For https://github.com/NixOS/nixpkgs/pull/125211 I tried to test
the fetcher with
nix-build -A dockerTools.examples.nixFromDockerHub --option substitute false
But it failed. I haven't figured out the cause, but the outputs
match, so it's probably the hashing method (flat/recursive) that
changed at some point. (The names did match.)
Adds includeStorePaths, allowing the omission of the store paths.
You generally want to leave it on, but tooling may disable this
to insert the store paths more efficiently via other means, such
as bind mounting the host store.
It is now possible to pass a `fromImage` to `buildLayeredImage` and
`streamLayeredImage`, similar to what `buildImage` currently supports.
This will prepend the layers of the given base image to the resulting
image, while ensuring that at most `maxLayers` are used. It will also
ensure that environment variables from the base image are propagated
to the final image.
When using `buildLayeredImage`, it is not possible to specify an image
name of the form `<registry>/my/image`, although it is a valid name.
This is due to derivations under `buildLayeredImage` using that image
name as their derivation name, but slashes are not permitted in that
context.
A while ago, #13099 fixed that exact same problem in `buildImage` by
using `baseNameOf name` in derivation names instead of `name`. This
change does the same thing for `buildLayeredImage`.
This provides a /etc/passwd and /etc/group that contain root and nobody.
Useful when packaging binaries that insist on using nss to look up
username/groups (like nginx).
The current nginx example used the `runAsRoot` parameter to setup
/etc/group and /etc/passwd (which also doesn't exist in
buildLayeredImage), so we can now just use fakeNss there and use
buildLayeredImage.
The image tag can be specified or generated from the output hash.
Previously, a generated tag could be recovered from the evaluated
image with some string operations.
However, with the introduction of streamLayeredImage, it's not
feasible to compute the generated tag yourself.
With this change, the imageTag attribute is set unconditionally,
for the buildImage, buildLayeredImage, streamLayeredImage functions.
This is useful when buildLayeredImage is called in a generic way
that should allow simple (base) images to be built, which may not
reference any store paths.
Fixes#78744
My previous change broke when there are more packages than the maximum
number of layers. I had assumed that the `store-path-to-layer.sh` was
only ever passed a single store path, but that is not the case if
there are multiple packages going into the final layer. To fix this, we
loop through the paths going into the final layer, appending them to the
tar file and making sure they end up at the right path.
Docker images used to be, essentially, a linked list of layers. Each
layer would have a tarball and a json document pointing to its parent,
and the image pointed to the top layer:
imageA ----> layerA
|
v
layerB
|
v
layerC
The current image spec changed this format to where the Image defined
the order and set of layers:
imageA ---> layerA
|--> layerB
`--> layerC
For backwards compatibility, docker produces images which follow both
specs: layers point to parents, and images also point to the entire
list:
imageA ---> layerA
| |
| v
|--> layerB
| |
| v
`--> layerC
This is nice for tooling which supported the older version and never
updated to support the newer format.
Our `buildImage` code only supported the old version, so in order for
`buildImage` to properly generate an image based on another image
with `fromImage`, the parent image's layers must fully support the old
mechanism.
This is not a problem in general, but is a problem with
`buildLayeredImage`.
`buildLayeredImage` creates images with newer image spec, because
individual store paths don't have a guaranteed parent layer. Including
a specific parent ID in the layer's json makes the output less likely
to cache hit when published or pulled.
This means until now, `buildLayeredImage` could not be the input to
`buildImage`.
The changes in this PR change `buildImage` to only use the layer's
manifest when locating parent IDs. This does break buildImage on
extremely old Docker images, though I do wonder how many of these
exist.
This work has been sponsored by Target.
