CouchDB 2.0 in Kubernetes

deployment-couchdb.yaml

# Start a 3 node cluster and join it together automatically. Uses
# local ephemeral disk for database storage.
 
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: couchdb
spec:
  replicas: 3
  template:
    metadata:
      labels:
        run: couchdb
    spec:
      containers:
        - name: couchdb
          image: kocolosk/couchdb:2.0-prod
          imagePullPolicy: Always
          env:
          - name: POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
          - name: ERL_FLAGS
            value: "-name couchdb@$(POD_IP) -setcookie monster"
          ports:
          - name: couchdb
            containerPort: 5984
          - name: epmd
            containerPort: 4369
          - containerPort: 9100
          volumeMounts:
          - name: database-storage
            mountPath: /var/lib/couchdb
        - name: mem3-kube
          image: kocolosk/mem3-kube
          imagePullPolicy: Always
      volumes:
        - name: database-storage
          emptyDir: {}

mem3_kube Dockerfile

FROM debian:jessie

MAINTAINER Adam Kocoloski adam@kocolosk.net

RUN groupadd -r couchdb && useradd -d /opt/couchdb -g couchdb couchdb

# Download dependencies
RUN apt-get update -y -qq && apt-get install -y --no-install-recommends \
    python python-pip \
 && pip install requests

COPY mem3_kube.py /opt/mem3_kube/

USER couchdb
WORKDIR /opt/mem3_kube

CMD ["mem3_kube.py"]
ENTRYPOINT ["/usr/bin/python"]

mem3_kube.py

# This file just grabs the list of pod IP addresses for the service
# called "couchdb" and feeds those as `couchdb@PODIP` nodes to mem3.
# It's just a proof of concept; the proper solution is likely a module
# in mem3 itself.

import json
import os
import requests
import time

def discover_peers():
    f = open("/var/run/secrets/kubernetes.io/serviceaccount/token", 'r')
    token = f.read()
    
    uri = 'https://{0}:{1}/api/v1/namespaces/{2}/endpoints/{3}'.format(
        os.environ.get("KUBERNETES_PORT_443_TCP_ADDR", "10.0.0.1"),
        os.environ.get("KUBERNETES_PORT_443_TCP_PORT", "443"),
        os.environ.get("POD_NAMESPACE", "default"),
        os.environ.get("COUCHDB_SERVICE", "couchdb")
    )
    headers = {
        'Authorization': "Bearer {0}".format(token)
    }
    resp = requests.get(uri, headers=headers, verify=False)
    if resp.status_code == 200:
        body = resp.json()
        for key in ('addresses', 'notReadyAddresses'):
            addresses = body['subsets'][0].get(key, [])
            ips = [addr['ip'] for addr in addresses]
            print key, ips
            connect_the_dots(ips)
        sleep_forever()
    else:
        print 'Error'
        print resp.text
     
def connect_the_dots(ips):
    for ip in ips:
        uri = "http://localhost:5986/_nodes/couchdb@{0}".format(ip)
        doc = {}
        r = requests.put(uri, data = json.dumps(doc))
        print ip, r.status_code

def sleep_forever():
    while True:
        time.sleep(5)

if __name__ == '__main__':
    print os.environ
    discover_peers()