[chore] Global server configuration overhaul (#575)

* move config flag names and usage to config package, rewrite config package to use global Configuration{} struct

Signed-off-by: kim <grufwub@gmail.com>

* improved code comment

Signed-off-by: kim <grufwub@gmail.com>

* linter

Signed-off-by: kim <grufwub@gmail.com>

* fix unmarshaling

Signed-off-by: kim <grufwub@gmail.com>

* remove kim's custom go compiler changes

Signed-off-by: kim <grufwub@gmail.com>

* generate setter and flag-name functions, implement these in codebase

Signed-off-by: kim <grufwub@gmail.com>

* update deps

Signed-off-by: kim <grufwub@gmail.com>

* small change

Signed-off-by: kim <grufwub@gmail.com>

* appease the linter...

Signed-off-by: kim <grufwub@gmail.com>

* move configuration into ConfigState structure, ensure reloading to/from viper settings to keep in sync

Signed-off-by: kim <grufwub@gmail.com>

* lint

Signed-off-by: kim <grufwub@gmail.com>

* update code comments

Signed-off-by: kim <grufwub@gmail.com>

* fix merge issue

Signed-off-by: kim <grufwub@gmail.com>

* fix merge issue

Signed-off-by: kim <grufwub@gmail.com>

* improved version string (removes time + go version)

Signed-off-by: kim <grufwub@gmail.com>

* fix version string build to pass test script + consolidate logic in func

Signed-off-by: kim <grufwub@gmail.com>

* add license text, update config.Defaults comment

Signed-off-by: kim <grufwub@gmail.com>

* add license text to generated config helpers file

Signed-off-by: kim <grufwub@gmail.com>

* defer unlock on config.Set___(), to ensure unlocked on panic

Signed-off-by: kim <grufwub@gmail.com>

* make it more obvious which cmd flags are being attached

Signed-off-by: kim <grufwub@gmail.com>

1 files changed, 136 insertions, 0 deletions

diff --git a/internal/config/state.go b/internal/config/state.go
new file mode 100644
index 000000000..70972a835
--- /dev/null
+++ b/internal/config/state.go
@@ -0,0 +1,136 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package config
+
+import (
+	"strings"
+	"sync"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+// ConfigState manages safe concurrent access to Configuration{} values,
+// and provides ease of linking them (including reloading) via viper to
+// environment, CLI and configuration file variables.
+type ConfigState struct { //nolint
+	viper  *viper.Viper
+	config Configuration
+	mutex  sync.Mutex
+}
+
+// NewState returns a new initialized ConfigState instance.
+func NewState() *ConfigState {
+	viper := viper.New()
+
+	// Flag 'some-flag-name' becomes env var 'GTS_SOME_FLAG_NAME'
+	viper.SetEnvPrefix("gts")
+	viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
+
+	// Load appropriate named vals from env
+	viper.AutomaticEnv()
+
+	// Create new ConfigState with defaults
+	state := &ConfigState{
+		viper:  viper,
+		config: Defaults,
+	}
+
+	// Perform initial load into viper
+	state.reloadToViper()
+
+	return state
+}
+
+// Config provides safe access to the ConfigState's contained Configuration,
+// and will reload the current Configuration back into viper settings.
+func (st *ConfigState) Config(fn func(*Configuration)) {
+	st.mutex.Lock()
+	defer func() {
+		st.reloadToViper()
+		st.mutex.Unlock()
+	}()
+	fn(&st.config)
+}
+
+// Viper provides safe access to the ConfigState's contained viper instance,
+// and will reload the current viper setting state back into Configuration.
+func (st *ConfigState) Viper(fn func(*viper.Viper)) {
+	st.mutex.Lock()
+	defer func() {
+		st.reloadFromViper()
+		st.mutex.Unlock()
+	}()
+	fn(st.viper)
+}
+
+// LoadEarlyFlags will bind specific flags from given Cobra command to ConfigState's viper
+// instance, and load the current configuration values. This is useful for flags like
+// .ConfigPath which have to parsed first in order to perform early configuration load.
+func (st *ConfigState) LoadEarlyFlags(cmd *cobra.Command) (err error) {
+	name := ConfigPathFlag()
+	flag := cmd.Flags().Lookup(name)
+	st.Viper(func(v *viper.Viper) {
+		err = v.BindPFlag(name, flag)
+	})
+	return
+}
+
+// BindFlags will bind given Cobra command's pflags to this ConfigState's viper instance.
+func (st *ConfigState) BindFlags(cmd *cobra.Command) (err error) {
+	st.Viper(func(v *viper.Viper) {
+		err = v.BindPFlags(cmd.Flags())
+	})
+	return
+}
+
+// Reload will reload the Configuration values from ConfigState's viper instance, and from file if set.
+func (st *ConfigState) Reload() (err error) {
+	st.Viper(func(v *viper.Viper) {
+		if st.config.ConfigPath != "" {
+			// Ensure configuration path is set
+			v.SetConfigFile(st.config.ConfigPath)
+
+			// Read in configuration from file
+			if err = v.ReadInConfig(); err != nil {
+				return
+			}
+		}
+	})
+	return
+}
+
+// reloadToViper will reload Configuration{} values into viper.
+func (st *ConfigState) reloadToViper() {
+	raw, err := st.config.MarshalMap()
+	if err != nil {
+		panic(err)
+	}
+	if err := st.viper.MergeConfigMap(raw); err != nil {
+		panic(err)
+	}
+}
+
+// reloadFromViper will reload Configuration{} values from viper.
+func (st *ConfigState) reloadFromViper() {
+	err := st.config.UnmarshalMap(st.viper.AllSettings())
+	if err != nil {
+		panic(err)
+	}
+}