cmd/root, pkg/utils: Add support for configuration files

It looks like there are some oddities with Viper [1]. The errors can't
be examined with errors.As [2] and Viper doesn't actually throw
ConfigFileNotFoundError if a configuration file is not found. Secondly,
there's no way to find out if a key was actually specified in a
configuration file. The InConfig API doesn't return 'true' even if a
key was mentioned in a configuration file, and the IsSet API returns
'true' even if the key was only set via SetDefault in the code.

Some changes by Debarshi Ray.

[1] https://pkg.go.dev/github.com/spf13/viper
[2] https://blog.golang.org/go1.13-errors

containers#828
containers#851

src/cmd/root.go

@@ -143,6 +143,10 @@ func preRun(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
+	if err := utils.SetUpConfiguration(); err != nil {
+		return err
+	}
+
 	return nil
 }
 

src/go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/mattn/go-isatty v0.0.8
 	github.com/sirupsen/logrus v1.4.2
 	github.com/spf13/cobra v0.0.5
+	github.com/spf13/viper v1.3.2
 	github.com/stretchr/testify v1.7.0
 	golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9
 	golang.org/x/sys v0.0.0-20190422165155-953cdadca894

src/go.sum

@@ -1,3 +1,4 @@
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/HarryMichal/go-version v1.0.0 h1:fXYa5vT46C3pULfSIgnfeNfSxJ9bCGZ2ERn/wKPlD6c=
 github.com/HarryMichal/go-version v1.0.0/go.mod h1:w3uLQ2NlFmZ01qBywppIbDplbPEjeBW8xywlluMcMsc=
@@ -21,31 +22,39 @@ github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/godbus/dbus/v5 v5.0.3 h1:ZqHaoEF7TBzh4jzPmqVhE/5A1z9of6orkAe5uHoAeME=
 github.com/godbus/dbus/v5 v5.0.3/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/hashicorp/hcl v1.0.0 h1:0Anlzjpi4vEasTeNFn2mLJgTSwt0+6sfsiTG8qcWGx4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1 h1:mweAR1A6xJ3oS2pRaGiHgQ4OO8tzTaLawm8vnODuwDk=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/magiconair/properties v1.8.0 h1:LLgXmsheXeRoUOBOjtwPQCWIYqM/LU1ayDtDePerRcY=
 github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/mattn/go-colorable v0.1.2 h1:/bC9yWikZXAL9uJdulbSfyVNIR3n3trXl+v8+1sx8mU=
 github.com/mattn/go-colorable v0.1.2/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-isatty v0.0.8 h1:HLtExJ+uU2HOZ+wI0Tt5DtUDrx8yhUqDcp7fYERX4CE=
 github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
+github.com/mitchellh/mapstructure v1.1.2 h1:fmNYVwqnSfB9mZU6OS2O6GsXM+wcskZDuKQzvN1EDeE=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
+github.com/pelletier/go-toml v1.2.0 h1:T5zMGML61Wp+FlcbWjRDT7yAxhJNAiPPLOFECq181zc=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
 github.com/sirupsen/logrus v1.4.2 h1:SPIRibHv4MatM3XXNO2BJeFLZwZ2LvZgfQ5+UNI2im4=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
+github.com/spf13/afero v1.1.2 h1:m8/z1t7/fwjysjQRYbP0RD+bUIF/8tJwPdEZsI83ACI=
 github.com/spf13/afero v1.1.2/go.mod h1:j4pytiNVoe2o6bmDsKpLACNPDBIoEAkihy7loJ1B0CQ=
+github.com/spf13/cast v1.3.0 h1:oget//CVOEoFewqQxwr0Ej5yjygnqGkvggSE/gB35Q8=
 github.com/spf13/cast v1.3.0/go.mod h1:Qx5cxh0v+4UWYiBimWS+eyWzqEqokIECu5etghLkUJE=
 github.com/spf13/cobra v0.0.5 h1:f0B+LkLX6DtmRH1isoNA9VTtNUK9K8xYd28JNNfOv/s=
 github.com/spf13/cobra v0.0.5/go.mod h1:3K3wKZymM7VvHMDS9+Akkh4K60UwM26emMESw8tLCHU=
+github.com/spf13/jwalterweatherman v1.0.0 h1:XHEdyB+EcvlqZamSM4ZOMGlc93t6AcsBEu9Gc1vn7yk=
 github.com/spf13/jwalterweatherman v1.0.0/go.mod h1:cQK4TGJAtQXfYWX+Ddv3mKDzgVb68N+wFjFa4jdeBTo=
 github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
 github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
+github.com/spf13/viper v1.3.2 h1:VUFqw5KcqRf7i70GOzW7N+Q7+gxVBkSSqiXB12+JQ4M=
 github.com/spf13/viper v1.3.2/go.mod h1:ZiWeW+zYFKm7srdB9IoDzzZXaJaI5eL9QjNiN/DMA2s=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -61,9 +70,11 @@ golang.org/x/sys v0.0.0-20181205085412-a5c9d58dba9a/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
 golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

src/pkg/utils/utils.go

@@ -35,6 +35,7 @@ import (
 	"github.com/docker/go-units"
 	"github.com/godbus/dbus/v5"
 	"github.com/sirupsen/logrus"
+	"github.com/spf13/viper"
 	"golang.org/x/sys/unix"
 )
 
@@ -570,6 +571,71 @@ func ImageReferenceHasDomain(image string) bool {
 	return true
 }
 
+func SetUpConfiguration() error {
+	logrus.Debug("Setting up configuration")
+
+	configFiles := []string{
+		"/etc/containers/toolbox.conf",
+	}
+
+	userConfigDir, err := os.UserConfigDir()
+	if err != nil {
+		logrus.Debugf("Setting up configuration: failed to get the user config directory: %s", err)
+		return errors.New("failed to get the user config directory")
+	}
+
+	userConfigPath := userConfigDir + "/containers/toolbox.conf"
+	configFiles = append(configFiles, []string{
+		userConfigPath,
+	}...)
+
+	viper.SetConfigType("toml")
+
+	for _, configFile := range configFiles {
+		viper.SetConfigFile(configFile)
+
+		if err := viper.MergeInConfig(); err != nil {
+			// Seems like Viper's errors can't be examined with
+			// errors.As.
+
+			// Seems like Viper doesn't actually throw
+			// viper.ConfigFileNotFoundError if a configuration
+			// file is not found. We still check for it for the
+			// sake of completion or in case Viper uses it in a
+			// different version.
+			_, ok := err.(viper.ConfigFileNotFoundError)
+			if ok || os.IsNotExist(err) {
+				logrus.Debugf("Setting up configuration: file %s not found", configFile)
+				continue
+			}
+
+			if _, ok := err.(viper.ConfigParseError); ok {
+				logrus.Debugf("Setting up configuration: failed to parse file %s: %s", configFile, err)
+				return fmt.Errorf("failed to parse file %s", configFile)
+			}
+
+			logrus.Debugf("Setting up configuration: failed to read file %s: %s", configFile, err)
+			return fmt.Errorf("failed to read file %s", configFile)
+		}
+	}
+
+	image, release, err := ResolveImageName("", "", "")
+	if err != nil {
+		logrus.Debugf("Setting up configuration: failed to resolve image name: %s", err)
+		return errors.New("failed to resolve image name")
+	}
+
+	container, err := ResolveContainerName("", image, release)
+	if err != nil {
+		logrus.Debugf("Setting up configuration: failed to resolve container name: %s", err)
+		return errors.New("failed to resolve container name")
+	}
+
+	ContainerNameDefault = container
+
+	return nil
+}
+
 // ShortID shortens provided id to first 12 characters.
 func ShortID(id string) string {
 	if len(id) > idTruncLength {
@@ -581,6 +647,9 @@ func ShortID(id string) string {
 func ParseRelease(distro, release string) (string, error) {
 	if distro == "" {
 		distro = distroDefault
+		if viper.IsSet("general.distro") {
+			distro = viper.GetString("general.distro")
+		}
 	}
 
 	if _, supportedDistro := supportedDistros[distro]; !supportedDistro {
@@ -694,30 +763,53 @@ func ResolveContainerName(container, image, release string) (string, error) {
 // If no image name is specified then the base image will reflect the platform of the host (even the version).
 //
 // If the host system is unknown then the base image will be 'fedora-toolbox' with a default version
-func ResolveImageName(distro, image, release string) (string, string, error) {
+func ResolveImageName(distroCLI, imageCLI, releaseCLI string) (string, string, error) {
 	logrus.Debug("Resolving image name")
-	logrus.Debugf("Distribution: '%s'", distro)
-	logrus.Debugf("Image: '%s'", image)
-	logrus.Debugf("Release: '%s'", release)
+	logrus.Debugf("Distribution (CLI): '%s'", distroCLI)
+	logrus.Debugf("Image (CLI): '%s'", imageCLI)
+	logrus.Debugf("Release (CLI): '%s'", releaseCLI)
 
-	if distro == "" {
+	distro, image, release := distroCLI, imageCLI, releaseCLI
+
+	if distroCLI == "" {
 		distro = distroDefault
+		if viper.IsSet("general.distro") {
+			distro = viper.GetString("general.distro")
+		}
 	}
 
-	if distro != distroDefault && release == "" {
+	if distro != distroDefault && releaseCLI == "" && !viper.IsSet("general.release") {
 		return "", "", fmt.Errorf("release not found for non-default distribution %s", distro)
 	}
 
-	if release == "" {
+	if releaseCLI == "" {
 		release = releaseDefault
+		if viper.IsSet("general.release") {
+			release = viper.GetString("general.release")
+		}
 	}
 
-	if image == "" {
+	if imageCLI == "" {
 		image = getDefaultImageForDistro(distro, release)
+
+		if viper.IsSet("general.image") && distroCLI == "" && releaseCLI == "" {
+			image = viper.GetString("general.image")
+
+			release = ImageReferenceGetTag(image)
+			if release == "" {
+				release = releaseDefault
+				if viper.IsSet("general.release") {
+					release = viper.GetString("general.release")
+				}
+			}
+		}
 	} else {
 		release = ImageReferenceGetTag(image)
 		if release == "" {
 			release = releaseDefault
+			if viper.IsSet("general.release") {
+				release = viper.GetString("general.release")
+			}
 		}
 	}