Airflow pull docker image from private google container repository - docker

Question

I am using the https://github.com/puckel/docker-airflow image to run Airflow. I had to add pip install docker in order for it to support DockerOperator.
Everything seems ok, but I can't figure out how to pull an image from a private google docker container repository.
I tried adding the connection in the admin section type of google cloud conenction and running the docker operator as.
t2 = DockerOperator(
task_id='docker_command',
image='eu.gcr.io/project/image',
api_version='2.3',
auto_remove=True,
command="/bin/sleep 30",
docker_url="unix://var/run/docker.sock",
network_mode="bridge",
docker_conn_id="google_con"
)
But always get an error...
[2019-11-05 14:12:51,162] {{taskinstance.py:1047}} ERROR - No Docker
registry URL provided
I also tried the docker_conf_option
t2 = DockerOperator(
task_id='docker_command',
image='eu.gcr.io/project/image',
api_version='2.3',
auto_remove=True,
command="/bin/sleep 30",
docker_url="unix://var/run/docker.sock",
network_mode="bridge",
dockercfg_path="/usr/local/airflow/config.json",
)
I get the following error:
[2019-11-06 13:59:40,522] {{docker_operator.py:194}} INFO - Starting
docker container from image
eu.gcr.io/project/image
[2019-11-06 13:59:40,524] {{taskinstance.py:1047}} ERROR -
('Connection aborted.', FileNotFoundError(2, 'No such file or
directory'))
I also tried using only dockercfg_path="config.json" and got the same error.
I can't really use Bash Operator to try to docker login as it does not recognize docker command...
What am I missing?
line 1: docker: command not found
t3 = BashOperator(
task_id='print_hello',
bash_command='docker login -u _json_key - p /usr/local/airflow/config.json eu.gcr.io'
)

Answer 1

airflow.hooks.docker_hook.DockerHook is using docker_default connection where one isn't configured.
Now in your first attempt, you set google_con for docker_conn_id and the error thrown is showing that host (i.e registry name) isn't configured.
Here are a couple of changes to do:
image argument passed in DockerOperator should be set to image tag without registry name prefixing it.
DockerOperator(api_version='1.21',
# docker_url='tcp://localhost:2375', #Set your docker URL
command='/bin/ls',
image='image',
network_mode='bridge',
task_id='docker_op_tester',
docker_conn_id='google_con',
dag=dag,
# added this to map to host path in MacOS
host_tmp_dir='/tmp',
tmp_dir='/tmp',
)
provide registry name, username and password for the underlying DockerHook to authenticate to Docker in your google_con connection.
You can obtain long lived credentials for authentication from a service account key. For username, use _json_key and in password field paste in the contents of the json key file.
Here are logs from running my task:
[2019-11-16 20:20:46,874] {base_task_runner.py:110} INFO - Job 443: Subtask docker_op_tester [2019-11-16 20:20:46,874] {dagbag.py:88} INFO - Filling up the DagBag from /Users/r7/OSS/airflow/airflow/example_dags/example_docker_operator.py
[2019-11-16 20:20:47,054] {base_task_runner.py:110} INFO - Job 443: Subtask docker_op_tester [2019-11-16 20:20:47,054] {cli.py:592} INFO - Running <TaskInstance: docker_sample.docker_op_tester 2019-11-14T00:00:00+00:00 [running]> on host 1.0.0.127.in-addr.arpa
[2019-11-16 20:20:47,074] {logging_mixin.py:89} INFO - [2019-11-16 20:20:47,074] {local_task_job.py:120} WARNING - Time since last heartbeat(0.01 s) < heartrate(5.0 s), sleeping for 4.989537 s
[2019-11-16 20:20:47,088] {logging_mixin.py:89} INFO - [2019-11-16 20:20:47,088] {base_hook.py:89} INFO - Using connection to: id: google_con. Host: gcr.io/<redacted-project-id>, Port: None, Schema: , Login: _json_key, Password: XXXXXXXX, extra: {}
[2019-11-16 20:20:48,404] {docker_operator.py:209} INFO - Starting docker container from image alpine
[2019-11-16 20:20:52,066] {logging_mixin.py:89} INFO - [2019-11-16 20:20:52,066] {local_task_job.py:99} INFO - Task exited with return code 0

Answer 2

I know the question is about GCR but it's worth noting that other container registries may expect the config in a different format.
For example Gitlab expects you to pass the fully qualified image name to the DAG and only put the Gitlab container registry host name in the connection:
DockerOperator(
task_id='docker_command',
image='registry.gitlab.com/group/project/image:tag',
api_version='auto',
docker_conn_id='gitlab_registry',
)
The set up your gitlab_registry connection like:
docker://gitlab+deploy-token-1234:ABDCtoken1234#registry.gitlab.com

Answer 3

Based on recent Cloud Composer documentation, it's recommended to use KubernetesPodOperator instead, like this:
from airflow.contrib.operators.kubernetes_pod_operator import KubernetesPodOperator
KubernetesPodOperator(
task_id='docker_op_tester',
name='docker_op_tester',
dag=dag,
namespace="default",
image="eu.gcr.io/project/image",
cmds=["ls"]
)

Answer 4

Further to #Tamlyn's answer, we can also skip the creation of connection (docker_conn_id) from airflow and use it with gitlab as under
On your development machine :
https://gitlab.com/yourgroup/yourproject/-/settings/repository (create a token here and get details for logging in)
docker login registry.gitlab.com (on the machine to login to docker from the machine to push the image to docker - enter your gitlab credentials when prompted)
docker build -t registry.gitlab.com/yourgroup/yourproject . && docker push registry.gitlab.com/yourgroup/yourproject (builds and pushes to your project repo's container registry)
On your airflow machine :
https://gitlab.com/yourgroup/yourproject/-/settings/repository (you can use the above created token for logging in)
docker login registry.gitlab.com (to login to docker from the machine to pull the image from docker, this skips the need for creating a docker registry connection - enter your gitlab credentials when prompted = this generates ~/.docker/config.json which is required Reference from docker docs )
In your dag :
dag = DAG(
"dag_id",
default_args = default_args,
schedule_interval = "15 1 * * *"
)
docker_trigger = DockerOperator(
task_id = "task_id",
api_version = "auto",
network_mode = "bridge",
image = "registry.gitlab.com/yourgroup/yourproject",
auto_remove = True, # use if required
force_pull = True, # use if required
xcom_all = True, # use if required
# tty = True, # turning this on screws up the log rendering
# command = "", # use if required
environment = { # use if required
"envvar1": "envvar1value",
"envvar2": "envvar2value",
},
dag = dag,
)
this works with Ubuntu 20.04.2 LTS (tried and tested) with airflow installed on the instance

Answer 5

You will need to instal Cloud SDK in your workstation which includes the gcloud command-line tool.
After installing Cloud SDK and Docker version 18.03 or newer
According to their documentation to pull from Container Registry, use the command:
docker pull [HOSTNAME]/[PROJECT-ID]/[IMAGE]:[TAG]
or
docker pull [HOSTNAME]/[PROJECT-ID]/[IMAGE]#[IMAGE_DIGEST]
where:
[HOSTNAME] is listed under Location in the console. It's one of four
options: gcr.io, us.gcr.io, eu.gcr.io, or asia.gcr.io.
[PROJECT-ID] is your Google Cloud Platform Console project ID.
[IMAGE] is the image's name in Container Registry.
[TAG] is the tag applied to the image. In a registry, tags are unique
to an image.
[IMAGE_DIGEST] is the sha256 hash value of the image contents. In the
console, click on the specific image to see its metadata. The digest
is listed as the Image digest.
To get the pull command for a specific image:
Click on the name of an image to go to the specific registry.
In the registry, check the box next to the version of the image that
you want to pull.
Click SHOW PULL COMMAND on the top of the page.
Copy the pull command, which identifies the image using either the
tag or the digest
*Also check that you have push and pull permissions from the registry.
**Configured Docker to use gcloud as a credential helper, or are using another authentication method. To use gcloud as the credential helper, run the command:
gcloud auth configure-docker