Note: This guide is based from - and has been updated - the origin Medium article.
So, your Tendermint application is finally ready and you want to distribute it and run it on several machines, or just run it locally by creating a dozen Docker containers. We have created mintnet-kubernetes to help you achieve this goal as fast as possible. Note that it should be primarily used for testing purposes or for tightly-defined chains operated by a single stakeholder (see the security precautions). If you want to launch an application with many stakeholders, consider using our set of Ansible scripts to deploy Tendermint.
mintnet-kubernetes is a configuration file for
Kubernetes.
Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications.
If you had never heard of it, it won’t hurt to read What is Kubernetes? and go through their interactive lessons. It won't take long, I promise.
There are several ways to install a Kubernetes cluster:
- a local Docker-based solution using Minikube
- hosted solutions using a Web UI or CLI (e.g. GCE)
- turn-key cloud solutions (e.g. AWS using Kubernetes Operations; AWS, Azure, GCE or bare metal using Kargo)
- custom solutions (e.g. Linux machines using kubeadm)
If you just want to play with your application, choose a local installation with Minikube. If you want to run it in the cloud or on bare metal, refer to Picking the Right Solution, taking into account the cost, safety, reliability, and configuration options of those solutions.
Further, we will assume that you have a standard 64-bit Linux desktop with VirtualBox or KVM installed.
curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl && chmod +x ./kubectl && sudo mv ./kubectl /usr/local/bin/kubectl
For Windows or OS X, please check out Installing and Setting Up kubectl guide.
curl -Lo minikube https://storage.googleapis.com/minikube/releases/v0.19.0/minikube-linux-amd64 && chmod +x minikube && sudo mv minikube /usr/local/bin/
For Windows or OS X, please check out Releases page.
minikube start
Get the config file:
curl -Lo app.yaml https://raw.githubusercontent.com/tendermint/tools/master/mintnet-kubernetes/examples/basecoin/app.yaml
Open it in the editor of your choice:
$EDITOR app.yaml
and configure the parameters required for your application.
The Cosmos SDK will help us create our own currency, extensible with plugins. Writing plugins is out of scope of this article, but you can read about it here.
Kubernetes DSL (Domain Specific Language) can be difficult for the beginner to grasp. Fortunately, we will need to change only a small piece of code.
The most important thing is the application’s genesis.json file. It
defines the initial distribution of assets. We have 4 nodes by default
(replicas: 4in StatefulSet). Generally, it is a good idea to split
assets evenly between them and have some large number for everyone.
Let’s change denom to “MyAwesomeCoin”. You are welcome to pick any other name you like.
---
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
genesis.json: |-
{
"chain_id": "chain-tTH4mi",
"app_options": {
"accounts": [
{
"pub_key": "tm-0",
"coins": [
{
"denom": "MyAwesomeCoin",
"amount": 1000000000
}
]
},
{
"pub_key": "tm-1",
"coins": [
{
"denom": "MyAwesomeCoin",
"amount": 1000000000
}
]
},
{
"pub_key": "tm-2",
"coins": [
{
"denom": "MyAwesomeCoin",
"amount": 1000000000
}
]
},
{
"pub_key": "tm-3",
"coins": [
{
"denom": "MyAwesomeCoin",
"amount": 1000000000
}
]
}
]
}
}
kubectl create -f ./app.yaml
Wait until all of the nodes are running:
kubectl get pods -w -o wide -L tm NAME READY STATUS RESTARTS AGE IP NODE TM tm-0 3/3 Running 0 3m 172.17.0.2 minikube <none> tm-1 3/3 Running 0 3m 172.17.0.3 minikube <none> tm-2 3/3 Running 1 3m 172.17.0.4 minikube <none> tm-3 3/3 Running 0 3m 172.17.0.7 minikube <none>
Let’s check the first account:
ADDR=$(kubectl exec -c app tm-0 -- cat /app/key.json | jq ".address" | tr -d "\"")
kubectl exec -c app tm-0 -- basecoin account $ADDR
{"pub_key":{"type":"ed25519","data":"793B7E33EF94132E16534CC9BA59F74944065FA917A98DB68ABA806D219A4529"},"sequence":1,"coins":[{"denom":"MyAwesomeCoin","amount":999999995}]}
Great! Let’s try to send a transaction from the first to the second account:
RECIPIENT=$(kubectl exec -c app tm-1 -- cat /app/key.json | jq ".address" | tr -d "\"") kubectl exec -c app tm-0 -- basecoin tx send --to 0x$RECIPIENT --amount 5MyAwesomeCoin --from /app/key.json --chain_id chain-tTH4mi Signed SendTx: 0100000000000000000104636F696E000000000000000001010114A677E98456071E3240EF0A2E0B80FFE7D36515BF010101066D79636F696E0000000000000005010201E6A038849655CD3C94D06BAC1CA74443D312855A9BC3575311842DF74AF7DB772673DF60F3AE08CC5260AE93DCE4DB588EF24D08768D0DE2752F001DDC1DEE0F0001010114E2AFEA4A193E85A2DBB8668D4EA0DC0B1A6AD63A010101066D79636F696E0000000000000005 Response: 3D54EECAAE072477E6119C6DF1762168F276F0C1 ;
Checking the first account’s balance we should see 5 coins making their way into the second account:
kubectl exec -c app tm-0 -- basecoin account $ADDR
{"pub_key":{"type":"ed25519","data":"793B7E33EF94132E16534CC9BA59F74944065FA917A98DB68ABA806D219A4529"},"sequence":2,"coins":[{"denom":"MyAwesomeCoin","amount":999999990}]}
As you can see, it was fairly simple to launch a new cryptocurrency in a Kubernetes cluster. Moreover, with Kubernetes you can add new nodes (pods) with a single command. And using federation, you can be sure that your currency will stay alive even after loss of the entire cluster!
kubectl delete -f ./app.yaml kubectl delete pvc -l app=tm