asset_delivery

package module
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 Go to latest Published: Oct 3, 2026 License: MIT Imports: 26 Imported by: 0

README

Asset Delivery

Delivers resized assets (images) in response to HTTP requests. It contains two parts:

  • Delivery server (asset-delivery Cloud Run service)
  • Resize worker (asset-resize Cloud Run service)

Both binaries are built from a single image (cloud/build.Dockerfile) and copied into per-service runtime images. The pipeline is wired in cloudbuild.yaml.

Delivery Server

The delivery server attempts to find an existing resized file from a storage location. If the resized file is found it returns the resized file. Otherwise, it delivers the original file and publishes a resize request to the asset-delivery-resize Pub/Sub topic.

HTTP Request

Each request needs the following URL parameters:

  • width
  • url
  • encoding (e.g., webp, jpeg, png)

For example, to request a version of https://host/path with width=100 and encoding=webp:

https://[host]?width=100&url=https://host/path&encoding=webp
Environment Variables
  • BUCKET: GCP Storage bucket name
  • HOST: GCP Storage host (optional). Used by emulators.
Command-Line Arguments
  • address: Bind address. Defaults to 0.0.0.0:80.
  • credentials: Path to a Google JWT file.
  • allow: Comma-separated allowed hosts for the url query param. Empty allows any.
  • project-id: Google Project ID (for logging & pubsub).

Resize Worker

The resize worker consumes messages from the asset-delivery-resize Pub/Sub topic via a push subscription. Each push delivery is an HTTP POST with the Pub/Sub envelope as the body (see Pub/Sub push docs). The worker unmarshals the embedded ResizeOptions, resizes the source image, and writes the result to the configured GCS bucket.

HTTP status drives Pub/Sub redelivery:

  • 2xx — message acked
  • 4xx — permanent failure (e.g., malformed payload); routed to dead letter after maxDeliveryAttempts
  • 5xx — transient failure; Pub/Sub retries with backoff
Environment Variables
  • PROJECTID: Google Project ID (used for Cloud Logging)
  • BUCKET: GCP Storage bucket name
  • HOST: GCP Storage host (optional)
  • DEFAULT_CACHE_CONTROL: Fallback Cache-Control value when the upstream response carries none
  • PORT: Bind port (Cloud Run sets this; defaults to 8080)
Pub/Sub Push Subscription

The push subscription on projects/connect-1321/topics/asset-delivery-resize should be configured to POST to the asset-resize Cloud Run service URL. For authenticated push, set the subscription's push auth service account and grant it roles/run.invoker on asset-resize. Configure a dead-letter topic + maxDeliveryAttempts to avoid hot-looping on poison messages.

Documentation

Index

Constants

View Source 
const MaxImageDimension = 4096
View Source 
const ResizeTopic = "asset-delivery-resize"

PubSub topic for sending and receiving resize request

Variables

View Source 
var (
	ErrFileNotHandled = errors.New("file type not handled")
	ErrInvalidBounds  = errors.New("invalid image bounds")
)
View Source 
var ErrNoFile = errors.New("no file")

Functions

func DefaultImageDecode 

func DefaultImageDecode(r io.Reader) (image.Image, error)

func GetImage 

func GetImage(url string) ([]byte, string, error)

func ImageToBytes 

func ImageToBytes(i image.Image, hint string, quality int) (*bytes.Buffer, error)

func IsExpired 

func IsExpired(info FileInfo) bool

IsExpired reports whether info is past its Cache-Control max-age. An object with no max-age never expires (returns false).

func NewGCloudLogger 

func NewGCloudLogger(project, name string, opts ...option.ClientOption) (*logging.Client, *logger.Google, error)

func ReaderToImage 

func ReaderToImage(r io.ReadSeeker, hint string) (image.Image, string, error)

ReaderToImage decodes r as an image, using hint's extension to pick the decoder when it names a supported format and falling back to image.Decode otherwise. The returned format is the auto-detected format name ("jpeg", "png", "webp", ...) when the fallback path is taken, or the format implied by the hint when the typed decoder succeeds. Callers can use it to choose an output encoding when the hint URL has no extension.

func Resize 

func Resize(fs FileSystem, opts ResizeOptions) error

func ResizeImage 

func ResizeImage(img image.Image, target uint) (image.Image, error)

func WriteError 

func WriteError(w http.ResponseWriter, err error)

Types

type FileInfo 

type FileInfo interface {
	FileInfoWrite
	FileInfoRead
}

type FileInfoRead 

type FileInfoRead interface {
	Created() time.Time
}

type FileInfoWrite 

type FileInfoWrite interface {
	CacheControl() string
}

type FileSystem 

type FileSystem interface {
	FromVolume(string) FileSystem
	ObjectURL(string) string
	Info(string) (FileInfo, error)
	ReadCloser(string) (io.ReadCloser, error)
	Write(string, io.Reader, FileInfoWrite) error
	Delete(string) error
}

type GCloudFileInfo 

type GCloudFileInfo struct {
	// contains filtered or unexported fields
}

func (*GCloudFileInfo) CacheControl 

func (i *GCloudFileInfo) CacheControl() string

func (*GCloudFileInfo) Created 

func (i *GCloudFileInfo) Created() time.Time

type GCloudFileSystem 

type GCloudFileSystem struct {
	Client *storage.Client
	Host   string
	Bucket string
	// contains filtered or unexported fields
}

func NewGCloudFileSystem 

func NewGCloudFileSystem(opts ...option.ClientOption) (*GCloudFileSystem, error)

func (*GCloudFileSystem) Delete 

func (fs *GCloudFileSystem) Delete(filename string) error

func (*GCloudFileSystem) FromVolume 

func (fs *GCloudFileSystem) FromVolume(name string) FileSystem

func (*GCloudFileSystem) GetBucket 

func (fs *GCloudFileSystem) GetBucket(bucket string) *storage.BucketHandle

func (*GCloudFileSystem) Info 

func (fs *GCloudFileSystem) Info(filename string) (FileInfo, error)

func (*GCloudFileSystem) ObjectURL 

func (fs *GCloudFileSystem) ObjectURL(filename string) string

func (*GCloudFileSystem) ReadCloser 

func (fs *GCloudFileSystem) ReadCloser(filename string) (io.ReadCloser, error)

func (*GCloudFileSystem) Write 

func (fs *GCloudFileSystem) Write(filename string, r io.Reader, info FileInfoWrite) error

type GCloudPubSub 

type GCloudPubSub struct {
	logger.Logger
	*pubsub.Client
}

func NewGCloudPubSub 

func NewGCloudPubSub(projectId string, opts ...option.ClientOption) (*GCloudPubSub, error)

func (*GCloudPubSub) Publish 

func (p *GCloudPubSub) Publish(subj string, data []byte) error

type HTTPError 

type HTTPError interface {
	Status() int
	Error() string
}

type Messager 

type Messager interface {
	Publisher
	Subscriber
	Close()
}

type ParamError 

type ParamError struct {
	Param     string
	Detail    string
	RootError error
}

func (*ParamError) Error 

func (err *ParamError) Error() string

func (*ParamError) Root 

func (err *ParamError) Root() error

func (*ParamError) Status 

func (err *ParamError) Status() int

type Publisher 

type Publisher interface {
	Publish(subj string, data []byte) error
}

type ResizeOptions 

type ResizeOptions struct {
	Width          uint
	CacheKey       string // stable identity; hashed when present
	Location       string // fetch URL; hashed when CacheKey empty (legacy)
	HashSum        string
	Encoding       string
	Prefix         string
	CacheControl   string
	IgnoreIfExists bool // skip fetch+resize+write when the object is warm + fresh
}

func (*ResizeOptions) DesiredEncoding 

func (opts *ResizeOptions) DesiredEncoding() string

func (*ResizeOptions) ObjectKey 

func (opts *ResizeOptions) ObjectKey() string

func (*ResizeOptions) PopulateHash 

func (opts *ResizeOptions) PopulateHash()

PopulateHash hashes CacheKey when present (gold-http path); else Location (legacy browser-url path, retained for the shared consumer).

type ResizeOptionsProcessed 

type ResizeOptionsProcessed struct {
	ResizeOptions
	URL   *url.URL
	Force bool
}

func NewResizeOptionsFromQuery 

func NewResizeOptionsFromQuery(m map[string][]string) (ResizeOptionsProcessed, error)

type RootError 

type RootError interface {
	Root() error
}

type Subscriber 

type Subscriber interface {
	Subscribe(subj string, h func([]byte)) (Subscription, error)
}

type Subscription 

type Subscription interface {
	Unsubscribe()
}

type SystemError 

type SystemError struct {
	RootError error
	Detail    string
}

func (*SystemError) Error 

func (err *SystemError) Error() string

func (*SystemError) Root 

func (err *SystemError) Root() error

func (*SystemError) Status 

func (err *SystemError) Status() int

type WriteInfo 

type WriteInfo struct {
	// contains filtered or unexported fields
}

func (*WriteInfo) CacheControl 

func (i *WriteInfo) CacheControl() string

Source Files

View all Source files

Directories

Path Synopsis
cmd
delivery command
resize command

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