Oracle Database on Docker

Deploying Oracle Database on
Docker: lessons learned
04.12.2018 Franck Pachot - Oracle on Docker 1

Who am I?
Franck Pachot
Data Engineer at CERN
• Twitter @FranckPachot
• Medium: https://medium.com/@FranckPachot
• Blog Databases at CERN: db-blog.web.cern.ch/

Oracle
Database
on Docker
lightweight ephemeral isolated
containers to run applications
persistent != ephemeral
shared != isolated
data != application
8GB Oracle Home != lightweight
+ 1GB for an empty database

Why running Oracle on Docker?
Because:
• “Docker is cool”
• “We run everything on Docker”
• “We do that with PostgreSQL, MySQL and we just want to do the same”
• “We don’t want to waste time in installation”
This has nothing to do with a solution to try to solve a problem 🤔

Build or run from existing?
Docker Hub:
• Oracle does not allow to distribute the software.
• You pay for all CPU where the software is installed
• So, except for Oracle XE, just forget it
Docker Store:
• Here you accept once and can pull the official image
docker login
• but look at the image…

Docker Store
The image is just a tar of Oracle Home and tar of Database:
# docker run -p 0.0.0.0:9001:1521 store/oracle/database-enterprise:12.2.0.1
…
untar DB bits ......
log file is : /home/oracle/setup/log/untarDB.log
untarDB.sh is done at 230 sec
…
Scripts in /home/oracle/setup Software in /tmp/dbsetup/dbtar
[oracle@523de29307ed setup]$ du -ha /tmp/dbsetup/dbtar
2.1G /tmp/dbsetup/dbtar/db12.2.0.1.0.tar.gz
573M /tmp/dbsetup/dbtar/dbf_12201.tar.gz
2.6G /tmp/dbsetup/dbtar

Docker Store
Oracle has its own repository: https://container-registry.oracle.com
• You login with your Oracle account and accept the licence
# docker login container-registry-frankfurt.oracle.com
Username: my-oracle-sso@pachot.net
Password:
# docker pull container-registry-frankfurt.oracle.com
/database/enterprise:12.2.0.1

racle build scripts
Maintained by Oracle, multiple versions, even RAC
https://github.com/oracle/docker-images/tree/master/OracleDatabase
But you need to download the installation .zip, send it to the context
(5GB), unzip… And at ‘docker run’ you will wait 15 minutes for the
database creation.
Good to test your config, but try to give that to your developers and you
will understand that you need to be more creative…

Containers
Docker container is process isolation
Namespaces
• Processes (PID)
• Networking (port)
• Filesystem (chroot)
Resources
• cgroups (control groups)
Security
• seccomp (security profiles)
https://jvns.ca/blog/2016/10/10/what-even-is-a-container
1982: chroot
2000: Freebsd jails
2001: Linux vserver
2004: Solaris zones
2005: OpenVZ
2008: LXC
2010: Systemd-nspawn
2013: Docker

Namespaces – PID 1 in host
[root@fpachot-docker ~]# pstree -p | more
systemd(1)-+-NetworkManager(689)-+-dhclient(1054)
|-dockerd(17964)-+-containerd(17981)-+-containerd-shim(22331)-+-bash(22348)-+-ora_aqpc_orclcd(22608)
| | | | |-ora_cjq0_orclcd(22921)
| | | | |-ora_ckpt_orclcd(22489)
| | | | |-ora_clmn_orclcd(22449)
| | | | |-ora_d000_orclcd(22515)
| | | | |-ora_dbrm_orclcd(22474)
| | | | |-ora_dbw0_orclcd(22485)
| | | | |-ora_dia0_orclcd(22483)
| | | | |-ora_diag_orclcd(22468)
| | | | |-ora_gen0_orclcd(22458)
[root@fpachot-docker ~]# ps –f -p 22348
UID PID PPID C STIME TTY TIME CMD
----- ----- ----- - ----- ----- -------- ------------------------------------------
54321 22348 22331 0 23:00 pts/0 00:00:00 /bin/bash /home/oracle/setup/dockerInit.sh

Namespaces – PID 1 in container
[root@fpachot-docker ~]# docker exec ora001 pstree -p | more
bash(1)-+-ora_aqpc_orclcd(118)
|-ora_cjq0_orclcd(349)
|-ora_ckpt_orclcd(68)
|-ora_clmn_orclcd(30)
|-ora_d000_orclcd(94)
|-ora_dbrm_orclcd(54)
|-ora_dbw0_orclcd(64)
|-ora_dia0_orclcd(62)
|-ora_diag_orclcd(48)
|-ora_gen0_orclcd(38)
[root@fpachot-docker ~]# docker exec cc ps –f -p 1
UID PID PPID C STIME TTY TIME CMD
----- ----- ----- - ----- ----- -------- ------------------------------------------
oracle 1 0 0 22:00 pts/0 00:00:00 /bin/bash /home/oracle/setup/dockerInit.sh

Layers…
Docker builds images as layers
• you pull an existing image
• you add layers for the build steps, components, options, updates…
• very easy to maintain: any change starts from previous layer
Once built, all image layers are read-only and can be shared
A container (created by ‘docker run’) reads from the image
and adds a read-write layer to run the application

Layers…
my runtime environment
my updated libraries
my additional option
my configuration files
my software libraries
my OS prerequisites
My base
image
Read-Write
Read-Only

Oracle Software
The distribution
.zip (or .rpm)
The Oracle Home
with many files used only for
install, create, relink,…

Tips to build the image
• send the context only once
- next layers on a new Dockerfile, or use ADD from a NFS server container
• long operations, access to internet,… in first steps
- all yum updates on first step, rm /var/cache/yum at the end
• use layers for better agility
- filesystem with compression, maybe deduplication
• shrink all that at the end (COPY --from= or docker commit)
you can try experimental build --squash (I’m not convinced)
• Goal: have a small image with fast docker run

Multiple stage build
The Dockerfile to send the 3.6 GB context
FROM oraclelinux:7-slim
WORKDIR /var/tmp
ADD oracle-database-xe-18c-1.0-1.x86_64.rpm .
# docker image build -t franck/oraclexe18c:rpm .
Another Dockerfile to update the packages
FROM franck/oraclexe18c:rpm
USER root
WORKDIR /var/tmp
RUN yum install -y oracle-database-preinstall-18c
RUN ORACLE_DOCKER_INSTALL=true yum -y localinstall oracle-datab*.rpm .
RUN rm oracle-database-xe-18c-1.0-1.x86_64.rpm

The storage driver
People are lazy and take the default (overlay2)
But what we do here is the opposite of the default Docker usage
Overlay2 copies the whole file when one byte is changed or appended
For big containers, you need copy-on-write at block level
• zfs is a good choice for high-density workloads such as PaaS.
• BTRFS does CoW at block level, as ZFS
• compression? de-duplication?

0
5
10
15
20
25
30
35
40
45
0
10
20
30
40
50
60
70
80
90
(blank)
lzo
(blank)
dedup
compress
compressdedup
(blank)
dedup
compress
compressdedup
(blank)
dedup
compress
compressdedup
(blank)
dedup
compress
compressdedup
(blank)
dedup
compress
compressdedup
btrfs zfs 128k zfs 32k zfs 16k zfs 8k zfs 2k
Average of Gbytes Average of Build(min) Average of Run(min)
Imagesize(Gbytes)
build/runtime(minutes)
ZFS vs. BTRFS

Which OS to run on?
Doc ID 2216342.1
• Oracle Linux 7 with UEK4 (and later)
• Red Hat Enterprise Linux 7
But actually, do you have the choice?
• Your container environment is not dedicated to Oracle database
- OpenShift cluster
- Developer Laptop
• You will have hard time to get the best OS and FS for Oracle Database

Oh… and about where to run…
Licensing in processor metric
• you pay Oracle for all processors
(cores in EE, Socket in SE2)
in the physical servers your containers may run
Licensing in NUP+ metric
• You still count the processors for the minimum NUP
- 25 NUP per processor (0.5 Intel Core) in EE
- 10 NUP per server in SE2
Do you still want to run Oracle on Docker?

Install Docker on Centos 7.5
yum-config-manager --add-repo
https://download.docker.com/linux/centos/docker-ce.repo
yum install docker-ce
==========================================================================
Package Arch Version Repository Size
==========================================================================
Installing:
docker-ce x86_64 3:18.09.0-3.el7 docker-ce-stable 19 M
Installing for dependencies:
container-selinux noarch 2:2.68-1.el7 extras 36 k
containerd.io x86_64 1.2.0-3.el7 docker-ce-stable 22 M
docker-ce-cli x86_64 1:18.09.0-3.el7 docker-ce-stable 14 M
libtool-ltdl x86_64 2.4.2-22.el7_3 base 49 k
systemctl enable docker ; systemctl start docker

Install BTRFS on Centos 7.5
yum install btfrs-progs
mkfs.btrfs -f /dev/sdc
mkdir /mnt/docker-root-btrfs
mount -t btrfs –o compress=lzo /dev/sdc /mnt/docker-root-btrfs
# set this filesystem as docker root (default is /var/lib/docker)
systemctl stop docker
sed -ie
'/ExecStart/s?dockerd.*?dockerd --data-root=/mnt/docker-root-btrfs?'
/lib/systemd/system/docker.service
systemctl start docker
docker info | grep Root

Image is built, but …
Happy to give a 8GB to the developers… which takes 5 minutes to run?
# docker run container-registry…/enterprise:12.2.0.1 2>&1 | ts
Nov 17 22:40:00 Setup Oracle Database
…
Nov 17 22:45:18 Completed: alter pluggable database ORCLPDB1 open
And each container takes a few GB non shareable 🤔
# docker container ps -as
CONTAINER ID IMAGE SIZE
6265a4c28128 …/enterprise:12.2.0.1 4.81GB (virtual 8.24GB)

.dbf in image or external volume?
If we create the database in the image, at build
- it is not persistent (containers should be ephemeral)
- but docker run is fast (instance startup only)
- ok for CI Unit Testing, not for Development database
If the database is in external volume (docker volume or dNFS)
- can be shared in the cluster, is backed-up
- but takes several minutes to start and is very large
The problem: not easy split of software between image and container

Where is the oracle software?
Docker should be software as container layers, data in external volume
ORACLE_HOME host directory
• the binaries (bin/oracle, lib/libserver18.so)
• some other files
• exclusively software in 18c Read-Only Oracle Home
shipped: as 8GB
useful: 300MB
SYSTEM/SYSAUX tablespaces
• the dbms packages, the dictionary views
• there is also non-software in those datafiles
shipped: as 600GB

Where is the database?
The mix of software (binaries) with data/metadata (configuration files,
log, audit, statistics,…) has evolved slowly:
• Read-Only Oracle Home in 18c
• Multitenant in 12c
But CDB$ROOT SYSTEM/SYSAUX tablespace does not only contain
software. We need a Read-Only SYSTEM tablespace!
3 ideas depending on the context…

1. CloneDB to write in sparse files
CDB
CDB$
ROOT
PDB$
SEED
PDB
PDB_APP1:USER_DATA1
PDB_APP1:SYSAUX
PDB$SEED:SYSAUX
PDB$SEED:SYSTEM
CDB$ROOT:UNDO
CDB$ROOT:SYSAUX
CDB$ROOT:SYSTEM
PDB_APP1:SYSTEM
control file
online redo logs
datafile sparse files
clonedb=true
clonedb_dir=…
Dockerimage
Externalvolume

1. CloneDB to write in sparse files
My 1st idea was to create the database in the container, set it read-only,
and have copy-on-write sparse files in external volume
• controlfile and redologs in volume as well
• works in multitenant 12c but not in 18c:
SQL> exec for i in (select name from v$datafile) loop
dbms_dnfs.clonedb_renamefile(i.name,i.name||'.cow'); end loop;
*
ERROR at line 1:
ORA-17644: clonedb_renamefile interface is not supported in a multitenant
container database.
ORA-06512: at "SYS.X$DBMS_DNFS", line 10

2. Multitenant: CDB in the image
CDB
CDB$
ROOT
PDB$
SEED
PDB
PDB_APP1:USER_DATA1
PDB_APP1:SYSAUX
PDB$SEED:SYSAUX
PDB$SEED:SYSTEM
CDB$ROOT:UNDO
CDB$ROOT:SYSAUX
CDB$ROOT:SYSTEM
PDB_APP1:SYSTEM
control file
online redo logs
Dockerimage
Externalvolume

2. Multitenant: CDB in the image
In multitenant, pluggable databases is what contains only user data
• this belongs to external volume
Can we create CDB$ROOT in the image?
• docker run will only CREATE PLUGGABLE DATABASE (fast & small)
- or plug and datapatch if the volume contains an unplugged PDB (.xml)
• docker stop will unplug the PDB, docker start will plug it
• docker kill will try to unplug the PDB.
• but a crash will need to start with the same container to recover it
- because consistency requires the CDB with redo log

3. Client containers + Multitenant
CDB
CDB$
ROOT
PDB$
SEED
PDB
PDB_APP1:USER_DATA1
PDB_APP1:SYSAUX
PDB$SEED:SYSAUX
PDB$SEED:SYSTEM
CDB$ROOT:UNDO
CDB$ROOT:SYSAUX
CDB$ROOT:SYSTEM
PDB_APP1:SYSTEM
control file
online redo logsDockerimage
ExternalCDB
SQL*Net
clientonly

3.Docker container + Multitenant
If the goal of the developer is to have a small fast container
• you can host the databases as PDBs in a CDB (can be Cloud)
- see it as an external volume
• you provide a small container to create/start /stop/kill
- which will do the CREATE/OPEN/CLOSE/DROP pluggable database calls
• The container may provide a connection proxy (ssh tunnel? CMAN?)
• The PDB can also be a Cloud service

Core Message
• Docker is not intended for Oracle Database
Oracle Database is not intended for Docker
- mismatch in all areas: install, deploy, store, run, operate, license…
• Some (unsupported) solutions may exist:
- first define a clear goal, and adapt to it,
“we want to run on Oracle on Docker” is not a requirement
• Multitenant: Pluggable Databases are the containers for databases

• Tim Hall (oracle-base.com)
- https://oracle-base.com/articles/linux/docker-oracle-database-on-docker
• Frits Hoogland (Dockerfile using Maris Elsins getMOSPatch.sh)
- https://fritshoogland.wordpress.com/2015/08/11/installing-the-oracle-database-in-docker/
• Gerald Venzl
- https://www.slideshare.net/gvenzl/dockerizing-oracle-database
• Tech18:
#PASSTHEKNOWLEDGE

Oracle Database on Docker

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