Add os-release gatherer (#283)

* Add os-release gatherer

internal/factsengine/gatherers/gatherer.go

@@ -34,6 +34,9 @@ func StandardGatherers() FactGatherersTree {
 		HostsFileGathererName: map[string]FactGatherer{
 			"v1": NewDefaultHostsFileGatherer(),
 		},
+		OSReleaseGathererName: map[string]FactGatherer{
+			"v1": NewDefaultOSReleaseGatherer(),
+		},
 		PackageVersionGathererName: map[string]FactGatherer{
 			"v1": NewDefaultPackageVersionGatherer(),
 		},

internal/factsengine/gatherers/osrelease.go

@@ -0,0 +1,88 @@
+package gatherers
+
+import (
+	"os"
+
+	"github.com/hashicorp/go-envparse"
+	log "github.com/sirupsen/logrus"
+	"github.com/trento-project/agent/pkg/factsengine/entities"
+)
+
+const (
+	OSReleaseGathererName = "os-release"
+	OSReleaseFilePath     = "/etc/os-release"
+)
+
+// nolint:gochecknoglobals
+var (
+	OSReleaseFileError = entities.FactGatheringError{
+		Type:    "os-release-file-error",
+		Message: "error reading /etc/os-release file",
+	}
+
+	OSReleaseDecodingError = entities.FactGatheringError{
+		Type:    "os-release-decoding-error",
+		Message: "error decoding file content",
+	}
+)
+
+type OSReleaseGatherer struct {
+	osReleaseFilePath string
+}
+
+func NewDefaultOSReleaseGatherer() *OSReleaseGatherer {
+	return NewOSReleaseGatherer(OSReleaseFilePath)
+}
+
+func NewOSReleaseGatherer(path string) *OSReleaseGatherer {
+	return &OSReleaseGatherer{
+		osReleaseFilePath: path,
+	}
+}
+
+func (g *OSReleaseGatherer) Gather(factsRequests []entities.FactRequest) ([]entities.Fact, error) {
+	facts := []entities.Fact{}
+	log.Infof("Starting %s facts gathering process", OSReleaseGathererName)
+
+	file, err := os.Open(g.osReleaseFilePath)
+	if err != nil {
+		log.Error(err)
+		return facts, OSReleaseFileError.Wrap(err.Error())
+	}
+	defer func() {
+		err := file.Close()
+		if err != nil {
+			log.Errorf("could not close os-release file %s, error: %s", g.osReleaseFilePath, err)
+		}
+	}()
+
+	osRelease, err := envparse.Parse(file)
+	if err != nil {
+		log.Error(err)
+		return facts, OSReleaseDecodingError.Wrap(err.Error())
+	}
+
+	osReleaseFactValue := mapOSReleaseToFactValue(osRelease)
+	if err != nil {
+		log.Error(err)
+		return facts, OSReleaseDecodingError.Wrap(err.Error())
+	}
+
+	for _, requestedFact := range factsRequests {
+		fact := entities.NewFactGatheredWithRequest(requestedFact, osReleaseFactValue)
+		facts = append(facts, fact)
+	}
+
+	log.Infof("Requested %s facts gathered", OSReleaseGathererName)
+	return facts, nil
+}
+
+func mapOSReleaseToFactValue(inputMap map[string]string) entities.FactValue {
+	factValueMap := make(map[string]entities.FactValue)
+
+	for key, value := range inputMap {
+		factValueMap[key] = &entities.FactValueString{Value: value}
+	}
+
+	return &entities.FactValueMap{Value: factValueMap}
+}

internal/factsengine/gatherers/osrelease_test.go

@@ -0,0 +1,88 @@
+package gatherers_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/trento-project/agent/internal/factsengine/gatherers"
+	"github.com/trento-project/agent/pkg/factsengine/entities"
+	"github.com/trento-project/agent/test/helpers"
+)
+
+type OSReleaseGathererTestSuite struct {
+	suite.Suite
+}
+
+func TestOSReleaseGathererTestSuite(t *testing.T) {
+	suite.Run(t, new(OSReleaseGathererTestSuite))
+}
+
+func (suite *OSReleaseGathererTestSuite) TestOSReleaseGathererSuccess() {
+	c := gatherers.NewOSReleaseGatherer(helpers.GetFixturePath("gatherers/os-release.basic"))
+
+	factRequests := []entities.FactRequest{
+		{
+			Name:     "os-release",
+			Gatherer: "os-release@v1",
+			CheckID:  "check1",
+		},
+	}
+
+	factResults, err := c.Gather(factRequests)
+
+	expectedResults := []entities.Fact{
+		{
+			Name: "os-release",
+			Value: &entities.FactValueMap{
+				Value: map[string]entities.FactValue{
+					"NAME":           &entities.FactValueString{Value: "openSUSE Leap"},
+					"VERSION":        &entities.FactValueString{Value: "15.2"},
+					"ID":             &entities.FactValueString{Value: "opensuse-leap"},
+					"ID_LIKE":        &entities.FactValueString{Value: "suse opensuse"},
+					"VERSION_ID":     &entities.FactValueString{Value: "15.2"},
+					"PRETTY_NAME":    &entities.FactValueString{Value: "openSUSE Leap 15.2"},
+					"ANSI_COLOR":     &entities.FactValueString{Value: "0;32"},
+					"CPE_NAME":       &entities.FactValueString{Value: "cpe:/o:opensuse:leap:15.2"},
+					"BUG_REPORT_URL": &entities.FactValueString{Value: "https://bugs.opensuse.org"},
+					"HOME_URL":       &entities.FactValueString{Value: "https://www.opensuse.org/"},
+				},
+			},
+			CheckID: "check1",
+		},
+	}
+
+	suite.NoError(err)
+	suite.ElementsMatch(expectedResults, factResults)
+}
+
+func (suite *OSReleaseGathererTestSuite) TestOSReleaseGathererFileNotExists() {
+	c := gatherers.NewOSReleaseGatherer("non_existing_file")
+
+	factRequests := []entities.FactRequest{
+		{
+			Name:     "os-release",
+			Gatherer: "os-release@v1",
+		},
+	}
+
+	_, err := c.Gather(factRequests)
+
+	suite.EqualError(err, "fact gathering error: os-release-file-error - error reading /etc/os-release file: "+
+		"open non_existing_file: no such file or directory")
+}
+
+func (suite *OSReleaseGathererTestSuite) TestOSReleaseGathererErrorDecoding() {
+
+	c := gatherers.NewOSReleaseGatherer(helpers.GetFixturePath("gatherers/os-release.invalid"))
+
+	factRequests := []entities.FactRequest{
+		{
+			Name:     "os-release",
+			Gatherer: "os-release",
+		},
+	}
+
+	_, err := c.Gather(factRequests)
+
+	suite.EqualError(err, "fact gathering error: os-release-decoding-error - error decoding file content: error on line 3: missing =")
+}

test/fixtures/gatherers/os-release.basic

@@ -0,0 +1,10 @@
+NAME="openSUSE Leap"
+VERSION="15.2"
+ID="opensuse-leap"
+ID_LIKE="suse opensuse"
+VERSION_ID="15.2"
+PRETTY_NAME="openSUSE Leap 15.2"
+ANSI_COLOR="0;32"
+CPE_NAME="cpe:/o:opensuse:leap:15.2"
+BUG_REPORT_URL="https://bugs.opensuse.org"
+HOME_URL="https://www.opensuse.org/"

test/fixtures/gatherers/os-release.invalid

@@ -0,0 +1,3 @@
+NAME="Ubuntu"
+VERSION="20.04.3 LTS (Focal Fossa)"
+ID_ubuntu