Introduce URL rewriting policy [THREESCALE-296]

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## Added
 
 - Definition of JSON schemas for policy configurations [PR #522](https://github.com/3scale/apicast/pull/522)
+- URL rewriting policy [PR #529](https://github.com/3scale/apicast/pull/529)
 
 ## Fixed
 

gateway/src/apicast/policy/url_rewriting/policy.lua

@@ -0,0 +1,75 @@
+--- URL rewriting policy
+-- This policy allows to modify the path of a request.
+
+local ipairs = ipairs
+local sub = ngx.re.sub
+local gsub = ngx.re.gsub
+
+local policy = require('apicast.policy')
+local _M = policy.new('URL rewriting policy')
+
+local new = _M.new
+
+local substitute_functions = { sub = sub, gsub = gsub }
+
+-- func needs to be ngx.re.sub or ngx.re.gsub.
+-- This method simply calls one of those 2. They have the same interface.
+local function substitute(func, subject, regex, replace, options)
+  local new_uri, num_changes, err = func(subject, regex, replace, options)
+
+  if not new_uri then
+    ngx.log(ngx.WARN, 'There was an error applying the regex: ', err)
+  end
+
+  return new_uri, num_changes > 0
+end
+
+-- Returns true when the URL was rewritten and false otherwise
+local function apply_rewrite_command(command)
+  local func = substitute_functions[command.op]
+
+  if not func then
+    ngx.log(ngx.WARN, "Unknown URL rewrite operation: ", command.op)
+  end
+
+  local new_uri, changed = substitute(
+    func, ngx.var.uri, command.regex, command.replace, command.options)
+
+  if changed then
+    ngx.req.set_uri(new_uri)
+  end
+
+  return changed
+end
+
+--- Initialize a URL rewriting policy
+-- @tparam[opt] table config Contains the rewrite commands.
+-- The rewrite commands are based on the 'ngx.re.sub' and 'ngx.re.gsub'
+-- functions provided by OpenResty. Please check
+-- https://github.com/openresty/lua-nginx-module for more details.
+-- Each rewrite command is a table with the following fields:
+--
+--   - op: can be 'sub' or 'gsub'.
+--   - regex: regular expression to be matched.
+--   - replace: string that will replace whatever is matched by the regex.
+--   - options[opt]: options to control how the regex match will be done.
+--     Accepted options are the ones in 'ngx.re.sub' and 'ngx.re.gsub'.
+--   - break[opt]: defaults to false. When set to true, if the command rewrote
+--     the URL, it will be the last command applied.
+function _M.new(config)
+  local self = new()
+  self.config = config or {}
+  return self
+end
+
+function _M:rewrite()
+  for _, command in ipairs(self.config) do
+    local rewritten = apply_rewrite_command(command)
+
+    if rewritten and command['break'] then
+      break
+    end
+  end
+end
+
+return _M

gateway/src/apicast/policy/url_rewriting/schema.json

@@ -0,0 +1,32 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "URL rewriting policy configuration",
+  "type": "object",
+  "properties": {
+    "commands": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties": {
+          "op": {
+            "type": "string",
+            "enum": ["sub", "gsub"]
+          },
+          "regex": {
+            "type": "string"
+          },
+          "replace": {
+            "type": "string"
+          },
+          "options": {
+            "type": "string"
+          },
+          "break": {
+            "type": "boolean"
+          }
+        },
+        "required": ["op", "regex", "replace"]
+      }
+    }
+  }
+}

t/apicast-policy-url-rewriting.t

@@ -0,0 +1,236 @@
+use lib 't';
+use TestAPIcastBlackbox 'no_plan';
+
+repeat_each(2);
+run_tests();
+
+__DATA__
+
+=== TEST 1: sub operation
+--- backend
+  location /transactions/authrep.xml {
+    content_by_lua_block {
+      local expected = "service_token=token-value&service_id=42&usage%5Bhits%5D=2&user_key=value"
+      local args = ngx.var.args
+      if args == expected then
+        ngx.exit(200)
+      else
+        ngx.log(ngx.ERR, expected, ' did not match: ', args)
+        ngx.exit(403)
+      end
+    }
+  }
+--- configuration
+{
+  "services": [
+    {
+      "id": 42,
+      "backend_version":  1,
+      "backend_authentication_type": "service_token",
+      "backend_authentication_value": "token-value",
+      "proxy": {
+        "api_backend": "http://test:$TEST_NGINX_SERVER_PORT/",
+        "proxy_rules": [
+          { "pattern": "/", "http_method": "GET", "metric_system_name": "hits", "delta": 2 }
+        ],
+        "policy_chain": [
+          { "name": "apicast.policy.apicast" },
+          {
+            "name": "apicast.policy.url_rewriting",
+            "configuration":
+              [
+                { "op": "sub", "regex": "original", "replace": "new" }
+              ]
+          }
+        ]
+      }
+    }
+  ]
+}
+--- upstream
+  location ~ /xxx_new_yyy$ {
+    content_by_lua_block {
+      ngx.say('yay, api backend');
+    }
+  }
+--- request
+GET /xxx_original_yyy?user_key=value
+--- response_body
+yay, api backend
+--- error_code: 200
+--- no_error_log
+[error]
+
+=== TEST 2: gsub operation
+--- backend
+  location /transactions/authrep.xml {
+    content_by_lua_block {
+      local expected = "service_token=token-value&service_id=42&usage%5Bhits%5D=2&user_key=value"
+      local args = ngx.var.args
+      if args == expected then
+        ngx.exit(200)
+      else
+        ngx.log(ngx.ERR, expected, ' did not match: ', args)
+        ngx.exit(403)
+      end
+    }
+  }
+--- configuration
+{
+  "services": [
+    {
+      "id": 42,
+      "backend_version":  1,
+      "backend_authentication_type": "service_token",
+      "backend_authentication_value": "token-value",
+      "proxy": {
+        "api_backend": "http://test:$TEST_NGINX_SERVER_PORT/",
+        "proxy_rules": [
+          { "pattern": "/", "http_method": "GET", "metric_system_name": "hits", "delta": 2 }
+        ],
+        "policy_chain": [
+          { "name": "apicast.policy.apicast" },
+          {
+            "name": "apicast.policy.url_rewriting",
+            "configuration":
+              [
+                { "op": "gsub", "regex": "original", "replace": "new" }
+              ]
+          }
+        ]
+      }
+    }
+  ]
+}
+--- upstream
+  location ~ /aaa_new_bbb_new_ccc$ {
+    content_by_lua_block {
+      ngx.say('yay, api backend');
+    }
+  }
+--- request
+GET /aaa_original_bbb_original_ccc?user_key=value
+--- response_body
+yay, api backend
+--- error_code: 200
+--- no_error_log
+[error]
+
+=== TEST 3: ordered commands
+Substitutions are applied in the order specified.
+--- backend
+  location /transactions/authrep.xml {
+    content_by_lua_block {
+      local expected = "service_token=token-value&service_id=42&usage%5Bhits%5D=2&user_key=value"
+      local args = ngx.var.args
+      if args == expected then
+        ngx.exit(200)
+      else
+        ngx.log(ngx.ERR, expected, ' did not match: ', args)
+        ngx.exit(403)
+      end
+    }
+  }
+--- configuration
+{
+  "services": [
+    {
+      "id": 42,
+      "backend_version":  1,
+      "backend_authentication_type": "service_token",
+      "backend_authentication_value": "token-value",
+      "proxy": {
+        "api_backend": "http://test:$TEST_NGINX_SERVER_PORT/",
+        "proxy_rules": [
+          { "pattern": "/", "http_method": "GET", "metric_system_name": "hits", "delta": 2 }
+        ],
+        "policy_chain": [
+          { "name": "apicast.policy.apicast" },
+          {
+            "name": "apicast.policy.url_rewriting",
+            "configuration":
+              [
+                { "op": "gsub", "regex": "aaa", "replace": "bbb", "options": "i" },
+                { "op": "sub", "regex": "bbb", "replace": "ccc" },
+                { "op": "sub", "regex": "ccc", "replace": "ddd" }
+              ]
+          }
+        ]
+      }
+    }
+  ]
+}
+--- upstream
+  location ~ /ddd_bbb$ {
+    content_by_lua_block {
+      ngx.say('yay, api backend');
+    }
+  }
+--- request
+GET /aaa_aaa?user_key=value
+--- response_body
+yay, api backend
+--- error_code: 200
+--- no_error_log
+[error]
+
+=== TEST 4: break
+We need to test 2 things:
+1) A break is only applied when the URL is rewritten.
+2) When break is specified in a command, it will be the last one applied.
+--- backend
+  location /transactions/authrep.xml {
+    content_by_lua_block {
+      local expected = "service_token=token-value&service_id=42&usage%5Bhits%5D=2&user_key=value"
+      local args = ngx.var.args
+      if args == expected then
+        ngx.exit(200)
+      else
+        ngx.log(ngx.ERR, expected, ' did not match: ', args)
+        ngx.exit(403)
+      end
+    }
+  }
+--- configuration
+{
+  "services": [
+    {
+      "id": 42,
+      "backend_version":  1,
+      "backend_authentication_type": "service_token",
+      "backend_authentication_value": "token-value",
+      "proxy": {
+        "api_backend": "http://test:$TEST_NGINX_SERVER_PORT/",
+        "proxy_rules": [
+          { "pattern": "/", "http_method": "GET", "metric_system_name": "hits", "delta": 2 }
+        ],
+        "policy_chain": [
+          { "name": "apicast.policy.apicast" },
+          {
+            "name": "apicast.policy.url_rewriting",
+            "configuration":
+              [
+                { "op": "sub", "regex": "does_not_match", "replace": "a", "break": true },
+                { "op": "sub", "regex": "aaa", "replace": "bbb" },
+                { "op": "sub", "regex": "bbb", "replace": "ccc", "break": true },
+                { "op": "sub", "regex": "ccc", "replace": "ddd" }
+              ]
+          }
+        ]
+      }
+    }
+  ]
+}
+--- upstream
+  location ~ /ccc$ {
+    content_by_lua_block {
+      ngx.say('yay, api backend');
+    }
+  }
+--- request
+GET /aaa?user_key=value
+--- response_body
+yay, api backend
+--- error_code: 200
+--- no_error_log
+[error]