can later be consulted from the 3scale admin portal.
 Find more information about the Response Codes feature on the [3scale support site](https://access.redhat.com/documentation/en-us/red_hat_3scale/2.saas/html/analytics/response-codes-tracking).
 
+### `APICAST_SERVICES_FILTER_BY_URL`
+**Value:** a regular expression
+**Default:**: .*
+**Example:** *.example.com
+
+Used to filter the service configured in the 3scale API Manager, the filter
+matches with the public base URL. Services that do not match the filter will be
+discarded. If the regular expression cannot be compiled no services will be
+loaded. 
+
+Note: If a service does not match, but is included in the
+`APICAST_SERVICES_LIST`, service will not be discarded
+
+Example:
+
+Regexp Filter: http:\/\/.*.google.com
+Service 1: backend endpoint http://www.google.com
+Service 2: backend endpoint http://www.yahoo.com
+Service 3: backend endpoint http://mail.google.com
+Service 4: backend endpoint http://mail.yahoo.com
+
+The services that will be configured in Apicast will be 1 and 3. Services 2 and
+4 will be discarded.
+
 ### `APICAST_SERVICES_LIST`
 **Value:** a comma-separated list of service IDs
 

gateway/src/apicast/configuration.lua

@@ -12,14 +12,17 @@ local insert = table.insert
 local setmetatable = setmetatable
 local null = ngx.null
 
-local re = require 'ngx.re'
 local env = require 'resty.env'
 local resty_url = require 'resty.url'
 local util = require 'apicast.util'
 local policy_chain = require 'apicast.policy_chain'
 local mapping_rule = require 'apicast.mapping_rule'
 local tab_new = require('resty.core.base').new_tab
 
+local re = require 'ngx.re'
+local match = ngx.re.match
+local default_regexp = ".*"
+
 local mt = { __index = _M, __tostring = function() return 'Configuration' end }
 
 local function map(func, tbl)
@@ -83,7 +86,6 @@ function _M.parse_service(service)
   local proxy = service.proxy or empty_t
   local backend = backend_endpoint(proxy)
 
-
   return Service.new({
       id = tostring(service.id or 'default'),
       backend_version = backend_version,
@@ -140,21 +142,47 @@ function _M.services_limit()
 end
 
 function _M.filter_services(services, subset)
-  subset = subset and util.to_hash(subset) or _M.services_limit()
-  if not subset or not next(subset) then return services end
+  local selected_services = {}
+  local service_regexp_filter  = env.value("APICAST_SERVICES_FILTER_BY_URL")
+  if service_regexp_filter == "" then
+      service_regexp_filter = default_regexp
+  end
+
+  if service_regexp_filter then
+    -- Checking that the regexp sent is correct, if not an empty service list
+    -- will be returned.
+    local _, err = match("", service_regexp_filter, 'oj')
+    if err then
+      -- @todo this return and empty list, Apicast will continue running maybe
+      -- process need to be stopped here.
+      ngx.log(ngx.ERR, "APICAST_SERVICES_FILTER_BY_URL cannot compile and all services are filtering out")
+      return selected_services
+    end
+  end
 
-  local s = {}
+  subset = subset and util.to_hash(subset) or _M.services_limit()
+  if (not subset or not next(subset)) and not service_regexp_filter then return services end
+  subset = subset or {}
 
   for i = 1, #services do
     local service = services[i]
+    local success = false
+
+    if service:match_host(service_regexp_filter) then
+      success = true
+    end
+
     if subset[service.id] then
-      insert(s, service)
+      success = true
+    end
+
+    if success then
+      insert(selected_services, service)
     else
       ngx.log(ngx.WARN, 'filtering out service ', service.id)
     end
   end
-
-  return s
+  return selected_services
 end
 
 function _M.new(configuration)

gateway/src/apicast/configuration/service.lua

@@ -8,7 +8,9 @@ local rawget = rawget
 local lower = string.lower
 local gsub = string.gsub
 local select = select
+
 local re = require 'ngx.re'
+local match = ngx.re.match
 
 local http_authorization = require 'resty.http_authorization'
 
@@ -264,4 +266,22 @@ function _M:get_usage(method, path)
   end
 end
 
+--- Validate that the given regexp match with one of the service hosts.
+--- This function needs a valid regexp, if not will return false
+-- @tparam string regexp Regular expresion to match with the host
+-- @return bool true if match
+function _M:match_host(regexp)
+  if not regexp then
+      return false
+  end
+
+  for j = 1, #self.hosts do
+    local val, _ = match(self.hosts[j], regexp, 'oj')
+    if val then
+      return true
+    end
+  end
+  return false
+end
+
 return _M

spec/configuration_spec.lua

@@ -25,7 +25,6 @@ describe('Configuration object', function()
       assert.same('example.com', config.hostname_rewrite)
     end)
 
-
     it('has a default message, content-type, and status for the auth failed error', function()
       local config = configuration.parse_service({})
 
@@ -112,19 +111,72 @@ describe('Configuration object', function()
   end)
 
   describe('.filter_services', function()
+    local Service = require 'apicast.configuration.service'
     local filter_services = configuration.filter_services
 
     it('works with nil', function()
-      local services = { { id = '42' } }
+      local services = { Service.new({id="42"})}
       assert.equal(services, filter_services(services))
     end)
 
     it('works with table with ids', function()
-      local services = { { id = '42' } }
-
+      local services = { Service.new({id="42"})}
       assert.same(services, filter_services(services, { '42' }))
       assert.same({}, filter_services(services, { '21' }))
     end)
+
+    describe("with service filter", function()
+
+      local mockservices = {
+        Service.new({id="42", hosts={"test.foo.com", "test.bar.com"}}),
+        Service.new({id="12", hosts={"staging.foo.com"}}),
+        Service.new({id="21", hosts={"prod.foo.com"}}),
+      }
+
+      it("with empty env variable", function()
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '')
+        assert.same(filter_services(mockservices, nil), mockservices)
+      end)
+
+      it("it does not discard any service when there is not regex", function()
+        assert.same(filter_services(mockservices, nil), mockservices)
+      end)
+
+      it("reads from environment variable", function()
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '.*.foo.com')
+        assert.same(filter_services(mockservices, nil), mockservices)
+
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '^test.*')
+        assert.same(filter_services(mockservices, nil), {mockservices[1]})
+
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '^(test|prod).*')
+        assert.same(filter_services(mockservices, nil), {mockservices[1], mockservices[3]})
+      end)
+
+      it("matches the second host", function()
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '^test.bar.com')
+        assert.same(filter_services(mockservices, nil), {mockservices[1]})
+      end)
+
+      it("validates invalid regexp", function()
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '^]')
+        assert.same(filter_services(mockservices, nil), {})
+      end)
+
+      it("combination with service list", function()
+        env.set('APICAST_SERVICES_FILTER_BY_URL', '^test.*')
+        env.set('APICAST_SERVICES_LIST', '42,21')
+
+        assert.same(filter_services(mockservices, {"21"}), {
+          mockservices[1],
+          mockservices[3]})
+
+        assert.same(filter_services(mockservices, nil), {
+          mockservices[1],
+          mockservices[3]})
+      end)
+    end)
+
   end)
 
   insulate('.services_limit', function()