Sealer -- Build, Share and Run Any Distributed Applications

Introduction

sealer[ˈsiːlər] provides the way for distributed application package and delivery based on kubernetes.

Concept

CloudImage : like Dockerimage, but the rootfs is kubernetes, and contains all the dependencies(docker images,yaml files or helm chart...) your application needs.
Kubefile : the file describe how to build a CloudImage.
Clusterfile : the config of using CloudImage to run a cluster.

We can write a Kubefile, and build a CloudImage, then using a Clusterfile to run a cluster.

sealer[ˈsiːlər] provides the way for distributed application package and delivery based on kubernetes.

It solves the delivery problem of complex applications by packaging distributed applications and dependencies(like database,middleware) together.

For example, build a dashboard CloudImage:

Kubefile:

# base CloudImage contains all the files that run a kubernetes cluster needed.
#    1. kubernetes components like kubectl kubeadm kubelet and apiserver images ...
#    2. docker engine, and a private registry
#    3. config files, yaml, static files, scripts ...
FROM registry.cn-qingdao.aliyuncs.com/sealer-io/kubernetes:v1.19.8
# download kubernetes dashboard yaml file
RUN wget https://raw.githubusercontent.com/kubernetes/dashboard/v2.2.0/aio/deploy/recommended.yaml
# when run this CloudImage, will apply a dashboard manifests
CMD kubectl apply -f recommended.yaml

Build dashobard CloudImage:

sealer build -t registry.cn-qingdao.aliyuncs.com/sealer-io/dashboard:latest .

Run a kubernetes cluster with dashboard:

# sealer will install a kubernetes on host 192.168.0.2 then apply the dashboard manifests
sealer run registry.cn-qingdao.aliyuncs.com/sealer-io/dashboard:latest --masters 192.168.0.2 --passwd xxx
# check the pod
kubectl get pod -A|grep dashboard

Push the CloudImage to the registry

# you can push the CloudImage to docker hub, Ali ACR, or Harbor
sealer push registry.cn-qingdao.aliyuncs.com/sealer-io/dashboard:latest

Usage scenarios & features

An extremely simple way to install kubernetes and other software in the kubernetes ecosystem in a production or offline environment.
Through Kubefile, you can easily customize the kubernetes CloudImage to package the cluster and applications, and submit them to the registry.
Powerful life cycle management capabilities, to perform operations such as cluster upgrade, cluster backup and recovery, node expansion and contraction in unimaginable simple ways
Very fast, complete cluster installation within 3 minutes
Support ARM x86, v1.20 and above versions support containerd, almost compatible with all Linux operating systems that support systemd
Does not rely on ansible haproxy keepalived, high availability is achieved through ipvs, takes up less resources, is stable and reliable
Many ecological software images can be used directly, like prometheus mysql..., and you can combine then together.

Quick start

Install a kubernetes cluster

#install Sealer binaries
wget https://github.com/sealerio/sealer/releases/download/v0.8.5/sealer-v0.8.5-linux-amd64.tar.gz && \
tar zxvf sealer-v0.8.5-linux-amd64.tar.gz && mv sealer /usr/bin
#run a kubernetes cluster
sealer run kubernetes:v1.19.8 --masters 192.168.0.2 --passwd xxx