Usage of CLI-suite for container

Owned by Steffen Drya
Last updated: Jul 12, 2023
17 min read

Terminology

  • Container: a docker container

  • Container type: a term describing a set of containers that have the same role, e.g. api, core, booking-engine. It is defined by a corresponding Task Definition.

  • ECS Service: manages the containers of a certain container type.

  • Image: a docker image

  • Docker Cluster: A logical entity consisting of a number of docker hosts

  • Task Definition: an extended, ECS-specific docker compose file (JSON)

  • ECS Task: Instance of a Task Definition, usually represents a single container

  • Desired Tasks: A number of containers based on the same image (horizontal scale)

  • Revision: Version of an ECS Task, that has a set of properties, such as an image-URL pointing to an image in a registry

  • Registry: a system for storing and managing images

  • Repository: a logical space seperator within the registry to separate images e.g. by type or purpose

The deployment process

Docker Container Deployment describes a process of updating a fleet of running docker containers that are operated via Amazon AWS EC2 Container Service (ECS).

Deployment strategies

Per default a rolling update is used, starting new containers based on a new docker image. The method is explained below in the context of a web application. Knowledge of  typical ECS terms  are useful. Besides rolling updates it is also possible to have replacing updates. This means running containers of a container type are terminated and then new ones are launched based on the submitted image.

The main difference between replacing and rolling updates is that deployments run with 0 downtime only in the later case. However, additional capacity has to be provided permanently. Thus increasing cost of permanently running docker hosts in the cluster.

Process example

  • Initiation of deployment from the bastion host via CLI for a Container Type providing a new image-URL

  • Creation of a new ECS Task Definition with the new image-URL, which has its own version number (revision)

  • Update of the respective ECS Service managing the Containers of the Container Type of consideration

  • Creation of new Containers based on the new image-URL in the Docker Cluster

  • All new Containers are taken into Service from the Load Balancer

  • Connections to all old containers are drained by the Load Balancer, meaning established ones are allowed to finish, bu no new ones are established to them

  • Shutdown of all old containers

  • Finish

Safeguards

Several mechanism are in place to recognize success and handle failure and rollback:

  • Container state verification

    • A deployment is successful if all new containers are recognized as running and the Load Balancer has taken them into service successfully

  • Image-URL verification

    • Checking to given Image-URL to be a valid String

    • If the docker registry images should be pulled from is part of your environment (within the same AWS account) we try to locate the given image

  • AWS Deployment Circuit Breaker

Native docker commands

The following commands can be called via "sudo" by default, meaning in every environment:

  • docker ps, docker ps -a

  • docker images, docker images -a

  • docker logs [OPTION] CONTAINERID

  • docker exec -it CONTAINERID bash, docker exec -it CONTAINERID sh

  • docker stats, docker stats CONTAINERID

  • docker inspect CONTAINERID

For non-productive environments root360 can also enable access to the following commands e.g. to support debugging and analysis:

  • docker run

  • docker pull

  • docker start

  • docker create

You can find further details about the individual commands in docker cli reference.

Example usage scenarios

A great example is the docker start command. If you deployed a new container image to your test environment and it wouldn't come up you are in a dilemma.

On the one hand you want to look into the failing container, but on the other hand AWS ECS keeps trying to launch and terminate containers. Thus it will constantly kill the container you are actually want to keep a little bit longer for analysis.

By using docker start to run a container image AWS ECS has created on a docker host before, you can do so without AWS ECS interfering anymore.

CLI-suite container commands

All commands operating on docker hosts and containers and the tasks to manipulate them are available in the r3 container subcommand. A general description how the r3 CLI Suite works can be found in 

In the following actual usage examples are presented.

What are the general command line options?

r3 container overview

USER@BASTIONHOST:~$ r3 container --help usage: r3 container [-h] [-d] [-q] {deploy,list,templates,instances,status,image,events,logs,show} ... options: -h, --help show this help message and exit -d, --debug Run in debug mode. (default: 0) -q, --quiet Run in quiet mode (only errors are shown). (default: False) command overview: {deploy,list,templates,instances,status,image,events,logs,show} deploy Deploy containers to hosts. list List running containers. templates List available container templates. instances List container instances. status Show container status. image Show container image. events Show container event log. logs Show container logs. show Show detailed information about containers.

Show which container is running on which host including resources overview as table

r3 container list

USER@BASTIONHOST:~$ r3 container list +---------------------------------------+----------------------+--------------+-----------------+---------+-----------------+------------+----------+---------------------+ | Container Name | Image | Reserved CPU | Reserved Memory | Status | Running/Desired | LaunchType | Host | LaunchTime | +---------------------------------------+----------------------+--------------+-----------------+---------+-----------------+------------+----------+---------------------+ | company-project-setting-hello-ec2 | hello-ec2:1.0 | 500 | 1000 | running | 2 / 2 | EC2 | 10.x.y.z | 2021-05-04_00:59:30 | +---------------------------------------+----------------------+--------------+-----------------+---------+-----------------+------------+----------+---------------------+ | company-project-setting-hello-ec2 | hello-ec2:1.0 | 500 | 1000 | running | 2 / 2 | EC2 | 10.x.y.z | 2021-05-04_00:59:41 | +---------------------------------------+----------------------+--------------+-----------------+---------+-----------------+------------+----------+---------------------+ | company-project-setting-hello-fargate | hello-fargate:latest | 512 | 1024 | running | 1 / 1 | FARGATE | 10.x.y.z | 2021-05-04_00:21:30 | +---------------------------------------+----------------------+--------------+-----------------+---------+-----------------+------------+----------+---------------------+ | company-project-setting-hello-multi | hello-fargate:latest | 512 | 1024 | running | 1 / 1 | FARGATE | 10.x.y.z | 2021-05-04_00:21:30 | | | hello-ec2:1.0 | | | | | | | | +---------------------------------------+----------------------+--------------+-----------------+---------+-----------------+------------+----------+---------------------+

Show which container is running on which host including resources overview as JSON

Using --format json you get JSON output which can be parsed using e.g. jq command line tool (Manual).

r3 container list --format json

USER@BASTIONHOST:~$ r3 container list --format json | jq { "instances": [ { "instance_ip": "10.x.y.z", "mem_registered": 7624, "mem_remaining": 4712, "cpu_registered": 4096, "cpu_remaining": 2096, "tasks": [ { "name": "company-project-setting-hello-ec2", "images": [ "hello-ec2:1.0" ] "cpu": "500", "memory": "1000", "status": "running" }, { "name": "company-project-setting-hello-ec2", "images": [ "hello-ec2:1.0" ] "cpu": "500", "memory": "1000", "status": "running" }, { "name": "company-project-setting-multi", "images": [ "hello-fargate:latest", "hello-ec2:1.0", ] "cpu": "500", "memory": "1000", "status": "running" } ] } ] }

Show all containers running on FARGATE using JSON and JQ

Show all containers including EC2 host ip address using JSON and JQ formated as CSV

Show all broken (not running) containers using JSON and JQ

Show all container instances and their services as table

Show all container instances and their services as JSON (more details)

Find instance where specific service is running using JSON and JQ

Show container logs for all containers

r3 container logs

Show container logs for specific container

r3 container logs --service ServiceName

Which container services can be deployed?

r3 container list --templates

How to start a new deployment for container-type x?

You can start deployments in background using --detach. To keep track of a detached deployment, you can use the r3 deployments --service ServiceName --deployment <id> --watch

Single container tasks

r3 container deploy --service Service-Name --image-url Registry/Repository:Tag

Multi container tasks

r3 container deploy --service Service-Name --image-url container1=Registry/Repository:Tag container2=Registry/Repository:Tag

How to list deployments?

r3 deployments --service ServiceName

On which image do the currently running containers of type X base?

r3 container image --service Service-Name

Show the latest events for a given container type

r3 container events --service ServiceName

Show the deployment status for a container-type

Show detailed information about all containers of container-type X (see following example for explanation)

r3 container status --service Service-Name

The important points here are:

  • "lastStatus" describes the current status

  • "desiredStatus" describes the target state

  • "stoppedReason": is only to be found with stopped containers and represents in detail the reason for the state.

Related tutorials

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