watch: add end-to-end test (#10801)

Add an end-to-end test that covers the core watch functionality,
i.e. CRUD on files & directories.

Signed-off-by: Milas Bowman <milas.bowman@docker.com>

pkg/e2e/fixtures/watch/compose.yaml

@@ -0,0 +1,34 @@
+x-dev: &x-dev
+  watch:
+    - action: sync
+      path: ./data
+      target: /app/data
+      ignore:
+        - '*.foo'
+        - ./ignored
+
+services:
+  alpine:
+    build:
+      dockerfile_inline: |-
+        FROM alpine
+        RUN mkdir -p /app/data
+    init: true
+    command: sleep infinity
+    x-develop: *x-dev
+  busybox:
+    build:
+      dockerfile_inline: |-
+        FROM busybox
+        RUN mkdir -p /app/data
+    init: true
+    command: sleep infinity
+    x-develop: *x-dev
+  debian:
+    build:
+      dockerfile_inline: |-
+        FROM debian
+        RUN mkdir -p /app/data
+    init: true
+    command: sleep infinity
+    x-develop: *x-dev

pkg/e2e/fixtures/watch/data/hello.txt

@@ -0,0 +1 @@
+hello world

pkg/e2e/watch_test.go

@@ -0,0 +1,184 @@
+/*
+   Copyright 2023 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 (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync/atomic"
+	"testing"
+
+	"github.com/distribution/distribution/v3/uuid"
+	"github.com/stretchr/testify/require"
+	"gotest.tools/v3/assert"
+	"gotest.tools/v3/assert/cmp"
+	"gotest.tools/v3/icmd"
+	"gotest.tools/v3/poll"
+)
+
+func TestWatch(t *testing.T) {
+	services := []string{"alpine", "busybox", "debian"}
+	for _, svcName := range services {
+		t.Run(svcName, func(t *testing.T) {
+			t.Helper()
+			doTest(t, svcName)
+		})
+	}
+}
+
+// NOTE: these tests all share a single Compose file but are safe to run concurrently
+func doTest(t *testing.T, svcName string) {
+	tmpdir := t.TempDir()
+	dataDir := filepath.Join(tmpdir, "data")
+	writeDataFile := func(name string, contents string) {
+		t.Helper()
+		dest := filepath.Join(dataDir, name)
+		require.NoError(t, os.MkdirAll(filepath.Dir(dest), 0o700))
+		t.Logf("writing %q to %q", contents, dest)
+		require.NoError(t, os.WriteFile(dest, []byte(contents+"\n"), 0o600))
+	}
+
+	composeFilePath := filepath.Join(tmpdir, "compose.yaml")
+	CopyFile(t, filepath.Join("fixtures", "watch", "compose.yaml"), composeFilePath)
+
+	projName := "e2e-watch-" + svcName
+	env := []string{
+		"COMPOSE_FILE=" + composeFilePath,
+		"COMPOSE_PROJECT_NAME=" + projName,
+	}
+
+	cli := NewParallelCLI(t, WithEnv(env...))
+
+	cleanup := func() {
+		cli.RunDockerComposeCmd(t, "down", svcName, "--timeout=0", "--remove-orphans", "--volumes")
+	}
+	cleanup()
+	t.Cleanup(cleanup)
+
+	cli.RunDockerComposeCmd(t, "up", svcName, "--wait", "--build")
+
+	cmd := cli.NewDockerComposeCmd(t, "--verbose", "alpha", "watch", svcName)
+	// stream output since watch runs in the background
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	r := icmd.StartCmd(cmd)
+	require.NoError(t, r.Error)
+	t.Cleanup(func() {
+		// IMPORTANT: watch doesn't exit on its own, don't leak processes!
+		if r.Cmd.Process != nil {
+			_ = r.Cmd.Process.Kill()
+		}
+	})
+	var testComplete atomic.Bool
+	go func() {
+		// if the process exits abnormally before the test is done, fail the test
+		if err := r.Cmd.Wait(); err != nil && !testComplete.Load() {
+			assert.Check(t, cmp.Nil(err))
+		}
+	}()
+
+	require.NoError(t, os.Mkdir(dataDir, 0o700))
+
+	checkFileContents := func(path string, contents string) poll.Check {
+		return func(pollLog poll.LogT) poll.Result {
+			if r.Cmd.ProcessState != nil {
+				return poll.Error(fmt.Errorf("watch process exited early: %s", r.Cmd.ProcessState))
+			}
+			res := icmd.RunCmd(cli.NewDockerComposeCmd(t, "exec", svcName, "cat", path))
+			if strings.Contains(res.Stdout(), contents) {
+				return poll.Success()
+			}
+			return poll.Continue(res.Combined())
+		}
+	}
+
+	waitForFlush := func() {
+		sentinelVal := uuid.Generate().String()
+		writeDataFile("wait.txt", sentinelVal)
+		poll.WaitOn(t, checkFileContents("/app/data/wait.txt", sentinelVal))
+	}
+
+	t.Logf("Writing to a file until Compose watch is up and running")
+	poll.WaitOn(t, func(t poll.LogT) poll.Result {
+		writeDataFile("hello.txt", "hello world")
+		return checkFileContents("/app/data/hello.txt", "hello world")(t)
+	})
+
+	t.Logf("Modifying file contents")
+	writeDataFile("hello.txt", "hello watch")
+	poll.WaitOn(t, checkFileContents("/app/data/hello.txt", "hello watch"))
+
+	t.Logf("Deleting file")
+	require.NoError(t, os.Remove(filepath.Join(dataDir, "hello.txt")))
+	waitForFlush()
+	cli.RunDockerComposeCmdNoCheck(t, "exec", svcName, "stat", "/app/data/hello.txt").
+		Assert(t, icmd.Expected{
+			ExitCode: 1,
+			Err:      "No such file or directory",
+		},
+		)
+
+	t.Logf("Writing to ignored paths")
+	writeDataFile("data.foo", "ignored")
+	writeDataFile(filepath.Join("ignored", "hello.txt"), "ignored")
+	waitForFlush()
+	cli.RunDockerComposeCmdNoCheck(t, "exec", svcName, "stat", "/app/data/data.foo").
+		Assert(t, icmd.Expected{
+			ExitCode: 1,
+			Err:      "No such file or directory",
+		},
+		)
+	cli.RunDockerComposeCmdNoCheck(t, "exec", svcName, "stat", "/app/data/ignored").
+		Assert(t, icmd.Expected{
+			ExitCode: 1,
+			Err:      "No such file or directory",
+		},
+		)
+
+	t.Logf("Creating subdirectory")
+	require.NoError(t, os.Mkdir(filepath.Join(dataDir, "subdir"), 0o700))
+	waitForFlush()
+	cli.RunDockerComposeCmd(t, "exec", svcName, "stat", "/app/data/subdir")
+
+	t.Logf("Writing to file in subdirectory")
+	writeDataFile(filepath.Join("subdir", "file.txt"), "a")
+	poll.WaitOn(t, checkFileContents("/app/data/subdir/file.txt", "a"))
+
+	t.Logf("Writing to file multiple times")
+	writeDataFile(filepath.Join("subdir", "file.txt"), "x")
+	writeDataFile(filepath.Join("subdir", "file.txt"), "y")
+	writeDataFile(filepath.Join("subdir", "file.txt"), "z")
+	poll.WaitOn(t, checkFileContents("/app/data/subdir/file.txt", "z"))
+	writeDataFile(filepath.Join("subdir", "file.txt"), "z")
+	writeDataFile(filepath.Join("subdir", "file.txt"), "y")
+	writeDataFile(filepath.Join("subdir", "file.txt"), "x")
+	poll.WaitOn(t, checkFileContents("/app/data/subdir/file.txt", "x"))
+
+	t.Logf("Deleting directory")
+	require.NoError(t, os.RemoveAll(filepath.Join(dataDir, "subdir")))
+	waitForFlush()
+	cli.RunDockerComposeCmdNoCheck(t, "exec", svcName, "stat", "/app/data/subdir").
+		Assert(t, icmd.Expected{
+			ExitCode: 1,
+			Err:      "No such file or directory",
+		},
+		)
+
+	testComplete.Store(true)
+}