Feature flag to enable/disable canary + optional prometheus install (#937)

featureconfig/config.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2018 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package featureconfig
+
+import (
+	"encoding/base64"
+	"fmt"
+	"io/ioutil"
+
+	"github.com/ghodss/yaml"
+)
+
+// GetFeatureConfig reads the configMap file and unmarshals the config into a feature config struct
+func GetFeatureConfig() (*FeatureConfig, error) {
+	// read the file
+	b64EncodedContent, err := ioutil.ReadFile(FeatureConfigFile)
+	if err != nil {
+		return nil, fmt.Errorf("error reading YAML file %s: %v", FeatureConfigFile, err)
+	}
+
+	// b64 decode file
+	yamlContent, err := base64.StdEncoding.DecodeString(string(b64EncodedContent))
+	if err != nil {
+		return nil, fmt.Errorf("error b64 decoding the config : %v", err)
+	}
+
+	// unmarshal into feature config
+	featureConfig := &FeatureConfig{}
+	err = yaml.Unmarshal(yamlContent, featureConfig)
+	if err != nil {
+		return nil, fmt.Errorf("error unmarshalling YAML config %v", err)
+	}
+
+	return featureConfig, err
+}

featureconfig/types.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2018 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package featureconfig
+
+const (
+	FeatureConfigFile = "/etc/config/config.yaml"
+)
+
+type (
+	// config.yaml contains config parameters for optional features
+	// To add new features with config parameters:
+	// 1. create a yaml block with feature name in charts/_helpers.tpl
+	// 2. define a corresponding struct with the feature config for the yaml unmarshal below
+	// 3. start the appropriate controllers needed for this feature
+
+	FeatureConfig struct {
+		// In the future more such feature configs can be added here for each optional feature
+		CanaryConfig CanaryFeatureConfig `json:"canary"`
+	}
+
+	// specific feature config
+	CanaryFeatureConfig struct {
+		IsEnabled     bool   `json:"enabled"`
+		PrometheusSvc string `json:"prometheusSvc"`
+	}
+)