Kubernetes application

A sample application that meets the requirements for successful execution in Kubernetes.

Main application criteria

• Implementation of health checks
• Configuring the application through environment variables
• Standard logging Interface
• Processing of system interrupt signals and graceful shutdown
• Continuous build of the application and whole CI/CD process
• Helm charts for deploying an application in Kubernetes
• SSL support in a secure connection, certificate integration
• Integration of the official package manager dep
• Versioning automation

Health checks

Kubernetes application must have two health checks for successful execution of the application. Integrated methods help correctly responding to Kubernetes queries.

Configuring

The twelve-factor app stores config in environment variables. The application has a built-in library for automatic recognition and placement the environment variables in struct with different types.

Logging

Provides a standard interface for a multi level logging. There is ability of choice of a logging library that supports a common interface.

type Logger interface {
    Debug(v ...interface{})
    Debugf(format string, v ...interface{})
    Info(v ...interface{})
    Infof(format string, v ...interface{})
    Warn(v ...interface{})
    Warnf(format string, v ...interface{})
    Error(v ...interface{})
    Errorf(format string, v ...interface{})
    Fatal(v ...interface{})
    Fatalf(format string, v ...interface{})
}

Just make your choice

func Run() (err error) {
    // log := xlog.New()
    // log := logrus.New()
    log := stdlog.New(&logger.Config{
        Level: logger.LevelDebug,
        Time:  true,
        UTC:   true,
    })
    ...
}

System signals

The application includes the ability to intercept system signals and transfer control to special methods for graceful shutdown.

type Signals struct {
    shutdown    []os.Signal
    reload      []os.Signal
    maintenance []os.Signal
}

Build automation

A series of commands for static cross-compilation of the application for any OS. Building the Docker image and loading it into the remote public/private repository. Optimal and compact docker image FROM SCRATCH

Testing

The command make test is running set of checks and tests:

• run go tool fmt on package sources
• run go linter on package sources
• run go tool vet on packages
• run tests on package sources excluding vendor
• compile and check of Helm charts

Helm charts and Continuous Delivery

Prepared set of basic templates for application deployment in Kubernetes. Only one command make deploy is loading the application into Kubernetes. Just wait for the successful result and the application is ready to go.

SSL support

Generating certificates to create a secure SSL connection in the Go client. Attaching the certificate to the Docker image.

FROM scratch

ENV K8SAPP_LOCAL_HOST 0.0.0.0
ENV K8SAPP_LOCAL_PORT 8080
ENV K8SAPP_LOG_LEVEL 0

EXPOSE $K8SAPP_LOCAL_PORT

COPY certs /etc/ssl/certs/
COPY bin/linux/k8sapp /

CMD ["/k8sapp"]

Package manager

To work correctly with the dependencies we should choose the package manager. dep is a prototype dependency management tool for Go.

Versioning automation

Using a special script to increase the release version

./bumper.sh
Current version 0.4.0.
Please enter bumped version [0.4.1]:

Contributing to the project

See the contribution guidelines for information on how to participate in the Kubernetes application project by submitting pull requests or issues.

License

MIT Public License