integration: init release upgrade test

The TestUpgrade downloads the latest of previous release's binary and
use them to setup pods and then use current release to recover the
existing pods.

Signed-off-by: Wei Fu <fuweid89@gmail.com>

integration/release_upgrade_utils_linux_test.go

@@ -0,0 +1,118 @@
+/*
+   Copyright The containerd 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 integration
+
+import (
+	"compress/gzip"
+	"context"
+	"fmt"
+	"net/http"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/mod/semver"
+	exec "golang.org/x/sys/execabs"
+
+	"github.com/containerd/containerd/v2/archive"
+	"github.com/containerd/containerd/v2/version"
+)
+
+// downloadPreviousReleaseBinary downloads the latest version of previous release
+// into the target dir.
+func downloadPreviousReleaseBinary(t *testing.T, targetDir string) {
+	ver := previousReleaseVersion(t)
+
+	targetURL := fmt.Sprintf("https://github.com/containerd/containerd/releases/download/%s/containerd-%s-linux-%s.tar.gz",
+		ver, strings.TrimPrefix(ver, "v"), runtime.GOARCH,
+	)
+
+	resp, err := http.Get(targetURL) //nolint:gosec
+	require.NoError(t, err, "failed to http-get %s", targetURL)
+
+	defer resp.Body.Close()
+	require.Equal(t, http.StatusOK, resp.StatusCode)
+
+	tarReader, err := gzip.NewReader(resp.Body)
+	require.NoError(t, err, "%s should be gzip stream", targetURL)
+
+	// NOTE: Use native applier to take release tar.gzip stream as first image layer :)
+	_, err = archive.Apply(context.Background(), targetDir, tarReader)
+	require.NoError(t, err, "failed to unpack %s gzip stream into %s", targetURL, targetDir)
+}
+
+// previousReleaseVersion returns the latest version of previous release.
+func previousReleaseVersion(t *testing.T) string {
+	majorMinor := ctrdPreviousMajorMinor(t)
+
+	tags := gitLsRemoteCtrdTags(t, fmt.Sprintf("refs/tags/%s.*", majorMinor))
+	require.True(t, len(tags) >= 1)
+
+	// sort them and get the latest version
+	semver.Sort(tags)
+	return tags[len(tags)-1]
+}
+
+// ctrdPreviousMajorMinor gets the current version of running containerd.
+//
+// TODO(fuweid): We should parse containerd --version to get the result.
+func ctrdPreviousMajorMinor(t *testing.T) string {
+	currentVer := "v" + version.Version
+
+	version := semver.MajorMinor(currentVer)
+	switch version {
+	case "v2.0":
+		return "v1.7"
+	case "v1.7":
+		return "v1.6"
+	default:
+		t.Fatalf("unexpected containerd version: %s", currentVer)
+		panic("unreachable")
+	}
+}
+
+// gitLsRemoteTags lists containerd tags based on pattern.
+func gitLsRemoteCtrdTags(t *testing.T, pattern string) (_tags []string) {
+	cmd := exec.Command("git", "ls-remote", "--tags", "--exit-code",
+		"https://github.com/containerd/containerd.git", pattern)
+
+	out, err := cmd.Output()
+	require.NoError(t, err, "failed to list tags by pattern %s", pattern)
+
+	// output is like
+	//
+	// 137288ad010d39ae6ef578fa53bf9b93d1356c3a        refs/tags/v1.6.8
+	// 9cd3357b7fd7218e4aec3eae239db1f68a5a6ec6        refs/tags/v1.6.8^{}
+	// cec2382030533cf5797d63a4cdb2b255a9c3c7b6        refs/tags/v1.6.9
+	// 1c90a442489720eec95342e1789ee8a5e1b9536f        refs/tags/v1.6.9^{}
+	refTags := strings.Fields(string(out))
+	require.True(t, len(refTags)%2 == 0)
+
+	tags := make([]string, 0, len(refTags)/2)
+	for i := 1; i < len(refTags); i += 2 {
+		rawTag := refTags[i]
+		require.True(t, strings.HasPrefix(rawTag, "refs/tags/"))
+
+		if strings.HasSuffix(rawTag, "^{}") {
+			continue
+		}
+		rawTag = strings.TrimPrefix(rawTag, "refs/tags/")
+		tags = append(tags, rawTag)
+	}
+	return tags
+}