oracle/instantclient:19 OCCI no connection

[DominikPutz]

I have a Oracle 19 DB running on a physical server in my environment. My goal is to run an application in a docker container that connects to the DB via Oracle OCCI.
I am using oracle/instantclient:19 and can build my application in this container successfully.
Additionally, it is also possible to connect to the database via sqlplus within the container after specifying the tnsnames.ora

DW = (DESCRIPTION =    (ADDRESS = (PROTOCOL = TCP)(HOST = host.docker.internal)(PORT = 1526))    (CONNECT_DATA =      (SERVER = DEDICATED)      (SERVICE_NAME = dw.world)    )  )

However, after running my application I cannot connect to the database and get an NLS territory error (ORA-12705: Cannot access NLS data).

Has anyone any experience with OCCI in a container? Is it work?

I am very thankful for any answer since I do not know any solution...

[cjbj]

Running in an appropriately configured container shouldn't be a problem.

You'll need to share your Dockerfile and a sample app that shows the problem.

[DominikPutz]

Thanks for the prompt reply.

Here are my steps to build my test container after pulling the image oracle/instantclient:19:
`
Run container
docker run -d -it -v /d/Temp/mount_dir:/home oracle/instantclient:19

update yum
yum update

copy sources to mounted directory

copy tnsnames

install gcc and cmake
dnf install cmake gcc-c++ make -y

ensure link of recent occi for linking (Need to do this)
cd /usr/lib/oracle/19.18/client64/lib
ln -s libocci.so.19.1 libocci.so

build
cd /home/sample
mkdir build
cd build
cmake ..
make
`

My tnsnames you can see in the opening post. It is working, because I can connect to the database.

my sample.cpp in the attachment
my CMakeLists.txt in the attachment

One thing to mention here: If I do not manually link to clntsh I get a lot of undefined references error. I found on stackoverflow, that there might be some kind of loop dependencies and I have to manually link it after OCCI, since it is automatically linked also before. This took me several hours to figure out, but anyhow - at least it is compiling without warnings/errors.

Then executing the test_occi executable:
sh-4.4# ./test_occi Opening Database Error: ORA-12705: Cannot access NLS data files or invalid environment specified free(): invalid pointer Aborted

Note, that in our mani application we use the NLS settings AMERICA and it is working. If I simply comment these two lines out and execute I get:
sh-4.4# ./test_occi Opening Database Error: ORA-24960: the attribute OCI_ATTR_USERNAME is greater than the maximum allowable length of 255 free(): invalid pointer Aborted

Thank you for your help!

sample.cpp.txt
CMakeLists.txt

[cjbj]

Can you share the Dockerfile that does the above steps? Can you do a quick check with Instant Client 21c? (The 21c RPMs create the libocci symlink(s)).

[DominikPutz]

Of course.
Thanks for the help.

Dockerfile.txt

[lesimoes]

@DominikPutz did you solve the problem?

[DominikPutz]

Not in the way I expected. It was with oracle not possible. We are now in the transition phase to postgres and I tried it already with a postgres container and it worked fine for me...

[cjbj]

Apps in containers can connect to Oracle DB without a problem. With more information about the specific container configuration we would be able to help.

[DominikPutz]

It's now almost a year but all steps are mentioned above, as well as the docker file and the sample program.
As far as I remember I could connect without problems via sqlplus from the container to an oracle db outside. But not with an OCCI application. Error message is above.