Allow use of Bazel repository externally

README.md

@@ -93,7 +93,7 @@ Note that we maintain the Go-related Bazel targets with [the Gazelle tool](https
 
 After changing any dependencies within the files covered by this Go module, it is helpful to run _go mod tidy_ to ensure that the module declarations match the state of the Go source code. In order to synchronize the Bazel rules with material changes to the Go module, run the following command to invoke [Gazelle's `update-repos` command](https://github.com/bazelbuild/bazel-gazelle#update-repos):
 ```bash
-bazel run //:gazelle -- update-repos -from_file=go.mod
+bazel run //:gazelle -- update-repos -from_file=go.mod -to_macro=bazel/deps.bzl%jsonnet_go_dependencies
 ```
 
 Similarly, after adding or removing Go source files, it may be necessary to synchronize the Bazel rules by running the following command:

WORKSPACE

@@ -4,84 +4,18 @@ load(
     "@bazel_tools//tools/build_defs/repo:http.bzl",
     "http_archive",
 )
-
+load(
-# Go and Gazelle
+    "@google_jsonnet_go//bazel:repositories.bzl",
-http_archive(
+    "jsonnet_go_repositories",
-    name = "io_bazel_rules_go",
-    sha256 = "a82a352bffae6bee4e95f68a8d80a70e87f42c4741e6a448bec11998fcc82329",
-    urls = ["https://github.com/bazelbuild/rules_go/releases/download/0.18.5/rules_go-0.18.5.tar.gz"],
 )
 
-http_archive(
+jsonnet_go_repositories()
-    name = "bazel_gazelle",
-    sha256 = "3c681998538231a2d24d0c07ed5a7658cb72bfb5fd4bf9911157c0e9ac6a2687",
-    urls = ["https://github.com/bazelbuild/bazel-gazelle/releases/download/0.17.0/bazel-gazelle-0.17.0.tar.gz"],
-)
 
 load(
-    "@io_bazel_rules_go//go:deps.bzl",
+    "@google_jsonnet_go//bazel:deps.bzl",
-    "go_register_toolchains",
+    "jsonnet_go_dependencies",
-    "go_rules_dependencies",
 )
 
-go_rules_dependencies()
+jsonnet_go_dependencies()
 
-go_register_toolchains()
+#gazelle:repository_macro bazel/deps.bzl%jsonnet_go_dependencies
-
-load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies", "go_repository")
-
-gazelle_dependencies()
-
-go_repository(
-    name = "com_github_davecgh_go_spew",
-    importpath = "github.com/davecgh/go-spew",
-    tag = "v1.1.0",
-)
-
-go_repository(
-    name = "com_github_fatih_color",
-    importpath = "github.com/fatih/color",
-    tag = "v1.7.0",
-)
-
-go_repository(
-    name = "com_github_mattn_go_colorable",
-    importpath = "github.com/mattn/go-colorable",
-    tag = "v0.1.1",
-)
-
-go_repository(
-    name = "com_github_mattn_go_isatty",
-    importpath = "github.com/mattn/go-isatty",
-    tag = "v0.0.7",
-)
-
-go_repository(
-    name = "com_github_pmezard_go_difflib",
-    importpath = "github.com/pmezard/go-difflib",
-    tag = "v1.0.0",
-)
-
-go_repository(
-    name = "com_github_sergi_go_diff",
-    importpath = "github.com/sergi/go-diff",
-    tag = "v1.0.0",
-)
-
-go_repository(
-    name = "com_github_stretchr_objx",
-    importpath = "github.com/stretchr/objx",
-    tag = "v0.1.0",
-)
-
-go_repository(
-    name = "com_github_stretchr_testify",
-    importpath = "github.com/stretchr/testify",
-    tag = "v1.3.0",
-)
-
-go_repository(
-    name = "org_golang_x_sys",
-    commit = "a9d3bda3a223",
-    importpath = "golang.org/x/sys",
-)

bazel/deps.bzl

@@ -0,0 +1,69 @@
+load(
+    "@io_bazel_rules_go//go:deps.bzl",
+    "go_register_toolchains",
+    "go_rules_dependencies",
+)
+load(
+    "@bazel_gazelle//:deps.bzl",
+    "gazelle_dependencies",
+    "go_repository",
+)
+
+def jsonnet_go_dependencies():
+    go_rules_dependencies()
+    go_register_toolchains()
+    gazelle_dependencies()
+    go_repository(
+        name = "com_github_davecgh_go_spew",
+        importpath = "github.com/davecgh/go-spew",
+        sum = "h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=",
+        version = "v1.1.0",
+    )
+    go_repository(
+        name = "com_github_fatih_color",
+        importpath = "github.com/fatih/color",
+        sum = "h1:DkWD4oS2D8LGGgTQ6IvwJJXSL5Vp2ffcQg58nFV38Ys=",
+        version = "v1.7.0",
+    )
+    go_repository(
+        name = "com_github_mattn_go_colorable",
+        importpath = "github.com/mattn/go-colorable",
+        sum = "h1:G1f5SKeVxmagw/IyvzvtZE4Gybcc4Tr1tf7I8z0XgOg=",
+        version = "v0.1.1",
+    )
+    go_repository(
+        name = "com_github_mattn_go_isatty",
+        importpath = "github.com/mattn/go-isatty",
+        sum = "h1:UvyT9uN+3r7yLEYSlJsbQGdsaB/a0DlgWP3pql6iwOc=",
+        version = "v0.0.7",
+    )
+    go_repository(
+        name = "com_github_pmezard_go_difflib",
+        importpath = "github.com/pmezard/go-difflib",
+        sum = "h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=",
+        version = "v1.0.0",
+    )
+    go_repository(
+        name = "com_github_sergi_go_diff",
+        importpath = "github.com/sergi/go-diff",
+        sum = "h1:Kpca3qRNrduNnOQeazBd0ysaKrUJiIuISHxogkT9RPQ=",
+        version = "v1.0.0",
+    )
+    go_repository(
+        name = "com_github_stretchr_objx",
+        importpath = "github.com/stretchr/objx",
+        sum = "h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=",
+        version = "v0.1.0",
+    )
+    go_repository(
+        name = "com_github_stretchr_testify",
+        importpath = "github.com/stretchr/testify",
+        sum = "h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=",
+        version = "v1.3.0",
+    )
+    go_repository(
+        name = "org_golang_x_sys",
+        importpath = "golang.org/x/sys",
+        sum = "h1:T5DasATyLQfmbTpfEXx/IOL9vfjzW6up+ZDkmHvIf2s=",
+        version = "v0.0.0-20190531175056-4c3a928424d2",
+    )

bazel/repositories.bzl

@@ -0,0 +1,31 @@
+load(
+    "@bazel_tools//tools/build_defs/repo:http.bzl",
+    "http_archive",
+)
+
+def _maybe(repo_rule, name, **kwargs):
+    """Executes the given repository rule if it hasn't been executed already.
+    Args:
+      repo_rule: The repository rule to be executed (e.g.,
+          `native.git_repository`.)
+      name: The name of the repository to be defined by the rule.
+      **kwargs: Additional arguments passed directly to the repository rule.
+    """
+    if not native.existing_rule(name):
+        repo_rule(name = name, **kwargs)
+
+def jsonnet_go_repositories():
+    _maybe(
+        http_archive,
+        name = "io_bazel_rules_go",
+        sha256 = "e6f8cb2da438cc4899809b66ba96d57397ed871640fe5c848ca9c56190b7c8ba",
+        strip_prefix = "rules_go-8ea79bbd5e6ea09dc611c245d1dc09ef7ab7118a",
+        urls = ["https://github.com/bazelbuild/rules_go/archive/8ea79bbd5e6ea09dc611c245d1dc09ef7ab7118a.zip"],
+    )
+    _maybe(
+        http_archive,
+        name = "bazel_gazelle",
+        sha256 = "c5faf839dd1da0065ed7d44ac248b01ab5ffcd0db46e7193439906df68867c39",
+        strip_prefix = "bazel-gazelle-38bd65ead186af23549480d6189b89c7c53c023e",
+        urls = ["https://github.com/bazelbuild/bazel-gazelle/archive/38bd65ead186af23549480d6189b89c7c53c023e.zip"],
+    )