feat: cascade delete of plugins_configurations. fix #107

This proposes a way to delete all `plugins_configurations` related to
`Consumers` or `APIs` when deleting one of the two later.

`:delete()` is simply overridden to iterate over all related
`plugins_configuration` and delete them one by one.

Caveats:
- I am very unhappy with how painful it is to use one DAO inside another
DAO. To avoid what would appear to be a cycling reference I rather opted
for instanciating a new DAO inside of the `delete` method.
- It is painful to perform a paginated query through the base_dao.
- It is even more painful to perform a find_by_keys query as a paginated
  query.

kong/dao/cassandra/apis.lua

@@ -1,5 +1,6 @@
 local BaseDao = require "kong.dao.cassandra.base_dao"
 local constants = require "kong.constants"
+local PluginsConfigurations = require "kong.dao.cassandra.plugins_configurations"
 
 local SCHEMA = {
   id = { type = constants.DATABASE_TYPES.ID },
@@ -50,4 +51,36 @@ function Apis:new(properties)
   Apis.super.new(self, properties)
 end
 
+-- @override
+function Apis:delete(api_id)
+  local ok, err = Apis.super.delete(self, api_id)
+  if not ok then
+    return err
+  end
+
+  -- delete all related plugins configurations
+  local plugins_dao = PluginsConfigurations(self._properties)
+  local query, args_keys, errors = plugins_dao:_build_where_query(plugins_dao._queries.select.query, {
+    api_id = api_id
+  })
+  if errors then
+    return nil, errors
+  end
+
+  for _, rows, page, err in plugins_dao:_execute_kong_query({query=query, args_keys=args_keys}, {api_id=api_id}, {auto_paging=true}) do
+    if err then
+      return nil, err
+    end
+
+    for _, row in ipairs(rows) do
+      local ok_del_plugin, err = plugins_dao:delete(row.id)
+      if not ok_del_plugin then
+        return nil, err
+      end
+    end
+  end
+
+  return ok
+end
+
 return Apis

kong/dao/cassandra/base_dao.lua

@@ -222,6 +222,33 @@ local function encode_cassandra_args(schema, t, args_keys)
   return args_to_bind, errors
 end
 
+function BaseDao:_build_where_query(query, t)
+  local args_keys = {}
+  local where_str = ""
+  local errors
+
+  -- if t is an args_keys, compute a WHERE statement
+  if t and utils.table_size(t) > 0 then
+    local where = {}
+    for k, v in pairs(t) do
+      if self._schema[k] and self._schema[k].queryable or k == "id" then
+        table.insert(where, string.format("%s = ?", k))
+        table.insert(args_keys, k)
+      else
+        errors = utils.add_error(errors, k, k.." is not queryable.")
+      end
+    end
+
+    if errors then
+      return nil, nil, DaoError(errors, error_types.SCHEMA)
+    end
+
+    where_str = "WHERE "..table.concat(where, " AND ").." ALLOW FILTERING"
+  end
+
+  return string.format(query, where_str), args_keys
+end
+
 -- Get a statement from the cache or prepare it (and thus insert it in the cache).
 -- The cache key will be the plain string query representation.
 -- @param `kong_query` A kong query from the _queries property.
@@ -267,6 +294,14 @@ function BaseDao:_execute(statement, args, options)
     return nil, err
   end
 
+  if options and options.auto_paging then
+    local _, rows, page, err = session:execute(statement, args, options)
+    for i, row in ipairs(rows) do
+      rows[i] = self:_unmarshall(row)
+    end
+    return _, rows, page, err
+  end
+
   local results, err = session:execute(statement, args, options)
   if err then
     err = DaoError(err, error_types.DATABASE)
@@ -521,31 +556,12 @@ end
 -- @param `paging_state` Start page from given offset. See lua-resty-cassandra's :execute() option.
 -- @return _execute_kong_query()
 function BaseDao:find_by_keys(t, page_size, paging_state)
-  local where, keys = {}, {}
-  local where_str = ""
-  local errors
-
-  -- if keys are passed, compute a WHERE statement
-  if t and utils.table_size(t) > 0 then
-    for k,v in pairs(t) do
-      if self._schema[k] and self._schema[k].queryable or k == "id" then
-        table.insert(where, string.format("%s = ?", k))
-        table.insert(keys, k)
-      else
-        errors = utils.add_error(errors, k, k.." is not queryable.")
-      end
-    end
-
-    if errors then
-      return nil, DaoError(errors, error_types.SCHEMA)
-    end
-
-    where_str = "WHERE "..table.concat(where, " AND ").." ALLOW FILTERING"
+  local select_where_query, args_keys, errors = self:_build_where_query(self._queries.select.query, t)
+  if errors then
+    return nil, errors
   end
 
-  local select_query = string.format(self._queries.select.query, where_str)
-
-  return self:_execute_kong_query({ query = select_query, args_keys = keys }, t, {
+  return self:_execute_kong_query({ query = select_where_query, args_keys = args_keys }, t, {
     page_size = page_size,
     paging_state = paging_state
   })

kong/dao/cassandra/consumers.lua

@@ -1,6 +1,7 @@
 local BaseDao = require "kong.dao.cassandra.base_dao"
-local constants = require "kong.constants"
 local stringy = require "stringy"
+local constants = require "kong.constants"
+local PluginsConfigurations = require "kong.dao.cassandra.plugins_configurations"
 
 local function check_custom_id_and_username(value, consumer_t)
   if (consumer_t.custom_id == nil or stringy.strip(consumer_t.custom_id) == "")
@@ -56,4 +57,36 @@ function Consumers:new(properties)
   Consumers.super.new(self, properties)
 end
 
+-- @override
+function Consumers:delete(consumer_id)
+  local ok, err = Consumers.super.delete(self, consumer_id)
+  if not ok then
+    return err
+  end
+
+  -- delete all related plugins configurations
+  local plugins_dao = PluginsConfigurations(self._properties)
+  local query, args_keys, errors = plugins_dao:_build_where_query(plugins_dao._queries.select.query, {
+    consumer_id = consumer_id
+  })
+  if errors then
+    return nil, errors
+  end
+
+  for _, rows, page, err in plugins_dao:_execute_kong_query({query=query, args_keys=args_keys}, {consumer_id=consumer_id}, {auto_paging=true}) do
+    if err then
+      return nil, err
+    end
+
+    for _, row in ipairs(rows) do
+      local ok_del_plugin, err = plugins_dao:delete(row.id)
+      if not ok_del_plugin then
+        return nil, err
+      end
+    end
+  end
+
+  return ok
+end
+
 return Consumers

kong/dao/cassandra/factory.lua

@@ -23,10 +23,11 @@ local LOCALHOST = "localhost"
 local LOCALHOST_IP = "127.0.0.1"
 
 -- Converts every occurence of "localhost" to "127.0.0.1"
--- @param host can either be a string or an array of hosts
+-- @param `host`  A string or an array of hosts
+-- @return `host` The normalized host (127.0.0.1)
 local function normalize_localhost(host)
   if type(host) == "table" then
-    for i,v in ipairs(host) do
+    for i, v in ipairs(host) do
       if v == LOCALHOST then
         host[i] = LOCALHOST_IP
       end
@@ -37,8 +38,8 @@ local function normalize_localhost(host)
   return host
 end
 
--- Instanciate a Cassandra DAO.
--- @param properties Cassandra properties
+-- Instanciate DAOs for collections.
+-- @param `properties` Cassandra properties defined in kong.yml
 function CassandraFactory:new(properties)
   self.type = "cassandra"
   self._properties = properties
@@ -56,6 +57,7 @@ function CassandraFactory:new(properties)
   self.keyauth_credentials = KeyAuthCredentials(properties)
 end
 
+-- Drop the database. Erase all data without erasing the schema.
 function CassandraFactory:drop()
   return self:execute_queries [[
     TRUNCATE apis;
@@ -67,15 +69,13 @@ function CassandraFactory:drop()
   ]]
 end
 
--- Prepare all statements of collections `._queries` property and put them
--- in a statements cache
---
+-- Prepare queries of collections `._queries` property through
+-- the base_dao `prepare_kong_statement()` method.
 -- Note:
--- Even if the BaseDAO's :_execute_kong_query() method support preparation of statements on-the-go,
--- this method should be called when Kong starts in order to detect any failure in advance
--- as well as test the connection to Cassandra.
---
--- @return error if any
+--   Even if the BaseDAO's :_execute_kong_query() method support preparation of statements
+--   on-the-go, this method should be called when Kong starts in order to detect any failure
+--   in advance and for performance reasons.
+-- @return `error` Error if any during execution
 function CassandraFactory:prepare()
   local function prepare_collection(collection, collection_queries)
     if not collection_queries then collection_queries = collection._queries end
@@ -107,9 +107,10 @@ end
 
 -- Execute a string of queries separated by ;
 -- Useful for huge DDL operations such as migrations
--- @param {string} queries Semicolon separated string of queries
--- @param {boolean} no_keyspace Won't set the keyspace if true
--- @return {string} error if any
+-- @param `queries`     Semicolon separated string of queries
+-- @param `no_keyspace` Won't set the keyspace for this query if true.
+--                      Useful for the first migration query which created the keyspace.
+-- @return `error`      Error if any
 function CassandraFactory:execute_queries(queries, no_keyspace)
   local ok, err
   local session = cassandra.new()
@@ -149,11 +150,12 @@ end
 local MIGRATION_IDENTIFIER = "migrations"
 
 -- Create a cassandra session and execute a query on given keyspace or default one (from properties).
--- @param query Query or prepared statement given to session:execute
--- @param args List of arguments given to session:execute
--- @param keyspace Optional: overrides properties keyspace if specified
--- @return query result
--- @return error if any
+-- Will `:close()` the session instead of putting it back in the socket pool like the base_dao
+-- @param `query`    Query or prepared statement given to session:execute
+-- @param `args`     List of arguments given to session:execute
+-- @param `keyspace` Optional. overrides properties keyspace if specified
+-- @return `results` Results of the query
+-- @return `error`   Error if any during execution
 function CassandraFactory:execute(query, args, keyspace)
   local ok, err
   local session = cassandra.new()
@@ -180,18 +182,19 @@ function CassandraFactory:execute(query, args, keyspace)
   return ok
 end
 
--- Log (add) given migration to schema_migrations table.
--- @param migration_name Name of the migration to log
--- @return query result
--- @return error if any
+-- Log (add) given migration to the schema_migrations table.
+-- @param `migration_name` Name of the migration to log
+-- @return `results`       Results of the query
+-- @return `error`         Error if any during execution
 function CassandraFactory:add_migration(migration_name)
   return self:execute("UPDATE schema_migrations SET migrations = migrations + ? WHERE id = ?",
                       { cassandra.list({ migration_name }), MIGRATION_IDENTIFIER })
 end
 
--- Return all logged migrations if any. Check if keyspace exists before to avoid error during the first migration.
--- @return A list of previously executed migration (as strings)
--- @return error if any
+-- Return all logged migrations if any. Check if keyspace exists before to avoid error
+-- if checking before the first migration.
+-- @return `migrations` A list of previously executed migration (as strings)
+-- @return `error`      Error if any during execution
 function CassandraFactory:get_migrations()
   local rows, err
 
@@ -212,8 +215,8 @@ function CassandraFactory:get_migrations()
 end
 
 -- Unlog (delete) given migration from the schema_migrations table.
--- @return query result
--- @return error if any
+-- @return `results` Results of the query
+-- @return `error`   Error if any during execution
 function CassandraFactory:delete_migration(migration_name)
   return self:execute("UPDATE schema_migrations SET migrations = migrations - ? WHERE id = ?",
                       { cassandra.list({ migration_name }), MIGRATION_IDENTIFIER })

kong/dao/cassandra/plugins_configurations.lua

@@ -121,7 +121,7 @@ function PluginsConfigurations:find_distinct()
   end
 
   local result = {}
-  for k,_ in pairs(distinct_names) do
+  for k, _ in pairs(distinct_names) do
     table.insert(result, k)
   end
 

kong/tools/faker.lua

@@ -53,7 +53,7 @@ Faker.FIXTURES = {
     { name = "keyauth", value = { key_names = { "apikey" }}, __api = 1 },
     { name = "tcplog", value = { host = "127.0.0.1", port = 7777 }, __api = 1 },
     { name = "udplog", value = { host = "127.0.0.1", port = 8888 }, __api = 1 },
-    { name = "filelog", value = { }, __api = 1 },
+    { name = "filelog", value = {}, __api = 1 },
     -- API 2
     { name = "basicauth", value = {}, __api = 2 },
     -- API 3
@@ -73,9 +73,9 @@ Faker.FIXTURES = {
     -- API 6
     { name = "cors", value = {}, __api = 6 },
     -- API 7
-    { name = "cors", value = { origin = "example.com", 
-                               methods = "GET", 
-                               headers = "origin, type, accepts", 
+    { name = "cors", value = { origin = "example.com",
+                               methods = "GET",
+                               headers = "origin, type, accepts",
                                exposed_headers = "x-auth-token",
                                max_age = 23,
                                credentials = true }, __api = 7 }