Django InformixDB

A database driver for Django to connect to an Informix database via informixdb python module.

Some limitations: - Do not support default values

Configure local environment

The following environment variables should exist:

INFORMIXDIR

The path to the Informix client install directory

INFORMIXSERVER

The name of the Informix service to which we need to connect

INFORMIXSQLHOSTS

The path to the sqlhosts file that the Informix driver should use

LD_LIBRARY_PATH

The path(s) to the various Informix library files: Usually $INFORIMIXDIR/lib:$INFORMIXDIR/lib/cli:$IMFORMIXDIR/lib/esql

You will also need to add an entry within your sqlhosts file for each remote/local Informix server connection in the following format:

<INFORMIX_SERVER_NAME>    onsoctcp     <INFORMIX_HOST_NAME>    <INFORMIX_SERVICE_NAME>
# e.g.
dev    onsoctcp    localhost    sqlexec

Finally, you need to ensure that the service name is in the /etc/services file:

sqlexec    9088/tcp

Configure settings.py

Django’s settings.py require the following format to connect to an Informix database:

'default': {
    'ENGINE': 'django_informixdb',
    'NAME': 'myproject',
    'SERVER': 'ifxserver',
    'USER' : 'testuser',
    'PASSWORD': 'passw0rd',
    'OPTIONS': {
        'DRIVER': '/path/to/iclit09b.so'. # Or iclit09b.dylib on macOS
    },
    'TEST': {
        'NAME': 'myproject',
        'CREATE_DB': False
    }
}

Using with the Docker Informix Dev Database

The docker image from IBM for the Informix developer database image behaves a little differently compared to other images. As such it needs a little extra handling, and doesn't seem to work with docker-compose

Firstly we need to download and getting it running:

$ docker run -itd --name iif_developer_edition --privileged -p 9088:9088 -p 9089:9089 -p 27017:27017 \
-p 27018:27018 -p 27883:27883 -e LICENSE=accept ibmcom/informix-developer-database:latest

This will download the image if it doesn't exist, and then run it with the name iif_developer_edition. The first time this run, the image will do a bunch of initial setup stuff. As we used the -d option, it will run in the background as a detached process. So don't be concerned that you do not see anything in the output.

You can stop and restart the container with:

docker stop iif_developer_edition
docker start iif_developer_edition

It seems that the Informix ODBC driver does not currently support creating databases. So we will need to do that manually, by attaching to the running container

docker attach iif_developer_edition

This will give you a shell on the running container, and you can therefore use dbaccess to create your database. You can exit this shell using Ctrl-p Ctrl-q without shutting down the whole container.

This Django database adaptor for Informix requires transaction support to be enabled in our database. This is not the default within the Informix Developer image. So you need to enable it on a per database basis:

$ docker attach iif_developer_edition
$ ontape -s -B <DB_NAME>

Again, you can detach using Ctrl-p Ctrl-q.

Finally you need to ensure that our local dev database is included in the sqlhosts file. e.g.:

dev    onsoctcp    localhost    sqlexec

and also in /etc/services:

sqlexec    9088/tcp

You should now be able to point Django to our local test database using the syntax detailed above.

Using Django InformixDB with docker-compose

It is possible to use the Informix developer docker image with docker-compose with a little effort.

Example docker-compose.yml

version: '3'

services:
    db:
        image: ibmcom/informix-developer-database
        tty: true # Needed to ensure container doesn't self terminate
        environment:
            LICENSE: accept
        privileged: true
        ports:
            - "9088:9088"
            - "9089:9089"
            - "27017:27017"
            - "27018:27018"
            - "27883:27883"

The key entry in the compose file which is out of the ordinary is tty: true. This allocates a (virtual) TTY to the container. The Informix developer database container expects a tty and terminates without one when run inside docker-compose.

Once it is up and running with docker-compose up you can run a bash shell on the running container with:

docker exec -it informix_db_1 bash

Where informix_db_1 is the name of the running container. From this shell you can create your DB with dbaccess etc.

Warning

This approach still requires the SDK to installed locally and the appropriate environmental variables to be set up. Along with entries in sqlhosts and /etc/services

Testing against an Informix Database

Due to a bug in the Informix ODBC driver, it is not currently possible to run Django tests normally. Specifically, it is not possible for Django to create a test database. As such, you will need to do it manually. By default Django will attempt to create a database with a name equal to the default database name with a test_ prefix. e.g. if you database name is my_database, the test database name would be test_my_database. This can be overridden with the NAME option under TEST.

To prevent Django from attempting to create a test database, set the CREATE_DB option under TEST to False: see 'Configure settings.py' above.

You can follow the steps above, in the section on using Informix locally with Docker to create a test database. Then when running the test you can tell Django to re-use an existing database, rather than trying to create a new one with the -k parameter:

./manage.py test -k