Implement OS release detection

Implement new 'system' feature source. It now detects OS release
information from the os-release file, assumed to be available at
/host-etc/os-release. It currently creates two labels (assuming that the
corresponding fields are found in the os-release file), with example
values:
  feature.node.kubernetes.io/system-os_release.ID=opensuse
  feature.node.kubernetes.io/system-os_release.VERSION_ID=42.3

Also, update the template spec to mount /etc/os-release file from the
host inside the container.

README.md

@@ -52,7 +52,7 @@ node-feature-discovery.
                               will override settings read from the config file.
                               [Default: ]
   --sources=<sources>         Comma separated list of feature sources.
-                              [Default: cpuid,iommu,kernel,local,memory,network,pci,pstate,rdt,selinux,storage]
+                              [Default: cpuid,iommu,kernel,local,memory,network,pci,pstate,rdt,selinux,storage,system]
   --no-publish                Do not publish discovered features to the
                               cluster-local Kubernetes API server.
   --label-whitelist=<pattern> Regular expression to filter label names to
@@ -85,6 +85,7 @@ The current set of feature sources are the following:
 - RDT ([Intel Resource Director Technology][intel-rdt])
 - Selinux
 - Storage
+- System
 
 ### Feature labels
 
@@ -120,6 +121,7 @@ the only label value published for features is the string `"true"`._
   "feature.node.kubernetes.io/rdt-<feature-name>": "true",
   "feature.node.kubernetes.io/selinux-<feature-name>": "true",
   "feature.node.kubernetes.io/storage-<feature-name>": "true",
+  "feature.node.kubernetes.io/system-<feature name>": "<feature value>",
   "feature.node.kubernetes.io/<hook name>-<feature name>": "<feature value>"
 }
 ```
@@ -290,6 +292,13 @@ for more information on NFD config.
 | :--------------:   | :---------------------------------------------------------------------------------: |
 | nonrotationaldisk  | Non-rotational disk, like SSD, is present in the node
 
+### System Features
+
+| Feature     | Attribute  | Description                                       |
+| ----------- | ---------- | --------------------------------------------------|
+| os_release  | ID         | Operating system identifier
+| <br>        | VERSION_ID | Operating system version identifier
+
 ## Getting started
 ### System requirements
 

main.go

@@ -12,6 +12,10 @@ import (
 
 	"github.com/docopt/docopt-go"
 	"github.com/ghodss/yaml"
+	api "k8s.io/api/core/v1"
+	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	k8sclient "k8s.io/client-go/kubernetes"
+	restclient "k8s.io/client-go/rest"
 	"sigs.k8s.io/node-feature-discovery/source"
 	"sigs.k8s.io/node-feature-discovery/source/cpuid"
 	"sigs.k8s.io/node-feature-discovery/source/fake"
@@ -26,10 +30,7 @@ import (
 	"sigs.k8s.io/node-feature-discovery/source/rdt"
 	"sigs.k8s.io/node-feature-discovery/source/selinux"
 	"sigs.k8s.io/node-feature-discovery/source/storage"
-	api "k8s.io/api/core/v1"
-	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	k8sclient "k8s.io/client-go/kubernetes"
-	restclient "k8s.io/client-go/rest"
+	"sigs.k8s.io/node-feature-discovery/source/system"
 )
 
 const (
@@ -182,7 +183,7 @@ func argsParse(argv []string) (args Args) {
                               will override settings read from the config file.
                               [Default: ]
   --sources=<sources>         Comma separated list of feature sources.
-                              [Default: cpuid,iommu,kernel,local,memory,network,pci,pstate,rdt,selinux,storage]
+                              [Default: cpuid,iommu,kernel,local,memory,network,pci,pstate,rdt,selinux,storage,system]
   --no-publish                Do not publish discovered features to the
                               cluster-local Kubernetes API server.
   --label-whitelist=<pattern> Regular expression to filter label names to
@@ -270,6 +271,7 @@ func configureParameters(sourcesWhiteList []string, labelWhiteListStr string) (e
 		rdt.Source{},
 		selinux.Source{},
 		storage.Source{},
+		system.Source{},
 		// local needs to be the last source so that it is able to override
 		// labels from other sources
 		local.Source{},

main_test.go

@@ -152,7 +152,7 @@ func TestArgsParse(t *testing.T) {
 				So(args.sleepInterval, ShouldEqual, 60*time.Second)
 				So(args.noPublish, ShouldBeTrue)
 				So(args.oneshot, ShouldBeTrue)
-				So(args.sources, ShouldResemble, []string{"cpuid", "iommu", "kernel", "local", "memory", "network", "pci", "pstate", "rdt", "selinux", "storage"})
+				So(args.sources, ShouldResemble, []string{"cpuid", "iommu", "kernel", "local", "memory", "network", "pci", "pstate", "rdt", "selinux", "storage", "system"})
 				So(len(args.labelWhiteList), ShouldEqual, 0)
 			})
 		})
@@ -174,7 +174,7 @@ func TestArgsParse(t *testing.T) {
 
 			Convey("args.labelWhiteList is set to appropriate value and args.sources is set to default value", func() {
 				So(args.noPublish, ShouldBeFalse)
-				So(args.sources, ShouldResemble, []string{"cpuid", "iommu", "kernel", "local", "memory", "network", "pci", "pstate", "rdt", "selinux", "storage"})
+				So(args.sources, ShouldResemble, []string{"cpuid", "iommu", "kernel", "local", "memory", "network", "pci", "pstate", "rdt", "selinux", "storage", "system"})
 				So(args.labelWhiteList, ShouldResemble, ".*rdt.*")
 			})
 		})

node-feature-discovery-daemonset.yaml.template

@@ -29,12 +29,18 @@ spec:
             - name: host-boot
               mountPath: "/host-boot"
               readOnly: true
+            - name: host-os-release
+              mountPath: "/host-etc/os-release"
+              readOnly: true
             - name: host-sys
               mountPath: "/host-sys"
       volumes:
         - name: host-boot
           hostPath:
             path: "/boot"
+        - name: host-os-release
+          hostPath:
+            path: "/etc/os-release"
         - name: host-sys
           hostPath:
             path: "/sys"

node-feature-discovery-job.yaml.template

@@ -31,6 +31,9 @@ spec:
             - name: host-boot
               mountPath: "/host-boot"
               readOnly: true
+            - name: host-os-release
+              mountPath: "/host-etc/os-release"
+              readOnly: true
             - name: host-sys
               mountPath: "/host-sys"
       restartPolicy: Never
@@ -38,6 +41,9 @@ spec:
         - name: host-boot
           hostPath:
             path: "/boot"
+        - name: host-os-release
+          hostPath:
+            path: "/etc/os-release"
         - name: host-sys
           hostPath:
             path: "/sys"

source/system/system.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2018 The Kubernetes 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 system
+
+import (
+	"bufio"
+	"log"
+	"os"
+	"regexp"
+	"strings"
+
+	"sigs.k8s.io/node-feature-discovery/source"
+)
+
+var osReleaseFields = [...]string{
+	"ID",
+	"VERSION_ID",
+}
+
+// Implement FeatureSource interface
+type Source struct{}
+
+func (s Source) Name() string { return "system" }
+
+func (s Source) Discover() (source.Features, error) {
+	features := source.Features{}
+
+	release, err := parseOSRelease()
+	if err != nil {
+		log.Printf("ERROR: failed to get os-release: %s", err)
+	} else {
+		for _, key := range osReleaseFields {
+			if value, exists := release[key]; exists {
+				features["os_release."+key] = value
+			}
+		}
+	}
+	return features, nil
+}
+
+// Read and parse os-release file
+func parseOSRelease() (map[string]string, error) {
+	release := map[string]string{}
+
+	f, err := os.Open("/host-etc/os-release")
+	if err != nil {
+		return nil, err
+	}
+
+	re := regexp.MustCompile(`^(?P<key>\w+)=(?P<value>.+)`)
+
+	// Read line-by-line
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		line := s.Text()
+		if m := re.FindStringSubmatch(line); m != nil {
+			release[m[1]] = strings.Trim(m[2], `"`)
+		}
+	}
+
+	return release, nil
+}