add github action environment variables (#29)

* add github action environment variables

* fix

* changes

* changes

* changes

* changes

main.go

@@ -139,7 +139,7 @@ func main() {
 			Source:     codedir,
 			Stdout:     os.Stdout,
 			Stderr:     os.Stderr,
-			Environ:    os.Environ(),
+			Environ:    github.Environ(os.Environ()),
 			OutputFile: outputFile,
 		}
 		if err := execer.Exec(ctx); err != nil {

plugin/github/env.go

@@ -14,11 +14,91 @@ import (
 	"strings"
 
 	"github.com/drone/plugin/plugin/internal/encoder"
+	"github.com/drone/plugin/plugin/internal/environ"
 	"github.com/joho/godotenv"
 	"github.com/pkg/errors"
 	"golang.org/x/exp/slog"
 )
 
+// Environ function converts harness or drone environment
+// variables to github action environment variables.
+func Environ(src []string) []string {
+	// make a copy of the environment variables
+	dst := environ.Map(src)
+
+	// convert drone environment variables to github action
+	// environment variables
+	for key, val := range dst {
+		// drone prefixes plugin input parameters, github action
+		// does not. trim the prefix and convert to lowercase
+		// for github action compatibility.
+		if strings.HasPrefix(key, "PLUGIN_") {
+			key = strings.TrimPrefix("PLUGIN_", "")
+			key = strings.ToLower(key)
+			dst[key] = val
+		}
+	}
+
+	tagName := dst["DRONE_TAG"]
+	branchName := dst["DRONE_BRANCH"]
+
+	arch := "X64"
+	if runtime.GOARCH == "arm64" {
+		arch = "arm64"
+	}
+
+	ostype := "Linux"
+	runner_tool_cache := "/opt/hostedtoolcache"
+
+	if runtime.GOOS == "darwin" {
+		ostype = "macOS"
+		runner_tool_cache = "/Users/anka/hostedtoolcache"
+	} else if runtime.GOOS == "windows" {
+		ostype = "Windows"
+		runner_tool_cache = "C:\\hostedtoolcache\\windows"
+	}
+
+	// github actions may depend on github action environment variables.
+	// map drone environment variables, which are already present
+	// in the execution envionment, to their github action equivalents.
+	//
+	// github action environment variable docs:
+	// https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables
+	dst = environ.Combine(dst, map[string]string{
+		"GITHUB_BASE_REF":         dst["DRONE_TARGET_BRANCH"],
+		"GITHUB_HEAD_REF":         dst["DRONE_SOURCE_BRANCH"],
+		"GITHUB_REF":              dst["DRONE_COMMIT_REF"],
+		"GITHUB_REPOSITORY":       dst["DRONE_REPO"],
+		"GITHUB_REPOSITORY_OWNER": parseOwner(dst["DRONE_REPO"]),
+		"SHA_REF":                 dst["DRONE_COMMIT_SHA"],
+		"GITHUB_RUN_ATTEMPT":      dst["DRONE_BUILD_NUMBER"],
+		"GITHUB_RUN_NUMBER":       dst["DRONE_BUILD_NUMBER"],
+		"GITHUB_WORKSPACE":        firstMatch(dst, "DRONE_WORKSPACE", "HARNESS_WORKSPACE"),
+		"RUNNER_ARCH":             arch,
+		"RUNNER_OS":               ostype,
+		"RUNNER_NAME":             "HARNESS HOSTED",
+		"RUNNER_TOOL_CACHE":       runner_tool_cache,
+	})
+
+	if tagName != "" {
+		dst["GITHUB_REF_NAME"] = tagName
+		dst["GITHUB_REF_TYPE"] = "tag"
+	} else if branchName != "" {
+		dst["GITHUB_REF_NAME"] = branchName
+		dst["GITHUB_REF_TYPE"] = "branch"
+	}
+
+	return environ.Slice(dst)
+}
+
+// helper function gets the owner from a repository slug.
+func parseOwner(s string) (owner string) {
+	if parts := strings.Split(s, "/"); len(parts) == 2 {
+		return parts[0]
+	}
+	return
+}
+
 func getWith(envVars map[string]string) (map[string]string, error) {
 	if val, ok := envVars["PLUGIN_WITH"]; ok {
 		with, err := strToMap(val)
@@ -129,3 +209,14 @@ func strToMap(s string) (map[string]string, error) {
 	}
 	return m, nil
 }
+
+// helper function find the first matching environment
+// variable in the map.
+func firstMatch(envs map[string]string, keys ...string) (val string) {
+	for _, key := range keys {
+		if env, ok := envs[key]; ok {
+			return env
+		}
+	}
+	return
+}

plugin/github/execer.go

@@ -36,6 +36,7 @@ func (e *Execer) Exec(ctx context.Context) error {
 	}
 
 	envVars := environ.Map(e.Environ)
+	envVars["RUNNER_TEMP"] = tmpDir
 	outputVars := getOutputVars(e.Source, e.Name)
 
 	workflowFile := filepath.Join(tmpDir, "workflow.yml")