app/featureset: implement feature flags

app/app.go

@@ -37,6 +37,7 @@ import (
 
 	"github.com/obolnetwork/charon/app/errors"
 	"github.com/obolnetwork/charon/app/eth2wrap"
+	"github.com/obolnetwork/charon/app/featureset"
 	"github.com/obolnetwork/charon/app/lifecycle"
 	"github.com/obolnetwork/charon/app/log"
 	"github.com/obolnetwork/charon/app/retry"
@@ -64,6 +65,7 @@ import (
 type Config struct {
 	P2P              p2p.Config
 	Log              log.Config
+	Feature          featureset.Config
 	ManifestFile     string
 	DataDir          string
 	MonitoringAddr   string
@@ -116,6 +118,10 @@ func Run(ctx context.Context, conf Config) (err error) {
 		return err
 	}
 
+	if err := featureset.Init(ctx, conf.Feature); err != nil {
+		return err
+	}
+
 	hash, timestamp := GitCommit()
 	log.Info(ctx, "Charon starting",
 		z.Str("version", version.Version),

app/app_test.go

@@ -34,6 +34,7 @@ import (
 
 	"github.com/obolnetwork/charon/app"
 	"github.com/obolnetwork/charon/app/errors"
+	"github.com/obolnetwork/charon/app/featureset"
 	"github.com/obolnetwork/charon/app/log"
 	"github.com/obolnetwork/charon/cmd"
 	"github.com/obolnetwork/charon/p2p"
@@ -168,6 +169,7 @@ func pingCluster(t *testing.T, test pingTest) {
 	for i := 0; i < n; i++ {
 		conf := app.Config{
 			Log:              log.DefaultConfig(),
+			Feature:          featureset.DefaultConfig(),
 			SimnetBMock:      true,
 			MonitoringAddr:   testutil.AvailableAddr(t).String(), // Random monitoring address
 			ValidatorAPIAddr: testutil.AvailableAddr(t).String(), // Random validatorapi address

app/featureset/config.go

@@ -0,0 +1,117 @@
+// Copyright © 2022 Obol Labs Inc.
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU 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 General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package featureset
+
+import (
+	"context"
+	"math"
+	"strings"
+	"testing"
+
+	"github.com/obolnetwork/charon/app/errors"
+	"github.com/obolnetwork/charon/app/log"
+	"github.com/obolnetwork/charon/app/z"
+)
+
+const (
+	enable  status = math.MaxInt
+	disable status = 0
+)
+
+// Config configures the feature set package.
+type Config struct {
+	// MinStatus defines the minimum enabled status.
+	MinStatus string
+	// Enabled overrides min status and enables a list of features.
+	Enabled []string
+	// Disabled overrides min status and disables a list of features.
+	Disabled []string
+}
+
+// DefaultConfig returns the default config enabling only stable features.
+func DefaultConfig() Config {
+	return Config{
+		MinStatus: statusStable.String(),
+	}
+}
+
+// Init initialises the global feature set state.
+func Init(ctx context.Context, config Config) error {
+	var ok bool
+	for s := statusAlpha; s < statusSentinel; s++ {
+		if strings.ToLower(config.MinStatus) == strings.ToLower(s.String()) {
+			minStatus = s
+			ok = true
+
+			break
+		}
+	}
+	if !ok {
+		return errors.New("unknown min status", z.Str("min_status", config.MinStatus))
+	}
+
+	for _, f := range config.Enabled {
+		var ok bool
+		for feature := range state {
+			if strings.ToLower(string(feature)) == strings.ToLower(f) {
+				state[feature] = enable
+				ok = true
+			}
+		}
+		if !ok {
+			log.Warn(ctx, "Ignoring unknown enabled feature", z.Str("feature", f))
+		}
+	}
+
+	for _, f := range config.Disabled {
+		var ok bool
+		for feature := range state {
+			if strings.ToLower(string(feature)) == strings.ToLower(f) {
+				state[feature] = disable
+				ok = true
+			}
+		}
+		if !ok {
+			log.Warn(ctx, "Ignoring unknown disabled feature", z.Str("feature", f))
+		}
+	}
+
+	return nil
+}
+
+// EnableForT enables a feature for testing.
+func EnableForT(t *testing.T, feature Feature) {
+	t.Helper()
+
+	cache := state[feature]
+	t.Cleanup(func() {
+		state[feature] = cache
+	})
+
+	state[feature] = enable
+}
+
+// DisableForT disables a feature for testing.
+func DisableForT(t *testing.T, feature Feature) {
+	t.Helper()
+
+	cache := state[feature]
+	t.Cleanup(func() {
+		state[feature] = cache
+	})
+
+	state[feature] = disable
+}

app/featureset/config_test.go

@@ -0,0 +1,70 @@
+// Copyright © 2022 Obol Labs Inc.
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU 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 General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package featureset_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/obolnetwork/charon/app/featureset"
+)
+
+// setup initialises global variable per test.
+func setup(t *testing.T) {
+	t.Helper()
+
+	err := featureset.Init(context.Background(), featureset.DefaultConfig())
+	require.NoError(t, err)
+}
+
+func TestConfig(t *testing.T) {
+	setup(t)
+
+	err := featureset.Init(context.Background(), featureset.DefaultConfig())
+	require.NoError(t, err)
+
+	err = featureset.Init(context.Background(), featureset.Config{
+		MinStatus: "alpha",
+		Enabled:   []string{"ignored"},
+	})
+	require.NoError(t, err)
+
+	require.True(t, featureset.Enabled(featureset.QBFTConsensus))
+}
+
+func TestEnableForT(t *testing.T) {
+	setup(t)
+
+	testFeature := featureset.Feature("test")
+	require.False(t, featureset.Enabled(testFeature))
+
+	featureset.EnableForT(t, testFeature)
+	require.True(t, featureset.Enabled(testFeature))
+
+	featureset.DisableForT(t, testFeature)
+	require.False(t, featureset.Enabled(testFeature))
+}
+
+func TestQBFT(t *testing.T) {
+	setup(t)
+
+	require.False(t, featureset.Enabled(featureset.QBFTConsensus))
+
+	featureset.EnableForT(t, featureset.QBFTConsensus)
+	require.True(t, featureset.Enabled(featureset.QBFTConsensus))
+}

app/featureset/featureset.go

@@ -0,0 +1,57 @@
+// Copyright © 2022 Obol Labs Inc.
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU 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 General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// Package featureset defines a set of global features and their rollout status.
+package featureset
+
+//go:generate stringer -type=status -trimprefix=status
+
+// status enumerates the rollout status of a feature.
+type status int
+
+const (
+	// statusAlpha is for internal devnet testing.
+	statusAlpha status = iota + 1
+	// statusBeta is for internal and external testnet testing.
+	statusBeta
+	// statusStable is for stable feature ready for production.
+	statusStable
+	// statusSentinel is an internal tail-end placeholder.
+	statusSentinel // Must always be last
+)
+
+// Feature is a feature being rolled out.
+type Feature string
+
+const (
+	// QBFTConsensus introduces qbft consensus, see https://github.com/ObolNetwork/charon/issues/445.
+	QBFTConsensus Feature = "qbft_consensus"
+)
+
+var (
+	// state defines the current rollout status of each feature.
+	state = map[Feature]status{
+		QBFTConsensus: statusAlpha,
+		// Add all features and there status here.
+	}
+
+	// minStatus defines the minimum enabled status.
+	minStatus = statusStable
+)
+
+// Enabled returns true if the feature is enabled.
+func Enabled(feature Feature) bool {
+	return state[feature] >= minStatus
+}

app/featureset/featureset_internal_test.go

@@ -0,0 +1,35 @@
+// Copyright © 2022 Obol Labs Inc.
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU 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 General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package featureset
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAllFeatureStatus(t *testing.T) {
+	// Add all features to this test
+	features := []Feature{
+		QBFTConsensus,
+	}
+
+	for _, feature := range features {
+		status, ok := state[feature]
+		require.True(t, ok)
+		require.Greater(t, status, 0)
+	}
+}

app/simnet_test.go

@@ -34,6 +34,7 @@ import (
 
 	"github.com/obolnetwork/charon/app"
 	"github.com/obolnetwork/charon/app/errors"
+	"github.com/obolnetwork/charon/app/featureset"
 	"github.com/obolnetwork/charon/app/log"
 	"github.com/obolnetwork/charon/core"
 	"github.com/obolnetwork/charon/core/leadercast"
@@ -132,6 +133,7 @@ func testSimnet(t *testing.T, args simnetArgs, propose bool) {
 	for i := 0; i < args.N; i++ {
 		conf := app.Config{
 			Log:              log.DefaultConfig(),
+			Feature:          featureset.DefaultConfig(),
 			SimnetBMock:      true,
 			SimnetVMock:      args.VMocks[i],
 			MonitoringAddr:   testutil.AvailableAddr(t).String(), // Random monitoring address