feature: cli supports --env-file

Signed-off-by: Lang Chi <21860405@zju.edu.cn>

cli/common_flags.go

@@ -36,6 +36,7 @@ func addCommonFlags(flagSet *pflag.FlagSet) *container {
 	flagSet.BoolVar(&c.enableLxcfs, "enableLxcfs", false, "Enable lxcfs for the container, only effective when enable-lxcfs switched on in Pouchd")
 	flagSet.StringVar(&c.entrypoint, "entrypoint", "", "Overwrite the default ENTRYPOINT of the image")
 	flagSet.StringArrayVarP(&c.env, "env", "e", nil, "Set environment variables for container('--env A=' means setting env A to empty, '--env B' means removing env B from container env inherited from image)")
+	flagSet.StringArrayVar(&c.env, "env-file", nil, "Read in a file of environment variables")
 	flagSet.StringVar(&c.hostname, "hostname", "", "Set container's hostname")
 	flagSet.BoolVar(&c.disableNetworkFiles, "disable-network-files", false, "Disable the generation of network files(/etc/hostname, /etc/hosts and /etc/resolv.conf) for container. If true, no network files will be generated. Default false")
 

cli/container.go

@@ -18,6 +18,7 @@ type container struct {
 	volumesFrom         []string
 	runtime             string
 	env                 []string
+	envfile             []string
 	entrypoint          string
 	workdir             string
 	user                string

cli/create.go

@@ -57,6 +57,12 @@ func (cc *CreateCommand) runCreate(args []string) error {
 	}
 	config.ContainerConfig.OpenStdin = cc.openstdin
 
+	// collect all the environment variables for the container
+	config.Env, err = readKVStrings(cc.envfile, cc.env)
+	if err != nil {
+		return nil
+	}
+
 	config.Image = args[0]
 	if len(args) > 1 {
 		config.Cmd = args[1:]

cli/envfile.go

@@ -0,0 +1,73 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// reads a file of line terminated key=value pairs, and overrides any keys
+// present in the file with additional pairs specified in the override parameter
+func readKVStrings(files []string, override []string) ([]string, error) {
+	envVariables := []string{}
+	for _, ef := range files {
+		parsedVars, err := ParseEnvFile(ef)
+		if err != nil {
+			return nil, err
+		}
+		envVariables = append(envVariables, parsedVars...)
+	}
+	// parse the '-e' and '--env' after, to allow override
+	envVariables = append(envVariables, override...)
+
+	return envVariables, nil
+}
+
+// ParseEnvFile reads a file with environment variables enumerated by lines
+func ParseEnvFile(filename string) ([]string, error) {
+	fh, err := os.Open(filename)
+	if err != nil {
+		return []string{}, err
+	}
+	defer fh.Close()
+
+	lines := []string{}
+	scanner := bufio.NewScanner(fh)
+	for scanner.Scan() {
+		// trim the line from all leading whitespace first
+		line := strings.TrimLeft(scanner.Text(), whiteSpaces)
+		// line is not empty, and not starting with '#'
+		if len(line) > 0 && !strings.HasPrefix(line, "#") {
+			data := strings.SplitN(line, "=", 2)
+
+			// trim the front of a variable, but nothing else
+			variable := strings.TrimLeft(data[0], whiteSpaces)
+			if strings.ContainsAny(variable, whiteSpaces) {
+				return []string{}, ErrBadEnvVariable{fmt.Sprintf("variable '%s' has white spaces", variable)}
+			}
+
+			if len(data) > 1 {
+
+				// pass the value through, no trimming
+				lines = append(lines, fmt.Sprintf("%s=%s", variable, data[1]))
+			} else {
+				// if only a pass-through variable is given, clean it up.
+				lines = append(lines, fmt.Sprintf("%s=%s", strings.TrimSpace(line), os.Getenv(line)))
+			}
+		}
+	}
+	return lines, scanner.Err()
+}
+
+var whiteSpaces = " \t"
+
+// ErrBadEnvVariable typed error for bad environment variable
+type ErrBadEnvVariable struct {
+	msg string
+}
+
+// Error implements error interface.
+func (e ErrBadEnvVariable) Error() string {
+	return fmt.Sprintf("poorly formatted environment: %s", e.msg)
+}

cli/envfile_test.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"reflect"
+	"testing"
+)
+
+func tmpFileWithContent(content string, t *testing.T) string {
+	tmpFile, err := ioutil.TempFile("", "envfile-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tmpFile.Close()
+
+	tmpFile.WriteString(content)
+	return tmpFile.Name()
+}
+
+// Test ParseEnvFile for a file with a few well formatted lines
+func TestParseEnvFileGoodFile(t *testing.T) {
+	content := `foo=bar
+    baz=quux
+# comment
+
+_foobar=foobaz
+with.dots=working
+and_underscore=working too
+`
+	// Adding a newline + a line with pure whitespace.
+	// This is being done like this instead of the block above
+	// because it's common for editors to trim trailing whitespace
+	// from lines, which becomes annoying since that's the
+	// exact thing we need to test.
+	content += "\n    \t  "
+	tmpFile := tmpFileWithContent(content, t)
+	defer os.Remove(tmpFile)
+
+	lines, err := ParseEnvFile(tmpFile)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expectedLines := []string{
+		"foo=bar",
+		"baz=quux",
+		"_foobar=foobaz",
+		"with.dots=working",
+		"and_underscore=working too",
+	}
+
+	if !reflect.DeepEqual(lines, expectedLines) {
+		t.Fatal("lines not equal to expected_lines")
+	}
+}

cli/run.go

@@ -66,6 +66,12 @@ func (rc *RunCommand) runRun(args []string) error {
 		return fmt.Errorf("failed to run container: %v", err)
 	}
 
+	// collect all the environment variables for the container
+	config.Env, err = readKVStrings(rc.envfile, rc.env)
+	if err != nil {
+		return nil
+	}
+
 	config.Image = args[0]
 	if len(args) > 1 {
 		config.Cmd = args[1:]