integration: basic s3 cache test

[crazy-max]

Adds basic integration test for s3 cache so we can get rid of the one from hack folder. Also pin busybox in current azblob_test related to #3469.

cc @bpaquet

[crazy-max]

Also pin busybox in current azblob_test related to #3469.

Has been fixed in #3475, removing that commit.

[bpaquet]

This is only one case. @crazy-max do you want help for others?

[crazy-max]

I think the basic one is fine for this use case:

buildkit/client/client_test.go

Lines 4556 to 4616 in 05c4d57

	func testBasicCacheImportExport(t *testing.T, sb integration.Sandbox, cacheOptionsEntryImport, cacheOptionsEntryExport []CacheOptionsEntry) {
	requiresLinux(t)
	c, err := New(sb.Context(), sb.Address())
	require.NoError(t, err)
	defer c.Close()
	busybox := llb.Image("busybox:latest")
	st := llb.Scratch()
	run := func(cmd string) {
	st = busybox.Run(llb.Shlex(cmd), llb.Dir("/wd")).AddMount("/wd", st)
	}
	run(`sh -c "echo -n foobar > const"`)
	run(`sh -c "cat /dev/urandom | head -c 100 | sha256sum > unique"`)
	def, err := st.Marshal(sb.Context())
	require.NoError(t, err)
	destDir := t.TempDir()
	_, err = c.Solve(sb.Context(), def, SolveOpt{
	Exports: []ExportEntry{
	{
	Type: ExporterLocal,
	OutputDir: destDir,
	},
	},
	CacheExports: cacheOptionsEntryExport,
	}, nil)
	require.NoError(t, err)
	dt, err := os.ReadFile(filepath.Join(destDir, "const"))
	require.NoError(t, err)
	require.Equal(t, string(dt), "foobar")
	dt, err = os.ReadFile(filepath.Join(destDir, "unique"))
	require.NoError(t, err)
	ensurePruneAll(t, c, sb)
	destDir = t.TempDir()
	_, err = c.Solve(sb.Context(), def, SolveOpt{
	Exports: []ExportEntry{
	{
	Type: ExporterLocal,
	OutputDir: destDir,
	}},
	CacheImports: cacheOptionsEntryImport,
	}, nil)
	require.NoError(t, err)
	dt2, err := os.ReadFile(filepath.Join(destDir, "const"))
	require.NoError(t, err)
	require.Equal(t, string(dt2), "foobar")
	dt2, err = os.ReadFile(filepath.Join(destDir, "unique"))
	require.NoError(t, err)
	require.Equal(t, string(dt), string(dt2))
	}

If you think about ones specific to s3, we can do that in follow-ups.

[crazy-max]

@bpaquet As discussed with @tonistiigi I will open a follow-up to check the bucket content like you've done. If you want to do it, let me know.

[guillenotfound]

Is this fixing importing cache from several targets (multi stage builds)? Currently that's not working very well and I cannot find much documentation to ping-pong what's going on.