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moby--moby/builder/builder.go
Tibor Vass e0ef11a4c2 Abstract builder and implement server-side dockerfile builder
This patch creates interfaces in builder/ for building Docker images.
It is a first step in a series of patches to remove the daemon
dependency on builder and later allow a client-side Dockerfile builder
as well as potential builder plugins.

It is needed because we cannot remove the /build API endpoint, so we
need to keep the server-side Dockerfile builder, but we also want to
reuse the same Dockerfile parser and evaluator for both server-side and
client-side.

builder/dockerfile/ and api/server/builder.go contain implementations
of those interfaces as a refactoring of the current code.

Signed-off-by: Tibor Vass <tibor@docker.com>
2015-10-06 19:10:19 -04:00

139 lines
5 KiB
Go

// Package builder defines interfaces for any Docker builder to implement.
//
// Historically, only server-side Dockerfile interpreters existed.
// This package allows for other implementations of Docker builders.
package builder
import (
"io"
"os"
// TODO: remove dependency on daemon
"github.com/docker/docker/daemon"
"github.com/docker/docker/image"
"github.com/docker/docker/runconfig"
)
// Builder abstracts a Docker builder whose only purpose is to build a Docker image referenced by an imageID.
type Builder interface {
// Build builds a Docker image referenced by an imageID string.
//
// Note: Tagging an image should not be done by a Builder, it should instead be done
// by the caller.
//
// TODO: make this return a reference instead of string
Build() (imageID string)
}
// Context represents a file system tree.
type Context interface {
// Close allows to signal that the filesystem tree won't be used anymore.
// For Context implementations using a temporary directory, it is recommended to
// delete the temporary directory in Close().
Close() error
// Stat returns an entry corresponding to path if any.
// It is recommended to return an error if path was not found.
Stat(path string) (FileInfo, error)
// Open opens path from the context and returns a readable stream of it.
Open(path string) (io.ReadCloser, error)
// Walk walks the tree of the context with the function passed to it.
Walk(root string, walkFn WalkFunc) error
}
// WalkFunc is the type of the function called for each file or directory visited by Context.Walk().
type WalkFunc func(path string, fi FileInfo, err error) error
// ModifiableContext represents a modifiable Context.
// TODO: remove this interface once we can get rid of Remove()
type ModifiableContext interface {
Context
// Remove deletes the entry specified by `path`.
// It is usual for directory entries to delete all its subentries.
Remove(path string) error
}
// FileInfo extends os.FileInfo to allow retrieving an absolute path to the file.
// TODO: remove this interface once pkg/archive exposes a walk function that Context can use.
type FileInfo interface {
os.FileInfo
Path() string
}
// PathFileInfo is a convenience struct that implements the FileInfo interface.
type PathFileInfo struct {
os.FileInfo
// FilePath holds the absolute path to the file.
FilePath string
}
// Path returns the absolute path to the file.
func (fi PathFileInfo) Path() string {
return fi.FilePath
}
// Hashed defines an extra method intended for implementations of os.FileInfo.
type Hashed interface {
// Hash returns the hash of a file.
Hash() string
SetHash(string)
}
// HashedFileInfo is a convenient struct that augments FileInfo with a field.
type HashedFileInfo struct {
FileInfo
// FileHash represents the hash of a file.
FileHash string
}
// Hash returns the hash of a file.
func (fi HashedFileInfo) Hash() string {
return fi.FileHash
}
// SetHash sets the hash of a file.
func (fi *HashedFileInfo) SetHash(h string) {
fi.FileHash = h
}
// Docker abstracts calls to a Docker Daemon.
type Docker interface {
// TODO: use digest reference instead of name
// LookupImage looks up a Docker image referenced by `name`.
LookupImage(name string) (*image.Image, error)
// Pull tells Docker to pull image referenced by `name`.
Pull(name string) (*image.Image, error)
// TODO: move daemon.Container to its own package
// Container looks up a Docker container referenced by `id`.
Container(id string) (*daemon.Container, error)
// Create creates a new Docker container and returns potential warnings
// TODO: put warnings in the error
Create(*runconfig.Config, *runconfig.HostConfig) (*daemon.Container, []string, error)
// Remove removes a container specified by `id`.
Remove(id string, cfg *daemon.ContainerRmConfig) error
// Commit creates a new Docker image from an existing Docker container.
Commit(*daemon.Container, *daemon.ContainerCommitConfig) (*image.Image, error)
// Copy copies/extracts a source FileInfo to a destination path inside a container
// specified by a container object.
// TODO: make an Extract method instead of passing `decompress`
// TODO: do not pass a FileInfo, instead refactor the archive package to export a Walk function that can be used
// with Context.Walk
Copy(c *daemon.Container, destPath string, src FileInfo, decompress bool) error
// Retain retains an image avoiding it to be removed or overwritten until a corresponding Release() call.
// TODO: remove
Retain(sessionID, imgID string)
// Release releases a list of images that were retained for the time of a build.
// TODO: remove
Release(sessionID string, activeImages []string)
}
// ImageCache abstracts an image cache store.
// (parent image, child runconfig) -> child image
type ImageCache interface {
// GetCachedImage returns a reference to a cached image whose parent equals `parent`
// and runconfig equals `cfg`. A cache miss is expected to return an empty ID and a nil error.
GetCachedImage(parentID string, cfg *runconfig.Config) (imageID string, err error)
}