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glambda.go
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/
glambda.go
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package glambda
import (
"context"
"errors"
"fmt"
"strings"
"time"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/service/iam"
iTypes "github.com/aws/aws-sdk-go-v2/service/iam/types"
"github.com/aws/aws-sdk-go-v2/service/lambda"
"github.com/aws/aws-sdk-go-v2/service/lambda/types"
"github.com/google/uuid"
)
var (
DefaultAssumeRolePolicy = `{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Service":"lambda.amazonaws.com"},"Action":"sts:AssumeRole"}]}`
AWSLambdaBasicExecutionRole = `arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole`
ThisAWSAccountCondition = `"Condition":{"StringEquals":{"aws:PrincipalAccount": "${aws:accountId}"}}"`
)
type Lambda struct {
Name string
HandlerPath string
ExecutionRole ExecutionRole
ResourcePolicy ResourcePolicy
}
type LambdaOptions func(l Lambda) Lambda
func NewLambda(name, handlerPath string, opts ...LambdaOptions) Lambda {
l := Lambda{
Name: name,
HandlerPath: handlerPath,
ExecutionRole: ExecutionRole{
RoleName: "glambda_exec_role_" + strings.ToLower(name),
AssumeRolePolicyDocument: DefaultAssumeRolePolicy,
},
}
for _, opt := range opts {
l = opt(l)
}
return l
}
type ExecutionRole struct {
RoleName string
AssumeRolePolicyDocument string
ManagedPolicies []string
InLinePolicy string
}
func (e ExecutionRole) CreateRoleCommand() iam.CreateRoleInput {
return iam.CreateRoleInput{
RoleName: aws.String(e.RoleName),
AssumeRolePolicyDocument: aws.String(e.AssumeRolePolicyDocument),
}
}
func (e ExecutionRole) AttachManagedPolicyCommand(policyARN string) iam.AttachRolePolicyInput {
return iam.AttachRolePolicyInput{
PolicyArn: aws.String(policyARN),
RoleName: aws.String(e.RoleName),
}
}
func (e ExecutionRole) AttachInLinePolicyCommand(policyName string) iam.PutRolePolicyInput {
return iam.PutRolePolicyInput{
PolicyName: aws.String(policyName),
PolicyDocument: aws.String(e.InLinePolicy),
RoleName: aws.String(e.RoleName),
}
}
type ResourcePolicy struct {
Sid string
Effect string
Principal string
Action string
Resource string
Condition string
}
func (r ResourcePolicy) CreateCommand(lambdaName, accountID string) lambda.AddPermissionInput {
if r.Sid == "" {
uuid := uuid.New().String()[0:8]
r.Sid = "glambda_" + uuid
}
return lambda.AddPermissionInput{
Action: aws.String(r.Action),
FunctionName: aws.String(lambdaName),
StatementId: aws.String(r.Sid),
Principal: aws.String(r.Principal),
SourceAccount: aws.String(accountID),
}
}
func WithExecutionRole(name string, opts ...RoleOptions) LambdaOptions {
executionRole := ExecutionRole{
RoleName: name,
AssumeRolePolicyDocument: DefaultAssumeRolePolicy,
ManagedPolicies: []string{
"arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole",
},
}
for _, opt := range opts {
opt(&executionRole)
}
return func(l Lambda) Lambda {
l.ExecutionRole = executionRole
return l
}
}
type RoleOptions func(role *ExecutionRole)
func expandManagedPolicies(policyARNs []string) []string {
var expandedPolicyArns []string
for _, policyARN := range policyARNs {
if strings.HasPrefix(policyARN, "arn:") {
expandedPolicyArns = append(expandedPolicyArns, policyARN)
} else {
expandedPolicyArns = append(expandedPolicyArns, "arn:aws:iam::aws:policy/"+policyARN)
}
}
return expandedPolicyArns
}
func WithManagedPolicies(policyARNs ...string) RoleOptions {
return func(role *ExecutionRole) {
role.ManagedPolicies = append(role.ManagedPolicies, expandManagedPolicies(policyARNs)...)
}
}
func WithInlinePolicy(policy string) RoleOptions {
return func(role *ExecutionRole) {
role.InLinePolicy = policy
}
}
func WithResourcePolicy(serviceName string) LambdaOptions {
resourcePolicy := ResourcePolicy{
Effect: "Allow",
Principal: serviceName,
Action: "lambda:InvokeFunction",
Resource: "*",
Condition: ThisAWSAccountCondition,
}
return func(l Lambda) Lambda {
l.ResourcePolicy = resourcePolicy
return l
}
}
type LambdaClient interface {
CreateFunction(ctx context.Context, params *lambda.CreateFunctionInput, optFns ...func(*lambda.Options)) (*lambda.CreateFunctionOutput, error)
UpdateFunctionCode(ctx context.Context, params *lambda.UpdateFunctionCodeInput, optFns ...func(*lambda.Options)) (*lambda.UpdateFunctionCodeOutput, error)
GetFunction(ctx context.Context, params *lambda.GetFunctionInput, optFns ...func(*lambda.Options)) (*lambda.GetFunctionOutput, error)
}
type Action interface {
Do(c LambdaClient) error
}
type CreateAction struct {
Name string
Role string
Pkg []byte
}
func (a CreateAction) Do(c LambdaClient) error {
var err error
cmd := createLambda(a.Name, a.Role, a.Pkg)
for i := 0; i < 3; i++ {
_, err = c.CreateFunction(context.Background(), &cmd)
if err == nil {
fmt.Printf("Lambda function %s created\n", a.Name)
return nil
}
if errors.Is(err, &types.InvalidParameterValueException{}) {
invalidParamErr := err.(*types.InvalidParameterValueException)
if !strings.Contains(*invalidParamErr.Message, "role defined for the function cannot be assumed by Lambda") {
return err
}
time.Sleep(3 * time.Second)
}
}
return err
}
type UpdateAction struct {
Name string
Pkg []byte
}
func (a UpdateAction) Do(c LambdaClient) error {
cmd := updateLambda(a.Name, a.Pkg)
_, err := c.UpdateFunctionCode(context.Background(), &cmd)
if err == nil {
fmt.Printf("Lambda function %s updated\n", a.Name)
}
return err
}
func (l Lambda) Deploy() error {
cfg, err := config.LoadDefaultConfig(context.Background())
if err != nil {
return err
}
roleARN, err := l.PrepareExecutionRole(cfg)
if err != nil {
return err
}
fmt.Println("Created execution role: ", roleARN)
c := lambda.NewFromConfig(cfg)
action, err := PrepareAction(c, l.Name, l.HandlerPath, roleARN)
if err != nil {
return err
}
err = action.Do(c)
if err != nil {
return err
}
accountID := strings.Split(roleARN, ":")[4]
resourcePolicy := l.ResourcePolicy.CreateCommand(l.Name, accountID)
_, err = c.AddPermission(context.Background(), &resourcePolicy)
if err != nil {
return err
}
return invokeUpdatedLambda(c, l.Name)
}
func (l Lambda) PrepareExecutionRole(cfg aws.Config) (string, error) {
c := iam.NewFromConfig(cfg)
resp, err := c.CreateRole(context.Background(), &iam.CreateRoleInput{
RoleName: aws.String(l.ExecutionRole.RoleName),
AssumeRolePolicyDocument: aws.String(l.ExecutionRole.AssumeRolePolicyDocument),
})
if err != nil {
var i *iTypes.EntityAlreadyExistsException
if errors.As(err, &i) {
resp, err := c.GetRole(context.Background(), &iam.GetRoleInput{
RoleName: aws.String(l.ExecutionRole.RoleName),
})
if err != nil {
return "", err
}
return *resp.Role.Arn, nil
}
}
_, err = c.AttachRolePolicy(context.Background(), &iam.AttachRolePolicyInput{
PolicyArn: aws.String("arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"),
RoleName: aws.String(l.ExecutionRole.RoleName),
})
for _, managedPolicy := range l.ExecutionRole.ManagedPolicies {
_, err = c.AttachRolePolicy(context.Background(), &iam.AttachRolePolicyInput{
PolicyArn: aws.String(managedPolicy),
RoleName: aws.String(l.ExecutionRole.RoleName),
})
if err != nil {
return "", err
}
}
uuid := uuid.New().String()[0:8]
guid := strings.ReplaceAll(uuid, "-", "")
if l.ExecutionRole.InLinePolicy != "" {
_, err = c.PutRolePolicy(context.Background(), &iam.PutRolePolicyInput{
PolicyName: aws.String("glambda_inline_policy_" + guid[:8]),
PolicyDocument: aws.String(l.ExecutionRole.InLinePolicy),
RoleName: aws.String(l.ExecutionRole.RoleName),
})
if err != nil {
return "", err
}
}
return *resp.Role.Arn, err
}
func PrepareAction(c LambdaClient, name, path, roleARN string) (Action, error) {
exists, err := lambdaExists(c, name)
if err != nil {
return nil, err
}
pkg, err := Package(path)
if err != nil {
return nil, err
}
var action Action
if exists {
action = UpdateAction{
Name: name,
Pkg: pkg,
}
} else {
action = CreateAction{
Name: name,
Role: roleARN,
Pkg: pkg,
}
}
return action, nil
}
func lambdaExists(c LambdaClient, name string) (bool, error) {
input := &lambda.GetFunctionInput{
FunctionName: aws.String(name),
}
_, err := c.GetFunction(context.Background(), input)
if err != nil {
var resourceNotFound *types.ResourceNotFoundException
if errors.As(err, &resourceNotFound) {
return false, nil
}
return false, err
}
return true, nil
}
func createLambda(name, role string, pkg []byte) lambda.CreateFunctionInput {
return lambda.CreateFunctionInput{
FunctionName: aws.String(name),
Role: aws.String(role),
Handler: aws.String("/var/task/bootstrap"),
Runtime: types.RuntimeProvidedal2023,
Architectures: []types.Architecture{
types.ArchitectureArm64,
},
Code: &types.FunctionCode{
ZipFile: pkg,
},
}
}
func updateLambda(name string, pkg []byte) lambda.UpdateFunctionCodeInput {
return lambda.UpdateFunctionCodeInput{
FunctionName: aws.String(name),
ZipFile: pkg,
Publish: true,
}
}
func invokeUpdatedLambda(c *lambda.Client, name string) error {
var version string
retryLimit := 10
fmt.Println("Waiting for lambda to become eventually consistent before invoking")
for i := 0; true; i++ {
versionOutput, err := c.PublishVersion(context.Background(), &lambda.PublishVersionInput{
FunctionName: aws.String(name),
})
if err == nil {
version = *versionOutput.Version
fmt.Printf("Lambda is consistent! Lambda version published: %s\n", version)
break
}
time.Sleep(3 * time.Second)
if i == retryLimit {
return fmt.Errorf("waited for lambda become consistent, but didn't after %d retries, %w", retryLimit, err)
}
}
resp, err := c.Invoke(context.Background(), &lambda.InvokeInput{
FunctionName: aws.String(name),
Qualifier: aws.String(version),
})
if err != nil {
return err
}
fmt.Println("Invocation result:")
if resp.FunctionError != nil {
fmt.Println("Error:")
fmt.Println(*resp.FunctionError)
}
if resp.Payload != nil {
fmt.Println("Payload:")
fmt.Println(string(resp.Payload))
}
if resp.LogResult != nil {
fmt.Println("Logs:")
fmt.Println(string(*resp.LogResult))
}
fmt.Println(resp.StatusCode)
return nil
}