Full Code of pires/kubernetes-nats-cluster for AI

Repository: pires/kubernetes-nats-cluster
Branch: master
Commit: 9cb5e43b8ad8
Files: 7
Total size: 22.2 KB

Directory structure:
gitextract_wobrug95/

├── .gitignore
├── LICENSE
├── README.md
├── nats.conf
├── nats.yml
├── route_checker/
│   └── main.go
└── ssl.cnf

================================================
FILE CONTENTS
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================================================
FILE: .gitignore
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*.pem
*.csr
*.srl


================================================
FILE: LICENSE
================================================
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================================================
FILE: README.md
================================================
# kubernetes-nats-cluster
NATS cluster on top of Kubernetes made easy.

**THIS PROJECT HAS BEEN ARCHIVED. SEE https://github.com/nats-io/nats-operator**

**NOTE:** This repository provides a configurable way to deploy secure, available
and scalable NATS clusters. However, [a _smarter_ solution](https://github.com/pires/nats-operator)
in on the way (see [#5](https://github.com/pires/kubernetes-nats-cluster/issues/5)).

## Pre-requisites

* Kubernetes cluster v1.8+ - tested with v1.9.0 on top of [Vagrant + CoreOS](https://github.com/pires/kubernetes-vagrant-coreos-cluster)
* At least 3 nodes available (see [Pod anti-affinity](#pod-anti-affinity))
* `kubectl` configured to access your cluster master API Server
* `openssl` for TLS certificate generation

## Deploy

We will be deploying a cluster of 3 NATS instances, with the following set-up:
- TLS on for clients, but not clustering because peer-auth requires real SANS DNS in certificate
- NATS client credentials: `nats_client_user:nats_client_pwd`
- NATS route/cluster credentials: `nats_route_user:nats_route_pwd`
- Logging: `debug:false`, `trace:true`, `logtime:true`

First, make sure to change `nats.conf` according to your needs.
Then create a Kubernetes configmap to store it:
```bash
kubectl create configmap nats-config --from-file nats.conf
```

Next, we need to generate valid TLS artifacts:
```bash
openssl genrsa -out ca-key.pem 2048
openssl req -x509 -new -nodes -key ca-key.pem -days 10000 -out ca.pem -subj "/CN=kube-ca"
openssl genrsa -out nats-key.pem 2048
openssl req -new -key nats-key.pem -out nats.csr -subj "/CN=kube-nats" -config ssl.cnf
openssl x509 -req -in nats.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out nats.pem -days 3650 -extensions v3_req -extfile ssl.cnf
```

Then, it's time to create a couple Kubernetes secrets to store the TLS artifacts:
- `tls-nats-server` for the NATS server TLS setup
- `tls-nats-client` for NATS client apps setup - one will need it to validate the self-signed certificate
used to secure NATS server
```bash
kubectl create secret generic tls-nats-server --from-file nats.pem --from-file nats-key.pem --from-file ca.pem
kubectl create secret generic tls-nats-client --from-file ca.pem
```

**ATTENTION:** Both using self-signed certificates and using the same certificates for securing
client and cluster connections is a significant security compromise. But for the sake of showing
how it can be done, I'm fine with doing just that.
In an ideal scenario, there should be:
- One centralized PKI/CA
- One certificate for securing NATS route/cluster connections
- One certificate for securing NATS client connections
- TLS route/cluster authentication should be enforced, so one TLS certificate per route/cluster peer
- TLS client authentication should be enforced, so one TLS certificate per client

And finally, we deploy NATS:
```bash
kubectl create -f nats.yml
```

Logs should be enough to make sure everything is working as expected:
```
$ kubectl logs -f nats-0
[1] 2017/12/17 12:38:37.801139 [INF] Starting nats-server version 1.0.4
[1] 2017/12/17 12:38:37.801449 [INF] Starting http monitor on 0.0.0.0:8222
[1] 2017/12/17 12:38:37.801580 [INF] Listening for client connections on 0.0.0.0:4242
[1] 2017/12/17 12:38:37.801772 [INF] TLS required for client connections
[1] 2017/12/17 12:38:37.801778 [INF] Server is ready
[1] 2017/12/17 12:38:37.802078 [INF] Listening for route connections on 0.0.0.0:6222
[1] 2017/12/17 12:38:38.874497 [TRC] 10.244.1.3:33494 - rid:1 - ->> [CONNECT {"verbose":false,"pedantic":false,"user":"nats_route_user","pass":"nats_route_pwd","tls_required":true,"name":"KGMPnL89We3gFLEjmp8S5J"}]
[1] 2017/12/17 12:38:38.956806 [TRC] 10.244.74.2:46018 - rid:3 - ->> [CONNECT {"verbose":false,"pedantic":false,"user":"nats_route_user","pass":"nats_route_pwd","tls_required":true,"name":"Skc5mx9enWrGPIQhyE7uzR"}]
[1] 2017/12/17 12:38:39.951160 [TRC] 10.244.1.4:46242 - rid:4 - ->> [CONNECT {"verbose":false,"pedantic":false,"user":"nats_route_user","pass":"nats_route_pwd","tls_required":true,"name":"0kaCfF3BU8g92snOe34251"}]
[1] 2017/12/17 12:40:38.956203 [TRC] 10.244.74.2:46018 - rid:3 - <<- [PING]
[1] 2017/12/17 12:40:38.958279 [TRC] 10.244.74.2:46018 - rid:3 - ->> [PING]
[1] 2017/12/17 12:40:38.958300 [TRC] 10.244.74.2:46018 - rid:3 - <<- [PONG]
[1] 2017/12/17 12:40:38.961791 [TRC] 10.244.74.2:46018 - rid:3 - ->> [PONG]
[1] 2017/12/17 12:40:39.951421 [TRC] 10.244.1.4:46242 - rid:4 - <<- [PING]
[1] 2017/12/17 12:40:39.952578 [TRC] 10.244.1.4:46242 - rid:4 - ->> [PONG]
[1] 2017/12/17 12:40:39.952594 [TRC] 10.244.1.4:46242 - rid:4 - ->> [PING]
[1] 2017/12/17 12:40:39.952598 [TRC] 10.244.1.4:46242 - rid:4 - <<- [PONG]
```

## Scale

**WARNING:** Due to the [Pod anti-affinity](#pod-anti-affinity) rule, for scaling up to _n_ NATS
instances, one needs _n_ available Kubernetes nodes.

```
kubectl scale statefulsets nats --replicas 5
```

Did it work?

```
NAME             TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                      AGE
svc/kubernetes   ClusterIP   10.100.0.1   <none>        443/TCP                      1h
svc/nats         ClusterIP   None         <none>        4222/TCP,6222/TCP,8222/TCP   4m

NAME        READY     STATUS    RESTARTS   AGE
po/nats-0   1/1       Running   0          4m
po/nats-1   1/1       Running   0          4m
po/nats-2   1/1       Running   0          4m
po/nats-3   1/1       Running   0          7s
po/nats-4   1/1       Running   0          6s
```

## Access the service

*Don't forget* that services in Kubernetes are only acessible from containers in the cluster.

In this case, we're using a [`headless service`](http://kubernetes.io/v1.1/docs/user-guide/services.html#headless-services).

Just point your client apps to:
```
nats:4222
```

<a id="pod-anti-affinity">

## Pod anti-affinity


One of the main advantages of running NATS on top of Kubernetes is how resilient the cluster becomes,
particularly during node restarts. However if all NATS pods are scheduled onto the same node(s), this
advantage decreases significantly and may even result in service downtime.

It is then **highly recommended** that one adopts [pod anti-affinity](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#inter-pod-affinity-and-anti-affinity-beta-feature)
in order to increase availability. This is enabled by default (see `nats.yml`).


================================================
FILE: nats.conf
================================================
listen: 0.0.0.0:4222
http: 0.0.0.0:8222

tls {
  cert_file:  "/etc/nats/tls/nats.pem"
  key_file:   "/etc/nats/tls/nats-key.pem"
  timeout:    2
}

# Authorization for client connections
authorization {
    user:     nats_client_user
    # ./util/mkpasswd -p T0pS3cr3t
    password: nats_client_pwd
    timeout:  1
}

# Cluster definition
cluster {
    listen: 0.0.0.0:6222

    # Disabled this because peer-auth requires real SANS DNS in certificate
    #tls {
    #    cert_file:  "/etc/nats/tls/nats.pem"
    #    key_file:   "/etc/nats/tls/nats-key.pem"
    #    ca_file:    "/etc/nats/tls/ca.pem"
    #    timeout:    5
    #}

    # Authorization for route connections
    authorization {
        user: nats_route_user
        password: nats_route_pwd
        timeout: 0.5
    }

    # Routes are actively solicited and connected to from this server.
    # Other servers can connect to us if they supply the correct credentials
    # in their routes definitions from above.
    routes = [
        nats://nats_route_user:nats_route_pwd@nats:6222
    ]
}

# logging options
debug:   false
trace:   true
logtime: true

# Some system overides

# max_connections
max_connections: 100

# maximum protocol control line
max_control_line: 512

# maximum payload
max_payload: 65536

# Duration the server can block on a socket write to a client.  Exceeding the
# deadline will designate a client as a slow consumer.
write_deadline: "2s"

================================================
FILE: nats.yml
================================================
apiVersion: v1
kind: Service
metadata:
  name: nats
  labels:
    component: nats
spec:
  selector:
    component: nats
  clusterIP: None
  ports:
  - name: client
    port: 4222
  - name: cluster
    port: 6222
  - name: monitor
    port: 8222
---
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
  name: nats
  labels:
    component: nats
spec:
  serviceName: nats
  replicas: 3
  template:
    metadata:
      labels:
        component: nats
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
                - key: component
                  operator: In
                  values:
                    - nats
            topologyKey: kubernetes.io/hostname
      containers:
      - name: nats
        image: nats:1.0.4
        args: [ "--config", "/etc/nats/config/nats.conf"]
        volumeMounts:
          - name: tls-volume
            mountPath: /etc/nats/tls
          - name: config-volume
            mountPath: /etc/nats/config
        ports:
        - containerPort: 4222
          name: client
        - containerPort: 6222
          name: cluster
        - containerPort: 8222
          name: monitor
        livenessProbe:
          httpGet:
            path: /
            port: 8222
          initialDelaySeconds: 10
          timeoutSeconds: 5
      volumes:
      - name: tls-volume
        secret:
          secretName: tls-nats-server
      - name: config-volume
        configMap:
          name: nats-config


================================================
FILE: route_checker/main.go
================================================
package main

import (
	"encoding/json"
	"flag"
	"io/ioutil"
	"log"
	"net"
	"net/http"
)

var (
	lookupName = flag.String("lookup", "nats", "Lookup name")
	server     = flag.String("server", "http://localhost:8222", "NATS URL to query")
)

type routez struct {
	RoutesCount int `json:"num_routes"`
}

func countInstancesInCluster(lookupName string) (int, error) {
	_, srvRecords, err := net.LookupSRV("", "", lookupName)
	if err != nil {
		return 0, err
	}

	return len(srvRecords), nil
}

func main() {
	flag.Parse()

	// if we're the only instance in the cluster, we're good to go
	// otherwise, we need to check if there are any routes established
	// and if not, exit with error.
	instances, err := countInstancesInCluster(*lookupName)
	if err != nil {
		log.Fatalf("There was an error while verifiying if this is the first instance in the cluster: %s\n", err.Error())
	} else {
		log.Printf("There are %d instances in the cluster.", instances)
	}

	if instances > 1 {
		// query NATS monitoring endpoint
		url := *server + "/routez"
		log.Printf("Querying server %s..\n", url)
		res, err := http.Get(url)
		if err != nil {
			log.Fatalf("There was an error while querying %s: %s\n", url, err.Error())
		}

		body, err := ioutil.ReadAll(res.Body)
		if err != nil {
			log.Fatalf("There was an error while reading response: %s\n", err.Error())
		}

		var data routez
		if err := json.Unmarshal(body, &data); err != nil {
			log.Fatalf("There was an error while decoding response: %s\n", err.Error())
		}

		// if enough routes aren't established, exit with error
		if data.RoutesCount < instances-1 {
			log.Fatalf("There aren't enough routes established. Only %d out of %d.", data.RoutesCount, instances-1)
		}
	}
}


================================================
FILE: ssl.cnf
================================================
[req]
req_extensions = v3_req
distinguished_name = req_distinguished_name
[req_distinguished_name]
[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names
[alt_names]
DNS.1 = nats