GoogleContainerTools/skaffold

Shouldn't default-repo be applied to cacheFrom directives?

Open

#3610 opened on Jan 29, 2020

View on GitHub
 (9 comments) (7 reactions) (0 assignees)Go (12,822 stars) (1,416 forks)batch import
area/cachehelp wantedkind/bugpriority/p2

Description

I'm trying very hard to optimize my DotNet multi-stage build process.

To do that I'm creating three profiles that I must execute in sequence.

Profile 1 - Base images Profile 2 - Dependency Builder Profile 3 - Final builder

The idea is to use caching and don't rebuild the whole system every time, and build in parallel things that are not dependent on others.

For each step, I want to use a previous image in cache or the image build in the latest profile. So was trying to use cacheFrom when I stumbled into that.

I use the --default-repo to set the image according to the branch, in runtime, and I expected the cache image to be pulled from my default repo, but It doesn't seem to be.

Additional

  • I would like to be able to use templating in the cacheFrom directive, so I can use the previous image and not necessarly the one tagged as latest.

Expected behavior

If default-repo is specified, cacheFrom images without full path should be rewriten if not fully qualified.

Actual behavior

Skaffold says the image could not be found.

Information

  • Skaffold version: 1.2.0
  • Operating system: Windows
  • Contents of skaffold.yaml:
profile:
- name: restore-stage
  build:
    local: 
      useBuildkit: false
    artifacts:
    - image: restore
      context: .
      docker:
        dockerfile: Dockerfile.default
        cacheFrom:
        - restore:latest
        target: pre_publish

Contributor guide

Tech stack
godocker
Domain
build systemdevopscli
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of Docker multi stage buildsFamiliarity with skaffold configurationBasic Go programming skills
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate how skaffold applies the default repo flag to artifact image names. The cacheFrom directive in skaffold.yaml currently appears to ignore default repo. Look at the code in pkg/skaffold/build/docker or similar that resolves cacheFrom images. The issue also requests templating in cacheFrom, but the primary fix is to apply default repo rewriting. Check if there are any existing tests or PRs related to this. Start by examining how default repo is applied to artifact images and extend that logic to cacheFrom entries. Consider adding a configuration option or automatic rewriting when the image is not fully qualified.