couchdb-docker-service

CouchDB as a docker swarm service

Set up

Run this on your primary box to initialize the docker swarm manager:

docker swarm init --advertise-addr <ip-address>

Then use the response to register other nodes in the swarm.

Create the network so that the CouchDB nodes can communicate with each other:

docker network create \
  --driver overlay \
  --subnet 10.0.9.0/24 \
  --opt encrypted \
  couchdb-network

Create a service

The following examples assume that you have the directory /home/ubuntu/common on each of the boxes in the swarm. Moreover, /home/ubuntu/common/data is a directory that will be mounted as a volume so that your CouchDB data will be persisted across restarts.

Hashing a password

All your CouchDB nodes need the same hashed password so that user sessions can work seamlessly between nodes. You can use the couch-hash-pwd utility to generate this hash. For example, if your password is admin you can use:

$ sudo npm install -g couch-hash-pwd
$ couchdb-hash-pwd -p admin

You'll then want to use the outputted value as the value of COUCHDB_HASHED_PASSWORD

Example:

docker service create --replicas 2 --name couchdb --network couchdb-network \
  --hostname="couchdb{{.Task.Slot}}" \
  --mount type=bind,source=/home/ubuntu/common,destination=/common \
  -e COUCHDB_COOKIE="mycookie" \
  -e COUCHDB_USER="admin" \
  -e COUCHDB_PASSWORD="admin" \
  -e COUCHDB_HASHED_PASSWORD="-pbkdf2-b1eb7a68b0778a529c68d30749954e9e430417fb,4da0f8f1d98ce649a9c5a3845241ae24,10" \
  -e COUCHDB_SECRET="mysecret" \
  -e NODENAME="couchdb{{.Task.Slot}}" \
  -e SERVICE_NAME="{{.Service.Name}}" \
  -e TASK_SLOT="{{.Task.Slot}}" \
  -e COUCHDB_DATA_DIR="/common/data/{{.Service.Name}}{{.Task.Slot}}" \
  -p 5984:5984 \
  --detach=true \
  redgeoff/couchdb-service

COUCHDB_COOKIE and COUCHDB_SECRET should be some random string of characters--you may want to use a password generator to generate these values.

Example with SSL:

We assume /home/ubuntu/common/ssl/mydomain.crt and /home/ubuntu/common/ssl/mydomain.key are the certificate and private key for your SSL config.

docker service create --replicas 2 --name couchdb --network couchdb-network \
  --hostname="couchdb{{.Task.Slot}}" \
  --mount type=bind,source=/home/ubuntu/common,destination=/common \
  -e COUCHDB_COOKIE="mycookie" \
  -e COUCHDB_USER="admin" \
  -e COUCHDB_PASSWORD="admin" \
  -e COUCHDB_HASHED_PASSWORD="-pbkdf2-b1eb7a68b0778a529c68d30749954e9e430417fb,4da0f8f1d98ce649a9c5a3845241ae24,10" \
  -e COUCHDB_SECRET="mysecret" \
  -e NODENAME="couchdb{{.Task.Slot}}" \
  -e SERVICE_NAME="{{.Service.Name}}" \
  -e TASK_SLOT="{{.Task.Slot}}" \
  -e COUCHDB_DATA_DIR="/common/data/{{.Service.Name}}{{.Task.Slot}}" \
  -e COUCHDB_CERT_FILE="/common/ssl/mydomain.crt" \
  -e COUCHDB_KEY_FILE="/common/ssl/mydomain.key" \
  -e COUCHDB_CACERT_FILE="/common/ssl/mydomain.crt" \
  -p 6984:6984 \
  --detach=true \
  redgeoff/couchdb-service

Example with SSL and custom local.ini:

We assume /home/ubuntu/common/etc/local.ini contains any custom config, e.g.

[chttpd]
bind_address = any

[httpd]
bind_address = any

[couchdb]
max_dbs_open=1000

Then run:

docker service create --replicas 2 --name couchdb --network couchdb-network \
  --hostname="couchdb{{.Task.Slot}}" \
  --mount type=bind,source=/home/ubuntu/common,destination=/common \
  --mount type=bind,source=/home/ubuntu/common/etc/local.ini,destination=/home/couchdb/couchdb/etc/local.d/local.ini \
  -e COUCHDB_COOKIE="mycookie" \
  -e COUCHDB_USER="admin" \
  -e COUCHDB_PASSWORD="admin" \
  -e COUCHDB_HASHED_PASSWORD="-pbkdf2-b1eb7a68b0778a529c68d30749954e9e430417fb,4da0f8f1d98ce649a9c5a3845241ae24,10" \
  -e COUCHDB_SECRET="mysecret" \
  -e NODENAME="couchdb{{.Task.Slot}}" \
  -e SERVICE_NAME="{{.Service.Name}}" \
  -e TASK_SLOT="{{.Task.Slot}}" \
  -e COUCHDB_DATA_DIR="/common/data/{{.Service.Name}}{{.Task.Slot}}" \
  -e COUCHDB_CERT_FILE="/common/ssl/mydomain.co.crt" \
  -e COUCHDB_KEY_FILE="/common/ssl/mydomain.co.key" \
  -e COUCHDB_CACERT_FILE="/common/ssl/mydomain.co.crt" \
  -p 6984:6984 \
  --detach=true \
  redgeoff/couchdb-service

To scale up

docker service scale couchdb=5

To scale down

TODO: To scale down, you should spin up a new cluster and replicate all the data from the old cluster to the new cluster and then delete the old cluster. See http://docs.couchdb.org/en/2.0.0/cluster/sharding.html#reshard-no-preshard

Upgrade to latest image

$ docker pull redgeoff/couchdb-service
$ docker service update --detach=true --image redgeoff/couchdb-service couchdb