Add support for getting the GitHub context

actions.go

@@ -29,6 +29,8 @@ import (
 	"os"
 	"strings"
 	"time"
+
+	"github.com/sethvargo/go-envconfig"
 )
 
 var (
@@ -449,3 +451,64 @@ func (c *Action) Getenv(key string) string {
 // GetenvFunc is an abstraction to make tests feasible for commands that
 // interact with environment variables.
 type GetenvFunc func(key string) string
+
+// GitHubContext of current workflow.
+//
+// Replicated from https://github.com/actions/toolkit/blob/main/packages/github/src/context.ts
+type GitHubContext struct {
+	EventPath  string `env:"GITHUB_EVENT_PATH"`
+	EventName  string `env:"GITHUB_EVENT_NAME"`
+	SHA        string `env:"GITHUB_SHA"`
+	Ref        string `env:"GITHUB_REF"`
+	Workflow   string `env:"GITHUB_WORKFLOW"`
+	Action     string `env:"GITHUB_ACTION"`
+	Actor      string `env:"GITHUB_ACTOR"`
+	Job        string `env:"GITHUB_JOB"`
+	RunNumber  int64  `env:"GITHUB_RUN_NUMBER"`
+	RunID      int64  `env:"GITHUB_RUN_ID"`
+	APIURL     string `env:"GITHUB_API_URL,default=https://api.github.com"`
+	ServerURL  string `env:"GITHUB_SERVER_URL,default=https://github.com"`
+	GraphqlURL string `env:"GITHUB_GRAPHQL_URL,default=https://api.github.com/graphql"`
+
+	// Event is populated by parsing the file at EventPath, if it exists.
+	Event map[string]any
+}
+
+// Context returns the context of current action with the payload object
+// that triggered the workflow
+func (c *Action) Context() (*GitHubContext, error) {
+	ctx := context.Background()
+	lookuper := &wrappedLookuper{f: c.getenv}
+
+	var githubContext GitHubContext
+	if err := envconfig.ProcessWith(ctx, &githubContext, lookuper); err != nil {
+		return nil, fmt.Errorf("could not process github context variables: %w", err)
+	}
+
+	if githubContext.EventPath != "" {
+		eventData, err := os.ReadFile(githubContext.EventPath)
+		if err != nil && !os.IsNotExist(err) {
+			return nil, fmt.Errorf("could not read event file: %w", err)
+		}
+		if eventData != nil {
+			if err := json.Unmarshal(eventData, &githubContext.Event); err != nil {
+				return nil, fmt.Errorf("failed to unmarshal event payload: %w", err)
+			}
+		}
+	}
+
+	return &githubContext, nil
+}
+
+// wrappedLookuper creates a lookuper that wraps a given getenv func.
+type wrappedLookuper struct {
+	f GetenvFunc
+}
+
+// Lookup implements a custom lookuper.
+func (w *wrappedLookuper) Lookup(key string) (string, bool) {
+	if v := w.f(key); v != "" {
+		return v, true
+	}
+	return "", false
+}

actions_root.go

@@ -144,3 +144,7 @@ func WithFieldsMap(m map[string]string) *Action {
 func GetIDToken(ctx context.Context, audience string) (string, error) {
 	return defaultAction.GetIDToken(ctx, audience)
 }
+
+func Context() (*GitHubContext, error) {
+	return defaultAction.Context()
+}

actions_test.go

@@ -25,6 +25,8 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+
+	"github.com/google/go-cmp/cmp"
 )
 
 func TestNew(t *testing.T) {
@@ -591,6 +593,113 @@ func TestAction_GetIDToken(t *testing.T) {
 	}
 }
 
+func TestAction_Context(t *testing.T) {
+	t.Parallel()
+
+	f, err := os.CreateTemp("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		os.Remove(f.Name())
+	})
+
+	if _, err := f.Write([]byte(`{"foo": "bar"}`)); err != nil {
+		t.Fatal(err)
+	}
+	if err := f.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	eventPayloadPath := f.Name()
+
+	cases := []struct {
+		name string
+		env  map[string]string
+		exp  *GitHubContext
+	}{
+		{
+			name: "empty",
+			env:  nil,
+			exp: &GitHubContext{
+				// Defaults
+				APIURL:     "https://api.github.com",
+				ServerURL:  "https://github.com",
+				GraphqlURL: "https://api.github.com/graphql",
+			},
+		},
+		{
+			name: "no_payload",
+			env: map[string]string{
+				"GITHUB_EVENT_NAME":  "event_name",
+				"GITHUB_SHA":         "abcd1234",
+				"GITHUB_REF":         "main",
+				"GITHUB_WORKFLOW":    "test",
+				"GITHUB_ACTION":      "foo/bar@v0",
+				"GITHUB_ACTOR":       "sethvargo",
+				"GITHUB_JOB":         "12",
+				"GITHUB_RUN_NUMBER":  "34",
+				"GITHUB_RUN_ID":      "56",
+				"GITHUB_API_URL":     "https://foo.com",
+				"GITHUB_SERVER_URL":  "https://bar.com",
+				"GITHUB_GRAPHQL_URL": "https://baz.com",
+			},
+			exp: &GitHubContext{
+				EventName:  "event_name",
+				SHA:        "abcd1234",
+				Ref:        "main",
+				Workflow:   "test",
+				Action:     "foo/bar@v0",
+				Actor:      "sethvargo",
+				Job:        "12",
+				RunNumber:  34,
+				RunID:      56,
+				APIURL:     "https://foo.com",
+				ServerURL:  "https://bar.com",
+				GraphqlURL: "https://baz.com",
+			},
+		},
+		{
+			name: "payload",
+			env: map[string]string{
+				"GITHUB_EVENT_PATH": eventPayloadPath,
+			},
+			exp: &GitHubContext{
+				EventPath: eventPayloadPath,
+
+				// Defaults
+				APIURL:     "https://api.github.com",
+				ServerURL:  "https://github.com",
+				GraphqlURL: "https://api.github.com/graphql",
+
+				Event: map[string]any{
+					"foo": "bar",
+				},
+			},
+		},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			a := New(WithGetenv(func(k string) string {
+				return tc.env[k]
+			}))
+			got, err := a.Context()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if diff := cmp.Diff(tc.exp, got); diff != "" {
+				t.Fatalf("mismatch (-want, +got):\n%s", diff)
+			}
+		})
+	}
+}
+
 // newFakeGetenvFunc returns a new GetenvFunc that is expected to be called with
 // the provided key. It returns the provided value if the call matches the
 // provided key. It reports an error on test t otherwise.

go.mod

@@ -15,3 +15,8 @@
 module github.com/sethvargo/go-githubactions
 
 go 1.18
+
+require (
+	github.com/google/go-cmp v0.4.1
+	github.com/sethvargo/go-envconfig v0.6.0
+)

go.sum

@@ -0,0 +1,6 @@
+github.com/google/go-cmp v0.4.1 h1:/exdXoGamhu5ONeUJH0deniYLWYvQwW66yvlfiiKTu0=
+github.com/google/go-cmp v0.4.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/sethvargo/go-envconfig v0.6.0 h1:GxxdoeiNpWgGiVEphNFNObgMYRN/ZvI2dN7rBwadyss=
+github.com/sethvargo/go-envconfig v0.6.0/go.mod h1:00S1FAhRUuTNJazWBWcJGvEHOM+NO6DhoRMAOX7FY5o=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=