Fix up handling of environment variables

The way docker works is if a user specifies a non `-e Name=Value`, IE
just a `-e Name`, then the environment variable Name from the clients
OS.ENV is used.

Also by default Docker containers run with the HOSTNAME environment set
to the HOSTNAME specified for the container.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

Closes: #21
Approved by: baude

1 files changed, 35 insertions, 28 deletions

diff --git a/cmd/kpod/parse.go b/cmd/kpod/parse.go
index e3143a793..7f6fc78df 100644
--- a/cmd/kpod/parse.go
+++ b/cmd/kpod/parse.go
@@ -327,55 +327,62 @@ func doesEnvExist(name string) bool {
 // 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
 // for env-file and labels-file flags
-func readKVStrings(files []string, override []string) ([]string, error) {
-	envVariables := []string{}
+func readKVStrings(env map[string]string, files []string, override []string) error {
 	for _, ef := range files {
-		parsedVars, err := parseEnvFile(ef)
-		if err != nil {
-			return nil, err
+		if err := parseEnvFile(env, ef); err != nil {
+			return err
+		}
+	}
+	for _, line := range override {
+		if err := parseEnv(env, line); err != nil {
+			return err
 		}
-		envVariables = append(envVariables, parsedVars...)
 	}
-	// parse the '-e' and '--env' after, to allow override
-	envVariables = append(envVariables, override...)
+	return nil
+}
+
+func parseEnv(env map[string]string, line string) error {
+	data := strings.SplitN(line, "=", 2)
+
+	// trim the front of a variable, but nothing else
+	name := strings.TrimLeft(data[0], whiteSpaces)
+	if strings.ContainsAny(name, whiteSpaces) {
+		return errors.Errorf("name %q has white spaces, poorly formatted name", name)
+	}
 
-	return envVariables, nil
+	if len(data) > 1 {
+		env[name] = data[1]
+	} else {
+		// if only a pass-through variable is given, clean it up.
+		val, exists := os.LookupEnv(name)
+		if !exists {
+			return errors.Errorf("environment variable %q does not exist", name)
+		}
+		env[name] = val
+	}
+	return nil
 }
 
 // parseEnvFile reads a file with environment variables enumerated by lines
-func parseEnvFile(filename string) ([]string, error) {
+func parseEnvFile(env map[string]string, filename string) error {
 	fh, err := os.Open(filename)
 	if err != nil {
-		return []string{}, err
+		return 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{}, errors.Errorf("variable %q has white spaces, poorly formatted environment", 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)))
+			if err := parseEnv(env, line); err != nil {
+				return err
 			}
 		}
 	}
-	return lines, scanner.Err()
+	return scanner.Err()
 }
 
 // NsIpc represents the container ipc stack.