Cannot get Variable replacement in Custom Templates to work

[phermsdorf]

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Hi,

I'm on a Busines Edition of Portainer 2.39.0 LTS and wanted to try out the Custom Templates functionality.

I've defined a compose.yml for the template like this:

services:
   wildfly:
      extends:
         file: docker-compose-base.yml
         service: wildfly-base
      image: wildfly-26-pr
      depends_on:
         postgres-casy:
            condition: service_healthy
      environment:
         PR_NUMBER: "{{ PULL_REQUEST }}"
      ports:
        - "{{ WILDFLY_PORT }}:8080"

   postgres-casy:
      extends:
         file: docker-compose-base.yml
         service: postgres-base
      image: postgres17-pr:casy
      ports:
        - "${POSTGRES_HOST_PORT:-5432}:5432"

I created a new Custom Templated based on this config from a git repo. I've added manually (they were not automatically extracted when pulling the .yml from git) the Variables PULL_REQUEST and WILDFLY_PORT.

When trying to create and start a stack based on this config and supplying a free port value for WILDFLY_PORT like 8090 i get the error message:
Failed to deploy a stack: failed to create compose project: failed to load the compose file : invalid hostPort: {{ WILDFLY_PORT }}

So from MPOV it looks like the replacemnt does not take place.

In the preview btw it seems to look correct:

ports:
        - "8090:8080"

When removing the double qoutes around the ports definition like this

      ports:
        - {{ WILDFLY_PORT }}:8080

the error changes to a parser error like this:
Failed to deploy a stack: failed to create compose project: failed to load the compose file : failed to parse /data/compose/36/1e997cc8844881123d6e2ec392481e74a1dfae83/portainer-templates/compose-casy.yml: yaml: line 14: did not find expected '-' indicator

I would have expected that the replacement takes place before handing the final file to docker compose.

Any ideas's und suggestions what else to try?

Thanks, Bye Peter

[phermsdorf]

when looking at the default templates eg. here https://github.com/portainer/templates/blob/v3/stacks/dokku/docker-compose.yml
i get the impression that using this {{ VAR_NAME }} syntax as stated here in the doc's does not seem to be right and lead to the problem i'm seeing ...

Using the ${VAR_NAME} syntax makes the parser errors go away, but the variables are not ending up in the started containers as well.

[Nick-Portainer]

Hi @phermsdorf can you please give me a breakdown to reproduce this.

Can you confirm you are referencing your compose template from a Git Repo, or are you using the web editor. if you are doing Git Based can you please provide screenshots of how you are assigning the variables for the template under "Variables definition"

[phermsdorf]

As stated above, I'm pulling the compose file and the referenced base yml file from a git repo.
The variables are configured like this:

As stated above: I've added these manually. I don't know if it would be the expected behaviour that they should get extracted automatically out of the yml file ...

[Nick-Portainer]

Thank you @phermsdorf We have reproduced this, from our findings when deploying a custom template via the Stack screen this does not cause any errors and deploys, but when deploying via the Custom template screen this is when the error occurs. Can you please confirm this is the same for you?

[phermsdorf]

yes that seems to be the case.
Thanks for looking into the issue.

[phermsdorf]

Should i create an issue for that problem or do you track that somewhere else?

[Nick-Portainer]

We are tracking this internally and will provide updates when we can.

internal: BE-12781