Add reading environment from Docker image (#771)

* fix: read envvars from image definition

* fix: add test

* fix: sort slices

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/container/docker_run.go

@@ -294,8 +294,15 @@ func (cr *containerReference) create(capAdd []string, capDrop []string) common.E
 		}
 		logger := common.Logger(ctx)
 		isTerminal := term.IsTerminal(int(os.Stdout.Fd()))
-
 		input := cr.input
+
+		insp, _, err := cr.cli.ImageInspectWithRaw(ctx, input.Image)
+		if err != nil {
+			logger.Error(err)
+		}
+
+		input.Env = mergeEnvFromImage(input.Env, insp.Config.Env)
+
 		config := &container.Config{
 			Image:      input.Image,
 			Cmd:        input.Cmd,
@@ -348,6 +355,39 @@ func (cr *containerReference) create(capAdd []string, capDrop []string) common.E
 	}
 }
 
+func mergeEnvFromImage(inputEnv, imageEnv []string) []string {
+	envMap := make(map[string]string)
+	for _, v := range inputEnv {
+		e := strings.Split(v, `=`)
+		if e[1] == "" {
+			envMap[e[0]] = ""
+		} else {
+			envMap[e[0]] = e[1]
+		}
+	}
+
+	for _, v := range imageEnv {
+		e := strings.SplitN(v, `=`, 2)
+		if env, ok := envMap[e[0]]; !ok {
+			if e[1] != "" {
+				envMap[e[0]] = e[1]
+			}
+		} else {
+			if e[0] == "PATH" {
+				if e[1] != "" {
+					envMap[e[0]] = strings.Join([]string{env, e[1]}, `:`)
+				}
+			}
+		}
+	}
+
+	out := make([]string, 0)
+	for k, v := range envMap {
+		out = append(out, strings.Join([]string{k, v}, `=`))
+	}
+	return out
+}
+
 var singleLineEnvPattern, mulitiLineEnvPattern *regexp.Regexp
 
 func (cr *containerReference) extractEnv(srcPath string, env *map[string]string) common.Executor {

pkg/container/docker_run_test.go

@@ -0,0 +1,34 @@
+package container
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMergeEnvFromImage(t *testing.T) {
+	inputEnv := []string{
+		"PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/sbin",
+		"GOPATH=/root/go",
+		"GOOS=linux",
+	}
+	imageEnv := []string{
+		"PATH=/root/go/bin",
+		"GOPATH=/tmp",
+		"GOARCH=amd64",
+	}
+
+	merged := mergeEnvFromImage(inputEnv, imageEnv)
+	sort.Strings(merged)
+
+	expected := []string{
+		"PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/sbin:/root/go/bin",
+		"GOPATH=/root/go",
+		"GOOS=linux",
+		"GOARCH=amd64",
+	}
+	sort.Strings(expected)
+
+	assert.Equal(t, expected, merged)
+}