add e2e tests to verify env variables priority

Signed-off-by: Guillaume Lours <guillaume.lours@docker.com>

pkg/compose/run.go

@@ -116,6 +116,9 @@ func applyRunOptions(project *types.Project, service *types.ServiceConfig, opts
 	if len(opts.Environment) > 0 {
 		env := types.NewMappingWithEquals(opts.Environment)
 		projectEnv := env.Resolve(func(s string) (string, bool) {
+			if _, ok := service.Environment[s]; ok {
+				return "", false
+			}
 			v, ok := project.Environment[s]
 			return v, ok
 		}).RemoveEmpty()

pkg/e2e/compose_environment_test.go

@@ -0,0 +1,113 @@
+/*
+   Copyright 2020 Docker Compose CLI authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package e2e
+
+import (
+	"os"
+	"strings"
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestEnvPriority(t *testing.T) {
+	c := NewParallelE2eCLI(t, binDir)
+
+	projectDir := "./fixtures/environment/env-file-override"
+
+	t.Run("up", func(t *testing.T) {
+		c.RunDockerOrExitError("rmi", "env-compose-priority")
+		c.RunDockerComposeCmd("-f", "./fixtures/environment/env-file-override/compose-with-env.yaml",
+			"--project-directory", projectDir, "up", "-d", "--build")
+	})
+
+	// Full options activated
+	// 1. Compose file <-- Result expected
+	// 2. Shell environment variables
+	// 3. Environment file
+	// 4. Dockerfile
+	// 5. Variable is not defined
+	t.Run("compose file priority", func(t *testing.T) {
+		os.Setenv("WHEREAMI", "shell") //nolint:errcheck
+		defer os.Unsetenv("WHEREAMI")  //nolint:errcheck
+
+		res := c.RunDockerComposeCmd("-f", "./fixtures/environment/env-file-override/compose-with-env.yaml",
+			"--project-directory", projectDir, "--env-file", "./fixtures/environment/env-file-override/.env.override",
+			"run", "--rm", "-e", "WHEREAMI", "env-compose-priority")
+
+		assert.Equal(t, strings.TrimSpace(res.Stdout()), "Compose File")
+	})
+
+	// No Compose file, all other options
+	// 1. Compose file
+	// 2. Shell environment variables <-- Result expected
+	// 3. Environment file
+	// 4. Dockerfile
+	// 5. Variable is not defined
+	t.Run("shell priority", func(t *testing.T) {
+		os.Setenv("WHEREAMI", "shell") //nolint:errcheck
+		defer os.Unsetenv("WHEREAMI")  //nolint:errcheck
+
+		res := c.RunDockerComposeCmd("-f", "./fixtures/environment/env-file-override/compose.yaml",
+			"--project-directory", projectDir, "--env-file", "./fixtures/environment/env-file-override/.env.override",
+			"run", "--rm", "-e", "WHEREAMI", "env-compose-priority")
+		assert.Equal(t, strings.TrimSpace(res.Stdout()), "shell")
+	})
+
+	//  No Compose file and env variable pass to the run command
+	// 1. Compose file
+	// 2. Shell environment variables <-- Result expected
+	// 3. Environment file
+	// 4. Dockerfile
+	// 5. Variable is not defined
+	t.Run("shell priority from run command", func(t *testing.T) {
+		res := c.RunDockerComposeCmd("-f", "./fixtures/environment/env-file-override/compose.yaml",
+			"--project-directory", projectDir, "--env-file", "./fixtures/environment/env-file-override/.env.override",
+			"run", "--rm", "-e", "WHEREAMI=shell-run", "env-compose-priority")
+		assert.Equal(t, strings.TrimSpace(res.Stdout()), "shell-run")
+	})
+
+	//  No Compose file & no env variable but override env file
+	// 1. Compose file
+	// 2. Shell environment variables
+	// 3. Environment file <-- Result expected
+	// 4. Dockerfile
+	// 5. Variable is not defined
+	t.Run("override env file", func(t *testing.T) {
+		res := c.RunDockerComposeCmd("-f", "./fixtures/environment/env-file-override/compose.yaml",
+			"--project-directory", projectDir, "--env-file", "./fixtures/environment/env-file-override/.env.override",
+			"run", "--rm", "-e", "WHEREAMI", "env-compose-priority")
+		assert.Equal(t, strings.TrimSpace(res.Stdout()), "override")
+	})
+
+	//  No Compose file & no env variable, using an empty override env file
+	// 1. Compose file
+	// 2. Shell environment variables
+	// 3. Environment file
+	// 4. Dockerfile   <-- Result expected
+	// 5. Variable is not defined
+	t.Run("use Dockerfile", func(t *testing.T) {
+		res := c.RunDockerComposeCmd("-f", "./fixtures/environment/env-file-override/compose.yaml",
+			"--project-directory", projectDir, "--env-file", "./fixtures/environment/env-file-override/.env.empty",
+			"run", "--rm", "-e", "WHEREAMI", "env-compose-priority")
+		assert.Equal(t, strings.TrimSpace(res.Stdout()), "Dockerfile")
+	})
+
+	t.Run("down", func(t *testing.T) {
+		c.RunDockerComposeCmd("--project-directory", projectDir, "down")
+	})
+}

pkg/e2e/fixtures/environment/env-file-override/.env

@@ -0,0 +1 @@
+WHEREAMI=Env File

pkg/e2e/fixtures/environment/env-file-override/.env.override

@@ -0,0 +1 @@
+WHEREAMI=override

pkg/e2e/fixtures/environment/env-file-override/Dockerfile

@@ -0,0 +1,17 @@
+#   Copyright 2020 Docker Compose CLI authors
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+FROM alpine
+ENV  WHEREAMI=Dockerfile
+CMD ["printenv", "WHEREAMI"]

pkg/e2e/fixtures/environment/env-file-override/compose-with-env.yaml

@@ -0,0 +1,7 @@
+services:
+  env-compose-priority:
+    image: env-compose-priority
+    build:
+      context: .
+    environment:
+      WHEREAMI: "Compose File"

pkg/e2e/fixtures/environment/env-file-override/compose.yaml

@@ -0,0 +1,3 @@
+services:
+  env-compose-priority:
+    image: env-compose-priority