dotcloud/docker

package dockerfile // import "github.com/docker/docker/builder/dockerfile"

import (
    "context"

    "github.com/containerd/log"
    "github.com/docker/docker/api/types/container"
    "github.com/docker/docker/builder"
    ocispec "github.com/opencontainers/image-spec/specs-go/v1"
)

// ImageProber exposes an Image cache to the Builder. It supports resetting a
// cache.
type ImageProber interface {
    Reset(ctx context.Context) error
    Probe(parentID string, runConfig *container.Config, platform ocispec.Platform) (string, error)
}

type resetFunc func(context.Context) (builder.ImageCache, error)

type imageProber struct {
    cache       builder.ImageCache
    reset       resetFunc
    cacheBusted bool
}

func newImageProber(ctx context.Context, cacheBuilder builder.ImageCacheBuilder, cacheFrom []string, noCache bool) (ImageProber, error) {
    if noCache {
        return &nopProber{}, nil
    }

    reset := func(ctx context.Context) (builder.ImageCache, error) {
        return cacheBuilder.MakeImageCache(ctx, cacheFrom)
    }

    cache, err := reset(ctx)
    if err != nil {
        return nil, err
    }
    return &imageProber{cache: cache, reset: reset}, nil
}

func (c *imageProber) Reset(ctx context.Context) error {
    newCache, err := c.reset(ctx)
    if err != nil {
        return err
    }
    c.cache = newCache
    c.cacheBusted = false
    return nil
}

// Probe checks if cache match can be found for current build instruction.
// It returns the cachedID if there is a hit, and the empty string on miss
func (c *imageProber) Probe(parentID string, runConfig *container.Config, platform ocispec.Platform) (string, error) {
    if c.cacheBusted {
        return "", nil
    }
    cacheID, err := c.cache.GetCache(parentID, runConfig, platform)
    if err != nil {
        return "", err
    }
    if len(cacheID) == 0 {
        log.G(context.TODO()).Debugf("[BUILDER] Cache miss: %s", runConfig.Cmd)
        c.cacheBusted = true
        return "", nil
    }
    log.G(context.TODO()).Debugf("[BUILDER] Use cached version: %s", runConfig.Cmd)
    return cacheID, nil
}

type nopProber struct{}

func (c *nopProber) Reset(ctx context.Context) error {
    return nil
}

func (c *nopProber) Probe(_ string, _ *container.Config, _ ocispec.Platform) (string, error) {
    return "", nil
}