Add gazelle plugin

README.md

@@ -10,6 +10,8 @@ While [rules_pkg](https://github.com/bazelbuild/rules_pkg/) _works_, `rules_nfpm
 - No host dependencies (e.g. `rpmbuild` is not needed in `PATH`)
 - Built-in templating of Bazel [workspace status](https://docs.bazel.build/versions/master/user-manual.html#workspace_status) key-value pairs
 
+A [plugin](https://github.com/bazelbuild/bazel-gazelle/blob/master/extend.rst) for [gazelle](https://github.com/bazelbuild/bazel-gazelle) is included that generates the rules and updates their dependencies.
+
 ## Setup
 
 Include the following snippet in your repository's WORKSPACE file:

docs/readme-header.md

@@ -8,6 +8,8 @@ While [rules_pkg](https://github.com/bazelbuild/rules_pkg/) _works_, `rules_nfpm
 - No host dependencies (e.g. `rpmbuild` is not needed in `PATH`)
 - Built-in templating of Bazel [workspace status](https://docs.bazel.build/versions/master/user-manual.html#workspace_status) key-value pairs
 
+A [plugin](https://github.com/bazelbuild/bazel-gazelle/blob/master/extend.rst) for [gazelle](https://github.com/bazelbuild/bazel-gazelle) is included that generates the rules and updates their dependencies.
+
 ## Setup
 
 Include the following snippet in your repository's WORKSPACE file:

example/BUILD.bazel

@@ -1 +1,14 @@
+load("@bazel_gazelle//:def.bzl", "DEFAULT_LANGUAGES", "gazelle", "gazelle_binary")
+
+gazelle_binary(
+    name = "gazelle_binary",
+    languages = DEFAULT_LANGUAGES + [
+        "@com_github_ericnorris_rules_nfpm//nfpm:gazelle_nfpm_language",
+    ],
+)
+
 # gazelle:prefix github.com/ericnorris/rules_nfpm/example
+gazelle(
+    name = "gazelle",
+    gazelle = ":gazelle_binary",
+)

example/README.md

@@ -1,10 +1,10 @@
 # rules_nfpm example
 
-This folder contains an example bazel WORKSPACE and BUILD setup that builds a small `go` binary and packages the binary into `deb` and `rpm` formats.
+This folder contains an example bazel WORKSPACE and BUILD setup that builds a small `go` binary and packages the binary into `deb` and `rpm` formats. The BUILD files for the packages was generated by Gazelle.
 
 ## Usage
 
-```
+```console
 $ bazel build packages/...
 
 $ rpm -qil -v ./bazel-bin/packages/helloworld.rpm
@@ -37,6 +37,38 @@ helloworld prints "hello, world" and then exits. This particular package was gen
 -r-xr-xr-x    1 root    root                  2169992 Jun 13 15:46 /usr/bin/helloworld
 ```
 
+### Gazelle
+
+```console
+$ rm packages/BUILD.bazel
+
+$ bazel run //:gazelle
+INFO: Analyzed target //:gazelle (1 packages loaded, 3 targets configured).
+INFO: Found 1 target...
+Target //:gazelle up-to-date:
+  bazel-bin/gazelle-runner.bash
+  bazel-bin/gazelle
+INFO: Elapsed time: 0.775s, Critical Path: 0.06s
+INFO: 1 process: 1 internal.
+INFO: Build completed successfully, 1 total action
+INFO: Build completed successfully, 1 total action
+
+$ cat packages/BUILD.bazel
+load("@com_github_ericnorris_rules_nfpm//nfpm:defs.bzl", "nfpm_package")
+
+nfpm_package(
+    name = "helloworld.deb",
+    config = "helloworld.nfpm.yaml",
+    deps = ["//cmd/helloworld"],
+)
+
+nfpm_package(
+    name = "helloworld.rpm",
+    config = "helloworld.nfpm.yaml",
+    deps = ["//cmd/helloworld"],
+)
+```
+
 ## Internals
 
 The directory's [.bazelrc](/example/.bazelrc) file configures the [workspace-status.sh](/example/workspace-status.sh) script to run on every `bazel build` invocation. The [workspace status](https://docs.bazel.build/versions/master/user-manual.html#workspace_status) script produces "stable" and "volatile" key-value pairs that are useable later; the values are hardcoded for the purposes of this example, but could be dynamically computed via `git` commands.

example/cmd/helloworld/BUILD.bazel

@@ -1,14 +1,14 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 
 go_library(
-    name = "go_default_library",
+    name = "helloworld_lib",
     srcs = ["main.go"],
     importpath = "github.com/ericnorris/rules_nfpm/example/cmd/helloworld",
     visibility = ["//visibility:private"],
 )
 
 go_binary(
     name = "helloworld",
-    embed = [":go_default_library"],
+    embed = [":helloworld_lib"],
     visibility = ["//visibility:public"],
 )

example/packages/BUILD.bazel

@@ -1,17 +1,13 @@
 load("@com_github_ericnorris_rules_nfpm//nfpm:defs.bzl", "nfpm_package")
 
 nfpm_package(
-    name = "helloworld.rpm",
-    config = "helloworld.yaml",
-    deps = [
-        "//cmd/helloworld",
-    ],
+    name = "helloworld.deb",
+    config = "helloworld.nfpm.yaml",
+    deps = ["//cmd/helloworld"],
 )
 
 nfpm_package(
-    name = "helloworld.deb",
-    config = "helloworld.yaml",
-    deps = [
-        "//cmd/helloworld",
-    ],
+    name = "helloworld.rpm",
+    config = "helloworld.nfpm.yaml",
+    deps = ["//cmd/helloworld"],
 )

go/internal/gazelle/BUILD.bazel

@@ -0,0 +1,16 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "gazelle",
+    srcs = ["main.go"],
+    importpath = "github.com/ericnorris/rules_nfpm/go/internal/gazelle",
+    visibility = ["//:__subpackages__"],
+    deps = [
+        "@bazel_gazelle//config:go_default_library",
+        "@bazel_gazelle//label:go_default_library",
+        "@bazel_gazelle//language:go_default_library",
+        "@bazel_gazelle//repo:go_default_library",
+        "@bazel_gazelle//resolve:go_default_library",
+        "@bazel_gazelle//rule:go_default_library",
+    ],
+)

go/internal/gazelle/main.go

@@ -0,0 +1,157 @@
+// Package gazelle is a gazelle plugin that adds nfpm_package rules for each .nfpm.yaml file it finds.
+package gazelle
+
+import (
+	"flag"
+	"io/ioutil"
+	"log"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"github.com/bazelbuild/bazel-gazelle/config"
+	"github.com/bazelbuild/bazel-gazelle/label"
+	"github.com/bazelbuild/bazel-gazelle/language"
+	"github.com/bazelbuild/bazel-gazelle/repo"
+	"github.com/bazelbuild/bazel-gazelle/resolve"
+	"github.com/bazelbuild/bazel-gazelle/rule"
+)
+
+type nfpmLanguage struct{}
+
+// NewLanguage returns a gazelle language plugin.
+func NewLanguage() language.Language {
+	return &nfpmLanguage{}
+}
+
+// Name returns the name of the language. This should be a prefix of the kinds of rules generated by
+// the language, e.g., "go" for the Go extension since it generates "go_library" rules.
+//
+// Since we are generating nfpm_package rules, we return "nfpm".
+func (nfpmLanguage) Name() string {
+	return "nfpm"
+}
+
+// Kinds returns a map of maps rule names (kinds) and information on how to match and merge
+// attributes that may be found in rules of those kinds. All kinds of rules generated for this
+// language may be found here.
+func (nfpmLanguage) Kinds() map[string]rule.KindInfo {
+	return map[string]rule.KindInfo{
+		"nfpm_package": {
+			// MatchAttrs is a list of attributes used in matching. For example, for go_library, this list
+			// contains "importpath". Attributes are matched in order.
+			//
+			// Because each config file may be used for both a debian and an rpm package, we cannot match
+			// on config, so we match on name.
+			MatchAttrs: []string{"name"},
+
+			// ResolveAttrs is a set of attributes that should be merged after
+			// dependency resolution. See rule.Merge.
+			ResolveAttrs: map[string]bool{"deps": true},
+		},
+	}
+}
+
+// Loads returns .bzl files and symbols they define. Every rule generated by
+// GenerateRules, now or in the past, should be loadable from one of these
+// files.
+func (nfpmLanguage) Loads() []rule.LoadInfo {
+	return []rule.LoadInfo{
+		{
+			Name:    "@com_github_ericnorris_rules_nfpm//nfpm:defs.bzl",
+			Symbols: []string{"nfpm_package"},
+		},
+	}
+}
+
+var _dependencyRegex = regexp.MustCompile("{{ index .Dependencies `(.*)`}}")
+
+// GenerateRules extracts build metadata from source files in a directory.
+// GenerateRules is called in each directory where an update is requested
+// in depth-first post-order.
+//
+// args contains the arguments for GenerateRules. This is passed as a
+// struct to avoid breaking implementations in the future when new
+// fields are added.
+//
+// A GenerateResult struct is returned. Optional fields may be added to this
+// type in the future.
+//
+// Any non-fatal errors this function encounters should be logged using
+// log.Print.
+func (nfpmLanguage) GenerateRules(args language.GenerateArgs) language.GenerateResult {
+	rules := make([]*rule.Rule, 0)
+	imports := make([]interface{}, 0)
+	for _, file := range args.RegularFiles {
+		if strings.HasSuffix(file, ".nfpm.yaml") {
+			deps := dependenciesFromYaml(args.Dir, file, "//"+args.Rel)
+			baseName := file[:len(file)-len(".nfpm.yaml")]
+
+			deb := makeRule(baseName+".deb", file, deps)
+			rpm := makeRule(baseName+".rpm", file, deps)
+
+			rules = append(rules, deb, rpm)
+			imports = append(imports, nil, nil)
+		}
+	}
+
+	return language.GenerateResult{
+		Gen:     rules,
+		Imports: imports,
+	}
+}
+
+func dependenciesFromYaml(dir, file, rel string) []string {
+	// ioutil.ReadFile can be replaced with os.ReadFile when we rely on go 1.16.
+	bytes, err := ioutil.ReadFile(filepath.Join(dir, file))
+	if err != nil {
+		log.Printf("Failed to read file due to %+v", err)
+		return nil
+	}
+	matches := _dependencyRegex.FindAllStringSubmatch(string(bytes), -1)
+	deps := make([]string, len(matches))
+	for i, ms := range matches {
+		m := ms[1]
+		if strings.HasPrefix(m, rel) {
+			deps[i] = m[len(rel):]
+		} else {
+			deps[i] = m
+		}
+	}
+	return deps
+}
+
+func makeRule(name, config string, deps []string) *rule.Rule {
+	r := rule.NewRule("nfpm_package", name)
+	r.SetAttr("config", config)
+	r.SetAttr("deps", deps)
+	return r
+}
+
+func (nfpmLanguage) RegisterFlags(fs *flag.FlagSet, cmd string, c *config.Config) {
+}
+
+func (nfpmLanguage) CheckFlags(fs *flag.FlagSet, c *config.Config) error {
+	return nil
+}
+
+func (nfpmLanguage) KnownDirectives() []string {
+	return nil
+}
+
+func (nfpmLanguage) Configure(c *config.Config, rel string, f *rule.File) {
+}
+
+func (nfpmLanguage) Fix(c *config.Config, f *rule.File) {
+}
+
+func (nfpmLanguage) Imports(c *config.Config, r *rule.Rule, f *rule.File) []resolve.ImportSpec {
+	return nil
+}
+
+func (nfpmLanguage) Embeds(r *rule.Rule, from label.Label) []label.Label {
+	return nil
+}
+
+func (nfpmLanguage) Resolve(c *config.Config, ix *resolve.RuleIndex, rc *repo.RemoteCache, r *rule.Rule, imports interface{}, from label.Label) {
+}

nfpm/BUILD.bazel

@@ -5,3 +5,9 @@ filegroup(
     srcs = glob(["*"]),
     visibility = ["//:__subpackages__"],
 )
+
+alias(
+    name = "gazelle_nfpm_language",
+    actual = "//go/internal/gazelle",
+    visibility = ["//visibility:public"],
+)

scripts/BUILD.bazel

@@ -1,11 +1,21 @@
-load("@bazel_gazelle//:def.bzl", "gazelle")
+load("@bazel_gazelle//:def.bzl", "DEFAULT_LANGUAGES", "gazelle", "gazelle_binary")
 load("@com_github_bazelbuild_buildtools//buildifier:def.bzl", "buildifier")
 
 #
 # Gazelle scripts
 #
 
-gazelle(name = "gazelle")
+gazelle_binary(
+    name = "gazelle_binary",
+    languages = DEFAULT_LANGUAGES + [
+        "//nfpm:gazelle_nfpm_language",
+    ],
+)
+
+gazelle(
+    name = "gazelle",
+    gazelle = ":gazelle_binary",
+)
 
 sh_binary(
     name = "generate-go-build-files",

tests/BUILD.bazel

@@ -1,20 +1,13 @@
-load("//nfpm:defs.bzl", "nfpm_package")
-
-filegroup(
-    name = "text-files",
-    srcs = glob([
-        "*.txt",
-    ]),
-)
+load("@com_github_ericnorris_rules_nfpm//nfpm:defs.bzl", "nfpm_package")
 
 nfpm_package(
-    name = "test.rpm",
-    config = "test-config.yaml",
-    deps = [":text-files"],
+    name = "test.deb",
+    config = "test.nfpm.yaml",
+    deps = [":meow.txt"],
 )
 
 nfpm_package(
-    name = "test.deb",
-    config = "test-config.yaml",
-    deps = [":text-files"],
+    name = "test.rpm",
+    config = "test.nfpm.yaml",
+    deps = [":meow.txt"],
 )