feat: support for release version info

Signed-off-by: Kush <[email protected]>

version/release.go

@@ -0,0 +1,101 @@
+package version
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"github.com/odpf/salt/log"
+
+	"github.com/hashicorp/go-version"
+	"github.com/pkg/errors"
+)
+
+var (
+	ReleaseInfoTimeout = time.Second * 1
+	GithubReleaseURL   = "https://api.github.com/repos/%s/releases/latest"
+)
+
+type Info struct {
+	Version string
+	TarURL  string
+}
+
+// GithubInfo fetches details related to provided release URL
+// releaseURL should point to a specific version
+// for example: https://api.github.com/repos/odpf/optimus/releases/latest
+func GithubInfo(releaseURL string) (*Info, error) {
+	httpClient := http.Client{
+		Timeout: ReleaseInfoTimeout,
+	}
+	req, err := http.NewRequest(http.MethodGet, releaseURL, nil)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to create request")
+	}
+	req.Header.Set("User-Agent", "odpf/salt")
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to reach releaseURL: %s", releaseURL)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.Wrapf(err, "failed to reach releaseURL: %s, returned: %d", releaseURL, resp.StatusCode)
+	}
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to read response body")
+	}
+
+	var releaseBody struct {
+		TagName string `json:"tag_name"`
+		Tarball string `json:"tarball_url"`
+	}
+	if err = json.Unmarshal(body, &releaseBody); err != nil {
+		return nil, errors.Wrapf(err, "failed to parse: %s", string(body))
+	}
+
+	return &Info{
+		Version: releaseBody.TagName,
+		TarURL:  releaseBody.Tarball,
+	}, nil
+}
+
+// IsCurrentLatest returns true if the current version string is greater than
+// or equal to latestVersion as per semantic versioning
+func IsCurrentLatest(currVersion, latestVersion string) (bool, error) {
+	currentV, err := version.NewVersion(currVersion)
+	if err != nil {
+		return false, errors.Wrapf(err, "failed to parse current version")
+	}
+	latestV, err := version.NewVersion(latestVersion)
+	if err != nil {
+		return false, errors.Wrapf(err, "failed to parse latest version")
+	}
+	if currentV.GreaterThan(latestV) {
+		return true, nil
+	}
+	return false, nil
+}
+
+// NotifyIfNotLatest prints a notification if current application version
+// is not latest
+func NotifyIfNotLatest(logger log.Logger, currentVersion, githubRepo string) error {
+	info, err := GithubInfo(fmt.Sprintf(GithubReleaseURL, githubRepo))
+	if err != nil {
+		return err
+	}
+
+	isLatest, err := IsCurrentLatest(currentVersion, info.Version)
+	if err != nil {
+		return nil
+	}
+	if isLatest {
+		logger.Info(fmt.Sprintf("a newer version is available: %s, consider updating the client", info.Version))
+	}
+	return nil
+}

version/release_test.go

@@ -0,0 +1,33 @@
+package version_test
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/odpf/salt/version"
+
+	"github.com/gorilla/mux"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetLatest(t *testing.T) {
+	muxRouter := mux.NewRouter()
+	server := httptest.NewServer(muxRouter)
+
+	t.Run("should return correct version tag for valid json response on release URL", func(t *testing.T) {
+		muxRouter.HandleFunc("/latest", func(rw http.ResponseWriter, r *http.Request) {
+			rw.Header().Set("Content-Type", "application/json")
+			response, _ := json.Marshal(struct {
+				TagName string `json:"tag_name"`
+			}{
+				TagName: "v0.0.2",
+			})
+			rw.Write(response)
+		})
+		info, err := version.GithubInfo("http://" + server.Listener.Addr().String() + "/latest")
+		assert.Nil(t, err)
+		assert.Equal(t, "v0.0.2", info.Version)
+	})
+}