Improved logging and standardized logging pattern

cmd/check.go

@@ -54,14 +54,23 @@ pinned-package-updater --remote <address of the upstream service> check [Dockerf
 			cobra.CheckErr(currentDirectoryErr)
 			defaultDockerfilePath := path.Join(currentDirectory, "Dockerfile")
 			args = append(args, defaultDockerfilePath)
-			log.Debugf("No dockerfile path provided, attempting to use the default %s dockerfile", defaultDockerfilePath)
+			log.WithFields(log.Fields{
+				"defaultFilePath": defaultDockerfilePath,
+			}).Debug("no dockerfile path provided, attempting to use the default dockerfile path")
 		}
 
 		// Aggregate the parsed updates
-		for _, dockerfilePath := range args {
-			log.Debugf("Parsing %s", dockerfilePath)
+		numberOfFiles := len(args)
+		for i, dockerfilePath := range args {
+			log.WithFields(log.Fields{
+				"filePath": dockerfilePath,
+			}).Debugf("parsing docker file %d/%d", i+1, numberOfFiles)
 			_, err := dockerfile.Parse(dockerfilePath)
 			if err != nil {
+				log.WithFields(log.Fields{
+					"filePath":    dockerfilePath,
+					"sourceError": err,
+				}).Fatal("unexpected error while parsing dockerfile")
 				return
 			}
 		}
@@ -77,7 +86,7 @@ func init() {
 
 	err := parser.InitCommandParsers()
 	if err != nil {
-		log.Errorf("Unexpected error while ")
+		log.Fatal("unexpected error while initializing command parsers")
 		return
 	}
 

cmd/root.go

@@ -31,14 +31,14 @@ import (
 type LogFormat enumflag.Flag
 
 const (
-	LoggingLogFmt LogFormat = iota
-	LoggingText
+	LoggingText LogFormat = iota
+	LoggingLogFmt
 	LoggingJson
 )
 
 var LogFormatIds = map[LogFormat][]string{
-	LoggingLogFmt: {"logfmt"},
 	LoggingText:   {"text"},
+	LoggingLogFmt: {"logfmt"},
 	LoggingJson:   {"json"},
 }
 
@@ -137,19 +137,22 @@ func initLogging() {
 	}
 
 	switch logFormat {
+	case LoggingText:
+		log.SetFormatter(&log.TextFormatter{})
 	case LoggingLogFmt:
 		log.SetFormatter(&log.TextFormatter{
 			DisableColors: true,
 			FullTimestamp: true,
 		})
-	case LoggingText:
-		log.SetFormatter(&log.TextFormatter{})
 	case LoggingJson:
 		log.SetFormatter(&log.JSONFormatter{})
 	default:
 		log.SetFormatter(&log.TextFormatter{})
 	}
 
-	log.Debugf("Set the logging level to %s", log.GetLevel().String())
-	log.Debugf("Set the logging formatter to '%s'", LogFormatIds[logFormat][0])
+	log.WithFields(log.Fields{
+		"loggingFormatter": LogFormatIds[logFormat][0],
+		"loggingLevel":     log.GetLevel().String(),
+		"loggingVerbosity": logVerbosity,
+	}).Info("configured logging")
 }

internal/parser/debian.go

@@ -33,17 +33,19 @@ type DebianCommandParser struct {
 }
 
 // GetRepositories Returns a list of Repository entries that were identified
-func (c DebianCommandParser) GetRepositories(command string) ([]*Repository, error) {
+func (c DebianCommandParser) GetRepositories(logger *log.Entry, command string) ([]*Repository, error) {
 	var repositories []*Repository
 
 	reader := strings.NewReader(command)
-	parsedScript, scriptParseErr := c.parser.Parse(reader, "")
-	if scriptParseErr != nil {
-		log.Fatalf("Failed to parse script \"%s\": %s", command, scriptParseErr)
-		return nil, scriptParseErr
+	parsedScript, err := c.parser.Parse(reader, "")
+	if err != nil {
+		logger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("failed to parse script")
+		return nil, err
 	}
 
-	var hasErrorWhileWalkingScript bool = false
+	var erroredWhileWalkingScript = false
 	var errorWhileWalkingScript error
 	syntax.Walk(parsedScript, func(node syntax.Node) bool {
 		switch parsedStatement := node.(type) {
@@ -51,22 +53,27 @@ func (c DebianCommandParser) GetRepositories(command string) ([]*Repository, err
 			switch parsedCommand := parsedStatement.Cmd.(type) {
 			case *syntax.CallExpr:
 				if isAddRepositoryExpression(*parsedCommand, parsedStatement.Redirs) {
-					repositoryInformation, repositoryParseErr := c.getAddedRepository(*parsedCommand, parsedStatement.Redirs)
-					if repositoryParseErr != nil {
-						log.Fatalf("Unexpected error while parsing repository from \"%s\": %s", c.shellNodeToString(node), repositoryParseErr)
-						hasErrorWhileWalkingScript = true
-						errorWhileWalkingScript = repositoryParseErr
+					repositoryInformation, err := c.getAddedRepository(*parsedCommand, parsedStatement.Redirs)
+					if err != nil {
+						logger.WithFields(log.Fields{
+							"rawScriptNode": c.shellNodeToString(node),
+							"sourceError":   err,
+						}).Fatal("unexpected error while parsing repository information")
+						erroredWhileWalkingScript = true
+						errorWhileWalkingScript = err
 						// Terminate walking early so we can raise an error
 						return false
 					}
 					repositories = append(repositories, &Repository{Information: repositoryInformation})
-					log.Debugf("Found repository \"%s\"", repositoryInformation)
+					logger.WithFields(log.Fields{
+						"repositoryInformation": repositoryInformation,
+					}).Debug("found repository")
 				}
 			}
 		}
 		return true
 	})
-	if hasErrorWhileWalkingScript {
+	if erroredWhileWalkingScript {
 		return repositories, errorWhileWalkingScript
 	}
 
@@ -74,17 +81,19 @@ func (c DebianCommandParser) GetRepositories(command string) ([]*Repository, err
 }
 
 // GetPinnedPackages get a list of all pinned packages
-func (c DebianCommandParser) GetPinnedPackages(command string) ([]*Package, error) {
+func (c DebianCommandParser) GetPinnedPackages(logger *log.Entry, command string) ([]*Package, error) {
 	var packages []*Package
 
 	reader := strings.NewReader(command)
-	parsedScript, scriptParseErr := c.parser.Parse(reader, "")
-	if scriptParseErr != nil {
-		log.Fatalf("Failed to parse script \"%s\"", command)
-		return nil, scriptParseErr
+	parsedScript, err := c.parser.Parse(reader, "")
+	if err != nil {
+		logger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("failed to parse script")
+		return nil, err
 	}
 
-	var hasErrorWhileWalkingScript bool = false
+	var erroredWhileWalkingScript = false
 	var errorWhileWalkingScript error
 	syntax.Walk(parsedScript, func(node syntax.Node) bool {
 		switch parsedStatement := node.(type) {
@@ -92,24 +101,29 @@ func (c DebianCommandParser) GetPinnedPackages(command string) ([]*Package, erro
 			switch parsedCommand := parsedStatement.Cmd.(type) {
 			case *syntax.CallExpr:
 				if isInstallerExpression(*parsedCommand) {
-					pinnedPackages, pinnedPackageParseErr := c.getInstalledPinnedPackages(*parsedCommand)
-					if pinnedPackageParseErr != nil {
-						log.Fatalf("Unexpected error while parsing pinned packages from \"%s\": %s", c.shellNodeToString(node), pinnedPackageParseErr)
-						hasErrorWhileWalkingScript = true
-						errorWhileWalkingScript = pinnedPackageParseErr
+					pinnedPackages, err := c.getInstalledPinnedPackages(*parsedCommand)
+					if err != nil {
+						logger.WithFields(log.Fields{
+							"rawScriptNode": c.shellNodeToString(node),
+							"sourceError":   err,
+						}).Fatal("unexpected error while parsing pinned packages")
+						erroredWhileWalkingScript = true
+						errorWhileWalkingScript = err
 						// Terminate walking early so we can raise an error
 						return false
 					}
 					for _, pinnedPackage := range pinnedPackages {
 						packages = append(packages, pinnedPackage)
-						log.Debugf("Found pinned package \"%s=%s\"", pinnedPackage.Name, pinnedPackage.Version)
+						logger.WithFields(log.Fields{
+							"pinnedPackageInformation": pinnedPackage,
+						}).Debug("found pinned package")
 					}
 				}
 			}
 		}
 		return true
 	})
-	if hasErrorWhileWalkingScript {
+	if erroredWhileWalkingScript {
 		return packages, errorWhileWalkingScript
 	}
 
@@ -194,6 +208,10 @@ func (c DebianCommandParser) getAddedRepository(command syntax.CallExpr, redirec
 	return "", errors.New("failed to parse repository")
 }
 
+/*
+Pinned Package Helpers
+*/
+
 // isAddRepositoryExpression Checks for expressions that add to the repository
 func isInstallerExpression(command syntax.CallExpr) bool {
 	// Adding via debian tooling
@@ -204,10 +222,6 @@ func isInstallerExpression(command syntax.CallExpr) bool {
 	return false
 }
 
-/*
-Pinned Package Helpers
-*/
-
 func (c DebianCommandParser) getInstalledPinnedPackages(command syntax.CallExpr) ([]*Package, error) {
 	var packages []*Package
 

internal/parser/dockerfile/dockerfile.go

@@ -19,7 +19,6 @@ package dockerfile
 
 import (
 	"errors"
-	"fmt"
 	"os"
 	"strings"
 
@@ -33,63 +32,118 @@ import (
 
 // Parse reads a Dockerfile, interprets the AST and returns information about the image(s) and package(s) defined
 func Parse(dockerfilePath string) (parser.ParseResult, error) {
-	dockerfile, dockerfileOpenErr := os.Open(dockerfilePath)
-	if dockerfileOpenErr != nil {
-		log.Fatalf("Unexpected error reading file %s: %s", dockerfilePath, dockerfileOpenErr)
-		return parser.ParseResult{}, dockerfileOpenErr
+
+	parseLogger := log.WithFields(log.Fields{
+		"filePath": dockerfilePath,
+	})
+
+	dockerfile, err := os.Open(dockerfilePath)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error reading file")
+		return parser.ParseResult{}, err
 	}
 	defer func(dockerfile *os.File) {
-		dockerfileCloseErr := dockerfile.Close()
-		if dockerfileCloseErr != nil {
-			log.Error("Unexpected error closing file %s: %s", dockerfilePath, dockerfileCloseErr)
+		err := dockerfile.Close()
+		if err != nil {
+			parseLogger.WithFields(log.Fields{
+				"sourceError": err,
+			}).Error("unexpected error closing file")
 		}
 	}(dockerfile)
 
-	parsedASTResult, ASTParseErr := buildkitParser.Parse(dockerfile)
-	if ASTParseErr != nil {
-		log.Fatalf("Unexpected error parsing Dockerfile %s: %s", dockerfilePath, ASTParseErr)
-		return parser.ParseResult{}, ASTParseErr
+	parsedASTResult, err := buildkitParser.Parse(dockerfile)
+	if err != nil {
+		parseLogger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error parsing Dockerfile")
+		return parser.ParseResult{}, err
 	}
 
-	parseResult, parseErr := parseDockerfileAST(parsedASTResult.AST)
-	if parseErr != nil {
-		log.Fatalf("Unexpected error while parsing AST for %s: %s", dockerfilePath, parseErr)
-		return parser.ParseResult{}, parseErr
+	parseResult, err := parseDockerfileAST(parseLogger, dockerfilePath, parsedASTResult.AST)
+	if err != nil {
+		parseLogger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error while parsing AST")
+		return parser.ParseResult{}, err
 	}
 
 	return parseResult, nil
 }
 
-// parseDockerfileAST Read the parsed AST and extract the required information from each stage
-func parseDockerfileAST(dockerfileAST *buildkitParser.Node) (parser.ParseResult, error) {
+/*
+General Helpers
+*/
+
+// getCommandLineLocation parse commandLineLocation information into the structure we will persist
+func getContentLocation(location []buildkitParser.Range) (parser.ContentLocation, error) {
+
+	commandLocationStart := location[0].Start
+	commandLocationEnd := location[len(location)-1].End
+
+	return parser.ContentLocation{
+		StartLine:      commandLocationStart.Line,
+		StartCharacter: commandLocationStart.Character,
+		EndLine:        commandLocationEnd.Line,
+		EndCharacter:   commandLocationEnd.Character,
+	}, nil
+}
+
+/*
+Parsing Helper
+*/
 
-	dockerfileStages, _, stageParsingErr := buildkitInstructions.Parse(dockerfileAST)
-	if stageParsingErr != nil {
-		log.Fatalf("Unexpected error while parsing Dockerfile Instructions: %s", stageParsingErr)
-		return parser.ParseResult{}, stageParsingErr
+// parseDockerfileAST Read the parsed AST and extract the required information from each stage
+func parseDockerfileAST(logger *log.Entry, dockerFilePath string, dockerfileAST *buildkitParser.Node) (parser.ParseResult, error) {
+
+	dockerfileStages, _, err := buildkitInstructions.Parse(dockerfileAST)
+	if err != nil {
+		logger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error while parsing Dockerfile instructions")
+		return parser.ParseResult{}, err
 	}
 
 	var stages []*parser.Stage
 	for stageIndex, stage := range dockerfileStages {
-		stage, stageErr := parseDockerfileStage(stage)
-		if stageErr != nil {
-			log.Fatal("Unexpected error while parsing stage %d", stageIndex)
-			return parser.ParseResult{}, stageErr
+		stageLogger := logger.WithFields(log.Fields{
+			"stageIndex": stageIndex,
+			"stageName":  stage.Name,
+		})
+		stage, err := parseDockerfileStage(stageLogger, stageIndex, stage)
+		if err != nil {
+			stageLogger.WithFields(log.Fields{
+				"sourceError": err,
+			}).Fatal("unexpected error while parsing stage")
+			return parser.ParseResult{}, err
 		}
 		stages = append(stages, &stage)
 	}
 
-	return parser.ParseResult{Stages: stages}, nil
+	return parser.ParseResult{FilePath: dockerFilePath, Stages: stages}, nil
 }
 
-func parseDockerfileStage(dockerfileStage buildkitInstructions.Stage) (parser.Stage, error) {
+func parseDockerfileStage(logger *log.Entry, dockerfileStageIndex int, dockerfileStage buildkitInstructions.Stage) (parser.Stage, error) {
+
+	stageLocation, err := getContentLocation(dockerfileStage.Location)
+	if err != nil {
+		logger.WithFields(log.Fields{
+			"rawStageLocation": dockerfileStage.Location,
+		}).Fatal("unexpected failure parsing stage location information")
+		return parser.Stage{}, err
+	}
+
+	stageLogger := logger.WithFields(log.Fields{
+		"stageImage":    dockerfileStage.BaseName,
+		"stageLocation": stageLocation,
+	})
 
 	imageParts := strings.Split(dockerfileStage.BaseName, ":")
 
 	if len(imageParts) < 2 {
-		message := fmt.Sprintf("Not enough information in image (%s) to determine base", imageParts)
-		log.Fatal(message)
-		return parser.Stage{}, errors.New(message)
+		stageLogger.Fatal("not enough information in image to determine base")
+		return parser.Stage{}, errors.New("not enough information in image to determine base")
 	}
 
 	name := dockerfileStage.Name
@@ -98,80 +152,125 @@ func parseDockerfileStage(dockerfileStage buildkitInstructions.Stage) (parser.St
 		Tag:  imageParts[1],
 	}
 
-	commandParser, commandParserRetrievalErr := parser.GetCommandParser(image)
-	if commandParserRetrievalErr != nil {
-		log.Fatalf("Unexpected error while determining command parser for image \"%s\": %s", image, commandParserRetrievalErr)
-		return parser.Stage{}, commandParserRetrievalErr
+	commandParser, err := parser.GetCommandParser(image)
+	if err != nil {
+		stageLogger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error while determining command parser for image")
+		return parser.Stage{}, err
 	}
 
-	repositories, repositoryCommandParseErr := parseRepositoriesFromDockerfileStage(dockerfileStage, commandParser)
-	if repositoryCommandParseErr != nil {
-		message := fmt.Sprintf("Unexpected error while parsing repositories from stage: %s", repositoryCommandParseErr)
-		log.Fatal(message)
-		return parser.Stage{}, errors.New(message)
+	repositories, repositoryCommandLocations, err := parseRepositoriesFromDockerfileStage(stageLogger, dockerfileStage, commandParser)
+	if err != nil {
+		stageLogger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error while parsing repositories from stage")
+		return parser.Stage{}, err
 	}
 
-	packages, packageCommandParseErr := parsePackagesFromDockerfileStage(dockerfileStage, commandParser)
-	if packageCommandParseErr != nil {
-		message := fmt.Sprintf("Unexpected error while parsing packages from stage: %s", packageCommandParseErr)
-		log.Fatal(message)
-		return parser.Stage{}, errors.New(message)
+	packages, packageCommandLocations, err := parsePackagesFromDockerfileStage(stageLogger, dockerfileStage, commandParser)
+	if err != nil {
+		stageLogger.WithFields(log.Fields{
+			"sourceError": err,
+		}).Fatal("unexpected error while parsing packages from stage")
+		return parser.Stage{}, err
 	}
 
+	var commandLocations []*parser.ContentLocation
+	commandLocations = append(commandLocations, repositoryCommandLocations...)
+	commandLocations = append(commandLocations, packageCommandLocations...)
+
 	return parser.Stage{
-		Name:         name,
-		Image:        &image,
-		Repositories: repositories,
-		Packages:     packages,
+		Index:            dockerfileStageIndex,
+		Name:             name,
+		Image:            &image,
+		StageLocation:    stageLocation,
+		Repositories:     repositories,
+		Packages:         packages,
+		CommandLocations: commandLocations,
 	}, nil
 }
 
-func parseRepositoriesFromDockerfileStage(dockerfileStage buildkitInstructions.Stage, commandParser *parser.CommandParser) ([]*parser.Repository, error) {
+func parseRepositoriesFromDockerfileStage(logger *log.Entry, dockerfileStage buildkitInstructions.Stage, commandParser *parser.CommandParser) ([]*parser.Repository, []*parser.ContentLocation, error) {
 	var repositories []*parser.Repository
+	var commandLocations []*parser.ContentLocation
+
 	typedCommandParser := *commandParser
 
 	for _, command := range dockerfileStage.Commands {
-		switch command.(type) {
+		switch typedCommand := command.(type) {
 		case *buildkitInstructions.RunCommand:
-			runCommand := command.(*buildkitInstructions.RunCommand)
-
-			log.Tracef("Parsing RunCommand \"%s\" for repositories", runCommand.CmdLine)
-
-			parsedRepositories, repositoryParseErr := typedCommandParser.GetRepositories(runCommand.CmdLine[0])
-			if repositoryParseErr != nil {
-				log.Fatalf("Unexpected error while parsing repositories: %s", repositoryParseErr)
-				return nil, repositoryParseErr
+			commandLocation, err := getContentLocation(typedCommand.Location())
+			if err != nil {
+				logger.WithFields(log.Fields{
+					"rawCommandLineLocation": typedCommand.Location(),
+				}).Fatal("unexpected failure parsing script location information")
+				return repositories, commandLocations, err
 			}
-			for _, parsedRepository := range parsedRepositories {
-				repositories = append(repositories, parsedRepository)
+			commandLocations = append(commandLocations, &commandLocation)
+
+			for _, line := range typedCommand.CmdLine {
+				logger.WithFields(log.Fields{
+					"commandLine":     line,
+					"commandLocation": commandLocation,
+				}).Trace("parsing RunCommand for repositories")
+				parsedRepositories, err := typedCommandParser.GetRepositories(logger, line)
+				if err != nil {
+					logger.WithFields(log.Fields{
+						"commandLine":     line,
+						"commandLocation": commandLocation,
+						"sourceError":     err,
+					}).Fatal("unexpected error while parsing repositories")
+					return repositories, commandLocations, err
+				}
+				for _, parsedRepository := range parsedRepositories {
+					repositories = append(repositories, parsedRepository)
+				}
 			}
 		}
 	}
 
-	return repositories, nil
+	return repositories, commandLocations, nil
 }
 
-func parsePackagesFromDockerfileStage(dockerfileStage buildkitInstructions.Stage, commandParser *parser.CommandParser) ([]*parser.Package, error) {
+func parsePackagesFromDockerfileStage(logger *log.Entry, dockerfileStage buildkitInstructions.Stage, commandParser *parser.CommandParser) ([]*parser.Package, []*parser.ContentLocation, error) {
 	var packages []*parser.Package
+	var commandLocations []*parser.ContentLocation
+
 	typedCommandParser := *commandParser
 
 	for _, command := range dockerfileStage.Commands {
-		switch command.(type) {
+		switch typedCommand := command.(type) {
 		case *buildkitInstructions.RunCommand:
-			runCommand := command.(*buildkitInstructions.RunCommand)
-
-			log.Tracef("Parsing RunCommand \"%s\" for packages", runCommand.CmdLine)
-
-			parsedPinnedPackages, packageParseErr := typedCommandParser.GetPinnedPackages(runCommand.CmdLine[0])
-			if packageParseErr != nil {
-				log.Fatalf("Unexpected error while parsing pinned packages: %s", packageParseErr)
-				return nil, packageParseErr
+			commandLocation, err := getContentLocation(typedCommand.Location())
+			if err != nil {
+				logger.WithFields(log.Fields{
+					"rawCommandLineLocation": typedCommand.Location(),
+				}).Fatal("unexpected failure parsing script location information")
+				return packages, commandLocations, err
 			}
-			for _, parsedPinnedPackage := range parsedPinnedPackages {
-				packages = append(packages, parsedPinnedPackage)
+			commandLocations = append(commandLocations, &commandLocation)
+
+			for _, line := range typedCommand.CmdLine {
+				logger.WithFields(log.Fields{
+					"commandLine":     line,
+					"commandLocation": commandLocation,
+				}).Trace("parsing RunCommand for packages")
+				parsedPinnedPackages, err := typedCommandParser.GetPinnedPackages(logger, line)
+				if err != nil {
+					logger.WithFields(log.Fields{
+						"commandLine":     line,
+						"commandLocation": commandLocation,
+						"sourceError":     err,
+					}).Fatal("unexpected error while parsing pinned packages")
+					return packages, commandLocations, err
+				}
+				for _, parsedPinnedPackage := range parsedPinnedPackages {
+					packages = append(packages, parsedPinnedPackage)
+				}
 			}
 		}
 	}
 
-	return packages, nil
+	return packages, commandLocations, nil
 }

internal/parser/parser.go

@@ -20,21 +20,62 @@ package parser
 import (
 	"errors"
 	"fmt"
-
 	log "github.com/sirupsen/logrus"
 )
 
 // ParseResult is the standard representation for am image declaration
 type ParseResult struct {
-	Stages []*Stage
+	FilePath string
+	Stages   []*Stage
+}
+
+// String implements fmt.Stringer interface
+func (pr ParseResult) String() string {
+	return fmt.Sprintf(
+		"%s with %d stage(s)",
+		pr.FilePath,
+		len(pr.Stages),
+	)
 }
 
 // Stage is the representation of a stage in the image declaration
 type Stage struct {
-	Name         string
-	Image        *Image
-	Repositories []*Repository
-	Packages     []*Package
+	Index            int
+	Name             string
+	Image            *Image
+	Repositories     []*Repository
+	Packages         []*Package
+	StageLocation    ContentLocation
+	CommandLocations []*ContentLocation
+}
+
+// String implements fmt.Stringer interface
+func (s Stage) String() string {
+	return fmt.Sprintf(
+		"%d %s %s",
+		s.Index,
+		s.Name,
+		s.Image,
+	)
+}
+
+// ContentLocation information about where a specific set of information exists within the file/manifest
+type ContentLocation struct {
+	StartLine      int
+	StartCharacter int
+	EndLine        int
+	EndCharacter   int
+}
+
+// String implements fmt.Stringer interface
+func (cl ContentLocation) String() string {
+	return fmt.Sprintf(
+		"%d.%d:%d.%d",
+		cl.StartLine,
+		cl.StartCharacter,
+		cl.EndLine,
+		cl.EndCharacter,
+	)
 }
 
 // Image is the representation of the reference to a container image layer
@@ -43,17 +84,43 @@ type Image struct {
 	Tag  string
 }
 
+// String implements fmt.Stringer interface
+func (i Image) String() string {
+	return fmt.Sprintf(
+		"%s:%s",
+		i.Name,
+		i.Tag,
+	)
+}
+
 // Package is the representation of an installed pinned package defined in an image stage declaration
 type Package struct {
 	Name    string
 	Version string
 }
 
+// String implements fmt.Stringer interface
+func (p Package) String() string {
+	return fmt.Sprintf(
+		"%s=%s",
+		p.Name,
+		p.Version,
+	)
+}
+
 // Repository is the representation of an added repository defined in a stage declaration
 type Repository struct {
 	Information string
 }
 
+// String implements fmt.Stringer interface
+func (r Repository) String() string {
+	return fmt.Sprintf(
+		"%s",
+		r.Information,
+	)
+}
+
 // CommandParserType represents the recognized type of parser usable for a specific image
 type CommandParserType int
 
@@ -61,12 +128,13 @@ const (
 	CommandParserTypeDebian CommandParserType = iota
 )
 
-// CommandParserTypeIds is a lookup map between CommandParserType and a representation string
+// commandParserTypeIds is a lookup map between CommandParserType and a representation string
 var commandParserTypeIds = map[CommandParserType][]string{
 	CommandParserTypeDebian: {"debian"},
 }
 
-func lookupCommandParserTypeName(parserType CommandParserType) string {
+// findCommandParserTypeName lookup the command parser name by type enum
+func findCommandParserTypeName(parserType CommandParserType) string {
 	if parserTypeName, ok := commandParserTypeIds[parserType]; ok {
 		return parserTypeName[0]
 	} else {
@@ -78,8 +146,8 @@ var availableCommandParsers = map[CommandParserType]CommandParser{}
 
 // CommandParser handles parsing commands from RUN arguments dependent on the base image type
 type CommandParser interface {
-	GetRepositories(runCommand string) ([]*Repository, error)
-	GetPinnedPackages(runCommand string) ([]*Package, error)
+	GetRepositories(logger *log.Entry, runCommand string) ([]*Repository, error)
+	GetPinnedPackages(logger *log.Entry, runCommand string) ([]*Package, error)
 }
 
 // InitCommandParsers exposes functionality to configure the behavior of mapping images to a CommandParser
@@ -88,21 +156,29 @@ func InitCommandParsers() error {
 	// Registering known parsers
 	availableCommandParsers[CommandParserTypeDebian] = newDebianCommandParser()
 
+	// TODO: Add dynamic loading from configuration
+
 	return nil
 }
 
 func GetCommandParser(image Image) (*CommandParser, error) {
-	parserType, determineParserErr := determineParserForImage(image)
-	if determineParserErr != nil {
-		log.Fatalf("Failed to determine a matching CommandParser for %s: %s", image, determineParserErr)
-		return nil, determineParserErr
+	parserType, err := determineParserForImage(image)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"imageName":   image.Name,
+			"imageTag":    image.Tag,
+			"sourceError": err,
+		}).Fatal("failed to determine a matching CommandParser for image")
+		return nil, err
 	}
 
 	if requestedCommandParser, ok := availableCommandParsers[parserType]; ok {
 		return &requestedCommandParser, nil
 	} else {
-		message := fmt.Sprintf("Unable to identify parser for %s", lookupCommandParserTypeName(parserType))
-		log.Fatal(message)
+		message := "unable to identify command parser type"
+		log.WithFields(log.Fields{
+			"commandParserType": findCommandParserTypeName(parserType),
+		}).Fatal(message)
 		return nil, errors.New(message)
 	}
 }