Cheatsheet for various container and VM thingies

vm_containers.md

Multipass

Tool to run Ubuntu VM's easily with command-line interface.

List available instances

• multipass list

Create and launch a new instance using the latest LTS release

• multipass launch --name my_instance

Access the instance shell

• multipass shell my_instance

Mount a shared folder in the instance

• multipass mount path/to/local/folder my_instance:path/to/instance/folder

Unmount all mounted folders of instance

• multipass umount my_instance

Stop an instance

• multipass stop my_instance

Start a previously created instance

• multipass start my_instance

Get info on a specific instance

• multipass info my_instance

Delete an instance (send it to the recycle bin)

• multipass delete my_instance

Recover a deleted instance

• multipas recover my_instance

Permanently delete all deleted instances

• multipass purge

Docker

Terminology

• Container: environment that runs an applications that is not dependent on the OS. Kind of like a lightweight VM. Containers are stateless; if you need to update the components inside, create another container instead.
• Image: template to create a container. Its components are defined by a Dockerfile.
• Volume: storage area detached from the container for maintaining state.
• Foreground/interactive vs background/detached: a detached container runs in the background whereas an interactive container will usually have a terminal of some sort for interacting with.

Commands

List your local images

• docker images

Clean up images (many ways)

• docker images -q -f dangling=true
• docker image rm
• docker image prune

List your running containers

• docker ps

Run a Docker image inside a container

• docker run -it --rm image_name:tag
  • -it is a combination of -i (interactive mode) and -t (allocate a terminal).
  • --rm means that the container will be removed when exited.
  • You may find Docker images at the Docker Hub.
  • This command will use the entrypoint defined by the image. It won't necesarily open a terminal inside the container.

Run a Docker image inside a container and override the entrypoint

• docker run -it --rm --entrypoint=bash image_name:version
  • This will override the entrypoint of your image and open a bash terminal inside the container instead.

Run a Docker image inside a container and map a port in the container to a port in the host machine

• docker run -it --rm -p 9696:9696 image_name:tag

Create a Dockerfile with instructions to create a basic custom Docker image.

# set base image
FROM python:3.9

# set the working directory in the container
WORKDIR /app

# copy dependencies to the working directory
COPY requirements.txt .

# Install dependencies
RUN pip install -r requirements

# Copy code to the working directory
COPY . /app

# command to run on container start
CMD ["python", "./main.py"]

• Docker will process each line as a layer. Some layers are cached, so in order to speed up build time, first copy and run immutable objects and then take care of your code/modules, as shown in this example.
• Base images are useful because they save a lot of work and build time. Choose a lean base image and avoid unnecessary packages.
• Each container should only have one concern. Decouple applications into multiple containers.

Create a slightly more complex Dockerfile with pipenv dependencies and specific entrypoints.

# set base image
FROM python:3.9

# (pipenv) install pipenv
RUN pip install pipenv

# set the working directory in the container
WORKDIR /app

# (pipenv) copy dependencies to the working directory
COPY ["Pipfile", "Pipfile.lock", "./"]

# (pipenv) Install dependencies
# (pipenv) We don't need a virtualenv in Docker, so we can install dependencies to the system
RUN pipenv install --system --deploy

# Copy the model
COPY ["predict.py", "model.bin", "./"]

# Expose a port on the container
# Remember to map the port to a port in the host when running the container!
EXPOSE 9696

# Specify entrypoint
ENTRYPOINT ["gunicorn", "--bind=0.0.0.0:9696", "predict:app"]

• The COPY instruction has 2 forms, shown here. The second form (like for pipenv in this example) must be used if any paths may contain whitespaces. The last param is always the destination directoy, which may be . or ./ for copying to the directory specified by WORKDIR.

Build an image based on a Dockerfile

• docker build -f Dockerfile -t my_image .
  • The default Dockerfile that the command will look for is $PATH/Dockerfile. If your Dockerfile is in the same directory that you will run the command and you have not named it something else, -f Dockerfile can be removed from the command.
  • my_image will be the name of your image. You may optionally tag it like so: my_image:my_tag.

Stop a running container

• docker stop container_id

Docker compose

Example docker-compose.yaml file.

version: "3.9"
services:
  model-server:
    image: zoomcamp-10-model:v1
  gateway:
    image: zoomcamp-10-gateway:v2
    environment:
      - TF_SERVING_HOST=model-server:8500
    ports:
      - "9696:9696"

• version is required by `docker-compose``
• The app has 2 components: model-server and gateway
• Each component must have a Docker image.
• You may specify environment variables with environment and port mappings with ports
  • The dash (-) means that the entry is a list. In this example there are 2 lists with a single element each.

Run the app.

docker-compose up

Run the app in detached mode.

docker-compose up -d

Shut down the app

docker-compose down

Kubernetes

Kind

Create local cluster

kind create cluster

Delete local cluster

kind delete cluster

Load an image to the local cluster

kind load docker-image docker-image:tag

eksctl

Create a default cluster on EKS.

eksctl create cluster

Create a cluster with a config YAML file

eksctl create cluster -f eks-config.yaml

Example eks-config.yaml

apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
  name: mlzoomcamp-eks
  region: eu-west-1

nodeGroups:
  - name: ng-m5-xlarge
    instanceType: m5.xlarge
    desiredCapacity: 1

• metadata contains both the name of the cluster as well as the AWS region.
• nodeGroups contains a list of node groups. In this example the list has a single entry.
  • desiredCapacity contains the amount of nodes inside the node group.
  • instanceType is the desired AWS EC2 instance type for the node group. All nodes will be of that instance type.

Delete a cluster

eksctl delete cluster -f eks-config.yaml

kubectl

kubectl command cheatsheet

Example deployment.yamlfile

apiVersion: apps/v1
kind: Deployment
metadata:
  name: <deployment-name>
spec:
  replicas: 1
  selector:
    matchLabels:
      app: <app-name>
  template:
    metadata:
      labels:
        app: <app-name>
    spec:
      containers:
      - name: <my-container>
        image: my-component-image:some-tag
        resources:
          limits:
            memory: "128Mi"
            cpu: "100m"
        ports:
        - containerPort: 9696
        env:
          - name: TF_SERVING_HOST
            value: <service-name>.<namespace>.svc.cluster.local:8500

• kind must be Deployment
• metadata.name contains the name of the deployment
• spec.replicas states how many pods should be replicated in the deployment. This example file only states 1 replica.
• spec.selector defines how the deployment finds which pods to manage. spec.selector.matchLabels is a rule that will match a label in the pod template (the label in this case is app:<app-name>)
• spec.template contains the blueprint for the pods:
  • metadata in this example contains the labels we use for the pods so that the deployment can find and manage them.
  • ..spec.containers contains a plethora of info:
    • name is the name of the containers inside the pod.
    • image is the Docker image to be used by the containers.
    • resources states the physical resource limits
      • For CPU, 100m means 100 milliCPUs, or 10% of the available CPU computing time.
    • ports contains the ports to use by the containers.
    • env contains names and values for nvironment variables, useful for apps to be able to find other containers by their internal cluster URL.
      • When defining a service, Kubernetes publishes a DNS entry inside the Cluster to make it possible for pods to find other pods. These DNS entries follow the <service-name>.<namespace>.svc.cluster.local:<port> format.
      • The default namespace is default.

Example service.yaml file.

apiVersion: v1
kind: Service
metadata:
  name: <service-name>
spec:
  type: LoadBalancer
  selector:
    app: <app-name>
  ports:
  - port: 80
    targetPort: 9696

• kind must be Service
• metadata.name contains the name of the service
• spec.type specifies the type of Service.
  • Internal services are of type ClusterIP. This is the default service type if this field is not stated in the file.
  • External services are of type LoadBalancer and are assigned an external IP.
• spec.selector contains the label to find the deployment to which it belongs to.
• spec.ports contains both the port of the service (port) as well as the port of the deployment (targetPort).