Allow env variables to reference previously defined env vars in same configuration file

[pdecat]

I often find myself having to reference environment variables from others, e.g.:

rtx env-vars TEST_RTX1="1"
rtx env-vars TEST_RTX2="{{env.TEST_RTX1}}/bin"
rtx error parsing config file: ~/.rtx.toml
rtx failed to parse template: env.TEST_RTX2='{{env.TEST_RTX1}}/bin'
rtx Failed to render '__tera_one_off'
rtx Variable `env.TEST_RTX1` not found in context while rendering '__tera_one_off'
rtx Run with --verbose or RTX_VERBOSE=1 for more information

[env]
TEST_RTX1 = "1"
TEST_RTX2 = "{{env.TEST_RTX1}}"

Would it possible to add support for this?

[pdecat]

Bonus points to allow referencing such variables in env_path too. :)

[jdx]

I think this could be done. We read each env var one at a time so we could modify the tera context while we read in the file.

Here is where we parse the env vars in the toml parser:

https://github.com/jdx/rtx/blob/2b4388833081d9cb7433c614d529b7c62716bc22/src/config/config_file/rtx_toml.rs#L116-L132

What it does is call parse_template() which uses self.context which has the env vars inside of it. The context is generated when the parsing starts:

https://github.com/jdx/rtx/blob/2b4388833081d9cb7433c614d529b7c62716bc22/src/config/config_file/rtx_toml.rs#L46-L47

Then it looks like it becomes immutable and never changes. I think what we would want to do is probably wrap it in a Mutex so we can modify it and each time we read an env var we will write to the context and update values.

However this is only within a single file. If you wanted to have ~/src/myproj/.rtx.toml read env vars that ~/.config/rtx/config.toml created that would be far, far more difficult because config parsing happens in parallel. I think what we would need to do is make just the env var populating happen in series but the rest of the parsing still happen in parallel.

[jdx]

you have no idea how much work this was, but it's out now. I had to completely rewrite basically everything involving env vars in the project. I felt this was an essential feature though.

[pdecat]

Awesome, thanks @jdx!