🍄 🚲 📔 Building containers without Docker 🆙 🤱🏽 🤝

Hello, Habr. We hear a lot about Kubernetis and Docker now. Probably, only the lazy doesn't know about them. But there are other options for working with containers. Here's a translation of an article by an enthusiast who decided to explore similar tools.

I want to talk about how to create containers without using Docker. I will be using OpenFaaS , which uses OCI container images for my workloads. We can say that OpenFaaS is a CaaS platform for Kubernetes that is able to run microservices and add FaaS and event management tools for free. We'll start by showing you how to use the built-in buildkit for the Docker command line interface, then describe the standalone buildkit (Linux only), and then the Google container builder , Kaniko .

What's wrong with Docker?

Yes, everything is like that with him. It works well on armhf, arm64 and on x86_64. The main Docker command line interface has gone a lot more than just build / push / run, it now comes with Docker Swarm and EE features.

Docker alternatives

There have been several attempts to bring Docker back to the familiar look we all fell in love with.

Docker - Docker itself now uses containerd to run containers and supports buildkit builds to create highly efficient caching builds.
Podman buildah — RedHat/IBM, OSS OCI. Podman root-, UNIX.
Pouch — Alibaba « ». containerd , Docker, runc « », runV. .
BuildKit -buildkit Docker Inc . buildkit , , . (fork) , .
img — buildkit. . 2018 , . , img buildctr, buildkit, , img x86_64 armhf/arm64.
k3c — Rancher, containerd buildkit , Docker. ARM.

k3c, , , containerd buildkit.

, «build» , :

buildkit Docker
buildkit
Kaniko

( ) , OpenFaaS CLI « »,

HTTP Golang middleware, , , OpenFaaS.

faas-cli template store pull golang-middleware

faas-cli new --lang golang-middleware \
  build-test --prefix=alexellis2

--lang

build-test —

--prefix Docker Hub, OCI.

./
├── build-test
│   └── handler.go
└── build-test.yml

1 directory, 2 files

, . Go.

package function

import (
	"fmt"
	"io/ioutil"
	"net/http"
)

func Handle(w http.ResponseWriter, r *http.Request) {
	var input []byte

	if r.Body != nil {
		defer r.Body.Close()

		body, _ := ioutil.ReadAll(r.Body)

		input = body
	}

	w.WriteHeader(http.StatusOK)
	w.Write([]byte(fmt.Sprintf("Hello world, input was: %s", string(input))))
}

faas-cli build -f build-test.yml

Dockerfile

./template/golang-middleware/Dockerfile

FROM openfaas/of-watchdog:0.7.3 as watchdog
FROM golang:1.13-alpine3.11 as build
FROM alpine:3.12

. , . faas-cli push -f build-test.yml.

Buildkit Docker

, .

DOCKER_BUILDKIT=1 faas-cli build -f build-test.yml

Docker buildkit. Buildkit :

, — , " " , "sdk" .
buildkit , FROM () .

buildkit , FROM () .

FROM openfaas/of-watchdog:0.7.3 as watchdog
FROM golang:1.13-alpine3.11 as build
FROM alpine:3.11

Mac, buildkit Docker, .

Buildkit

Buildkit buildkit Linux, Mac.

faas-cli build docker, — . , , , :

faas-cli build -f build-test.yml --shrinkwrap

[0] > Building build-test.
Clearing temporary build folder: ./build/build-test/
Preparing ./build-test/ ./build/build-test//function
Building: alexellis2/build-test:latest with golang-middleware template. Please wait..
build-test shrink-wrapped to ./build/build-test/
[0] < Building build-test done in 0.00s.
[0] Worker done.

Total build time: 0.00

./build/build-test/ Dockerfile.

./build/build-test/
├── Dockerfile
├── function
│   └── handler.go
├── go.mod
├── main.go
└── template.yml

1 directory, 5 files

buildkit.

curl -sSLf https://github.com/moby/buildkit/releases/download/v0.6.3/buildkit-v0.6.3.linux-amd64.tar.gz | sudo tar -xz -C /usr/local/bin/ --strip-components=1

, buildkit, armhf arm64, .

buildkit :

sudo buildkitd 
WARN[0000] using host network as the default            
INFO[0000] found worker "l1ltft74h0ek1718gitwghjxy", labels=map[org.mobyproject.buildkit.worker.executor:oci org.mobyproject.buildkit.worker.hostname:nuc org.mobyproject.buildkit.worker.snapshotter:overlayfs], platforms=[linux/amd64 linux/386] 
WARN[0000] skipping containerd worker, as "/run/containerd/containerd.sock" does not exist 
INFO[0000] found 1 workers, default="l1ltft74h0ek1718gitwghjxy" 
WARN[0000] currently, only the default worker can be used. 
INFO[0000] running server on /run/buildkit/buildkitd.sock

, . buildctl. buildctl — , , , , , tar, .

buildctl build --help
NAME:
   buildctl build - build

USAGE:
   
  To build and push an image using Dockerfile:
    $ buildctl build --frontend dockerfile.v0 --opt target=foo --opt build-arg:foo=bar --local context=. --local dockerfile=. --output type=image,name=docker.io/username/image,push=true
  

OPTIONS:
   --output value, -o value  Define exports for build result, e.g. --output type=image,name=docker.io/username/image,push=true
   --progress value          Set type of progress (auto, plain, tty). Use plain to show container output (default: "auto")
   --trace value             Path to trace file. Defaults to no tracing.
   --local value             Allow build access to the local directory
   --frontend value          Define frontend used for build
   --opt value               Define custom options for frontend, e.g. --opt target=foo --opt build-arg:foo=bar
   --no-cache                Disable cache for all the vertices
   --export-cache value      Export build cache, e.g. --export-cache type=registry,ref=example.com/foo/bar, or --export-cache type=local,dest=path/to/dir
   --import-cache value      Import build cache, e.g. --import-cache type=registry,ref=example.com/foo/bar, or --import-cache type=local,src=path/to/dir
   --secret value            Secret value exposed to the build. Format id=secretname,src=filepath
   --allow value             Allow extra privileged entitlement, e.g. network.host, security.insecure
   --ssh value               Allow forwarding SSH agent to the builder. Format default|<id>[=<socket>|<key>[,<key>]]

, Docker DOCKER_BUILDKIT :

sudo -E buildctl build --frontend dockerfile.v0 \
 --local context=./build/build-test/ \
 --local dockerfile=./build/build-test/ \
 --output type=image,name=docker.io/alexellis2/build-test:latest,push=true

docker login $HOME/.docker/config.json` .

ASCII .

img buildkit

img , , .

, , , . armhf ARM64 .

x86_64 v0.5.7 7 2019, Go 1.11, 1.13 Go :

sudo curl -fSL "https://github.com/genuinetools/img/releases/download/v0.5.7/img-linux-amd64" -o "/usr/local/bin/img" \
	&& sudo chmod a+x "/usr/local/bin/img"

buildctl:

img build --help
Usage: img build [OPTIONS] PATH

Build an image from a Dockerfile.

Flags:

  -b, --backend  backend for snapshots ([auto native overlayfs]) (default: auto)
  --build-arg    Set build-time variables (default: [])
  -d, --debug    enable debug logging (default: false)
  -f, --file     Name of the Dockerfile (Default is 'PATH/Dockerfile') (default: <none>)
  --label        Set metadata for an image (default: [])
  --no-cache     Do not use cache when building the image (default: false)
  --no-console   Use non-console progress UI (default: false)
  --platform     Set platforms for which the image should be built (default: [])
  -s, --state    directory to hold the global state (default: /home/alex/.local/share/img)
  -t, --tag      Name and optionally a tag in the 'name:tag' format (default: [])
  --target       Set the target build stage to build (default: <none>)

sudo img build -f ./build/build-test/Dockerfile -t alexellis2/build-test:latest ./build/build-test/

img . , root-.

fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0xe5 pc=0x7f84d067c420]

runtime stack:
runtime.throw(0xfa127f, 0x2a)
	/home/travis/.gimme/versions/go1.11.10.linux.amd64/src/runtime/panic.go:608 +0x72
runtime.sigpanic()
	/home/travis/.gimme/versions/go1.11.10.linux.amd64/src/runtime/signal_unix.go:374 +0x2f2

goroutine 529 [syscall]:
runtime.cgocall(0xc9d980, 0xc00072d7d8, 0x29)
	/home/travis/.gimme/versions/go1.11.10.linux.amd64/src/runtime/cgocall.go:128 +0x5e fp=0xc00072d7a0 sp=0xc00072d768 pc=0x4039ee
os/user._Cfunc_mygetgrgid_r(0x2a, 0xc000232260, 0x7f84a40008c0, 0x400, 0xc0004ba198, 0xc000000000)

Kaniko

Kaniko — Google, . .

docker run -v $PWD/build/build-test:/workspace \
 -v ~/.docker/config.json:/kaniko/config.json \
 --env DOCKER_CONFIG=/kaniko \
 gcr.io/kaniko-project/executor:latest \
 -d alexellis2/build-test:latest

–d , .
-v Kaniko, config.json .

Kaniko , , Kaniko one-shot , , Buildkit.

— . Docker , . , . , Docker, , IP-.
buildkit. . DOCKER_BUILDKIT=1
buildkit. , Docker, CI box runner. Linux, MacOS. , TCP?

. faasd, containerd CNI, Docker Kubernetes.

Kaniko. , Kaniko, - Docker, .

OpenFaaS faas-cli build –shrinkwrap . OpenFaaS:

OpenFaaS CI/CD shrinkwrap buildkit. Docker Docker buildkit.

faasd containerd docker, buildkit.

We have not touched on one of the important parts of the workflow - deployment. Any OCI container can be deployed in the OpenFaaS control plane on top of Kubernetes as long as it meets the definition of a serverless workload .

Building containers without Docker

What's wrong with Docker?

Buildkit Docker

Buildkit

img buildkit

Kaniko

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