Multi-level logging (#185)

Closes #93

Summary of changes:

- Adds the [uber-go-/zap](https://github.com/uber-go/zap) library for leveled logging (69040996e0bcbd2f211d0d8d576147027e928e3b)
- A new CLI arg `--log-level` which can take the values `debug` `info` `warn` `error` `fatal` `panic`. The default is `info`, and the existing `--quiet` flag is treated as `--log-level warn`
- All `helm.exec` calls are preceded by a one-line summary. The current information on the full helm command line arguments `exec: helm exec ... ` is only output at `debug` level. This means sensitive command line arguments which may include passwords and `--set` arguments should be hidden by default.

helmexec/exec.go

@@ -1,9 +1,11 @@
 package helmexec
 
 import (
-	"fmt"
 	"io"
 	"strings"
+
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
 )
 
 const (
@@ -13,16 +15,33 @@ const (
 type execer struct {
 	helmBinary  string
 	runner      Runner
-	writer      io.Writer
+	logger      *zap.SugaredLogger
 	kubeContext string
 	extra       []string
 }
 
+func NewLogger(writer io.Writer, logLevel string) *zap.SugaredLogger {
+	var cfg zapcore.EncoderConfig
+	cfg.MessageKey = "message"
+	out := zapcore.AddSync(writer)
+	var level zapcore.Level
+	err := level.Set(logLevel)
+	if err != nil {
+		panic(err)
+	}
+	core := zapcore.NewCore(
+		zapcore.NewConsoleEncoder(cfg),
+		out,
+		level,
+	)
+	return zap.New(core).Sugar()
+}
+
 // New for running helm commands
-func New(writer io.Writer, kubeContext string) *execer {
+func New(logger *zap.SugaredLogger, kubeContext string) *execer {
 	return &execer{
 		helmBinary:  command,
-		writer:      writer,
+		logger:      logger,
 		kubeContext: kubeContext,
 		runner:      &ShellRunner{},
 	}
@@ -45,68 +64,77 @@ func (helm *execer) AddRepo(name, repository, certfile, keyfile, username, passw
 	if username != "" && password != "" {
 		args = append(args, "--username", username, "--password", password)
 	}
+	helm.logger.Infof("Adding repo %v %v", name, repository)
 	out, err := helm.exec(args...)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) UpdateRepo() error {
+	helm.logger.Info("Updating repo")
 	out, err := helm.exec("repo", "update")
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) UpdateDeps(chart string) error {
+	helm.logger.Infof("Updating dependency %v", chart)
 	out, err := helm.exec("dependency", "update", chart)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) SyncRelease(name, chart string, flags ...string) error {
+	helm.logger.Infof("Upgrading %v", chart)
 	out, err := helm.exec(append([]string{"upgrade", "--install", "--reset-values", name, chart}, flags...)...)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) ReleaseStatus(name string) error {
+	helm.logger.Infof("Getting status %v", name)
 	out, err := helm.exec(append([]string{"status", name})...)
-	if helm.writer != nil {
-		helm.writer.Write(out)
-	}
+	helm.write(out)
 	return err
 }
 
 func (helm *execer) DecryptSecret(name string) (string, error) {
+	helm.logger.Infof("Decrypting secret %v", name)
 	out, err := helm.exec(append([]string{"secrets", "dec", name})...)
 	helm.write(out)
 	return name + ".dec", err
 }
 
 func (helm *execer) DiffRelease(name, chart string, flags ...string) error {
+	helm.logger.Infof("Comparing %v %v", name, chart)
 	out, err := helm.exec(append([]string{"diff", "upgrade", "--allow-unreleased", name, chart}, flags...)...)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) Lint(chart string, flags ...string) error {
+	helm.logger.Infof("Linting %v", chart)
 	out, err := helm.exec(append([]string{"lint", chart}, flags...)...)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) Fetch(chart string, flags ...string) error {
+	helm.logger.Infof("Fetching %v", chart)
 	out, err := helm.exec(append([]string{"fetch", chart}, flags...)...)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) DeleteRelease(name string, flags ...string) error {
+	helm.logger.Infof("Deleting %v", name)
 	out, err := helm.exec(append([]string{"delete", name}, flags...)...)
 	helm.write(out)
 	return err
 }
 
 func (helm *execer) TestRelease(name string, flags ...string) error {
+	helm.logger.Infof("Testing %v", name)
 	out, err := helm.exec(append([]string{"test", name}, flags...)...)
 	helm.write(out)
 	return err
@@ -120,12 +148,12 @@ func (helm *execer) exec(args ...string) ([]byte, error) {
 	if helm.kubeContext != "" {
 		cmdargs = append(cmdargs, "--kube-context", helm.kubeContext)
 	}
-	helm.write([]byte(fmt.Sprintf("exec: %s %s\n", helm.helmBinary, strings.Join(cmdargs, " "))))
+	helm.logger.Debugf("exec: %s %s", helm.helmBinary, strings.Join(cmdargs, " "))
 	return helm.runner.Execute(helm.helmBinary, cmdargs)
 }
 
 func (helm *execer) write(out []byte) {
-	if helm.writer != nil {
-		helm.writer.Write(out)
+	if len(out) > 0 {
+		helm.logger.Infof("%s", out)
 	}
 }