• Introducing mount points
• How to share data between the host and a container
• How to share data between containers
• Using temporary, in-memory filesystems
• Managing data with volumes

• Advanced storage with volume plugins

  4.1 File trees and mount points

  the image that a container is created from is mouted at that container’s file tree root.
  The best place to start is by understanding the three most common types of storage mounted into containers:

• Bind mounts

• In-memory storage
• Docker volumes

  4.2 Bind mounts

  touch ~/example.log
  cat >~/example.conf <<EOF
  server {
  listen 80;
  server_name localhost;
  access_log /var/log/nginx/custom.host.access.log main;
  location / {
  root /usr/share/nginx/html;
  index index.html index.htm;
  }
  }
  EOF

  CONF_SRC=~/example.conf; \
  CONF_DST=/etc/nginx/conf.d/default.conf; \
  LOG_SRC=~/example.log; \
  LOG_DST=/var/log/nginx/custom.host.access.log; \
  docker run -d --name diaweb \
  --mount type=bind,src=${CONF_SRC},dst=${CONF_DST} \
  --mount type=bind,src=${LOG_SRC},dst=${LOG_DST} \
  -p 80:80 \
  nginx:latest

  ```shell docker rm -f diaweb

CONF_SRC=~/example.conf; \ CONF_DST=/etc/nginx/conf.d/default.conf; \ LOG_SRC=~/example.log; \ LOG_DST=/var/log/nginx/custom.host.access.log; \ docker run -d —name diaweb \ —mount type=bind,src=${CONF_SRC},dst=${CONF_DST},readonly=true \ —mount type=bind,src=${LOG_SRC},dst=${LOG_DST} \ -p 80:80 \ nginx:latest

<a name="H6MkW"></a>
# 4.3 In-memory storage
```shell
docker run --rm \
--mount type=tmpfs,dst=/tmp \
--entrypoint mount \
alpine:latest -v

docker run --rm \
--mount type=tmpfs,dst=/tmp,tmpfs-size=16k,tmpfs-mode=1770 \
--entrypoint mount \
alpine:latest -v

4.4 Docker volumes

docker volume create \
--driver local \
--label example=location \
location-example
docker volume inspect \
--format "{{json .Mountpoint}}" \
location-example

4.4.1 Volumes provide container-independent data management

4.4.2 Using volumes with a NoSQL database

docker volume create \
 --driver local \
 --label example=cassandra \
 cass-shared

docker run -d \
--volume cass-shared:/var/lib/cassandra/data \
--name cass1 \
cassandra:2.2

docker run -it --rm \
--link cass1:cass \
cassandra:2.2 cqlsh cass

select * 
from system.schema_keyspaces 
where keyspace_name = 'docker_hello_world';

create keyspace docker_hello_world 
with replication = { 
 'class' : 'SimpleStrategy',
 'replication_factor': 1
};

select * 
from system.schema_keyspaces 
where keyspace_name = 'docker_hello_world';

docker run -d \
 --volume cass-shared:/var/lib/cassandra/data \
 --name cass2 \
 cassandra:2.2
docker run -it --rm \
 --link cass2:cass \
 cassandra:2.2 \
 cqlsh cass
select * 
from system.schema_keyspaces 
where keyspace_name = 'docker_hello_world';

4.5 Shared mount points and sharing files

LOG_SRC=~/web-logs-example
mkdir ${LOG_SRC}
docker run --name plath -d \
--mount type=bind,src=${LOG_SRC},dst=/data \
dockerinaction/ch4_writer_a
docker run --rm \
--mount type=bind,src=${LOG_SRC},dst=/data \
alpine:latest \
head /data/logA
cat ${LOG_SRC}/logA

docker volume create \
--driver local \
logging-example
docker run --name plath -d \
--mount type=volume,src=logging-example,dst=/data \
dockerinaction/ch4_writer_a
docker run --rm \
--mount type=volume,src=logging-example,dst=/data \
alpine:latest \
head /data/logA
#the following command is not useful
cat "$(docker volume inspect \
--format "{{json .Mountpoint}}" logging-example)"/logA
docker stop plath

4.5.1 Anonymous volumes and the volumes-from flag

docker run --name fowler \
--mount type=volume,dst=/library/PoEAA \
--mount type=bind,src=/tmp,dst=/library/DSL \
alpine:latest \
echo "Fowler collection created"
docker run --name knuth \
--mount type=volume,dst=/library/TAoCP.vol1 \
--mount type=volume,dst=/library/TAoCP.vol2 \
 --mount type=volume,dst=/library/TAoCP.vol3 \
 --mount type=volume,dst=/library/TAoCP.vol4.a \
 alpine:latest \
 echo "Knuth collection created"
 docker run --name reader \
 --volumes-from fowler \
 --volumes-from knuth \
 alpine:latest ls -l /library/
 docker inspect --format "{{json .Mounts}}" reader

4.6 Cleaning up volumes

docker volume prune --filter example=cassandra

4.7 Advanced storage with volume plugins