Other cool apps for Kubernetes¶

Here is a list of some more apps that a cool to have.

KubePug / Deprecations¶

KubePug/Deprecations is intended to be a kubectl plugin, which:

Downloads a swagger.json from a specific Kubernetes version
Parses this Json finding deprecation notices
Verifies the current kubernetes cluster or input files checking whether exists objects in this deprecated API Versions, allowing the user to check before migrating

This is a tool that you can use locally or in your CI to ensure you're not working with deprecated resources.

install¶

kubectl krew install deprecations

Usage¶

Full cluster scan

This will walk you through all your k8s resources (in the local context) and compare them to the target version (here 1.25). You will get warnings if you still have resources using deprecated APIs :
```
kubectl deprecations --k8s-version v1.25.0
```
File scan

This command will look at the resources inside the ../yaml/sample_app.yaml and compare it to the Kubernetes API version v1.25.0. It will report every resource that is outdated:
```
kubectl deprecations --k8s-version v1.25.0 --input-file ../yaml/sample_app.yaml
```

Dive¶

Dive is an utility to inspect Docker Images. While it is not directly used with Kubernetes, it can help improve size and security in the pod's images.

Install¶

brew install dive

Note

If using podman or any Docker-For-desktop replacement, you need to ensure Dive will be able to connect to the Docker Daemon. Set DOCKER_HOST variable accordinately:

export DOCKER_HOST="unix://$HOME/.local/share/containers/podman/machine/podman-machine-default/podman.sock"

Usage¶

check Alpine image
```
dive alpine:latest
```

Dasel¶

Use Dasel to query and modify data structures using selector strings.

It is Comparable to jq / yq, but supports JSON, YAML, TOML, XML and CSV with zero runtime dependencies.

This is the swiss army knife of the structrued file (in the command line).

Install¶

Apple MacOS XGo

brew install dasel

go install github.com/tomwright/dasel/cmd/dasel@master

Usage¶

Here's some sample usage, taken from the doc:

# Pretty Print JSON
echo '[{"name": "Tom"},{"name": "Paul"}]' | dasel -p json
[
  {
    "name": "Tom"
  },
  {
    "name": "Paul"
  }
]

# JSON to YAML
echo '[{"name": "Tom"},{"name": "Paul"}]' | dasel -r json -w yaml
- name: Tom
- name: Paul

While this is some good example, here's some real-case usage with K8s.

Let's create a sample deployment file:

cat > deployment.yaml << EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-app
  namespace: test
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
    app: example-app
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: example-app
    spec:
      containers:
      - image: alpine:latest
        imagePullPolicy: Always
        name: manager
        ports:
        - containerPort: 8080
          name: web
          protocol: TCP
EOF

Warning

It is important to keep the .yaml extension of the file as Dasel use it to auto-find the right language. If not, you can force it using the -p or --parser flag, or the individual --read and --write.

Select the image of the manager container

dasel -p yaml select -f deployment.yaml -s "spec.template.spec.containers.(name=manager).image"

alpine

Change the image of the manager containe in-place

dasel put string -f deployment.yaml -s "spec.template.spec.containers.(name=manager).image" "ubuntu:latest"

Update replicas to 3 in-place

dasel put int -f deployment.yaml -s "spec.replicas" 3

Add a new env var to the deployment

dasel put object -f deployment.yaml -s "spec.template.spec.containers.(name=manager).env.[]" -t string -t string name=MY_NEW_ENV_VAR value=MY_NEW_VALUE

Update an existing env var

dasel put string -f deployment.yaml -s "spec.template.spec.containers.(name=manager).env.(name=MY_NEW_ENV_VAR).value" NEW_VALUE

Warning

The above commands are not fail-proof, and executing dasel put multiple times may generate invalid yaml.

Next¶

This is the end of the tutorial. If you want, use the Cleanup script to remove most of what you installed.