feature: the tfvars store keeps Terraform modules, their instances and the instances' variable files in PostgreSQL.

server/sql/tfvars_store.sql

@@ -0,0 +1,117 @@
+-- The store of Terraform modules, their instances and the instances' variable files: the tables tf_modules,
+-- tf_instances and tf_variable_files, and the functions and procedures the store calls. The store applies the file on
+-- its first use in the schema its connection's search path names; every statement can run again.
+
+CREATE TABLE IF NOT EXISTS tf_modules (
+  name             text PRIMARY KEY CHECK (name ~ '^[a-z][a-z0-9-]*$'),
+  root             text NOT NULL CHECK (root <> ''),
+  description      text NOT NULL DEFAULT '',
+  configurator_url text
+);
+
+CREATE TABLE IF NOT EXISTS tf_instances (
+  module       text NOT NULL REFERENCES tf_modules (name),
+  name         text NOT NULL CHECK (name ~ '^[a-z][a-z0-9-]*$'),
+  state_schema text NOT NULL UNIQUE CHECK (state_schema ~ '^[a-z_][a-z0-9_]*$'),
+  created      timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY (module, name)
+);
+
+CREATE TABLE IF NOT EXISTS tf_variable_files (
+  module   text NOT NULL,
+  instance text NOT NULL,
+  name     text NOT NULL CHECK (name ~ '^[A-Za-z0-9_.-]+\.tfvars\.json$'),
+  content  jsonb NOT NULL CHECK (jsonb_typeof(content) = 'object'),
+  previous jsonb CHECK (jsonb_typeof(previous) = 'object'),
+  updated  timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY (module, instance, name),
+  FOREIGN KEY (module, instance) REFERENCES tf_instances (module, name) ON DELETE CASCADE
+);
+
+-- The modules, by name.
+CREATE OR REPLACE FUNCTION tf_modules_list()
+RETURNS TABLE (name text, root text, description text, configurator_url text)
+LANGUAGE sql STABLE
+SET search_path FROM CURRENT
+AS $$
+  SELECT m.name, m.root, m.description, m.configurator_url FROM tf_modules m ORDER BY m.name
+$$;
+
+-- Creates a module, or changes the one of that name.
+CREATE OR REPLACE PROCEDURE tf_module_put(module_name text, module_root text, module_description text, module_configurator_url text)
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  INSERT INTO tf_modules (name, root, description, configurator_url)
+  VALUES (module_name, module_root, module_description, module_configurator_url)
+  ON CONFLICT (name) DO UPDATE SET root = excluded.root, description = excluded.description, configurator_url = excluded.configurator_url
+$$;
+
+-- Deletes a module; the foreign key of tf_instances refuses it while the module has instances.
+CREATE OR REPLACE PROCEDURE tf_module_delete(module_name text)
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  DELETE FROM tf_modules WHERE name = module_name
+$$;
+
+-- The instances of a module, by name.
+CREATE OR REPLACE FUNCTION tf_instances_list(module_name text)
+RETURNS TABLE (module text, name text, state_schema text, created timestamptz)
+LANGUAGE sql STABLE
+SET search_path FROM CURRENT
+AS $$
+  SELECT i.module, i.name, i.state_schema, i.created FROM tf_instances i WHERE i.module = module_name ORDER BY i.name
+$$;
+
+-- Creates an instance of a module with the schema of its state.
+CREATE OR REPLACE PROCEDURE tf_instance_create(module_name text, instance_name text, instance_state_schema text)
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  INSERT INTO tf_instances (module, name, state_schema) VALUES (module_name, instance_name, instance_state_schema)
+$$;
+
+-- Deletes an instance with its variable files.
+CREATE OR REPLACE PROCEDURE tf_instance_delete(module_name text, instance_name text)
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  DELETE FROM tf_instances WHERE module = module_name AND name = instance_name
+$$;
+
+-- The variable files of an instance, by name: content, whether the content it replaced is kept, and the time of the
+-- last write.
+CREATE OR REPLACE FUNCTION tf_variable_files_read(module_name text, instance_name text)
+RETURNS TABLE (name text, content jsonb, previous boolean, updated timestamptz)
+LANGUAGE sql STABLE
+SET search_path FROM CURRENT
+AS $$
+  SELECT f.name, f.content, f.previous IS NOT NULL, f.updated FROM tf_variable_files f
+  WHERE f.module = module_name AND f.instance = instance_name ORDER BY f.name
+$$;
+
+-- Keeps other writers out until the end of the transaction, from the comparison of the version to the commit.
+CREATE OR REPLACE PROCEDURE tf_variable_files_lock()
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  LOCK TABLE tf_variable_files IN EXCLUSIVE MODE
+$$;
+
+-- Writes a variable file of an instance, keeping the content it replaces as previous.
+CREATE OR REPLACE PROCEDURE tf_variable_file_put(module_name text, instance_name text, file_name text, file_content jsonb)
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  INSERT INTO tf_variable_files (module, instance, name, content) VALUES (module_name, instance_name, file_name, file_content)
+  ON CONFLICT (module, instance, name) DO UPDATE SET previous = tf_variable_files.content, content = excluded.content, updated = now()
+$$;
+
+-- Deletes a variable file of an instance.
+CREATE OR REPLACE PROCEDURE tf_variable_file_delete(module_name text, instance_name text, file_name text)
+LANGUAGE sql
+SET search_path FROM CURRENT
+AS $$
+  DELETE FROM tf_variable_files WHERE module = module_name AND instance = instance_name AND name = file_name
+$$;