kops/pkg/model/iam.go

/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package model

import (
	"encoding/json"
	"fmt"
	"k8s.io/kops/pkg/apis/kops"
	"k8s.io/kops/pkg/model/iam"
	"k8s.io/kops/upup/pkg/fi"
	"k8s.io/kops/upup/pkg/fi/cloudup/awstasks"
	"reflect"
	"strings"
	"text/template"
)

// IAMModelBuilder configures IAM objects
type IAMModelBuilder struct {
	*KopsModelContext
}

var _ fi.ModelBuilder = &IAMModelBuilder{}

const RolePolicyTemplate = `{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": { "Service": "{{ IAMServiceEC2 }}"},
      "Action": "sts:AssumeRole"
    }
  ]
}`

func (b *IAMModelBuilder) Build(c *fi.ModelBuilderContext) error {
	// Collect the roles in use
	var roles []kops.InstanceGroupRole
	for _, ig := range b.InstanceGroups {
		found := false
		for _, r := range roles {
			if r == ig.Spec.Role {
				found = true
			}
		}
		if !found {
			roles = append(roles, ig.Spec.Role)
		}
	}

	// Generate IAM objects etc for each role
	for _, role := range roles {
		name := b.IAMName(role)

		var iamRole *awstasks.IAMRole
		{
			rolePolicy, err := b.buildAWSIAMRolePolicy()
			if err != nil {
				return err
			}

			iamRole = &awstasks.IAMRole{
				Name:               s(name),
				RolePolicyDocument: fi.WrapResource(rolePolicy),
			}
			c.AddTask(iamRole)

		}

		policy, err := b.buildAWSIAMPolicy(role)
		if err != nil {
			return err
		}
		{
			t := &awstasks.IAMRolePolicy{
				Name:           s(name),
				Role:           iamRole,
				PolicyDocument: fi.WrapResource(fi.NewStringResource(policy)),
			}
			c.AddTask(t)
		}

		var iamInstanceProfile *awstasks.IAMInstanceProfile
		{
			iamInstanceProfile = &awstasks.IAMInstanceProfile{
				Name: s(name),
			}
			c.AddTask(iamInstanceProfile)
		}

		{
			iamInstanceProfileRole := &awstasks.IAMInstanceProfileRole{
				Name: s(name),

				InstanceProfile: iamInstanceProfile,
				Role:            iamRole,
			}
			c.AddTask(iamInstanceProfileRole)
		}

		// Generate additional policies if needed, and attach to existing instance profile
		if b.Cluster.Spec.AdditionalPolicies != nil {
			roleAsString := reflect.ValueOf(role).String()
			additionalPolicies := *(b.Cluster.Spec.AdditionalPolicies)

			if additionalPolicy, ok := additionalPolicies[strings.ToLower(roleAsString)]; ok {
				roleName := "additional." + name

				var iamRole *awstasks.IAMRole
				{
					rolePolicy, err := b.buildAWSIAMRolePolicy()
					if err != nil {
						return err
					}

					iamRole = &awstasks.IAMRole{
						Name:               s(roleName),
						RolePolicyDocument: fi.WrapResource(rolePolicy),
					}
					c.AddTask(iamRole)

				}

				{
					p := &iam.IAMPolicy{
						Version: iam.IAMPolicyDefaultVersion,
					}

					statements := make([]*iam.IAMStatement, 0)
					json.Unmarshal([]byte(additionalPolicy), &statements)
					p.Statement = append(p.Statement, statements...)

					policy, err := p.AsJSON()
					if err != nil {
						return fmt.Errorf("error building IAM policy: %v", err)
					}

					t := &awstasks.IAMRolePolicy{
						Name:           s(roleName),
						Role:           iamRole,
						PolicyDocument: fi.WrapResource(fi.NewStringResource(policy)),
					}
					c.AddTask(t)
				}

				{
					iamInstanceProfileRole := &awstasks.IAMInstanceProfileRole{
						Name: s(roleName),

						InstanceProfile: iamInstanceProfile,
						Role:            iamRole,
					}
					c.AddTask(iamInstanceProfileRole)
				}
			}
		}
	}

	return nil
}

// buildAWSIAMPolicy produces the AWS IAM policy for the given role
func (b *IAMModelBuilder) buildAWSIAMPolicy(role kops.InstanceGroupRole) (string, error) {
	pb := &iam.IAMPolicyBuilder{
		Cluster: b.Cluster,
		Role:    role,
		Region:  b.Region,
	}

	policy, err := pb.BuildAWSIAMPolicy()
	if err != nil {
		return "", fmt.Errorf("error building IAM policy: %v", err)
	}
	json, err := policy.AsJSON()
	if err != nil {
		return "", fmt.Errorf("error building IAM policy: %v", err)
	}
	return json, nil
}

// buildAWSIAMRolePolicy produces the AWS IAM role policy for the given role
func (b *IAMModelBuilder) buildAWSIAMRolePolicy() (fi.Resource, error) {
	functions := template.FuncMap{
		"IAMServiceEC2": func() string {
			// IAMServiceEC2 returns the name of the IAM service for EC2 in the current region
			// it is ec2.amazonaws.com everywhere but in cn-north, where it is ec2.amazonaws.com.cn
			switch b.Region {
			case "cn-north-1":
				return "ec2.amazonaws.com.cn"
			default:
				return "ec2.amazonaws.com"
			}
		},
	}

	templateResource, err := NewTemplateResource("AWSIAMRolePolicy", RolePolicyTemplate, functions, nil)
	if err != nil {
		return nil, err
	}
	return templateResource, nil
}