feat: interceptors system (#86)

Signed-off-by: Thulio Ferraz Assis <thulio@aspect.dev>

cmd/aspect/build/BUILD.bazel

@@ -10,8 +10,8 @@ go_library(
         "//pkg/aspect/build",
         "//pkg/aspecterrors",
         "//pkg/bazel",
+        "//pkg/interceptors",
         "//pkg/ioutils",
-        "//pkg/pathutils",
         "//pkg/plugin/system",
         "//pkg/plugin/system/bep",
         "@com_github_spf13_cobra//:cobra",

cmd/aspect/build/build.go

@@ -7,6 +7,7 @@ Not licensed for re-use.
 package build
 
 import (
+	"context"
 	"errors"
 	"fmt"
 
@@ -16,8 +17,8 @@ import (
 	"aspect.build/cli/pkg/aspect/build"
 	"aspect.build/cli/pkg/aspecterrors"
 	"aspect.build/cli/pkg/bazel"
+	"aspect.build/cli/pkg/interceptors"
 	"aspect.build/cli/pkg/ioutils"
-	"aspect.build/cli/pkg/pathutils"
 	"aspect.build/cli/pkg/plugin/system"
 	"aspect.build/cli/pkg/plugin/system/bep"
 )
@@ -38,38 +39,42 @@ func NewBuildCmd(
 	pluginSystem system.PluginSystem,
 	bzl bazel.Bazel,
 ) *cobra.Command {
-	cmd := &cobra.Command{
+	return &cobra.Command{
 		Use:   "build",
 		Short: "Builds the specified targets, using the options.",
 		Long: "Invokes bazel build on the specified targets. " +
 			"See 'bazel help target-syntax' for details and examples on how to specify targets to build.",
-		RunE: pathutils.InvokeCmdInsideWorkspace(func(workspaceRoot string, cmd *cobra.Command, args []string) (exitErr error) {
-			isInteractiveMode, err := cmd.Root().PersistentFlags().GetBool(rootFlags.InteractiveFlagName)
-			if err != nil {
-				return err
-			}
+		RunE: interceptors.Run(
+			[]interceptors.Interceptor{
+				interceptors.WorkspaceRootInterceptor(),
+				pluginSystem.BESBackendInterceptor(),
+			},
+			func(ctx context.Context, cmd *cobra.Command, args []string) (exitErr error) {
+				isInteractiveMode, err := cmd.Root().PersistentFlags().GetBool(rootFlags.InteractiveFlagName)
+				if err != nil {
+					return err
+				}
 
-			// TODO(f0rmiga): test this post-build hook.
-			defer func() {
-				errs := pluginSystem.ExecutePostBuild(isInteractiveMode).Errors()
-				if len(errs) > 0 {
-					for _, err := range errs {
-						fmt.Fprintf(streams.Stderr, "Error: failed to run build command: %v\n", err)
-					}
-					var err *aspecterrors.ExitError
-					if errors.As(exitErr, &err) {
-						err.ExitCode = 1
+				// TODO(f0rmiga): test this post-build hook.
+				defer func() {
+					errs := pluginSystem.ExecutePostBuild(isInteractiveMode).Errors()
+					if len(errs) > 0 {
+						for _, err := range errs {
+							fmt.Fprintf(streams.Stderr, "Error: failed to run build command: %v\n", err)
+						}
+						var err *aspecterrors.ExitError
+						if errors.As(exitErr, &err) {
+							err.ExitCode = 1
+						}
 					}
-				}
-			}()
+				}()
 
-			bzl.SetWorkspaceRoot(workspaceRoot)
-			b := build.New(streams, bzl)
-			return pluginSystem.WithBESBackend(cmd.Context(), func(besBackend bep.BESBackend) error {
+				workspaceRoot := ctx.Value(interceptors.WorkspaceRootKey).(string)
+				bzl.SetWorkspaceRoot(workspaceRoot)
+				b := build.New(streams, bzl)
+				besBackend := ctx.Value(system.BESBackendInterceptorKey).(bep.BESBackend)
 				return b.Run(args, besBackend)
-			})
-		}),
+			},
+		),
 	}
-
-	return cmd
 }

cmd/aspect/clean/BUILD.bazel

@@ -8,8 +8,8 @@ go_library(
     deps = [
         "//pkg/aspect/clean",
         "//pkg/bazel",
+        "//pkg/interceptors",
         "//pkg/ioutils",
-        "//pkg/pathutils",
         "@com_github_mattn_go_isatty//:go-isatty",
         "@com_github_spf13_cobra//:cobra",
     ],

cmd/aspect/clean/clean.go

@@ -7,15 +7,16 @@ Not licensed for re-use.
 package clean
 
 import (
+	"context"
 	"os"
 
 	"github.com/mattn/go-isatty"
 	"github.com/spf13/cobra"
 
 	"aspect.build/cli/pkg/aspect/clean"
 	"aspect.build/cli/pkg/bazel"
+	"aspect.build/cli/pkg/interceptors"
 	"aspect.build/cli/pkg/ioutils"
-	"aspect.build/cli/pkg/pathutils"
 )
 
 // NewDefaultCleanCmd creates a new default clean cobra command.
@@ -61,14 +62,20 @@ Workaround inconistent state:
 	Such problems are fixable and these bugs are a high priority.
 	If you ever find an incorrect incremental build, please file a bug report,
 	and only use clean as a temporary workaround.`,
-		RunE: pathutils.InvokeCmdInsideWorkspace(func(workspaceRoot string, cmd *cobra.Command, args []string) (exitErr error) {
-			bzl.SetWorkspaceRoot(workspaceRoot)
-			isInteractive := isatty.IsTerminal(os.Stdout.Fd()) || isatty.IsCygwinTerminal(os.Stdout.Fd())
-			c := clean.NewDefault(bzl, isInteractive)
-			c.Expunge = expunge
-			c.ExpungeAsync = expungeAsync
-			return c.Run(cmd, args)
-		}),
+		RunE: interceptors.Run(
+			[]interceptors.Interceptor{
+				interceptors.WorkspaceRootInterceptor(),
+			},
+			func(ctx context.Context, cmd *cobra.Command, args []string) (exitErr error) {
+				workspaceRoot := ctx.Value(interceptors.WorkspaceRootKey).(string)
+				bzl.SetWorkspaceRoot(workspaceRoot)
+				isInteractive := isatty.IsTerminal(os.Stdout.Fd()) || isatty.IsCygwinTerminal(os.Stdout.Fd())
+				c := clean.NewDefault(bzl, isInteractive)
+				c.Expunge = expunge
+				c.ExpungeAsync = expungeAsync
+				return c.Run(cmd, args)
+			},
+		),
 	}
 
 	cmd.PersistentFlags().BoolVarP(&expunge, "expunge", "", false, `Remove the entire output_base tree.

cmd/aspect/info/BUILD.bazel

@@ -7,8 +7,8 @@ go_library(
     visibility = ["//visibility:public"],
     deps = [
         "//pkg/aspect/info",
+        "//pkg/interceptors",
         "//pkg/ioutils",
-        "//pkg/pathutils",
         "@com_github_spf13_cobra//:cobra",
     ],
 )

cmd/aspect/info/info.go

@@ -10,8 +10,8 @@ import (
 	"github.com/spf13/cobra"
 
 	"aspect.build/cli/pkg/aspect/info"
+	"aspect.build/cli/pkg/interceptors"
 	"aspect.build/cli/pkg/ioutils"
-	"aspect.build/cli/pkg/pathutils"
 )
 
 func NewDefaultInfoCmd() *cobra.Command {
@@ -43,7 +43,12 @@ the bazel User Manual, and can be programmatically obtained with
 See also 'bazel version' for more detailed bazel version
 information.`,
 		Args: cobra.MaximumNArgs(1),
-		RunE: pathutils.InvokeCmdInsideWorkspace(v.Run),
+		RunE: interceptors.Run(
+			[]interceptors.Interceptor{
+				interceptors.WorkspaceRootInterceptor(),
+			},
+			v.Run,
+		),
 	}
 
 	cmd.PersistentFlags().BoolVarP(&v.ShowMakeEnv, "show_make_env", "", false, `include the set of key/value pairs in the "Make" environment,

cmd/aspect/test/BUILD.bazel

@@ -8,8 +8,8 @@ go_library(
     deps = [
         "//pkg/aspect/test",
         "//pkg/bazel",
+        "//pkg/interceptors",
         "//pkg/ioutils",
-        "//pkg/pathutils",
         "@com_github_spf13_cobra//:cobra",
     ],
 )

cmd/aspect/test/test.go

@@ -7,20 +7,22 @@ Not licensed for re-use
 package test
 
 import (
+	"context"
+
 	"github.com/spf13/cobra"
 
 	"aspect.build/cli/pkg/aspect/test"
 	"aspect.build/cli/pkg/bazel"
+	"aspect.build/cli/pkg/interceptors"
 	"aspect.build/cli/pkg/ioutils"
-	"aspect.build/cli/pkg/pathutils"
 )
 
 func NewDefaultTestCmd() *cobra.Command {
 	return NewTestCmd(ioutils.DefaultStreams, bazel.New())
 }
 
 func NewTestCmd(streams ioutils.Streams, bzl bazel.Bazel) *cobra.Command {
-	cmd := &cobra.Command{
+	return &cobra.Command{
 		Use:   "test",
 		Short: "Builds the specified targets and runs all test targets among them.",
 		Long: `Builds the specified targets and runs all test targets among them (test targets
@@ -34,12 +36,16 @@ don't forget to pass all your 'build' options to 'test' too.
 See 'bazel help target-syntax' for details and examples on how to
 specify targets.
 `,
-		RunE: pathutils.InvokeCmdInsideWorkspace(func(workspaceRoot string, cmd *cobra.Command, args []string) (exitErr error) {
-			bzl.SetWorkspaceRoot(workspaceRoot)
-			t := test.New(streams, bzl)
-			return t.Run(cmd, args)
-		}),
+		RunE: interceptors.Run(
+			[]interceptors.Interceptor{
+				interceptors.WorkspaceRootInterceptor(),
+			},
+			func(ctx context.Context, cmd *cobra.Command, args []string) (exitErr error) {
+				workspaceRoot := ctx.Value(interceptors.WorkspaceRootKey).(string)
+				bzl.SetWorkspaceRoot(workspaceRoot)
+				t := test.New(streams, bzl)
+				return t.Run(cmd, args)
+			},
+		),
 	}
-
-	return cmd
 }

cmd/docgen/BUILD.bazel

@@ -7,6 +7,8 @@ go_library(
     visibility = ["//visibility:private"],
     deps = [
         "//cmd/aspect/root",
+        "//pkg/ioutils",
+        "//pkg/plugin/system",
         "@com_github_spf13_cobra//doc",
     ],
 )

cmd/docgen/main.go

@@ -4,16 +4,25 @@ import (
 	"log"
 	"os"
 
-	"aspect.build/cli/cmd/aspect/root"
 	"github.com/spf13/cobra/doc"
+
+	"aspect.build/cli/cmd/aspect/root"
+	"aspect.build/cli/pkg/ioutils"
+	"aspect.build/cli/pkg/plugin/system"
 )
 
 func main() {
 	if len(os.Args) != 2 {
 		log.Fatal("Usage: cmd/docgen /path/to/outdir")
 	}
 
-	err := doc.GenMarkdownTree(root.NewDefaultRootCmd(nil), os.Args[1])
+	pluginSystem := system.NewPluginSystem()
+	if err := pluginSystem.Configure(ioutils.DefaultStreams); err != nil {
+		log.Fatal(err)
+	}
+	defer pluginSystem.TearDown()
+
+	err := doc.GenMarkdownTree(root.NewDefaultRootCmd(pluginSystem), os.Args[1])
 	if err != nil {
 		log.Fatal(err)
 	}

pkg/aspect/info/BUILD.bazel

@@ -8,6 +8,7 @@ go_library(
     deps = [
         "//pkg/aspecterrors",
         "//pkg/bazel",
+        "//pkg/interceptors",
         "//pkg/ioutils",
         "@com_github_spf13_cobra//:cobra",
     ],

pkg/aspect/info/info.go

@@ -7,7 +7,10 @@ Not licensed for re-use.
 package info
 
 import (
+	"context"
+
 	"aspect.build/cli/pkg/bazel"
+	"aspect.build/cli/pkg/interceptors"
 	"aspect.build/cli/pkg/ioutils"
 	"github.com/spf13/cobra"
 
@@ -26,14 +29,15 @@ func New(streams ioutils.Streams) *Info {
 	}
 }
 
-func (v *Info) Run(workspaceRoot string, _ *cobra.Command, args []string) error {
+func (v *Info) Run(ctx context.Context, _ *cobra.Command, args []string) error {
 	bazelCmd := []string{"info"}
 	if v.ShowMakeEnv {
 		// Propagate the flag
 		bazelCmd = append(bazelCmd, "--show_make_env")
 	}
 	bazelCmd = append(bazelCmd, args...)
 	bzl := bazel.New()
+	workspaceRoot := ctx.Value(interceptors.WorkspaceRootKey).(string)
 	bzl.SetWorkspaceRoot(workspaceRoot)
 
 	if exitCode, err := bzl.Spawn(bazelCmd); exitCode != 0 {

pkg/interceptors/BUILD.bazel

@@ -0,0 +1,30 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "interceptors",
+    srcs = [
+        "run.go",
+        "workspace.go",
+    ],
+    importpath = "aspect.build/cli/pkg/interceptors",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/pathutils",
+        "@com_github_spf13_cobra//:cobra",
+    ],
+)
+
+go_test(
+    name = "interceptors_test",
+    srcs = [
+        "run_test.go",
+        "workspace_test.go",
+    ],
+    embed = [":interceptors"],
+    deps = [
+        "//pkg/pathutils/mock",
+        "@com_github_golang_mock//gomock",
+        "@com_github_onsi_gomega//:gomega",
+        "@com_github_spf13_cobra//:cobra",
+    ],
+)

pkg/interceptors/run.go

@@ -0,0 +1,40 @@
+/*
+Copyright © 2021 Aspect Build Systems Inc
+
+Not licensed for re-use.
+*/
+
+package interceptors
+
+import (
+	"context"
+
+	"github.com/spf13/cobra"
+)
+
+// RunEFn matches the cobra command.RunE signature.
+type RunEFn func(cmd *cobra.Command, args []string) error
+
+// RunEContextFn is the signature based on RunEFn that injects the context as
+// an argument.
+type RunEContextFn func(ctx context.Context, cmd *cobra.Command, args []string) error
+
+// Interceptor represents an interceptor in the CLI command chain. It's
+// represented as a function signature.
+type Interceptor func(ctx context.Context, cmd *cobra.Command, args []string, next RunEContextFn) error
+
+// Run returns a function that matches the cobra RunE signature. It assembles
+// the interceptors and main command to be run in the correct sequence.
+func Run(interceptors []Interceptor, fn RunEContextFn) RunEFn {
+	return func(cmd *cobra.Command, args []string) error {
+		current := fn
+		for i := len(interceptors) - 1; i > 0; i-- {
+			j := i
+			next := current
+			current = func(ctx context.Context, cmd *cobra.Command, args []string) error {
+				return interceptors[j](ctx, cmd, args, next)
+			}
+		}
+		return interceptors[0](cmd.Context(), cmd, args, current)
+	}
+}