Can I use multiply import-cache images (like cache-from)?

[alexander-xyz]

Hello. Can I use multiply images for import-cache?
--import-cache type=registry,ref=docker.io/username/image:latest
--import-cache type=registry,ref=docker.io/username/image:BRANCH-NAME
etc?

[tonistiigi]

Yes

[alexander-xyz]

Wow, thanks!
Does the order of --import-cache arguments matter ? What cache image has higher priority?

[tonistiigi]

The longest matching cache chain is matched. On equal length, it should prefer the record with a newer timestamp.

[henridwyer]

What is a cache chain? How could I get buildkit to first check a local cache before a registry cache for example?

[henridwyer]

@tonistiigi

[tonistiigi]

Local cache always has higher priority

[alexander-xyz]

Also, can I use multiple export-cache options?

[tonistiigi]

Not atm

[alexander-xyz]

What about "output"? Can be multiple?

[tonistiigi]

not yet #2760

[alexander-xyz]

So, if I want to push image to private repository with 3 tags, with "output" option I can do it only for one tag from set, for other two, I need to do:
docker push $tag1
docker push $tag2
?
For example:

buildctl build ...\
  --import-cache type=registry,ref=docker.io/username/image:latest
  --import-cache type=registry,ref=docker.io/username/image:BRANCH-NAME
  --export-cache type=registry,ref=docker.io/username/image:BRANCH-NAME,mode=max
  --output type=image,name=docker.io/username/image:BRANCH-NAME,push=true \
  --tag docker.io/username/image:latest
  --tag docker.io/username/image:one_more_tag

docker push docker.io/username/image:latest
docker push docker.io/username/image:one_more_tag

is it correct?

[tonistiigi]

You can set multiple names with single --output #797

There is no --tag in buildctl.

[alexander-xyz]

Thank you!
One more question please.
This is my dockerfile:

FROM php:7.2-fpm-alpine as php-image

# run some commands

FROM node:14-alpine AS node-image
RUN npm install -g grunt-cli npm@latest

FROM php-image as builder

COPY --from=node-image /usr/lib /usr/lib
COPY --from=node-image /usr/local/share /usr/local/share
COPY --from=node-image /usr/local/lib /usr/local/lib
COPY --from=node-image /usr/local/include /usr/local/include
COPY --from=node-image /usr/local/bin /usr/local/bin
COPY --from=node-image /opt /opt

RUN npm config -g set user root

Do I have to build and cache the intermediate stages with a --opt target= for multistage builds, for better caching?

buildctl build ...\
  --import-cache type=registry,ref=docker.io/username/image:php-image
  --export-cache type=registry,ref=docker.io/username/image:php-image,mode=max
  --opt target=php-image

buildctl build ...\
  --import-cache type=registry,ref=docker.io/username/image:node-image
  --export-cache type=registry,ref=docker.io/username/image:node-image,mode=max
  --opt target=node-image

buildctl build ...\
  --import-cache type=registry,ref=docker.io/username/image:php-image
  --import-cache type=registry,ref=docker.io/username/image:node-image
  --import-cache type=registry,ref=docker.io/username/image:builder
  --export-cache type=registry,ref=docker.io/username/image:builder,mode=max
  --opt target=builder

Or, I can build just need target, and all intermediate stages will be cached well?

buildctl build ...\
  --import-cache type=registry,ref=docker.io/username/image:builder
  --export-cache type=registry,ref=docker.io/username/image:builder,mode=max
  --opt target=builder