Improve buildctl import and export cache to use GitHub env variables

README.md

@@ -414,8 +414,6 @@ Following attributes are required to authenticate against the [Github Actions Ca
 where `url` and `token` will be automatically set. To use this backend in a inline `run` step, you have to include [crazy-max/ghaction-github-runtime](https://github.com/crazy-max/ghaction-github-runtime)
 in your workflow to expose the runtime.
 
-:warning: If used directly with `buildctl` CLI, you must inline `url` and `token` attributes. For instance : `type=gha,url=$ACTIONS_CACHE_URL,token=$ACTIONS_RUNTIME_TOKEN`
-
 `--export-cache` options:
 * `type=gha`
 * `mode=min` (default): only export layers for the resulting image

cmd/buildctl/build/exportcache.go

@@ -39,6 +39,9 @@ func parseExportCacheCSV(s string) (client.CacheOptionsEntry, error) {
 	if _, ok := ex.Attrs["mode"]; !ok {
 		ex.Attrs["mode"] = "min"
 	}
+	if ex.Type == "gha" {
+		return bindGithubCacheAttributes(ex)
+	}
 	return ex, nil
 }
 

cmd/buildctl/build/importcache.go

@@ -36,6 +36,9 @@ func parseImportCacheCSV(s string) (client.CacheOptionsEntry, error) {
 	if im.Type == "" {
 		return im, errors.New("--import-cache requires type=<type>")
 	}
+	if im.Type == "gha" {
+		return bindGithubCacheAttributes(im)
+	}
 	return im, nil
 }
 

cmd/buildctl/build/importcache_test.go

@@ -48,7 +48,36 @@ func TestParseImportCache(t *testing.T) {
 				},
 			},
 		},
+		{
+			importCaches: []string{"type=gha,url=https://foo.bar,token=foo"},
+			expected: []client.CacheOptionsEntry{
+				{
+					Type: "gha",
+					Attrs: map[string]string{
+						"url":   "https://foo.bar",
+						"token": "foo",
+					},
+				},
+			},
+		},
+		{
+			importCaches: []string{"type=gha"},
+			expected: []client.CacheOptionsEntry{
+				{
+					Type: "gha",
+					Attrs: map[string]string{
+						"url":   "https://github.com/test", // Set from env below
+						"token": "bar",                     // Set from env below
+					},
+				},
+			},
+		},
 	}
+
+	// Set values for GitHub parse cache
+	t.Setenv("ACTIONS_CACHE_URL", "https://github.com/test")
+	t.Setenv("ACTIONS_RUNTIME_TOKEN", "bar")
+
 	for _, tc := range testCases {
 		im, err := ParseImportCache(tc.importCaches)
 		if tc.expectedErr == "" {