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Skaffold: K8s Development Made Easy
Skaffold: K8s Development Made Easy
In this post, look at Skaffold for automatic building and deploying our application to a Kubernetes cluster during development.
Mar. 10, 20 · Cloud Zone ·
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Skaffold is a command line tool developed by Google, which aims to facilitate continuous development for Kubernetes applications. It will automate the task of building and deploying to a Kubernetes cluster whereas you, as a developer, can stay focused on writing code. It seems interesting enough to take a closer look at it!
Introduction
In November 2019 a generally available release was announced promising to save developers time by automating the development workflow. What will Skaffold do for us?
- It detects source changes while you are developing
- It automatically builds and creates your artifacts (your Docker image) based on a Dockerfile or Jib
- It tags the artifacts
- It pushes and deploys the artifacts to your Kubernetes cluster
In order to get acquainted with Skaffold, we will run a local Kubernetes cluster with the help of minikube and we will deploy by means of kubectl, the command line interface tool for Kubernetes.
It is advised to take a look at the official Skaffold documentation and examples for more in-depth information. The sources we are using in this post are available at GitHub.
You might also like: The Complete Kubernetes Collection [Tutorials and Tools]
Prerequisites
Before getting started, we need to install minikube, kubectl, and Skaffold if you have not done so already. We will be using Ubuntu 18.04.
Install Minikube
Installation of minikube (version 1.6.2) is quite easy when working with Linux. If you are working with Windows, please take a look at one of our previous posts, it was quite of a struggle way then, but maybe things have improved in the meanwhile.
First, check whether our system has virtualization support enabled:
xxxxxxxxxx$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no yesThe output of the command is yes, which means we do not need to execute any extra steps.
Download and install minikube:
xxxxxxxxxx$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.debStart minikube:
xxxxxxxxxx$ minikube startminikube v1.6.2 on Ubuntu 18.04Automatically selected the 'virtualbox' driver (alternates: [none])Downloading VM boot image ...$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 0
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 1
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 2
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 3
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 4
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 5
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 6
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 7
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 8
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 9
Install Kubectl
Installation instructions for kubectl can be found here. For Linux, we have to execute the steps below, with kubectl version we verify the successful installation:
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Install Skaffold
Installation instructions for Skaffold can be found here. The instructions are very similar to the one for kubectl.
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Create Demo Application
We will create a simple Spring Boot demo application. We use Spring MVC and create one REST endpoint, which will return a greeting message.
Our pom contains the following dependencies and plugins:
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$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb0
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb1
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb2
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb3
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb4
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb5
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb6
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb7
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb8
$ curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube_1.6.2.deb && sudo dpkg -i minikube_1.6.2.deb9
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The HelloController contains one method, which returns the greeting message and the address of the host where it is executed.
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$ minikube start0
$ minikube start1
$ minikube start2
$ minikube start3
$ minikube start4
$ minikube start5
$ minikube start6
$ minikube start7
$ minikube start8
$ minikube start9
minikube v1.6.2 on Ubuntu 18.040
minikube v1.6.2 on Ubuntu 18.041
minikube v1.6.2 on Ubuntu 18.042
minikube v1.6.2 on Ubuntu 18.043
minikube v1.6.2 on Ubuntu 18.044
Use Skaffold
Now that we have finished all the necessary preparations, it is time to start using Skaffold. Currently, we deliberately have left out some important configuration, which Skaffold will need, but this will allow us to verify which error messages are returned and how to solve them.
Generate skaffold.yaml
Skaffold will need a skaffold.yaml file that contains the development workflow you want to use. The file can be generated when the init command is executed from within your project directory.
minikube v1.6.2 on Ubuntu 18.045
minikube v1.6.2 on Ubuntu 18.046
minikube v1.6.2 on Ubuntu 18.047
Skaffold init does not create the Kubernetes manifest files for us, we will need to create them manually.
We will create a k8s deployment file with the help of kubectl. We copy the output of the command to file deployment.yaml in the k8s directory. The CLI parameter --dry-run ensures us that the deployment is not executed yet, the parameter -oyaml will output the configuration, which will allow us to just copy the contents.
minikube v1.6.2 on Ubuntu 18.048
minikube v1.6.2 on Ubuntu 18.049
Automatically selected the 'virtualbox' driver (alternates: [none])0
Automatically selected the 'virtualbox' driver (alternates: [none])1
Automatically selected the 'virtualbox' driver (alternates: [none])2
Automatically selected the 'virtualbox' driver (alternates: [none])3
Automatically selected the 'virtualbox' driver (alternates: [none])4
Automatically selected the 'virtualbox' driver (alternates: [none])5
Automatically selected the 'virtualbox' driver (alternates: [none])6
Automatically selected the 'virtualbox' driver (alternates: [none])7
Automatically selected the 'virtualbox' driver (alternates: [none])8
Automatically selected the 'virtualbox' driver (alternates: [none])9
Downloading VM boot image ...0
Downloading VM boot image ...1
Downloading VM boot image ...2
Downloading VM boot image ...3
Downloading VM boot image ...4
Downloading VM boot image ...5
Downloading VM boot image ...6
Downloading VM boot image ...7
Downloading VM boot image ...8
Downloading VM boot image ...9
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 00
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 01
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 02
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 03
Running skaffold init again, returns a new error:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 04
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 05
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 06
We could have expected this, because we did not provide a Dockerfile or Jib configuration. We will make use of Jib after our positive experiences with it in our previous post. Add the Jib Maven Plugin to our pom. We do not provide credentials this time, because we are not going to push the Docker image to a Docker registry.
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 07
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 08
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 09
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 10
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 11
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 12
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 13
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 14
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 15
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 16
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 17
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 18
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 19
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 20
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 21
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 22
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 23
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 24
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 25
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 26
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 27
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 28
In order to use Jib, we need to add the flag --XXenableJibInit, see also this issue.
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 29
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 30
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 31
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 32
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 33
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 34
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 35
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 36
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 37
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 38
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 39
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 40
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 41
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 42
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 43
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 44
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 45
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 46
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 47
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 48
Skaffold Continuous Development
We have set up all necessary configuration in order to experiment with the skaffold dev command. This will scan our project for any changes and automatically build and deploy them to our Kubernetes cluster. Run the following command:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 49
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 50
Our application is being built and deployed to our Kubernetes cluster. We can also verify this with the minikube dashboard:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 51
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 52
We cannot invoke our URL yet because we did not create a service yet. We will map port 8080 via a NodePort. Generate the service yaml and add the contents (without the labels) to file service.yaml in the k8s directory:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 53
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 54
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 55
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 56
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 57
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 58
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 59
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 60
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 61
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 62
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 63
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 64
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 65
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 66
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 67
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 68
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 69
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 70
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 71
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 72
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 73
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 74
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 75
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 76
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 77
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 78
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 79
Also, add the service.yaml as manifest file to the skaffold.yaml file:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 80
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 81
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 82
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 83
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 84
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 85
Skaffold immediately notices this change and creates the service. This can be verified in the Skaffold console output:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 86
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 87
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 88
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 89
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 90
Verify the creation of the service with kubectl:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 91
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 92
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 93
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 94
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 95
The NodePort that has been assigned is port 30272 (see PORT(S) column). We are now able to invoke our Rest endpoint:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 96
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 97
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 98
Change the greeting text in the HelloController:
$ egrep -q 'vmx|svm' /proc/cpuinfo && echo yes || echo no 99
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Again, the change is automatically detected by Skaffold, and in the background, our application is being built and deployed. Invoke the URL again:
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We can also use command skaffold run in order to deploy on request:
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Again, check the NodePort the service is running and invoke the URL.
Troubleshooting
We once encountered the following error when running skaffold dev and skaffold run:
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We solved this by adding the following lines to the skaffold.yaml file. Later on, it seemed not to be necessary anymore.
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Conclusion
In this post, we looked at Skaffold for automatic building and deploying our application to a Kubernetes cluster during development. We only scratched the surface of what Skaffold is capable of, but we were very impressed by this tool. Definitely something to use and to keep an eye on.
Further Reading
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