Merge pull request #90 from grammarly/f-fix-onbuild-variables-expansion

Expand variables at the time of ONBUILD command execution

src/build/commands.go

@@ -1395,6 +1395,14 @@ func (c *CommandOnbuildWrap) Execute(b *Build) (State, error) {
 	return c.cmd.Execute(b)
 }
 
+// ReplaceEnv implements EnvReplacableCommand interface
+func (c *CommandOnbuildWrap) ReplaceEnv(env []string) error {
+	if command, ok := c.cmd.(EnvReplacableCommand); ok {
+		return command.ReplaceEnv(env)
+	}
+	return nil
+}
+
 ////////// Private stuff //////////
 
 func replaceEnv(args []string, env []string) (err error) {

test/env_test.go

@@ -0,0 +1,32 @@
+package tests
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestEnvExpansion(t *testing.T) {
+
+	err := runRockerBuildWithOptions(`
+FROM alpine
+ENV foo=bar
+ENV qux=replaced-$foo
+RUN touch /$qux
+RUN ls -l /replaced-bar`, "--no-cache")
+
+	assert.Nil(t, err, "should expand variable in ENV command")
+}
+
+func TestEnvExpansionInOnbuild(t *testing.T) {
+
+	err := runRockerBuildWithOptions(`
+FROM alpine
+ENV foo=bar
+ONBUILD ENV qux=replaced-onbuild-$foo
+TAG bla
+FROM bla
+RUN touch /$qux
+RUN ls -l /replaced-onbuild-bar`, "--no-cache")
+
+	assert.Nil(t, err, "should expand variable in ONBUILD command")
+}