CouchDB using Portworx on DCOS

DC/OS provides a CouchDB service that makes it easy to deploy and manage CouchDB on Mesosphere DC/OS. This guide will help you to install and run the containerized CouchDB service backed by Portworx volumes for persistent DCOS storage.

The source code for these services can be found here: Portworx DCOS-Commons Frameworks

Please make sure you have installed Portworx on DCOS before proceeding further.

Install

Adding the repository for the service

For this step you will need to login to a node which has the dcos cli installed and is authenticated to your DCOS cluster.

Run the following command to add the repository to your DCOS cluster:

dcos package repo add --index=0 portworx-couchdb-aws https://universe-converter.mesosphere.com/transform?url=https://px-dcos-dev.s3.amazonaws.com/autodelete7d/portworx-couchdb/20180108-191814-r2aJF3ibkK2ltugj/stub-universe-portworx-couchdb.json

Once you have run the above command you should see the portworx-couchdb service available in your universe

Default Install

If you want to use the defaults, you can now run the dcos command to install the service

dcos package install --yes portworx-couchdb

You can also click on the “Install” button on the WebUI next to the service and then click “Install Package”. The default install will create Portworx volumes of size 10GB with 1 replica.

Advanced Install and Volume Options

If you want to modify the default, click on the “Install” button next to the package on the DCOS UI and then click on “Advanced Installation”

Here you have the option to change the service name, volume name, volume size, and provide any additional options for the Portworx volume. You can also configure other CouchDB related parameters on this page including the number of CouchDB nodes.

Click on “Review and Install” and then “Install” to start the installation of the service.

Install Status

Once you have started the install you can go to the Services page to monitor the status of the installation.

If you click on the portworx-couchdb service you should be able to look at the status of the nodes being created. There will be one service for the scheduler and one service each for the CouchDB nodes.

When the Scheduler service as well as the CouchDB nodes are in Running (green) status, you should be ready to start using the CouchDB cluster.

If you check your Portworx cluster, you should see multiple volumes that were automatically created using the options provided during install, one for each node of the CouchDB cluster.

If you run the “dcos service” command you should see the portworx-couchdb service in ACTIVE state with 3 running tasks, one for each CouchDB node.

dcos service

NAME                   HOST      ACTIVE  TASKS  CPU   MEM     DISK   ID
marathon          192.168.65.90   True     2    1.5  2048.0   0.0    b69b8ce2-fe89-4688-850c-9a70438fc8f3-0000
metronome         192.168.65.90   True     0    0.0   0.0     0.0    b69b8ce2-fe89-4688-850c-9a70438fc8f3-0001
portworx             a1.dcos      True     2    0.6  2048.0  1024.0  b69b8ce2-fe89-4688-850c-9a70438fc8f3-0022
portworx-couchdb     a1.dcos      True     3    1.5  6144.0   0.0    b69b8ce2-fe89-4688-850c-9a70438fc8f3-0029

Verify Setup

From the DCOS client, install the new command for portworx-couchdb

dcos package install portworx-couchdb --cli

Find out all CouchDB client endpoints

dcos portworx-couchdb endpoints cluster-port

{
  "address": [
    "192.168.65.131:5984",
    "192.168.65.121:5984",
    "192.168.65.111:5984"
  ],
  "dns": [
    "couchdb-0-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984",
    "couchdb-1-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984",
    "couchdb-2-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984"
  ]
}

Connect to the main node to access the CouchDB service

dcos node ssh --master-proxy --leader

From the DCOS main node, run the CouchDB REST API to any of the nodes on port 5984. The default credentials are admin:password for accessing the REST APIs. A json output of the members in the CouchDB cluster from one of the nodes is shown below.

curl -s "http://admin:password@couchdb-0-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984/_membership" | python -m json.tool

{
    "all_nodes": [
        "couchdb@couchdb-0-install.portworx-couchdb.autoip.dcos.thisdcos.directory",
        "couchdb@couchdb-1-install.portworx-couchdb.autoip.dcos.thisdcos.directory",
        "couchdb@couchdb-2-install.portworx-couchdb.autoip.dcos.thisdcos.directory"
    ],
    "cluster_nodes": [
        "couchdb@couchdb-0-install.portworx-couchdb.autoip.dcos.thisdcos.directory",
        "couchdb@couchdb-1-install.portworx-couchdb.autoip.dcos.thisdcos.directory",
        "couchdb@couchdb-2-install.portworx-couchdb.autoip.dcos.thisdcos.directory"
    ]
}

To verify the CouchDB cluster we try to create a new database testdb and add a simple document to it.

curl -s -X PUT "http://admin:password@couchdb-0-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984/testdb" -d {} | python -m json.tool

{
    "ok": true
}

curl -s -X PUT "http://admin:password@couchdb-0-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984/testdb/001" -d '{"name":"Alice"}' | python -m json.tool

{
    "id": "001",
    "ok": true,
    "rev": "1-4cb726bf80cfbb1457e6cce338834b1f"
}

Verify the inserted document

curl -s "http://admin:password@couchdb-1-install.portworx-couchdb.autoip.dcos.thisdcos.directory:5984/testdb/001" | python -m json.tool

{
    "_id": "001",
    "_rev": "1-4cb726bf80cfbb1457e6cce338834b1f",
    "name": "Alice"
}

Scaling

You do not need to create additional Portworx volumes manually to scale up your cluster. Just go to the CouchDB service page, click on the three dots on the top right corner of the page, select “nodes”, scroll down and increase the nodes parameter to the desired nodes.

Click on “Review and Run” and then “Run Service”. The service scheduler should restart with the updated node count and create more CouchDB nodes with newly created Portworx volumes. Please make sure you have enough resources and nodes available to scale up the number of nodes. You also need to make sure Portworx is installed on all the agents in the DCOS cluster.

You can also increase the capacity of your CouchDB data nodes by using the pxctl volume update command without taking the service offline.