Experimental Physics and
Industrial Control System

Hello Dale, hello Florian,

many thanks for your helpful advises. Now I could solve the issue simply by adding "network_mode: host" to the service "epicsbase".

Now my working docker-compose.yml  looks like:

services:
    epicsbase:
       image: softioc
       container_name: epicsbase
       volumes:
          - ./epicsbase/db:/usr/local/db
       working_dir: /usr/local/epics
       command:
          - /bin/sh
          - -c
          - |
          echo start first Soft IOC
          screen -d -m /usr/local/epics/epics-base/bin/linux-x86_64/softIoc -D /usr/local/epics/epics-base/dbd/softIoc.dbd -d /usr/local/db/test.db
          tail -f /dev/null # keep alive

       network_mode: host

Best regards
Carsten

--------------------Ursprüngliche Nachricht--------------------
Von: Dale Cox <cdc05g at acu.edu>
Gesendet: Montag 25. März 2024 21:14
An: Carsten Winkler <carsten.winkler at helmholtz-berlin.de>
CC: tech-talk at aps.anl.gov
Betreff: Re: How can I get a PV from an external server from inside a docker container?

sorry, this might show up twice.  I replied with the wrong email address.

Hello Carsten,

We run a couple of EPICS services in docker containers at NEXT, so hopefully this is helpful.  I don't think we have any docker IOC's, but we run the archivers dockerized, which use channel access.  If I'm not mistaken - the initial connection when an IOC advertises is done via broadcast.  Docker overlay networks don't pass on broadcast traffic by default.  So we had to find a way to allow that initial handshake to happen.  We created a macvlan network on the docker host, which will pass on broadcasts.

https://docs.docker.com/network/drivers/macvlan/

So after creating the macvlan network shown in the above link, the relevant docker-compose section would reference that network.  You can see that our archive engine has it's own IP address:

---

services:

  archive-engine:
    ...
    networks:
      epics:
        ipv4_address: 10.0.0.2

...

networks:
  epics:
    external: true
    name: epics_macvlan

---

That's what we did anyway, and my archive engine is able to span 2 different networks and talk to iocs, as well as write data to the database on a different network.

Dale

On Mon, Mar 25, 2024 at 8:55 AM Carsten Winkler via Tech-talk <tech-talk at aps.anl.gov> wrote:

Hello,

I have 3 SoftIOCs.
    1.) local host       = 193.100.100.100 with PV: "local_pv"
    2.) external host  = 192.200.200.200 with PV: "external_pv"
    3.) docker container    on local host   with PV: "docker_pv"

From local host I can read all PVs (caget local_pv external_pv docker_pv). 👍
From inside the docker container I can read the local_pv and the docker_pv
but not the external_pv. 🤔

Here is my docker compose configuration:

services:
    epicsbase:
       image: softioc
       container_name: epicsbase
       volumes:
          - ./epicsbase/db:/usr/local/db
       working_dir: /usr/local/epics
       command:
          - /bin/sh
          - -c
          - |
          echo start first Soft IOC
          screen -d -m /usr/local/epics/epics-base/bin/linux-x86_64/softIoc -D /usr/local/epics/epics-base/dbd/softIoc.dbd -d /usr/local/db/test.db
          tail -f /dev/null # keep alive
       networks:
          - ioc-net
networks:
    ioc-net:

From inside the docker container I have also already tried EPICS_CA_AUTO_ADDR_LIST / EPICS_CA_ADDR_LIST. Unfortunately without success.
With and without these environment variables I only get the local_pv and the docker_pv.

How can I also read the external_pv from inside the docker container?

Best regards
Carsten

--

Dale Cox

Instrumentation and Electrical Engineer

ACU NEXT Lab 

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