add more debugging information (#65)

- makes debugging configuration issues easier by adding more context
  instead of misleading "missing signature key" and similar

clair/clair.go

@@ -65,8 +65,10 @@ func (c *Clair) getJSON(url string, response interface{}) (http.Header, error) {
 		return nil, err
 	}
 	defer resp.Body.Close()
+	c.Logf("clair.clair resp.Status=%s", resp.Status)
 
 	if err := json.NewDecoder(resp.Body).Decode(response); err != nil {
+		c.Logf("clair.clair resp.Status=%s, body=%s", resp.Status, response)
 		return nil, err
 	}
 

clair/layer.go

@@ -39,6 +39,7 @@ func (c *Clair) PostLayer(layer *Layer) (*Layer, error) {
 		return nil, err
 	}
 	defer resp.Body.Close()
+	c.Logf("clair.clair resp.Status=%s", resp.Status)
 
 	var respLayer layerEnvelope
 	if err := json.NewDecoder(resp.Body).Decode(&respLayer); err != nil {
@@ -67,6 +68,7 @@ func (c *Clair) DeleteLayer(name string) error {
 		return err
 	}
 	defer resp.Body.Close()
+	c.Logf("clair.clair resp.Status=%s", resp.Status)
 
 	if resp.StatusCode == http.StatusOK || resp.StatusCode == http.StatusAccepted || resp.StatusCode == http.StatusNotFound {
 		return nil

clair/vulns.go

@@ -110,6 +110,7 @@ func (c *Clair) NewClairLayer(r *registry.Registry, image string, fsLayers []sch
 	}
 
 	if token == "" || useBasicAuth {
+    c.Logf("clair.vulns using basic auth")
 		h = map[string]string{
 			"Authorization": fmt.Sprintf("Basic %s", base64.StdEncoding.EncodeToString([]byte(r.Username+":"+r.Password))),
 		}

main.go

@@ -300,9 +300,12 @@ func main() {
 
 				// filter out the empty layers
 				var filteredLayers []schema1.FSLayer
-				for _, layer := range m.FSLayers {
+				for i, layer := range m.FSLayers {
 					if !clair.IsEmptyLayer(layer.BlobSum) {
 						filteredLayers = append(filteredLayers, layer)
+						logrus.Debugf("%d: layer=%s <-- append", i, layer)
+					} else {
+						logrus.Debugf("%d: layer=%s", i, layer)
 					}
 				}
 				m.FSLayers = filteredLayers
@@ -310,6 +313,7 @@ func main() {
 					fmt.Printf("No need to analyse image %s:%s as there is no non-emtpy layer", repo, ref)
 					return nil
 				}
+				fmt.Printf("Analysing %d layers\n", len(m.FSLayers))
 
 				// initialize clair
 				cr, err := clair.New(c.String("clair"), c.GlobalBool("debug"))

registry/manifest.go

@@ -33,6 +33,7 @@ func (r *Registry) Manifest(repository, ref string) (distribution.Manifest, erro
 	if err != nil {
 		return nil, err
 	}
+	r.Logf("registry.manifests resp.Status=%s, body=%s", resp.Status, body)
 
 	m, _, err := distribution.UnmarshalManifest(resp.Header.Get("Content-Type"), body)
 	if err != nil {
@@ -49,6 +50,7 @@ func (r *Registry) ManifestList(repository, ref string) (manifestlist.ManifestLi
 
 	var m manifestlist.ManifestList
 	if _, err := r.getJSON(uri, &m, true); err != nil {
+		r.Logf("registry.manifests response=%v", m)
 		return m, err
 	}
 
@@ -62,6 +64,7 @@ func (r *Registry) ManifestV2(repository, ref string) (schema2.Manifest, error)
 
 	var m schema2.Manifest
 	if _, err := r.getJSON(uri, &m, true); err != nil {
+		r.Logf("registry.manifests response=%v", m)
 		return m, err
 	}
 
@@ -75,6 +78,7 @@ func (r *Registry) ManifestV1(repository, ref string) (schema1.SignedManifest, e
 
 	var m schema1.SignedManifest
 	if _, err := r.getJSON(uri, &m, false); err != nil {
+		r.Logf("registry.manifests response=%v", m)
 		return m, err
 	}
 

registry/registry.go

@@ -123,6 +123,7 @@ func (r *Registry) getJSON(url string, response interface{}, addV2Header bool) (
 		return nil, err
 	}
 	defer resp.Body.Close()
+	r.Logf("registry.registry resp.Status=%s", resp.Status)
 
 	if err := json.NewDecoder(resp.Body).Decode(response); err != nil {
 		return nil, err