Add a configuration to exclude images

Adds two configuration options that let the user skip images that are
either matching the configured image name or tag.

Related: stacklok#150

pkg/utils/config/config.go

@@ -59,6 +59,7 @@ func FromCommand(cmd *cobra.Command) (*Config, error) {
 type Config struct {
 	Platform  string    `yaml:"platform" mapstructure:"platform"`
 	GHActions GHActions `yaml:"ghactions" mapstructure:"ghactions"`
+	Images    Images    `yaml:"images" mapstructure:"images"`
 }
 
 // GHActions is the GitHub Actions configuration.
@@ -72,15 +73,39 @@ type Filter struct {
 	Exclude []string `yaml:"exclude" mapstructure:"exclude"`
 }
 
+// Images is the image configuration.
+type Images struct {
+	ImageFilter `yaml:",inline" mapstructure:",inline"`
+}
+
+// ImageFilter is the image filter configuration.
+type ImageFilter struct {
+	// ExcludeImages is a regex that must match in order for an image to be excluded and not pinned
+	ExcludeImages []string `yaml:"exclude_images" mapstructure:"exclude_images"`
+	ExcludeTags   []string `yaml:"exclude_tags" mapstructure:"exclude_tags"`
+}
+
 // ParseConfigFile parses a configuration file.
 func ParseConfigFile(configfile string) (*Config, error) {
 	bfs := osfs.New(".")
 	return ParseConfigFileFromFS(bfs, configfile)
 }
 
+func defaultConfig() *Config {
+	return &Config{
+		Platform: "linux/amd64",
+		Images: Images{
+			ImageFilter: ImageFilter{
+				ExcludeImages: []string{"scratch"},
+				ExcludeTags:   []string{"latest"},
+			},
+		},
+	}
+}
+
 // ParseConfigFileFromFS parses a configuration file from a filesystem.
 func ParseConfigFileFromFS(fs billy.Filesystem, configfile string) (*Config, error) {
-	cfg := &Config{}
+	cfg := defaultConfig()
 	cleancfgfile := filepath.Clean(configfile)
 	cfgF, err := fs.Open(cleancfgfile)
 	if err != nil {
@@ -94,10 +119,9 @@ func ParseConfigFileFromFS(fs billy.Filesystem, configfile string) (*Config, err
 
 	dec := yaml.NewDecoder(cfgF)
 	if err := dec.Decode(cfg); err != nil {
-		if err == io.EOF {
-			return cfg, nil
+		if err != io.EOF {
+			return nil, fmt.Errorf("failed to decode config file: %w", err)
 		}
-		return nil, fmt.Errorf("failed to decode config file: %w", err)
 	}
 
 	return cfg, nil

pkg/utils/config/config_test.go

@@ -82,7 +82,7 @@ func TestParseConfigFile(t *testing.T) {
 		{
 			name:           "FileNotFound",
 			fileName:       "nonexistent.yaml",
-			expectedResult: &Config{},
+			expectedResult: defaultConfig(),
 		},
 		{
 			name:        "InvalidYaml",
@@ -100,6 +100,11 @@ ghactions:
   exclude:
     - pattern1
     - pattern2
+images:
+  exclude_images:
+    - notthisone
+  exclude_tags:
+    - notthistag	
 `,
 			},
 			expectedResult: &Config{
@@ -109,13 +114,19 @@ ghactions:
 						Exclude: []string{"pattern1", "pattern2"},
 					},
 				},
+				Images: Images{
+					ImageFilter: ImageFilter{
+						ExcludeImages: []string{"notthisone"},
+						ExcludeTags:   []string{"notthistag"},
+					},
+				},
 			},
 		},
 		{
 			name:           "EmptyFile",
 			fileName:       "empty.yaml",
 			fsContent:      map[string]string{"empty.yaml": ""},
-			expectedResult: &Config{},
+			expectedResult: defaultConfig(),
 		},
 	}
 
@@ -141,6 +152,12 @@ ghactions:
 				if cfg.GHActions.Exclude != nil {
 					require.Equal(t, tt.expectedResult.GHActions.Exclude, cfg.GHActions.Exclude)
 				}
+				if cfg.Images.ExcludeImages != nil {
+					require.Equal(t, tt.expectedResult.Images.ExcludeImages, cfg.Images.ExcludeImages)
+				}
+				if cfg.Images.ExcludeTags != nil {
+					require.Equal(t, tt.expectedResult.Images.ExcludeTags, cfg.Images.ExcludeTags)
+				}
 			}
 		})
 	}