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backend.go
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backend.go
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package fsthttp
import (
"errors"
"fmt"
"strconv"
"time"
"github.com/fastly/compute-sdk-go/internal/abi/fastly"
)
var (
// ErrDynamicBackendDisallowed indicates the service is not allowed to
// create dynamic backends.
ErrDynamicBackendDisallowed = errors.New("dynamic backends not supported for this service")
// ErrBackendNameInUse indicates the backend name is already in use.
ErrBackendNameInUse = errors.New("backend name already in use")
// ErrBackendNotFound indicates the provided backend was not found.
ErrBackendNotFound = errors.New("backend not found")
// ErrUnexpected indicates an unexpected error occurred.
ErrUnexpected = errors.New("unexpected error")
)
type BackendHealth uint32
// Constants for dynamic backend health status
const (
BackendHealthUnknown BackendHealth = 0
BackendHealthHealthy BackendHealth = 1
BackendHealthUnhealthy BackendHealth = 2
)
type TLSVersion uint32
// Constants for dynamic backend TLS configuration
const (
TLSVersion1_0 TLSVersion = 0
TLSVersion1_1 TLSVersion = 1
TLSVersion1_2 TLSVersion = 2
TLSVersion1_3 TLSVersion = 3
)
// BackendOption is a builder for the configuration of a dynamic backend.
type BackendOptions struct {
abiOpts fastly.BackendConfigOptions
}
// Backend is a fastly backend
type Backend struct {
name string
target string
// has the config been populated
dynamic bool
hostOverride string
connectTimeout time.Duration
firstByteTimeout time.Duration
betweenBytesTimeout time.Duration
isSSL bool
sslMinVersion TLSVersion
sslMaxVersion TLSVersion
}
func BackendFromName(name string) (*Backend, error) {
var err error
exists, err := fastly.BackendExists(name)
if err != nil {
return nil, err
}
if !exists {
return nil, ErrBackendNotFound
}
b := &Backend{
name: name,
}
if err := b.populateConfig(); err != nil {
return nil, err
}
return b, nil
}
func (b *Backend) populateConfig() error {
var err error
b.dynamic, err = fastly.BackendIsDynamic(b.name)
if err := ignoreNoneError(err); err != nil {
return err
}
host, err := fastly.BackendGetHost(b.name)
if err := ignoreNoneError(err); err != nil {
return err
}
port, err := fastly.BackendGetPort(b.name)
if err := ignoreNoneError(err); err != nil {
return err
}
b.target = host + ":" + strconv.Itoa(port)
b.hostOverride, err = fastly.BackendGetOverrideHost(b.name)
if err := ignoreNoneError(err); err != nil {
return err
}
// Timing-related calls return FastlyStatusUnsupported under
// Viceroy, so filter that out for these hostcalls too.
b.connectTimeout, err = fastly.BackendGetConnectTimeout(b.name)
if err := ignoreUnsupportedError(ignoreNoneError(err)); err != nil {
return err
}
b.firstByteTimeout, err = fastly.BackendGetFirstByteTimeout(b.name)
if err := ignoreUnsupportedError(ignoreNoneError(err)); err != nil {
return err
}
b.betweenBytesTimeout, err = fastly.BackendGetBetweenBytesTimeout(b.name)
if err := ignoreUnsupportedError(ignoreNoneError(err)); err != nil {
return err
}
b.isSSL, err = fastly.BackendIsSSL(b.name)
if err := ignoreNoneError(err); err != nil {
return err
}
if b.isSSL {
// SSL version calls also return FastlyStatusUnsupported under
// Viceroy.
var v fastly.TLSVersion
v, err = fastly.BackendGetSSLMaxVersion(b.name)
if err := ignoreUnsupportedError(ignoreNoneError(err)); err != nil {
return err
}
b.sslMaxVersion = TLSVersion(v)
v, err = fastly.BackendGetSSLMinVersion(b.name)
if err := ignoreUnsupportedError(ignoreNoneError(err)); err != nil {
return err
}
b.sslMinVersion = TLSVersion(v)
}
return nil
}
// Name returns the name associated with this backend.
func (b *Backend) Name() string {
return b.name
}
// Target returns the target associated with this backend.
func (b *Backend) Target() string {
return b.target
}
// Health dynamically checks the backend's health status.
func (b *Backend) Health() (BackendHealth, error) {
v, err := fastly.BackendIsHealthy(b.name)
if err != nil {
return BackendHealthUnknown, err
}
return BackendHealth(v), nil
}
// IsDynamic returns whether the backend is dynamic.
func (b *Backend) IsDynamic() bool {
return b.dynamic
}
func (b *Backend) HostOverride() string {
return b.hostOverride
}
func (b *Backend) ConnectTimeout() time.Duration {
return b.connectTimeout
}
func (b *Backend) FirstByteTimeout() time.Duration {
return b.firstByteTimeout
}
func (b *Backend) BetweenBytesTimeout() time.Duration {
return b.betweenBytesTimeout
}
func (b *Backend) IsSSL() bool {
return b.isSSL
}
func (b *Backend) SSLMaxVersion() TLSVersion {
return b.sslMaxVersion
}
func (b *Backend) SSLMinVersion() TLSVersion {
return b.sslMinVersion
}
func NewBackendOptions() *BackendOptions {
return &BackendOptions{}
}
// HostOverride sets the HTTP Host header on connections to this backend.
func (b *BackendOptions) HostOverride(host string) *BackendOptions {
b.abiOpts.HostOverride(host)
return b
}
// ConnectTimeout sets the maximum duration to wait for a connection to this backend to be established.
func (b *BackendOptions) ConnectTimeout(t time.Duration) *BackendOptions {
b.abiOpts.ConnectTimeout(t)
return b
}
// FirstByteTimeout sets the maximum duration to wait for the server response to begin after a TCP connection is established and the request has been sent.
func (b *BackendOptions) FirstByteTimeout(t time.Duration) *BackendOptions {
b.abiOpts.FirstByteTimeout(t)
return b
}
// BetweenBytesTimeout sets the maximum duration that Fastly will wait while receiving no data on a download from a backend.
func (b *BackendOptions) BetweenBytesTimeout(t time.Duration) *BackendOptions {
b.abiOpts.BetweenBytesTimeout(t)
return b
}
// UseSSL sets whether or not to require TLS for connections to this backend.
func (b *BackendOptions) UseSSL(v bool) *BackendOptions {
b.abiOpts.UseSSL(v)
return b
}
// SSLMinVersion sets the minimum allowed TLS version on SSL connections to this backend.
func (b *BackendOptions) SSLMinVersion(min TLSVersion) *BackendOptions {
b.abiOpts.SSLMinVersion(fastly.TLSVersion(min))
return b
}
// SSLMaxVersion sets the maximum allowed TLS version on SSL connections to this backend.
func (b *BackendOptions) SSLMaxVersion(max TLSVersion) *BackendOptions {
b.abiOpts.SSLMaxVersion(fastly.TLSVersion(max))
return b
}
// CertHostname sets the hostname that the server certificate should declare.
func (b *BackendOptions) CertHostname(host string) *BackendOptions {
b.abiOpts.CertHostname(host)
return b
}
// CACert sets the CA certificate to use when checking the validity of the backend.
func (b *BackendOptions) CACert(cert string) *BackendOptions {
b.abiOpts.CACert(cert)
return b
}
// Ciphers sets the list of OpenSSL ciphers to support for connections to this origin.
func (b *BackendOptions) Ciphers(ciphers string) *BackendOptions {
b.abiOpts.Ciphers(ciphers)
return b
}
// SNIHostname sets the SNI hostname to use on connections to this backend.
func (b *BackendOptions) SNIHostname(host string) *BackendOptions {
b.abiOpts.SNIHostname(host)
return b
}
// Register a new dynamic backend.
func RegisterDynamicBackend(name string, target string, options *BackendOptions) (*Backend, error) {
var abiOpts *fastly.BackendConfigOptions
if options != nil {
abiOpts = &options.abiOpts
} else {
abiOpts = &fastly.BackendConfigOptions{}
}
err := fastly.RegisterDynamicBackend(name, target, abiOpts)
if err != nil {
status, ok := fastly.IsFastlyError(err)
switch {
case ok && status == fastly.FastlyStatusUnsupported:
return nil, ErrDynamicBackendDisallowed
case ok && status == fastly.FastlyStatusError:
return nil, ErrBackendNameInUse
case ok:
return nil, fmt.Errorf("%w (%s)", ErrUnexpected, status)
default:
return nil, err
}
}
b := Backend{
name: name,
target: target,
}
if err := b.populateConfig(); err != nil {
return nil, err
}
return &b, nil
}
func ignoreNoneError(err error) error {
status, ok := fastly.IsFastlyError(err)
if ok && status == fastly.FastlyStatusNone {
return nil
}
return err
}
func ignoreUnsupportedError(err error) error {
status, ok := fastly.IsFastlyError(err)
if ok && status == fastly.FastlyStatusUnsupported {
return nil
}
return err
}