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Development

This doc explains the development workflow so you can get started contributing to Kaniko!

Getting started

First you will need to setup your GitHub account and create a fork:

  1. Create a GitHub account
  2. Setup GitHub access via SSH
  3. Create and checkout a repo fork

Once you have those, you can iterate on kaniko:

  1. Run your instance of kaniko
  2. Verifying kaniko builds
  3. Run kaniko tests

When you're ready, you can create a PR!

Checkout your fork

The Go tools require that you clone the repository to the src/github.com/GoogleContainerTools/kaniko directory in your GOPATH.

To check out this repository:

  1. Create your own fork of this repo
  2. Clone it to your machine:
mkdir -p ${GOPATH}/src/github.com/GoogleContainerTools
cd ${GOPATH}/src/github.com/GoogleContainerTools
git clone git@github.com:${YOUR_GITHUB_USERNAME}/kaniko.git
cd kaniko
git remote add upstream git@github.com:GoogleContainerTools/kaniko.git
git remote set-url --push upstream no_push

Adding the upstream remote sets you up nicely for regularly syncing your fork.

Verifying kaniko builds

Images built with kaniko should be no different from images built elsewhere. While you iterate on kaniko, you can verify images built with kaniko by:

  1. Build the image using another system, such as docker build
  2. Use container-diff to diff the images

Testing kaniko

kaniko has both unit tests and integration tests.

Please note that the tests require a Linux machine - use Vagrant to quickly set up the test environment needed if you work with macOS or Windows.

Unit Tests

The unit tests live with the code they test and can be run with:

make test

These tests will not run correctly unless you have checked out your fork into your $GOPATH.

Lint Checks

The helper script to install and run lint is placed here at the root of project.

./hack/linter.sh

To fix any gofmt issues, you can simply run gofmt with -w flag like this

find . -name "*.go" | grep -v vendor/ | xargs gofmt -l -s -w

Integration tests

Currently the integration tests that live in integration can be run against your own gcloud space or a local registry.

These tests will be kicked off by reviewers for submitted PRs using GitHub Actions.

In either case, you will need the following tools:

GCloud

To run integration tests with your GCloud Storage, you will also need the following tools:

  • gcloud
  • gsutil
  • A bucket in GCS which you have write access to via the user currently logged into gcloud
  • An image repo which you have write access to via the user currently logged into gcloud
  • A docker account and a ~/.docker/config.json with login credentials if you run into rate limiting problems during tests.

Once this step done, you must override the project using environment variables:

  • GCS_BUCKET - The name of your GCS bucket
  • IMAGE_REPO - The path to your docker image repo

This can be done as follows:

export GCS_BUCKET="gs://<your bucket>"
export IMAGE_REPO="gcr.io/somerepo"

Login for both user and application credentials

gcloud auth login
gcloud auth application-default login

Then you can launch integration tests as follows:

make integration-test

You can also run tests with go test, for example to run tests individually:

go test ./integration -v --bucket $GCS_BUCKET --repo $IMAGE_REPO -run TestLayers/test_layer_Dockerfile_test_copy_bucket

These tests will be kicked off by reviewers for submitted PRs by the kokoro task.

Local integration tests

To run integration tests locally against a local registry and gcs bucket, set the LOCAL environment variable

LOCAL=1 make integration-test

Running integration tests for a specific dockerfile

In order to test only specific dockerfiles during local integration testing, you can specify a pattern to match against inside the integration/dockerfiles directory.

DOCKERFILE_PATTERN="Dockerfile_test_add*" make integration-test-run

This will only run dockerfiles that match the pattern Dockerfile_test_add*

Benchmarking

The goal is for Kaniko to be at least as fast at building Dockerfiles as Docker is, and to that end, we've built in benchmarking to check the speed of not only each full run, but also how long each step of each run takes. To turn on benchmarking, just set the BENCHMARK_FILE environment variable, and kaniko will output all the benchmark info of each run to that file location.

docker run -v $(pwd):/workspace -v ~/.config:/root/.config \
-e BENCHMARK_FILE=/workspace/benchmark_file \
gcr.io/kaniko-project/executor:latest \
--dockerfile=<path to Dockerfile> --context=/workspace \
--destination=gcr.io/my-repo/my-image

Additionally, the integration tests can output benchmarking information to a benchmarks directory under the integration directory if the BENCHMARK environment variable is set to true.

BENCHMARK=true go test -v --bucket $GCS_BUCKET --repo $IMAGE_REPO

Benchmarking your GCB runs

If you are GCB builds are slow, you can check which phases in kaniko are bottlenecks or taking more time. To do this, add "BENCHMARK_ENV" to your cloudbuild.yaml like this.

steps:
- name: 'gcr.io/kaniko-project/executor:latest'
  args:
  - --build-arg=NUM=${_COUNT}
  - --no-push
  - --snapshot-mode=redo
  env:
  - 'BENCHMARK_FILE=gs://$PROJECT_ID/gcb/benchmark_file'

You can download the file gs://$PROJECT_ID/gcb/benchmark_file using gsutil cp command.

Creating a PR

When you have changes you would like to propose to kaniko, you will need to:

  1. Ensure the commit message(s) describe what issue you are fixing and how you are fixing it (include references to issue numbers if appropriate)
  2. Create a pull request

Reviews

Each PR must be reviewed by a maintainer. This maintainer will add the kokoro:run label to a PR to kick of the integration tests, which must pass for the PR to be submitted.