Add placeholder-name CLI

- main and unit tests for main
- client package to be done in a future commit

Signed-off-by: Aram Price <pricear@vmware.com>

cmd/placeholder-name/main.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2020 VMware, Inc.
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+
+	"k8s.io/client-go/pkg/apis/clientauthentication"
+
+	"github.com/suzerain-io/placeholder-name/internal/constable"
+	"github.com/suzerain-io/placeholder-name/pkg/client"
+)
+
+func main() {
+	err := run(os.LookupEnv, client.ExchangeToken, os.Stdout)
+	if err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "%s", err.Error())
+		os.Exit(1)
+	}
+}
+
+type envGetter func(string) (string, bool)
+type tokenExchanger func(token, caBundle, apiEndpoint string) (*clientauthentication.ExecCredential, error)
+
+const EnvVarNotSetError = constable.Error("failed to login: environment variable not set")
+
+func run(envGetter envGetter, tokenExchanger tokenExchanger, outputWriter io.Writer) error {
+	token, varExists := envGetter("PLACEHOLDER_NAME_TOKEN")
+	if !varExists {
+		return envVarNotSetError("PLACEHOLDER_NAME_TOKEN")
+	}
+
+	caBundle, varExists := envGetter("PLACEHOLDER_NAME_CA_BUNDLE")
+	if !varExists {
+		return envVarNotSetError("PLACEHOLDER_NAME_CA_BUNDLE")
+	}
+
+	apiEndpoint, varExists := envGetter("PLACEHOLDER_NAME_K8S_API_ENDPOINT")
+	if !varExists {
+		return envVarNotSetError("PLACEHOLDER_NAME_K8S_API_ENDPOINT")
+	}
+
+	execCredential, err := tokenExchanger(token, caBundle, apiEndpoint)
+	if err != nil {
+		return fmt.Errorf("failed to login: %w", err)
+	}
+
+	err = json.NewEncoder(outputWriter).Encode(execCredential)
+	if err != nil {
+		return fmt.Errorf("failed to marshall response to stdout: %w", err)
+	}
+
+	return nil
+}
+
+func envVarNotSetError(varName string) error {
+	return fmt.Errorf("%w: %s", EnvVarNotSetError, varName)
+}

cmd/placeholder-name/main_test.go

@@ -0,0 +1,112 @@
+/*
+Copyright 2020 VMware, Inc.
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"k8s.io/client-go/pkg/apis/clientauthentication"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/sclevine/spec"
+	"github.com/sclevine/spec/report"
+)
+
+func TestRun(t *testing.T) {
+	spec.Run(t, "Run", func(t *testing.T, when spec.G, it spec.S) {
+		var buffer *bytes.Buffer
+		var tokenExchanger tokenExchanger
+		var fakeEnv map[string]string
+
+		var envGetter envGetter = func(envVarName string) (string, bool) {
+			value, present := fakeEnv[envVarName]
+			if !present {
+				return "", false
+			}
+			return value, true
+		}
+
+		it.Before(func() {
+			buffer = new(bytes.Buffer)
+			fakeEnv = map[string]string{
+				"PLACEHOLDER_NAME_TOKEN":            "token from env",
+				"PLACEHOLDER_NAME_CA_BUNDLE":        "ca bundle from env",
+				"PLACEHOLDER_NAME_K8S_API_ENDPOINT": "k8s api from env",
+			}
+		})
+
+		when("env vars are missing", func() {
+			it("returns an error when PLACEHOLDER_NAME_TOKEN is missing", func() {
+				fakeEnv = map[string]string{
+					"PLACEHOLDER_NAME_K8S_API_ENDPOINT": "a",
+					"PLACEHOLDER_NAME_CA_BUNDLE":        "b",
+				}
+				err := run(envGetter, tokenExchanger, buffer)
+				require.Error(t, err, "failed to login: environment variable not set: PLACEHOLDER_NAME_TOKEN")
+			})
+
+			it("returns an error when PLACEHOLDER_NAME_CA_BUNDLE is missing", func() {
+				fakeEnv = map[string]string{
+					"PLACEHOLDER_NAME_K8S_API_ENDPOINT": "a",
+					"PLACEHOLDER_NAME_TOKEN":            "b",
+				}
+				err := run(envGetter, tokenExchanger, buffer)
+				require.Error(t, err, "failed to login: environment variable not set: PLACEHOLDER_NAME_CA_BUNDLE")
+			})
+
+			it("returns an error when PLACEHOLDER_NAME_K8S_API_ENDPOINT is missing", func() {
+				fakeEnv = map[string]string{
+					"PLACEHOLDER_NAME_TOKEN":     "a",
+					"PLACEHOLDER_NAME_CA_BUNDLE": "b",
+				}
+				err := run(envGetter, tokenExchanger, buffer)
+				require.Error(t, err, "failed to login: environment variable not set: PLACEHOLDER_NAME_K8S_API_ENDPOINT")
+			})
+		}, spec.Parallel())
+
+		when("the token exchange fails", func() {
+			it.Before(func() {
+				tokenExchanger = func(token, caBundle, apiEndpoint string) (*clientauthentication.ExecCredential, error) {
+					return nil, fmt.Errorf("some error")
+				}
+			})
+
+			it("returns an error", func() {
+				err := run(envGetter, tokenExchanger, buffer)
+				require.Error(t, err, "failed to login: some error")
+			})
+		}, spec.Parallel())
+
+		when("the token exchange succeeds", func() {
+			var actualToken, actualCaBundle, actualAPIEndpoint string
+
+			it.Before(func() {
+				tokenExchanger = func(token, caBundle, apiEndpoint string) (*clientauthentication.ExecCredential, error) {
+					actualToken, actualCaBundle, actualAPIEndpoint = token, caBundle, apiEndpoint
+					return &clientauthentication.ExecCredential{
+						Status: &clientauthentication.ExecCredentialStatus{Token: "some token"},
+					}, nil
+				}
+			})
+
+			it("writes the execCredential to the given writer", func() {
+				err := run(envGetter, tokenExchanger, buffer)
+				require.NoError(t, err)
+				require.Equal(t, fakeEnv["PLACEHOLDER_NAME_TOKEN"], actualToken)
+				require.Equal(t, fakeEnv["PLACEHOLDER_NAME_CA_BUNDLE"], actualCaBundle)
+				require.Equal(t, fakeEnv["PLACEHOLDER_NAME_K8S_API_ENDPOINT"], actualAPIEndpoint)
+				expected := `{
+					"Spec": {"Interactive": false, "Response": null},
+					"Status": {"ClientCertificateData": "", "ClientKeyData": "", "ExpirationTimestamp": null, "Token": "some token"}
+				}`
+				require.JSONEq(t, expected, buffer.String())
+			})
+		}, spec.Parallel())
+	}, spec.Report(report.Terminal{}))
+}