integ-cli: also preserve SystemRoot env var

Windows CI fails to dial remote test host over tcp in the test cases where
we clear environment variables during `exec(dockerBinary, ...)` in the
absence of `SystemRoot` environment variable (typically points to `c:\windows`).

This fixes tests:
- `TestRunEnvironmentErase`
- `TestRunEnvironmentOverride`

Signed-off-by: Ahmet Alp Balkan <ahmetalpbalkan@gmail.com>

integration-cli/docker_cli_proxy_test.go

@@ -9,7 +9,7 @@ import (
 
 func TestCliProxyDisableProxyUnixSock(t *testing.T) {
 	cmd := exec.Command(dockerBinary, "info")
-	cmd.Env = appendDockerHostEnv([]string{"HTTP_PROXY=http://127.0.0.1:9999"})
+	cmd.Env = appendBaseEnv([]string{"HTTP_PROXY=http://127.0.0.1:9999"})
 
 	if out, _, err := runCommandWithOutput(cmd); err != nil {
 		t.Fatal(err, out)

integration-cli/docker_cli_run_test.go

@@ -869,7 +869,7 @@ func TestRunEnvironmentErase(t *testing.T) {
 	defer deleteAllContainers()
 
 	cmd := exec.Command(dockerBinary, "run", "-e", "FOO", "-e", "HOSTNAME", "busybox", "env")
-	cmd.Env = appendDockerHostEnv([]string{})
+	cmd.Env = appendBaseEnv([]string{})
 
 	out, _, err := runCommandWithOutput(cmd)
 	if err != nil {
@@ -908,7 +908,7 @@ func TestRunEnvironmentOverride(t *testing.T) {
 	defer deleteAllContainers()
 
 	cmd := exec.Command(dockerBinary, "run", "-e", "HOSTNAME", "-e", "HOME=/root2", "busybox", "env")
-	cmd.Env = appendDockerHostEnv([]string{"HOSTNAME=bar"})
+	cmd.Env = appendBaseEnv([]string{"HOSTNAME=bar"})
 
 	out, _, err := runCommandWithOutput(cmd)
 	if err != nil {

integration-cli/docker_utils.go

@@ -919,12 +919,23 @@ func setupRegistry(t *testing.T) func() {
 	return func() { reg.Close() }
 }
 
-// appendDockerHostEnv adds given env slice DOCKER_HOST value if set in the
-// environment. Useful when environment is cleared but we want to preserve DOCKER_HOST
-// to execute tests against a remote daemon.
-func appendDockerHostEnv(env []string) []string {
-	if dockerHost := os.Getenv("DOCKER_HOST"); dockerHost != "" {
-		env = append(env, fmt.Sprintf("DOCKER_HOST=%s", dockerHost))
+// appendBaseEnv appends the minimum set of environment variables to exec the
+// docker cli binary for testing with correct configuration to the given env
+// list.
+func appendBaseEnv(env []string) []string {
+	preserveList := []string{
+		// preserve remote test host
+		"DOCKER_HOST",
+
+		// windows: requires preserving SystemRoot, otherwise dial tcp fails
+		// with "GetAddrInfoW: A non-recoverable error occurred during a database lookup."
+		"SystemRoot",
+	}
+
+	for _, key := range preserveList {
+		if val := os.Getenv(key); val != "" {
+			env = append(env, fmt.Sprintf("%s=%s", key, val))
+		}
 	}
 	return env
 }