Environment and pre-defined variables are not supported in `forwardPorts` and keys of `portsAttributes`

[i-ky]

To avoid hardcoding hostnames I am using environment variables, e.g. ${POSTGRES_HOSTNAME}. This allows pointing application or any supplementary scripts to the correct host depending on the environment (e.g. in and out of dev container). Same variables are used as hostname: in Docker Compose files:

services:
  postgres:
    image: postgres:latest
    hostname: ${POSTGRES_HOSTNAME}
    ...
  ...

And same variables should be used in forwardPorts and portsAttributes of dev container configuration:

{
    ...
    "forwardPorts": [
        "${containerEnv:POSTGRES_HOSTNAME}:5432",
        ...
    ],
    "portsAttributes": {
        "${containerEnv:POSTGRES_HOSTNAME}:5432": {
            ...
        },
        ...
    },
    ...
}

Unfortunately, forwardPorts and portsAttributes don't support variables, so it needs to be hardcoded instead:

{
    ...
    "forwardPorts": [
        "postgres:5432",
        ...
    ],
    "portsAttributes": {
        "postgres:5432": {
            ...
        },
        ...
    },
    ...
}

...meaning that hostname needs to be changed manually in two more places if the environment variable changes.

[chrmarti]

Does ${localEnv:POSTGRES_HOSTNAME} work?

[i-ky]

Hi @chrmarti!

Thank you for looking into this.

I am not sure what "work" means if we are talking about the spec here. Do you have a specific implementation in mind?

https://containers.dev/implementors/json_reference/ seems to talk about pre-defined variables as a whole. Either

Environment and pre-defined variables may be referenced in the values.

...or nothing at all. So my expectation is that if containerEnv: does not work, neither will localEnv:.

[chrmarti]

containerEnv: only works with container env variables and I don't see from your report if you set POSTGRES_HOSTNAME in the container. I do see that you are using the local env variable POSTGRES_HOSTNAME in the docker-compose.yml, so localEnv: might work, depending on where you set POSTGRES_HOSTNAME locally.

[i-ky]

I don't see from your report if you set POSTGRES_HOSTNAME in the container. I do see that you are using the local env variable POSTGRES_HOSTNAME in the docker-compose.yml, so localEnv: might work, depending on where you set POSTGRES_HOSTNAME locally.

Sorry, I didn't mention it. POSTGRES_HOSTNAME is set in .env file (from there POSTGRES_HOSTNAME gets into Compose file) and .env file is also passed to the dev container in Compose file as env_file: (this is how POSTGRES_HOSTNAME gets into container environment).

Since POSTGRES_HOSTNAME is not set in host environment, I think that localEnv: will not work. Do you want me to try?

[LabTopProductions]

Please help me with this issue and report back on things that are not working properly in my dev containers for the account I have been using for the last two months I need to get a new one I don’t know what to do with this issue but please advise

Brecht Vrolix

On Tue, 17 Sep 2024 at 11:20, i-ky @.***> wrote:

I don't see from your report if you set POSTGRES_HOSTNAME in the container. I do see that you are using the local env variable POSTGRES_HOSTNAME in the docker-compose.yml, so localEnv: might work, depending on where you set POSTGRES_HOSTNAME locally.

Sorry, I didn't mention it. POSTGRES_HOSTNAME is set in .env file (from there POSTGRES_HOSTNAME gets into Compose file) and .env file is also passed to the dev container in Compose file as env_file: (this is how POSTGRES_HOSTNAME gets into container environment).

Since POSTGRES_HOSTNAME is not set in host environment, I think that localEnv: will not work. Do you want me to try?

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[chrmarti]

Since POSTGRES_HOSTNAME is not set in host environment, I think that localEnv: will not work. Do you want me to try?

You're right. Support for env files has come up before. Related: https://github.com/microsoft/vscode-remote-release/issues/3007

[i-ky]

Since POSTGRES_HOSTNAME is not set in host environment, I think that localEnv: will not work. Do you want me to try?

You're right. Support for env files has come up before. Related: microsoft/vscode-remote-release#3007

Are you implying that if POSTGRES_HOSTNAME was set in host environment then localEnv: would work in forwardPorts?