Understanding the difference in sequence of ENTRYPOINT/CMD between Dockerfile and docker run - docker

Question

Docker noob here...
I am trying to build and run an IBM DataPower container from a Dockerfile, but it doesn't seem to work the same as when just running docker run and passing the same parameters in the terminal.
This works (docker run)
docker run -it \
-v $PWD/config:/drouter/config \
-e DATAPOWER_ACCEPT_LICENSE=true \
-e DATAPOWER_INTERACTIVE=true \
-e DATAPOWER_WORKER_THREADS=4 \
-p 9090:9090 \
--name mydatapower \
ibmcom/datapower
... the key part being that it mounts the ./config folder and the custom configuration is picked up by datapower running in the container.
This doesn't (Dockerfile)
Dockerfile:
FROM ibmcom/datapower
ENV DATAPOWER_ACCEPT_LICENSE=true
ENV DATAPOWER_INTERACTIVE=true
ENV DATAPOWER_WORKER_THREADS=4
EXPOSE 9090
COPY config/auto-startup.cfg /drouter/config/auto-startup.cfg
Build:
docker build -t local/datapower .
Run:
docker run -it \
-p 9090:9090 \
--name mydatapower local/datapower
The problem is that DataPower doesn't pick up the auto-startup.cfg file, so the additional config options doesn't get used. I know the source file path is correct because if I misspell the file name docker throws an error.
I have a theory that it might be running the inherited ENTRYPOINT or CMD before the config file is available. I don't know how to test or prove this. I don't know what the ENTRYPOINT or CMD is because the inherited image is not open source and I can't figure out how to find it.
Does that seem likely?
UPDATE:
The content of the auto-startup.cfg is:
top; co
ssh
web-mgmt
admin enabled
port 9090
exit
It simply enables the DataPower WebGUI.
The output when running it in the commandline with:
docker run -it -v $PWD/config:/drouter/config -v $PWD/local:/drouter/local -e DATAPOWER_ACCEPT_LICENSE=true -e DATAPOWER_INTERACTIVE=true -e DATAPOWER_WORKER_THREADS=4 -p 9091:9090 --name myconfigureddatapower ibmcom/datapower`
...contains this:
20170908T121729.015Z [0x8100006e][system][notice] : Executing startup configuration.
20170908T121729.970Z [0x00350014][mgmt][notice] web-mgmt(WebGUI-Settings): tid(303): Operational state up
...but with Dockerfile it doesn't. That's why I think the config files may be copied into place too late.
I've tried adding CMD ["/bin/drouter"] to the end of my Dockerfile to no avail.

Answer 1

I have tested your Dockerfile and it seems to be working. My auto-startup.cfg file is copied in the proper location and when I launch the container it's reading the file.
I get this output:
[root#ip-172-30-2-164 tmp]# docker run -ti -p 9090:9090 test
20170908T123728.818Z [0x8040006b][system][notice] logging target(default-log): Logging started.
20170908T123729.067Z [0x804000fe][system][notice] : Container instance UUID: 36bcca0e-6139-4694-91b0-2b7b66c3a498, Cores: 4, vCPUs: 4, CPU model: Intel(R) Xeon(R) CPU E5-2676 v3 # 2.40GHz, Memory: 16049.1MB, Platform: docker, OS: dpos, Edition: developers-limited, Up time: 0 minutes
20170908T123729.071Z [0x8040001c][system][notice] : DataPower IDG is on-line.
20170908T123729.071Z [0x8100006f][system][notice] : Executing default startup configuration.
20170908T123729.416Z [0x8100006d][system][notice] : Executing system configuration.
20170908T123729.417Z [0x8100006b][mgmt][notice] domain(default): tid(8143): Domain operational state is up.
708f98be1390
Unauthorized access prohibited.
20170908T123731.239Z [0x806000dd][system][notice] cert-monitor(Certificate Monitor): tid(399): Enabling Certificate Monitor to scan once every 1 days for soon to expire certificates
20170908T123731.552Z [0x8100006e][system][notice] : Executing startup configuration.
20170908T123732.436Z [0x8100003b][mgmt][notice] domain(default): Domain configured successfully.
20170908T123732.449Z [0x00350014][mgmt][notice] web-mgmt(WebGUI-Settings): tid(303): Operational state up
login:
To check that your file has been copied to the container you can run docker run -ti local/datapower sh to enter the container and then check the content of /drouter/config/.
Your base image command is: CMD ["/bin/drouter"] you can check it running docker history ibmcom/datapower.
UPDATE:
The drouter user in the container must be able to read the auto-startup.cfg file. You have 2 options:
set your local auto-startup.cfg with the proper permissions (chmod 644 config/autostart.cfg).
or add these line in the Dockerfile so drouter can read the file:
USER root
RUN chown drouter /drouter/config/auto-startup.cfg
USER drouter