You can use Redis as a cache, database, or for messaging. Here is an example of durable storage for containers with container-granular controls.

This example shows how to create a volume for Redis, run and write to Redis, and then snapshot just that Redis volume’s state. Portworx snapshots are thinly provisioned and copy on write.

Create a storage volume for Redis

To create a Portworx storage volume for Redis, use the docker volume create command.

# docker volume create -d pxd --name=redis_vol --opt \
     	size=4 --opt block_size=64 --opt repl=1 --opt fs=ext4

That command creates a volume to attach to your redis-server container. The redis-server container stores its data in the /data directory. Use the Docker `-v’ option to attach the Portworx volume to this directory.

Start the Redis container

To start the Redis container, run the following command, using the redis_vol volume created above.

# docker run --name some-redis  -v redis_vol:/data --volume-driver=pxd  -d redis redis-server --appendonly yes

Your redis-server container is now available for use at port 6379.

Start the redis CLI client container

docker run -it --link some-redis:redis --rm redis redis-cli -h redis -p 6379

Populate the redis instance with some data

redis:6379> set foo 100
OK
redis:6379> incr foo
(integer) 101
redis:6379> append foo abcxxx
(integer) 9
redis:6379> get foo
"101abcxxx"
redis:6379>

Kill the ‘some-redis’ instance

docker kill some-redis

Start a new redis-server instance with volume persistance

Start another redis-server container called other-redis using the original redis_vol to show data persistance.

docker run --name other-redis  -v redis_vol:/data --volume-driver=pxd  -d redis redis-server --appendonly yes

Start a redis CLI container

Connect to the new other-redis container with the following command.

docker run -it --link other-redis:redis --rm redis redis-cli -h redis -p 6379

See that the original data has persisted

redis:6379> get foo
"101abcxxx"

Create snapshot of your volume

You can create container-granular snapshots, by saving just this container’s state. Snapshots are then immedidately available as a volume.

Create a snapshot of the redis_vol volume using pxctl.

# pxctl volume list
ID			NAME		SIZE	HA	STATUS
416765532972737036	redis_vol	2.0 GiB	1	up - attached on 3abe5484-756c-4076-8a80-7b7cd5306b28
# pxctl snap create 416765532972737036
Volume successfully snapped:  3291428813175937263

Update the volume with new data

# docker run -it --link other-redis:redis --rm redis redis-cli -h redis -p 6379
redis:6379> get foo
"101abcxxx"
redis:6379> set foo foobar
OK
redis:6379> get foo
"foobar"

See that the snapshot volume still contains the original data

# docker run --name snap-redis -v 3291428813175937263:/data --volume-driver=pxd -d redis redis-server --appendonly yes
940d2ad6b87df9776e26d29e746eb05fb6081c0e6019d46ba77915d7c8305308
# docker run -it --link snap-redis:redis --rm redis redis-cli -h redis -p 6379
redis:6379> get foo
"101abcxxx"
redis:6379>