I have configured gitlab runner within kubernetes , which is not able to connect to docker daemon . Showing below error .

$ docker build --cache-from "${DOCKER_IMAGE_TAG}" -t "${DOCKER_IMAGE_TAG}" .

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running? ERROR: Job failed: command terminated with exit code 1

stages:
  - push_to_docker

docker_image:
 image: 'docker:latest'
 services:
  - docker:dind
 stage: push_to_docker
 variables:
    DOCKER_IMAGE_TAG: 'gcr.io/abcd-project/test'
 script:
   - docker build --cache-from "${DOCKER_IMAGE_TAG}" -t "${DOCKER_IMAGE_TAG}" .
   - echo "$SERVICE_ACCOUNT_KEY" > key.json
   - docker login -u _json_key --password-stdin https://gcr.io < key.json
   - docker push ${DOCKER_IMAGE_TAG}
 only:
   - master
 tags:
   - abcd

My config.toml file is as below

listen_address = "[::]:9252"
concurrent = 4
check_interval = 3
log_level = "info"

[session_server]
  session_timeout = 1800

[[runners]]
  name = "runner-gitlab-runner-78c7db94bc-lzv76"
  request_concurrency = 1
  url = "https://gitlab.com/"
  token = "*********"
  executor = "kubernetes"
  [runners.custom_build_dir]
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]
  [runners.kubernetes]
    host = ""
    bearer_token_overwrite_allowed = false
    image = "ubuntu:16.04"
    namespace = "gitlab-managed-apps"
    namespace_overwrite_allowed = ""
    privileged = true
    service_account_overwrite_allowed = ""
    pod_annotations_overwrite_allowed = ""
    [runners.kubernetes.pod_security_context]
    [runners.kubernetes.volumes]

Checked with configuration as below

    image: docker:19.03.1
    services:
    - docker:19.03.1-dind
    variables:
      DOCKER_HOST: tcp://docker:2375

And my .gitlab-ci.yml file after changing the configuration is as below:

stages:
  - push_to_docker
  - deploy_into_kubernetes
variables:
  DOCKER_IMAGE_TAG: 'gcr.io/abcd-project/test:$CI_COMMIT_SHORT_SHA'
  DOCKER_HOST: tcp://docker:2375

docker_image_creation:
 image: docker:19.03.1
 services:
  - docker:19.03.1-dind

 stage: push_to_docker

 script:
   - docker build -t "${DOCKER_IMAGE_TAG}" .
   - echo "$SERVICE_ACCOUNT_KEY" > key.json
   - docker login -u _json_key --password-stdin https://gcr.io < key.json
   - docker push ${DOCKER_IMAGE_TAG}
 tags:
   - cluster
   - kubernetes

but getting bellow error :

Skipping Git submodules setup $ docker build -t "${DOCKER_IMAGE_TAG}" . time="2019-11-04T08:07:37Z" level=error msg="failed to dial gRPC: cannot connect to the Docker daemon. Is 'docker daemon' running on this host?: dial tcp: lookup docker on 10.0.0.10:53: no such host" error during connect: Post http://docker:2375/v1.40/build?buildargs=%7B%7D&cachefrom=%5B%5D&cgroupparent=&cpuperiod=0&cpuquota=0&cpusetcpus=&cpusetmems=&cpushares=0&dockerfile=Dockerfile&labels=%7B%7D&memory=0&memswap=0&networkmode=default&rm=1&session=l1ce41pzm1p9a4jdhs31z9p64&shmsize=0&t=gcr.io%2Fupbeat-flame-247110%2Fgitlab-runner-poc%3A25b1faa0&target=&ulimits=null&version=1: context canceled