This docker image provides PostgreSQL initalized for the DICOM Archive dcm4chee-arc-light. It extends the official postgres image.

How to use this image

start a postgres instance

$ docker run --name postgres \
           -p 5432:5432 \
           -v /etc/localtime:/etc/localtime \
           -e POSTGRES_DB=pacsdb \
           -e POSTGRES_USER=pacs\
           -e POSTGRES_PASSWORD=pacs \
           -v /var/local/dcm4chee-arc/db:/var/lib/postgresql/data \
           -d dcm4che/postgres-dcm4chee:13.1-23

connect to it from the DICOM Archive application

$ docker run --link postgres:db ... -d dcm4che/dcm4chee-arc-psql

Environment Variables

This image does not define additional environment variables to those inherited from the PostgreSQL image. But in opposite to the base image, they are required - except PGDATA - to be specified, because the DICOM Archive application relies on their provision.

`POSTGRES_USER`

This environment variable is used in conjunction with POSTGRES_PASSWORD to set a user and its password. This variable will create the specified user with superuser power.

`POSTGRES_USER_FILE`

Superuser via file input (alternative to POSTGRES_USER).

`POSTGRES_PASSWORD`

Superuser password for PostgreSQL. In the above example, it is being set to pacs.

`POSTGRES_PASSWORD_FILE`

Superuser password for PostgreSQL via file input (alternative to POSTGRES_PASSWORD).

`POSTGRES_DB`

This environment variable defines the name for the default database that is created when the image is first started.

`PGDATA`

This optional environment variable can be used to define another location - like a subdirectory - for the database files. The default is /var/lib/postgresql/data, but if the data volume you're using is a fs mountpoint (like with GCE persistent disks), Postgres initdb recommends a subdirectory (for example /var/lib/postgresql/data/pgdata ) be created to contain the data.

Setup Master/Slave Replication

Start a container with Postgres acting as 'master' DB:

$ docker run --name db1 \
             -p 5432:5432 \
             -e POSTGRES_DB=pacsdb \
             -e POSTGRES_USER=pacs \
             -e POSTGRES_PASSWORD=pacs \
             -v /path/to/db1:/var/lib/postgresql/data \
             -d dcm4che/postgres-dcm4chee:13.1-23

Allow all hosts to replicate with this 'master' DB:

$ echo 'host replication replicator 0.0.0.0/0 trust' >> /path/to/db1/pg_hba.conf
$ cat << EOF >> /path/to/db1/postgresql.conf
wal_level = hot_standby
max_wal_senders = 3
wal_keep_size = 128
EOF

Restart the container:
```
$ docker restart db1
```

Create a user for replication:

$ docker exec -it db1 \
              su -c "psql -c \"CREATE USER replicator REPLICATION LOGIN PASSWORD 'replpass';\" pacsdb pacs"

Initialize database files of the 'slave' DB by running pg_basebackup against the 'master' DB:

$ docker run -v /path/to/db2:/var/lib/postgresql/data \
             --rm -it dcm4che/postgres-dcm4chee:13.1-23 \
             su -c "pg_basebackup -h <ip-of-db1-host> -D /var/lib/postgresql/data -Ureplicator -P -v -Xfetch -R"

Start another container with Postgres acting as 'slave' DB connected with the 'master' DB:

$ docker run --name db2 \
             -p 6432:5432 \
             -e POSTGRES_DB=pacsdb \
             -e POSTGRES_USER=pacs \
             -e POSTGRES_PASSWORD=pacs \
             -v /path/to/db2:/var/lib/postgresql/data \
             -d dcm4che/postgres-dcm4chee:13.1-23

Initiate failover from 'master' DB to 'slave' DB

Execute pg_ctl promote as user postgres in the container acting as 'slave' DB:

$ docker exec db2 runuser -u postgres pg_ctl promote
waiting for server to promote.... done
server promoted

to exit standby mode and switch the server to normal operation to act as new 'master' DB'.

Recover previous 'master' DB after failover to 'slave' DB

Ensure the previous 'master' DB is stopped and remove the container:
```
$ docker stop db1
$ docker rm -v db1
```
Delete the database files of the 'master' DB:
```
$ rm -r /path/to/db1
```

Initialize database files of the new 'slave' DB by running pg_basebackup against the new 'master' DB:

$ docker run -v /path/to/db1:/var/lib/postgresql/data \
             --rm -it dcm4che/postgres-dcm4chee:13.1-23 \
             su -c "pg_basebackup -h <ip-of-db2-host> -D /var/lib/postgresql/data -Ureplicator -P -v -Xfetch -R"

Start another container with Postgres acting as new 'slave' DB connected with the new 'master' DB:

$ docker run --name db1 \
             -p 5432:5432 \
             -e POSTGRES_DB=pacsdb \
             -e POSTGRES_USER=pacs \
             -e POSTGRES_PASSWORD=pacs \
             -v /path/to/db1:/var/lib/postgresql/data \
             -d dcm4che/postgres-dcm4chee:13.1-23

triplesixlvl / postgres-dcm4chee