This repo holds a simple PoC about building an image using Kaniko
The image we are about to create using Kaniko is just an nginx base image with a custom hello world html file.
Kaniko will be running inside a Kubernetes Kind cluster.
kind create cluster --config kind/cluster.yaml --name kaniko
Creating cluster "kaniko" ...
✓ Ensuring node image (kindest/node:v1.20.2) 🖼
✓ Preparing nodes 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
Set kubectl context to "kind-kaniko"
You can now use your cluster with:
kubectl cluster-info --context kind-kaniko
The Kubernetes Kind cluster is created
kind get clusters
kaniko
Kubernetes control-plane (also a worker in this PoC) node is working as a docker container.
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
57a47cf629b9 kindest/node:v1.20.2 "/usr/local/bin/entr…" 4 minutes ago Up 4 minutes 127.0.0.1:42021->6443/tcp kaniko-control-plane
We can also check our build context is mounted inside a node from the kubernetes cluster
docker exec -it kaniko-control-plane ls -l /build-context/
total 0
-rwxrwxrwx 1 1000 1000 58 May 18 11:11 Dockerfile
-rwxrwxrwx 1 1000 1000 31 May 18 11:10 hello.html
Pull the image
docker pull registry
Load the image into kind cluster
kind load docker-image --name kaniko registry
Start the kubernetes deployment/service for the registry
kubectl apply -f k8s/registry.yaml
Please note this is a really simple configuration. Do not use in production environments.
Pull the kaniko image
docker pull gcr.io/kaniko-project/executor:debug
Debug image will allow us to bash into the container, to see for example if the build context has been correctly loaded.
Load the image into the kind cluster
kind load docker-image --name kaniko gcr.io/kaniko-project/executor:debug
Start the building process.
kubectl apply -f k8s/kaniko.yaml
And the image building process starts. As it is a very small image, the building process is very fast.
The job is completed
kubectl get jobs
NAME COMPLETIONS DURATION AGE
kaniko-job 1/1 24s 85s
The pod holding the job is also completed
kubectl get pods
NAME READY STATUS RESTARTS AGE
kaniko-job-k6mq4 0/1 Completed 0 99s
The logs from the kaniko process.
kubectl logs kaniko-job-k6mq4
INFO[0000] Retrieving image manifest nginx:latest
INFO[0000] Retrieving image nginx:latest from registry index.docker.io
INFO[0001] Built cross stage deps: map[]
INFO[0001] Retrieving image manifest nginx:latest
INFO[0001] Returning cached image manifest
INFO[0001] Executing 0 build triggers
INFO[0001] Unpacking rootfs as cmd COPY hello.html /usr/share/nginx/html requires it.
INFO[0015] COPY hello.html /usr/share/nginx/html
INFO[0015] Taking snapshot of files...
INFO[0015] Pushing image to docker-registry-service:5000/nginx-hello-world:latest
INFO[0022] Pushed image to 1 destinations
The image is being created inside the docker registry pod
kubectl get pods
NAME READY STATUS RESTARTS AGE
docker-registry-deployment-6876ff49f5-tmh7k 1/1 Running 2 18h
kubectl exec --stdin --tty docker-registry-deployment-6876ff49f5-tmh7k
-- ls -l /var/lib/registry/docker/registry/v2/repositories
drwxr-xr-x 5 root root 4096 May 19 06:06 nginx-hello-world
We can query the registry for the images
kubectl port-forward docker-registry-deployment-6876ff49f5-tmh7k 5000
curl http://localhost:5000/v2/nginx-hello-world/tags/list
{"name":"nginx-hello-world","tags":["latest"]}
And also we can pull the image. It is important to note the tls-verify option as the registry is insecure and it will fail with regular options.
podman pull --tls-verify=false localhost:5000/nginx-hello-world:latest
Trying to pull localhost:5000/nginx-hello-world:latest...
Getting image source signatures
Copying blob de9813870342 skipped: already exists
Copying blob cfcd0711b93a skipped: already exists
Copying blob 49f7d34d62c1 skipped: already exists
Copying blob 69692152171a skipped: already exists
Copying blob 5f97dc5d71ab skipped: already exists
Copying blob 63d9f7b0e991 [--------------------------------------] 0.0b / 0.0b
Copying blob be6172d7651b [--------------------------------------] 0.0b / 0.0b
Copying config 4ae7080d6c done
Writing manifest to image destination
Storing signatures
4ae7080d6c04440a3515fa292f2c4dc6468a6904967d3c651cb4916e548abc0b
Note: if we add an entry in hosts file, we can replace localhost with docker-registry-service
127.0.0.1 docker-registry-service
There are two images, the same hash
podman image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
localhost:5000/nginx-hello-world latest 4ae7080d6c04
docker-registry-service:5000/nginx-hello-world latest 4ae7080d6c04
Run a container based on the image
podman run -it --rm --name nginx -p 8080:80 docker-registry-service:5000/nginx-hello-world
curl http://localhost:8080
I have been built using Kaniko.
From https://kind.sigs.k8s.io/docs/user/quick-start/#loading-an-image-into-your-cluster
You can get a list of images present on a cluster node by using docker exec:
docker exec -it my-node-name crictl images
Where my-node-name is the name of the Docker container (e.g. kind-control-plane).