Token authentication for Operators on cloud providers

# ...
install:
  spec:
    clusterPermissions:
    - rules:
      - apiGroups:
        - "cloudcredential.openshift.io"
        resources:
        - credentialsrequests
        verbs:
        - create
        - delete
        - get
        - list
        - patch
        - update
        - watch

import (
   minterv1 "github.com/openshift/cloud-credential-operator/pkg/apis/cloudcredential/v1"
   corev1 "k8s.io/api/core/v1"
   metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

var in = minterv1.AWSProviderSpec{
   StatementEntries: []minterv1.StatementEntry{
      {
         Action: []string{
            "s3:*",
         },
         Effect:   "Allow",
         Resource: "arn:aws:s3:*:*:*",
      },
   },
	STSIAMRoleARN: "<role_arn>",
}

var codec = minterv1.Codec
var ProviderSpec, _ = codec.EncodeProviderSpec(in.DeepCopyObject())

const (
   name      = "<credential_request_name>"
   namespace = "<namespace_name>"
)

var CredentialsRequestTemplate = &minterv1.CredentialsRequest{
   ObjectMeta: metav1.ObjectMeta{
       Name:      name,
       Namespace: "openshift-cloud-credential-operator",
   },
   Spec: minterv1.CredentialsRequestSpec{
      ProviderSpec: ProviderSpec,
      SecretRef: corev1.ObjectReference{
         Name:      "<secret_name>",
         Namespace: namespace,
      },
      ServiceAccountNames: []string{
         "<service_account_name>",
      },
      CloudTokenPath:   "",
   },
}

// CredentialsRequest is a struct that represents a request for credentials
type CredentialsRequest struct {
  APIVersion string `yaml:"apiVersion"`
  Kind       string `yaml:"kind"`
  Metadata   struct {
     Name      string `yaml:"name"`
     Namespace string `yaml:"namespace"`
  } `yaml:"metadata"`
  Spec struct {
     SecretRef struct {
        Name      string `yaml:"name"`
        Namespace string `yaml:"namespace"`
     } `yaml:"secretRef"`
     ProviderSpec struct {
        APIVersion     string `yaml:"apiVersion"`
        Kind           string `yaml:"kind"`
        StatementEntries []struct {
           Effect   string   `yaml:"effect"`
           Action   []string `yaml:"action"`
           Resource string   `yaml:"resource"`
        } `yaml:"statementEntries"`
        STSIAMRoleARN   string `yaml:"stsIAMRoleARN"`
     } `yaml:"providerSpec"`

     // added new field
      CloudTokenPath   string `yaml:"cloudTokenPath"`
  } `yaml:"spec"`
}

// ConsumeCredsRequestAddingTokenInfo is a function that takes a YAML filename and two strings as arguments
// It unmarshals the YAML file to a CredentialsRequest object and adds the token information.
func ConsumeCredsRequestAddingTokenInfo(fileName, tokenString, tokenPath string) (*CredentialsRequest, error) {
  // open a file containing YAML form of a CredentialsRequest
  file, err := os.Open(fileName)
  if err != nil {
     return nil, err
  }
  defer file.Close()

  // create a new CredentialsRequest object
  cr := &CredentialsRequest{}

  // decode the yaml file to the object
  decoder := yaml.NewDecoder(file)
  err = decoder.Decode(cr)
  if err != nil {
     return nil, err
  }

  // assign the string to the existing field in the object
  cr.Spec.CloudTokenPath = tokenPath

  // return the modified object
  return cr, nil
}

// apply credentialsRequest on install
credReq := credreq.CredentialsRequestTemplate
credReq.Spec.CloudTokenPath = webIdentityTokenPath

c := mgr.GetClient()
if err := c.Create(context.TODO(), credReq); err != nil {
   if !errors.IsAlreadyExists(err) {
      setupLog.Error(err, "unable to create CredRequest")
      os.Exit(1)
   }
}

// WaitForSecret is a function that takes a Kubernetes client, a namespace, and a v1 "k8s.io/api/core/v1" name as arguments
// It waits until the secret object with the given name exists in the given namespace
// It returns the secret object or an error if the timeout is exceeded
func WaitForSecret(client kubernetes.Interface, namespace, name string) (*v1.Secret, error) {
  // set a timeout of 10 minutes
  timeout := time.After(10 * time.Minute) (1)

  // set a polling interval of 10 seconds
  ticker := time.NewTicker(10 * time.Second)

  // loop until the timeout or the secret is found
  for {
     select {
     case <-timeout:
        // timeout is exceeded, return an error
        return nil, fmt.Errorf("timed out waiting for secret %s in namespace %s", name, namespace)
           // add to this error with a pointer to instructions for following a manual path to a Secret that will work on STS
     case <-ticker.C:
        // polling interval is reached, try to get the secret
        secret, err := client.CoreV1().Secrets(namespace).Get(context.Background(), name, metav1.GetOptions{})
        if err != nil {
           if errors.IsNotFound(err) {
              // secret does not exist yet, continue waiting
              continue
           } else {
              // some other error occurred, return it
              return nil, err
           }
        } else {
           // secret is found, return it
           return secret, nil
        }
     }
  }
}

func SharedCredentialsFileFromSecret(secret *corev1.Secret) (string, error) {
   var data []byte
   switch {
   case len(secret.Data["credentials"]) > 0:
       data = secret.Data["credentials"]
   default:
       return "", errors.New("invalid secret for aws credentials")
   }


   f, err := ioutil.TempFile("", "aws-shared-credentials")
   if err != nil {
       return "", errors.Wrap(err, "failed to create file for shared credentials")
   }
   defer f.Close()
   if _, err := f.Write(data); err != nil {
       return "", errors.Wrapf(err, "failed to write credentials to %s", f.Name())
   }
   return f.Name(), nil
}

sharedCredentialsFile, err := SharedCredentialsFileFromSecret(secret)
if err != nil {
   // handle error
}
options := session.Options{
   SharedConfigState: session.SharedConfigEnable,
   SharedConfigFiles: []string{sharedCredentialsFile},
}