Adds an action for fetching rust dependency updates

README.md

@@ -53,6 +53,7 @@ The Pipeline Builder is a collection of tools related to GitHub Actions and othe
     - [Paketo Deps Dependency](#paketo-deps-dependency)
     - [Aternity Dependency](#aternity-dependency)
     - [Rustup Init Dependency](#rustup-init-dependency)
+    - [Rust Dependency](#rust-dependency)
     - [Skywalking Dependency](#skywalking-dependency)
     - [Spring Generations](#spring-generations)
     - [Tomcat Dependency](#tomcat-dependency)
@@ -631,6 +632,16 @@ with:
   token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
 ```
 
+### Rust Dependency
+The Rust Dependency queries the [Rust Github Project](https://github.com/rust-lang/rust) for the latest version. The `target` specifies the target triple to download.
+
+```yaml
+uses: docker://ghcr.io/paketo-buildpacks/actions/rust-dependency:main
+with:
+  target: x86_64-unknown-linux-gnu
+  token: ${{ secrets.PAKETO_BOT_GITHUB_TOKEN }}
+```
+
 ### Skywalking Dependency
 The Skywalking Dependency watches the [Apache Skywalking Download Page](https://downloads.apache.org/skywalking) for new versions.
 

actions/rust-dependency/main.go

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/google/go-github/v43/github"
+	"golang.org/x/oauth2"
+
+	"github.com/paketo-buildpacks/pipeline-builder/actions"
+)
+
+const (
+	ORG  = "rust-lang"
+	REPO = "rust"
+)
+
+func main() {
+	inputs := actions.NewInputs()
+
+	target, ok := inputs["target"]
+	if !ok {
+		panic(fmt.Errorf("target must be specified"))
+	}
+
+	var c *http.Client
+	if s, ok := inputs["token"]; ok {
+		c = oauth2.NewClient(context.Background(), oauth2.StaticTokenSource(&oauth2.Token{AccessToken: s}))
+	}
+	gh := github.NewClient(c)
+
+	versions := make(actions.Versions)
+
+	// pull latest version
+	release, _, err := gh.Repositories.GetLatestRelease(context.Background(), ORG, REPO)
+	if err != nil {
+		panic(fmt.Errorf("unable to list existing tags for %s/%s\n%w", ORG, REPO, err))
+	}
+
+	normalVersion, err := actions.NormalizeVersion(*release.TagName)
+	if err != nil {
+		panic(err)
+	}
+
+	versions[normalVersion] = fmt.Sprintf("https://static.rust-lang.org/dist/"+
+		"rust-%s-%s.tar.gz", normalVersion, target)
+
+	if o, err := versions.GetLatest(inputs); err != nil {
+		panic(err)
+	} else {
+		o.Write(os.Stdout)
+	}
+}