apko_tags: handle provides better (#293)

Today sometimes configs request some package, say, `nodejs`, which gets
provided by a package named `nodejs-21`. When it comes time to get the
tags for this config, we can't pass `nodejs` today because the resulting
config has no package with that name. And callers don't necessarily know
it's called `nodejs-21`, or else they would have requested that.

This makes `apko_tags` aware of this scenario and slightly less dumb,
and if it can't find a package named `nodejs`, will look for a package
named `nodejs-*` and assume that's the desired package.

---------

Signed-off-by: Jason Hall <jason@chainguard.dev>
Signed-off-by: James Petersen <jpetersenames@gmail.com>
Co-authored-by: James Petersen <jpetersenames@gmail.com>

internal/provider/tags_data_source.go

@@ -102,22 +102,46 @@ func (d *TagsDataSource) Read(ctx context.Context, req datasource.ReadRequest, r
 		return
 	}
 
-	found := false
+	pkgs := map[string]string{}
+	var found string
 	for _, pkg := range ic.Contents.Packages {
-		if strings.HasPrefix(pkg, data.TargetPackage.ValueString()+"=") {
-			fullVersion := strings.TrimPrefix(pkg, data.TargetPackage.ValueString()+"=")
-			data.Tags = getStemmedVersionTags(fullVersion)
-			data.Tags = append(data.Tags, fullVersion)
-			sort.Strings(data.Tags)
-			found = true
-			break
+		pkg, version, ok := strings.Cut(pkg, "=")
+		if !ok {
+			resp.Diagnostics.AddError("Invalid package", fmt.Sprintf("Invalid package: %s", pkg))
+			return
 		}
+		pkgs[pkg] = version
 	}
-	if !found {
-        resp.Diagnostics.AddError(fmt.Sprintf("Unable to find package: %s...", data.TargetPackage.ValueString()), fmt.Sprintf("...in package list:\n\t%s", strings.Join(ic.Contents.Packages, "\n\t")))
+	if _, ok := pkgs[data.TargetPackage.ValueString()]; ok {
+		found = data.TargetPackage.ValueString()
+	} else {
+		var foundver string
+		for pkg, ver := range pkgs {
+			// If the package name didn't match exactly, see if we have a package that starts with the target package name.
+			// This is to handle the common case where a package named "foo" might be provided by a package named "foo-1.23".
+			// In case there are multiple packages that match that provide different versions, we'll error out.
+			if strings.HasPrefix(pkg, data.TargetPackage.ValueString()+"-") {
+				if found != "" && foundver != ver {
+					resp.Diagnostics.AddError("Multiple packages match", fmt.Sprintf("Multiple packages match with different versions: %s (%s) and %s (%s)", found, foundver, pkg, ver))
+					return
+				}
+
+				found = pkg
+				foundver = ver
+				// Don't stop; keep looking in case there are multiple matches!
+			}
+		}
+	}
+
+	if found == "" {
+    resp.Diagnostics.AddError(fmt.Sprintf("Unable to find package: %s...", data.TargetPackage.ValueString()), fmt.Sprintf("...in package list:\n\t%s", strings.Join(ic.Contents.Packages, "\n\t")))
 		return
 	}
 
+	data.Tags = getStemmedVersionTags(pkgs[found])
+	data.Tags = append(data.Tags, pkgs[found])
+	sort.Strings(data.Tags)
+
 	data.Id = types.StringValue(strings.Join(data.Tags, ","))
 
 	tflog.Trace(ctx, "read a data source")

internal/provider/tags_data_source_test.go

@@ -28,6 +28,7 @@ contents:
   - ca-certificates-bundle=20230506-r0
   - glibc-locale-posix=2.37-r6
   - ko=0.13.0-r3
+  - nodejs=21.7.3-r1 # Initial request will be satisfied by 'provides'
 EOF
   extra_packages = ["tzdata=2023c-r0"]
 }
@@ -56,6 +57,16 @@ data "apko_tags" "ko" {
   config         = data.apko_config.this.config
   target_package = "ko"
 }
+
+data "apko_tags" "nodejs" {
+  config         = data.apko_config.this.config
+  target_package = "nodejs" # Tags can be inferred from 'provides'
+}
+
+data "apko_tags" "nodejs-21" {
+  config         = data.apko_config.this.config
+  target_package = "nodejs-21"
+}
 `,
 			Check: resource.ComposeAggregateTestCheckFunc(
 				resource.TestCheckResourceAttr("data.apko_tags.glibc", "tags.#", "3"),
@@ -85,6 +96,22 @@ data "apko_tags" "ko" {
 				resource.TestCheckResourceAttr("data.apko_tags.ko", "tags.2", "0.13.0"),
 				resource.TestCheckResourceAttr("data.apko_tags.ko", "tags.3", "0.13.0-r3"),
 				resource.TestCheckResourceAttr("data.apko_tags.ko", "id", "0,0.13,0.13.0,0.13.0-r3"),
+
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs", "tags.#", "4"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs", "tags.0", "21"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs", "tags.1", "21.7"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs", "tags.2", "21.7.3"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs", "tags.3", "21.7.3-r1"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs", "id", "21,21.7,21.7.3,21.7.3-r1"),
+
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs-21", "tags.#", "4"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs-21", "tags.0", "21"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs-21", "tags.1", "21.7"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs-21", "tags.2", "21.7.3"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs-21", "tags.3", "21.7.3-r1"),
+				resource.TestCheckResourceAttr("data.apko_tags.nodejs-21", "id", "21,21.7,21.7.3,21.7.3-r1"),
+
+				//21.7.3-r1.apk
 			),
 		}},
 	})
@@ -112,6 +139,7 @@ contents:
   - ca-certificates-bundle=20230506-r0
   - glibc-locale-posix=2.37-r6
   - ko=0.13.0-r3
+  - nodejs=21.7.3-r1
 EOF
   extra_packages = ["tzdata=2023c-r0"]
 }