Fix issue 416 (nektos#423)

This is a solution to issue nektos#416 where environment variables created or
changed in the previous step are not usable in the next step because
the rc.ExprEval is from the beginning of the previous step.

This change refactors setupEnv so that before interpolating the environment
variables a NewExpressionEvaluator is created.


Fixes: 416

pkg/runner/run_context.go

@@ -202,15 +202,11 @@ func (rc *RunContext) newStepExecutor(step *model.Step) common.Executor {
 			Outputs: make(map[string]string),
 		}
 
-		_ = sc.setupEnv()(ctx)
-
-		if sc.Env != nil {
-			err := rc.JobContainer.UpdateFromGithubEnv(&sc.Env)(ctx)
-			if err != nil {
-				return err
-			}
+		exprEval, err := sc.setupEnv(ctx)
+		if err != nil {
+			return err
 		}
-		rc.ExprEval = sc.NewExpressionEvaluator()
+		rc.ExprEval = exprEval;
 
 		runStep, err := rc.EvalBool(sc.Step.If)
 		if err != nil {

pkg/runner/step_context.go

@@ -79,33 +79,53 @@ func (sc *StepContext) Executor() common.Executor {
 	return common.NewErrorExecutor(fmt.Errorf("Unable to determine how to run job:%s step:%+v", rc.Run, step))
 }
 
-func (sc *StepContext) setupEnv() common.Executor {
+func (sc *StepContext) mergeEnv() map[string]string {
 	rc := sc.RunContext
 	job := rc.Run.Job()
 	step := sc.Step
-	return func(ctx context.Context) error {
-		var env map[string]string
-		c := job.Container()
-		if c != nil {
-			env = mergeMaps(rc.GetEnv(), c.Env, step.GetEnv())
-		} else {
-			env = mergeMaps(rc.GetEnv(), step.GetEnv())
-		}
 
-		if (rc.ExtraPath != nil) && (len(rc.ExtraPath) > 0) {
-			s := append(rc.ExtraPath, `/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin`)
-			env["PATH"] = strings.Join(s, `:`)
-		}
+	var env map[string]string
+	c := job.Container()
+	if c != nil {
+		env = mergeMaps(rc.GetEnv(), c.Env, step.GetEnv())
+	} else {
+		env = mergeMaps(rc.GetEnv(), step.GetEnv())
+	}
+
+	if (rc.ExtraPath != nil) && (len(rc.ExtraPath) > 0) {
+		s := append(rc.ExtraPath, `/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin`)
+		env["PATH"] = strings.Join(s, `:`)
+	}
+
+	sc.Env = rc.withGithubEnv(env)
+	return env
+}
+
 
-		for k, v := range env {
-			env[k] = rc.ExprEval.Interpolate(v)
+func (sc *StepContext) interpolateEnv(exprEval ExpressionEvaluator) {
+	for k, v := range sc.Env {
+		sc.Env[k] = exprEval.Interpolate(v)
+	}
+}
+
+
+func (sc *StepContext) setupEnv(ctx context.Context) (ExpressionEvaluator, error) {
+	rc := sc.RunContext
+	sc.Env = sc.mergeEnv()
+	if sc.Env != nil {
+		err := rc.JobContainer.UpdateFromGithubEnv(&sc.Env)(ctx)
+		if err != nil {
+			return nil, err
 		}
-		sc.Env = rc.withGithubEnv(env)
-		log.Debugf("setupEnv => %v", sc.Env)
-		return nil
 	}
+	evaluator := sc.NewExpressionEvaluator()
+	sc.interpolateEnv(evaluator)
+
+	log.Debugf("setupEnv: %v", sc.Env)
+	return evaluator, nil
 }
 
+
 func (sc *StepContext) setupShellCommand() common.Executor {
 	rc := sc.RunContext
 	step := sc.Step