I'm not sure about this; my worry is that there's no relation whatsoever with the actual image. This keeps track of when the build command is last executed, but not when the image is last updated, which seems completely separate.

Take the following example;

$ docker build -t foo -<<EOF
FROM busybox
RUN date > /lastupdated
EOF

Sending build context to Docker daemon  2.048kB
Step 1/2 : FROM busybox
 ---> 7968321274dc
Step 2/2 : RUN date > /lastupdated
 ---> Running in 256bcc697e92
 ---> a678cb68731c
Removing intermediate container 256bcc697e92
Successfully built a678cb68731c

Inspecting the image;

$ docker inspect -f '{{.LastUpdated}}' foo
2017-03-06T12:59:26.91289454Z

Building the image again will use the cache, so no image is built;

$ docker build -t foo -<<EOF
FROM busybox
RUN date > /lastupdated
EOF

Sending build context to Docker daemon  2.048kB
Step 1/2 : FROM busybox
 ---> 7968321274dc
Step 2/2 : RUN date > /lastupdated
 ---> Using cache
 ---> a678cb68731c
Successfully built a678cb68731c

But LastUpdated gives the impression that the image has been updated;

$ docker inspect -f '{{.LastUpdated}}' foo
2017-03-06T13:01:55.397159895Z

If we go this direction, I would also prefer that the "metadata" that's separate from the actual image would be in a separate "struct" in the inspect output. Perhaps we want to add more metadata that's independent from the image (the lengthy discussions about labels that can be set without altering the actual image)

This keeps track of when the build command is last executed, but not when the image is last updated, which seems completely separate.

True, so I guess I need to either:

• change the field name to lastBuildTime
• also set lastUpdated when an image is pulled (and maybe also change the field name to something else)

I prefer the second. What do you think?

I would also prefer that the "metadata" that's separate from the actual image would be in a separate "struct" in the inspect output.

That seems reasonable, Parent is already mixed in, so I copied that, but it is probably a good idea to fix that now instead of continue with the pattern.

If this is about the last time it was tagged, maybe we shouldn't call it last build time :)

Changed it to LastTagTime

I would also prefer that the "metadata" that's separate from the actual image would be in a separate "struct" in the inspect output.

@dnephin did you have a look at making that change? I think others agreed on this when we were discussing

I've made that change

ping @tiborvass PTAL

Needs a rebase, but LGTM.

I rebased (because it was only the api-chances), but looks like it needed more changes due to 3aa4a00#diff-1ed32f2ce4c90e536bbbb9ede729120c (#33241) being merged; these are the changes I added;

diff --git a/daemon/image_inspect.go b/daemon/image_inspect.go
index a2b1d59..3baf265 100644
--- a/daemon/image_inspect.go
+++ b/daemon/image_inspect.go
@@ -61,7 +61,7 @@ func (daemon *Daemon) LookupImage(name string) (*types.ImageInspect, error) {
 		comment = img.History[len(img.History)-1].Comment
 	}

-	lastUpdated, err := daemon.imageStore.GetLastUpdated(img.ID())
+	lastUpdated, err := daemon.stores[platform].imageStore.GetLastUpdated(img.ID())
 	if err != nil {
 		return nil, err
 	}
diff --git a/daemon/image_tag.go b/daemon/image_tag.go
index 4516c5e..5f28dae 100644
--- a/daemon/image_tag.go
+++ b/daemon/image_tag.go
@@ -32,7 +32,7 @@ func (daemon *Daemon) TagImageWithReference(imageID image.ID, platform string, n
 		return err
 	}

-	if err := daemon.imageStore.SetLastUpdated(imageID); err != nil {
+	if err := daemon.stores[platform].imageStore.SetLastUpdated(imageID); err != nil {
 		return err
 	}
 	daemon.LogImageEvent(imageID.String(), reference.FamiliarString(newTag), "tag")

ping @cpuguy83 @johnstep PTAL

ugh; more work to do 😅

Culprit was due to 6052f2b (#32614). I'll push an update

diff --git a/image/store_test.go b/image/store_test.go
index 87101cb..fc6d461 100644
--- a/image/store_test.go
+++ b/image/store_test.go
@@ -154,16 +154,16 @@ func TestGetAndSetLastUpdated(t *testing.T) {
        defer cleanup()

        id, err := store.Create([]byte(`{"comment": "abc1", "rootfs": {"type": "layers"}}`))
-       assert.NilError(t, err)
+       assert.NoError(t, err)

        updated, err := store.GetLastUpdated(id)
-       assert.NilError(t, err)
+       assert.NoError(t, err)
        assert.Equal(t, updated.IsZero(), true)

-       assert.NilError(t, store.SetLastUpdated(id))
+       assert.NoError(t, store.SetLastUpdated(id))

        updated, err = store.GetLastUpdated(id)
-       assert.NilError(t, err)
+       assert.NoError(t, err)
        assert.Equal(t, updated.IsZero(), false)
 }