semaphore-docker-build.sh

#!/bin/bash

set -e

registry_version="2"
local_registry_port="5000"
local_registry_name="localhost"
local_registry_url="${local_registry_name}:${local_registry_port}"
docker_image_name="$SEMAPHORE_REPO_SLUG"
base_image_name="${local_registry_url}/${docker_image_name}"
semaphore_build_tag="${REVISION}_${SEMAPHORE_BUILD_NUMBER}"
semaphore_build_image="${base_image_name}:${semaphore_build_tag}"

function setup-local-registry(){
  if ! (docker ps | grep "registry:$registry_version" &> /dev/null); then
    echo ">> Setting up local Docker registry on port ${local_registry_port}"

    echo "{\"insecure-registries\" : [\"$local_registry_url\"]}" | sudo tee /etc/docker/daemon.json

    registry_cid=$(docker run -d -p $local_registry_port:$local_registry_port -v $SEMAPHORE_CACHE_DIR/registry:/var/lib/registry --restart=always --name registry-$(date +%s) registry:$registry_version)

    echo ">> Waiting for the local registry to be accessible"

    while true; do
     curl http://${local_registry_url}/v2/_catalog 2>/dev/null && break

     sleep 2
    done
 fi
}

function semaphore-docker-build(){
  setup-local-registry

  docker pull $base_image_name || true

  echo $SEMAPHORE_CACHE_DIR >> .dockerignore

  if (docker pull $base_image_name &> /dev/null); then
    echo ">> Base image $base_image_name pulled from local registry."
  fi

  echo ">> Building image"
  docker build --cache-from $base_image_name -t ${semaphore_build_image} $@

  echo ">> Tagging image"
  docker tag $semaphore_build_image ${base_image_name}:latest

  echo ">> Uploading to local Docker registry"
  docker push $semaphore_build_image
  docker push $base_image_name

  echo ">> Stopping local Docker registry"
  docker stop $registry_cid

  echo ">> Done"
}

semaphore-docker-build "$@"

Starts a local registry and stores built images inside it.

Install the script

wget https://gist.githubusercontent.com/ervinb/bae1417d6a86fb6dda869092b5fc87cc/raw/semaphore-docker-build.sh
sudo ln -fs "$(pwd)/semaphore-docker-build.sh" /usr/bin/semaphore-docker-build
chmod +x /usr/bin/semaphore-docker-build

Usage

semaphore-docker-build -t my:image .