clear.sh

#!/bin/bash

while read l; do
	echo Removing $l
	docker image rm $l
done < images.txt

e2e.sh

#!/bin/bash

# Clear cached images
./clear.sh

# Pull using docker pull
time ./simple.sh

# Make sure the pulled image works
docker run gcr.io/cloud-builders/docker version

# Clear cached images
./clear.sh

# Pull using Go script
time go run main.go

# Make sure thep pulled image works
docker run gcr.io/cloud-builders/docker version

images.txt

gcr.io/cloud-builders/docker
gcr.io/cloud-builders/npm
gcr.io/cloud-builders/yarn
gcr.io/cloud-builders/mvn
gcr.io/cloud-builders/gradle

main.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"log"
	"os"
	"strings"

	"github.com/google/go-containerregistry/pkg/name"
	"github.com/google/go-containerregistry/pkg/v1/daemon"
	"github.com/google/go-containerregistry/pkg/v1/remote"
	"golang.org/x/sync/errgroup"
)

var (
	filename = flag.String("f", "images.txt", "Name of file containing images to pull")
)

func main() {
	flag.Parse()
	f, err := os.Open(*filename)
	if err != nil {
		log.Fatalf("Error opening %q: %v", *filename, err)
	}
	defer f.Close()

	var errg errgroup.Group
	s := bufio.NewScanner(f)
	for s.Scan() {
		line := s.Text()
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		log.Printf("Pulling %q", line)

		tag, err := name.NewTag(line, name.WeakValidation)
		if err != nil {
			log.Fatalf("Error parsing %q: %v", line, err)
		}

		errg.Go(func() error {
			i, err := remote.Image(tag)
			if err != nil {
				return fmt.Errorf("Error pulling %q: %v", tag, err)
			}

			if _, err := daemon.Write(tag, i, daemon.WriteOptions{}); err != nil {
				return fmt.Errorf("Error writing %q to daemon: %v", tag, err)
			}
			log.Printf("Finished pulling %q", tag)
			return nil
		})
	}
	if err := s.Err(); err != nil {
		log.Fatalf("Error reading %q: %v", *filename, err)
	}

	if err := errg.Wait(); err != nil {
		log.Fatalf("Error pulling an image: %v", err)
	}
}

simple.sh

#!/bin/bash

while read l; do
	echo Pulling $l
	docker pull $l
done < images.txt