Add use subcommand

BUILD.bazel

@@ -34,6 +34,7 @@ go_library(
         "//command/install:go_default_library",
         "//command/release:go_default_library",
         "//command/targets:go_default_library",
+        "//command/use:go_default_library",
         "@com_github_urfave_cli//:go_default_library",
     ],
 )

README.md

@@ -4,11 +4,8 @@
 versions of bazel.  You can install different versions and easily switch between
 them.
 
-## Install bzl
-
-`bzl` ships as a single executable go binary. Download the file directly from
-the [Github Releases Page](https://github.com/bzl-io/bzl/releases) for the
-precompiled platform of your choice (or build from source).
+`bzl` is a drop-in replacement for `bazel`. Any commands not recognized by `bzl`
+are passed through as-is to `bazel`.
 
 ## How is `bzl` pronounced?
 
@@ -19,32 +16,86 @@ it's function (a wrapper around bazel).
 > add functions to a watch without complicating the movement, and so the
 > external watch bezel was born.
 
+## Install bzl
+
+`bzl` ships as a single executable go binary. Download the file directly from
+the [Github Releases Page](https://github.com/bzl-io/bzl/releases) for the
+precompiled platform of your choice (or build from source).
+
+Once downloaded `chmod +x` and `mv bzl ~/bin/bazel` and type `bazel install` to
+list the available versions.
+
+Specify the version of bazel to use either via an environment variable or
+command line flag (example: `BAZEL_VERSION=0.24.1`; `--bazel=0.19.2`).
+
 ## `bzl` commands
 
-### `$ bzl --help`
+### `$ bazel --help`
 
 Show help.
 
-### `$ bzl install`
+### `$ bazel install`
 
 List or install available bazel installs.
 
 Examples:
 
 | Command | Description |
 | --- | --- |
-| `$ bzl install` | List all available releases |
-| `$ bzl install 0.8.0` | Install bazel release 0.8.0 |
-| `$ bzl install --list 0.8.0` | Show the assets bundled in install 0.8.0 |
+| `$ bazel install` | List all available releases |
+| `$ bazel install 0.8.0` | Install bazel release 0.8.0 |
+| `$ bazel install --list 0.8.0` | Show the assets bundled in install 0.8.0 |
+
+### `$ bazel use`
+
+Print a repository rule for a github bazel repository.
 
-### `$ bzl target`
+Without a release tag, list available releases:
+
+```
+$ bazel use grpc-ecosystem/grpc-gateway 
+
+v1.8.5        Fri Mar 15 2019
+v1.8.4        Wed Mar 13 2019
+v1.8.3        Mon Mar 11 2019
+v1.8.2        Thu Mar 07 2019
+v1.8.1        Sat Mar 02 2019
+```
+
+With a release tag, output an `http_archive` rule:
+
+```
+$ bazel use grpc-ecosystem/grpc-gateway v1.8.5
+
+http_archive(
+    name = "grpc_ecosystem_grpc_gateway",
+    urls = ["https://github.com/grpc-ecosystem/grpc-gateway/archive/v1.8.5.tar.gz"],
+    strip_prefix = "grpc-gateway-1.8.5",
+    sha256 = "9d7cf2ce799002024f215d3ff2df4882c347563478093a4671b13154ba37982c",
+)
+```
+
+The `bazelbuild` organization is assumed if you leave out the organization name:
+
+```
+$ bazel use rules_go
+
+0.18.3    Fri Apr 12 2019
+0.17.4    Fri Apr 12 2019
+0.16.10   Fri Apr 12 2019
+0.18.2    Sat Apr 06 2019
+...
+```
+
+### `$ bazel target`
 
 Pretty-print available targets in the current workspace.
 
 Example:
 
 ```
-$ bzl targets
+$ bazel targets
+
 go_library        rule  //proto/bes:go_default_library
 go_library        rule  //:go_default_library
 go_library        rule  //command:go_default_library
@@ -67,7 +118,7 @@ go_library        rule  //command/use:go_default_library
 _buildifier       rule  //:buildifier
 ```
 
-### `$ bzl release`
+### `$ bazel release`
 
 Publish a release for a `go_binary` target.
 
@@ -92,7 +143,7 @@ rules_go.  Here's what the command does:
 Example:
 
 ```
-$ bzl release \
+$ bazel release \
     --owner=bzl-io \
     --repo=bzl \
     --commit=91801a92ea21cd73471e5a83ad2519d1a3f257f0 \

WORKSPACE

@@ -1,11 +1,18 @@
+workspace(name = "io_bzl_bzl")
+
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive", "http_file")
 
 local_repository(
     name = "build_stack_rules_proto",
     path = "/home/pcj/go/src/github.com/stackb/rules_proto",
 )
 
-load("@build_stack_rules_proto//:deps.bzl", "bazel_gazelle", "com_github_bazelbuild_buildtools", "io_bazel_rules_go")
+load(
+    "@build_stack_rules_proto//:deps.bzl",
+    "bazel_gazelle",
+    "com_github_bazelbuild_buildtools",
+    "io_bazel_rules_go",
+)
 
 io_bazel_rules_go()
 
@@ -93,12 +100,6 @@ go_repository(
     importpath = "github.com/pkg/errors",
 )
 
-# go_repository(
-#     name = "com_github_mattn_go_runewidth",
-#     importpath = "github.com/mattn/go-runewidth",
-#     commit = "97311d9f7767e3d6f422ea06661bc2c7a19e8a5d",
-# )
-
 go_repository(
     name = "org_golang_x_tools",
     commit = "9b61fcc4c548d69663d915801fc4b42a43b6cd9c",
@@ -123,9 +124,9 @@ go_repository(
     importpath = "github.com/mitchellh/go-homedir",
 )
 
-# There exist multiple options for terminal-based progress bars, but
-# this is the only one I could find that cross-compiles cleanly with
-# current version of rules_go.  Not super fancy though.
+# There exist multiple options for terminal-based progress bars, but this is the
+# only one I could find that cross-compiles cleanly with current version of
+# rules_go.  Not super fancy though.
 go_repository(
     name = "com_github_mitchellh_ioprogress",
     commit = "8163955264568045f462ae7e2d6d07b2001fc997",

app.go

@@ -11,6 +11,7 @@ import (
 	"github.com/bzl-io/bzl/command/install"
 	"github.com/bzl-io/bzl/command/release"
 	"github.com/bzl-io/bzl/command/targets"
+	"github.com/bzl-io/bzl/command/use"
 )
 
 // Will be replaced at link time to `git rev-parse HEAD`
@@ -39,6 +40,7 @@ func NewApp() *App {
 	app.EnableBashCompletion = true
 	app.Usage = "Wrapper for the Bazel build tool"
 	app.Version = fmt.Sprintf("https://github.com/bzl-io/bzl/tree/%s (%s)", BuildScmRevision, BuildScmDate)
+	app.HideHelp = true
 
 	// Global flags for bzl app
 	app.Flags = []cli.Flag{
@@ -54,6 +56,7 @@ func NewApp() *App {
 		*install.Command,
 		*targets.Command,
 		*release.Command,
+		*use.Command,
 	}
 
 	instance := &App{

command/install/install.go

@@ -266,7 +266,7 @@ func downloadAsset(baseDir string, asset *github.ReleaseAsset) (string, error) {
 		err = downloadUrl(redirect, out, int64(*asset.Size), *asset.Name)
 	} else {
 		defer rc.Close()
-		err = dl(rc, out, int64(*asset.Size), *asset.Name)
+		err = Download(rc, out, int64(*asset.Size), *asset.Name)
 	}
 
 	return filename, nil
@@ -285,7 +285,7 @@ func downloadUrl(url string, out io.Writer, size int64, title string) error {
 		return err
 	}
 
-	return dl(resp.Body, out, size, title)
+	return Download(resp.Body, out, size, title)
 }
 
 func downloadUrl2(url string, out io.Writer, size int64, title string) error {
@@ -295,12 +295,12 @@ func downloadUrl2(url string, out io.Writer, size int64, title string) error {
 	}
 	defer f.Close()
 
-	return dl(f, out, size, title)
+	return Download(f, out, size, title)
 }
 
 // download accepts a reader, writer, and expected asset size, copies
 // the bytes through and displays progress to the console.
-func dl(reader io.Reader, writer io.Writer, size int64, title string) error {
+func Download(reader io.Reader, writer io.Writer, size int64, title string) error {
 	// Attempt 1:
 	// bar := pb.New(size).SetUnits(pb.U_BYTES)
 	// bar.Prefix(title)

command/targets/targets.go

@@ -25,10 +25,13 @@ func execute(c *cli.Context) error {
 		pattern = "//..."
 	}
 
+	fmt.Printf("args: %+v", c.Command)
+
 	query, err := bazelutil.New().Query(pattern)
 	if err != nil {
 		return err
 	}
+
 	//fmt.Println("Targets:", len(query.GetTarget()))
 	w := tabwriter.NewWriter(os.Stdout, 0, 0, 1, ' ', 0)
 
@@ -49,7 +52,6 @@ func execute(c *cli.Context) error {
 }
 
 func printRule(w io.Writer, rule *build.Rule) {
-	//fmt.Fprintln(w, "rule\t", *rule.Name, "\t", *rule.RuleClass)
 	fmt.Fprintln(w, *rule.RuleClass, "\trule\t", *rule.Name)
 }
 

command/use/BUILD.bazel

@@ -2,8 +2,13 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
-    srcs = ["install.go"],
+    srcs = ["use.go"],
     importpath = "github.com/bzl-io/bzl/command/use",
     visibility = ["//visibility:public"],
-    deps = ["@com_github_urfave_cli//:go_default_library"],
+    deps = [
+        "//command/install:go_default_library",
+        "//gh:go_default_library",
+        "@com_github_google_go_github//github:go_default_library",
+        "@com_github_urfave_cli//:go_default_library",
+    ],
 )