Adding datasourceReachable function

Signed-off-by: Dave Henderson <dhenderson@gmail.com>

2 files changed, 38 insertions, 0 deletions

diff --git a/data/datasource.go b/data/datasource.go
index e4336fb5..6370bd5f 100644
--- a/data/datasource.go
+++ b/data/datasource.go
@@ -257,6 +257,17 @@ func (d *Data) Datasource(alias string, args ...string) (interface{}, error) {
 	return nil, errors.Errorf("Datasources of type %s not yet supported", source.Type)
 }
 
+// DatasourceReachable - Determines if the named datasource is reachable with
+// the given arguments. Reads from the datasource, and discards the returned data.
+func (d *Data) DatasourceReachable(alias string, args ...string) bool {
+	source, ok := d.Sources[alias]
+	if !ok {
+		return false
+	}
+	_, err := d.ReadSource(source, args...)
+	return err == nil
+}
+
 // Include -
 func (d *Data) Include(alias string, args ...string) (string, error) {
 	source, ok := d.Sources[alias]
diff --git a/data/datasource_test.go b/data/datasource_test.go
index dbf1f0af..ab71a060 100644
--- a/data/datasource_test.go
+++ b/data/datasource_test.go
@@ -170,6 +170,33 @@ func TestDatasource(t *testing.T) {
 	assert.Equal(t, "", actual)
 }
 
+func TestDatasourceReachable(t *testing.T) {
+	fname := "foo.json"
+	fs := memfs.Create()
+	_ = fs.Mkdir("/tmp", 0777)
+	f, _ := vfs.Create(fs, "/tmp/"+fname)
+	_, _ = f.Write([]byte("{}"))
+
+	sources := map[string]*Source{
+		"foo": {
+			Alias: "foo",
+			URL:   &url.URL{Scheme: "file", Path: "/tmp/" + fname},
+			Ext:   "json",
+			Type:  "application/json",
+			FS:    fs,
+		},
+		"bar": {
+			Alias: "bar",
+			URL:   &url.URL{Scheme: "file", Path: "/bogus"},
+			FS:    fs,
+		},
+	}
+	data := &Data{Sources: sources}
+
+	assert.True(t, data.DatasourceReachable("foo"))
+	assert.False(t, data.DatasourceReachable("bar"))
+}
+
 func TestDatasourceExists(t *testing.T) {
 	sources := map[string]*Source{
 		"foo": {Alias: "foo"},