env-file: update functionality and docs

Multiple flags allowed. Order prescribed. Examples provided. Multiline
accounted for.

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)

docs/sources/reference/commandline/cli.rst

@@ -1289,12 +1289,47 @@ explains in detail how to manipulate ports in Docker.
 
     $ sudo docker run -e MYVAR1 --env MYVAR2=foo --env-file ./env.list ubuntu bash
 
-This sets environmental variables to the container. For illustration all three
-flags are shown here. Where -e and --env can be repeated, take an environment 
-variable and value, or if no "=" is provided, then that variable's current
-value is passed through (i.e. $MYVAR1 from the host is set to $MYVAR1 in the
-container). The --env-file flag takes a filename as an argument and expects each
-line to be a VAR=VAL format.
+This sets environmental variables in the container. For illustration all three
+flags are shown here. Where ``-e``, ``--env`` take an environment variable and
+value, or if no "=" is provided, then that variable's current value is passed
+through (i.e. $MYVAR1 from the host is set to $MYVAR1 in the container). All
+three flags, ``-e``, ``--env``  and ``--env-file`` can be repeated.
+
+Regardless of the order of these three flags, the ``--env-file`` are processed
+first, and then ``-e``/``--env`` flags. So that they can override VAR as needed.
+
+.. code-block:: bash
+
+    $ cat ./env.list
+    TEST_FOO=BAR
+    $ sudo docker run --env TEST_FOO="This is a test" --env-file ./env.list busybox env | grep TEST_FOO
+    TEST_FOO=This is a test
+
+The ``--env-file`` flag takes a filename as an argument and expects each line
+to be in the VAR=VAL format.  The VAL is Unquoted, so if you need a multi-line
+value, then use `\n` escape characters inside of a double quoted VAL. Single
+quotes are literal. An example of a file passed with ``--env-file``
+
+.. code-block:: bash
+
+    $ cat ./env.list
+    TEST_FOO=BAR
+    TEST_APP_DEST_HOST=10.10.0.127
+    TEST_APP_DEST_PORT=8888
+    TEST_SOME_MULTILINE_VAR="this is first line\nthis is second line"
+    TEST_SOME_LITERAL_VAR='this\nwill\nall\nbe\none\nline'
+    $ sudo docker run --env-file ./env.list busybox env
+    HOME=/
+    PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+    HOSTNAME=215d54a814bc
+    TEST_FOO=BAR
+    TEST_APP_DEST_HOST=10.10.0.127
+    TEST_APP_DEST_PORT=8888
+    TEST_SOME_MULTILINE_VAR=this is first line
+    this is second line
+    TEST_SOME_LITERAL_VAR='this\nwill\nall\nbe\none\nline'
+    container=lxc
+
 
 .. code-block:: bash
 

pkg/opts/envfile.go

@@ -2,9 +2,10 @@ package opts
 
 import (
 	"bufio"
-	"bytes"
-	"io"
+	"fmt"
 	"os"
+	"strconv"
+	"strings"
 )
 
 /*
@@ -17,30 +18,20 @@ func ParseEnvFile(filename string) ([]string, error) {
 	}
 	defer fh.Close()
 
-	var (
-		lines       []string = []string{}
-		line, chunk []byte
-	)
-	reader := bufio.NewReader(fh)
-	line, isPrefix, err := reader.ReadLine()
-
-	for err == nil {
-		if isPrefix {
-			chunk = append(chunk, line...)
-		} else if !isPrefix && len(chunk) > 0 {
-			line = chunk
-			chunk = []byte{}
-		} else {
-			chunk = []byte{}
+	lines := []string{}
+	scanner := bufio.NewScanner(fh)
+	for scanner.Scan() {
+		line := scanner.Text()
+		// line is not empty, and not starting with '#'
+		if len(line) > 0 && !strings.HasPrefix(line, "#") && strings.Contains(line, "=") {
+			data := strings.SplitN(line, "=", 2)
+			key := data[0]
+			val := data[1]
+			if str, err := strconv.Unquote(data[1]); err == nil {
+				val = str
+			}
+			lines = append(lines, fmt.Sprintf("%s=%s", key, val))
 		}
-
-		if !isPrefix && len(line) > 0 && bytes.Contains(line, []byte("=")) {
-			lines = append(lines, string(line))
-		}
-		line, isPrefix, err = reader.ReadLine()
-	}
-	if err != nil && err != io.EOF {
-		return []string{}, err
 	}
 	return lines, nil
 }

runconfig/parse.go

@@ -203,7 +203,6 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 
 	// collect all the environment variables for the container
 	envVariables := []string{}
-	envVariables = append(envVariables, flEnv.GetAll()...)
 	for _, ef := range flEnvFile.GetAll() {
 		parsedVars, err := opts.ParseEnvFile(ef)
 		if err != nil {
@@ -211,6 +210,8 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 		}
 		envVariables = append(envVariables, parsedVars...)
 	}
+	// parse the '-e' and '--env' after, to allow override
+	envVariables = append(envVariables, flEnv.GetAll()...)
 	// boo, there's no debug output for docker run
 	//utils.Debugf("Environment variables for the container: %#v", envVariables)