vieter/src/env.v

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Coq
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module env
import os
// The prefix that every environment variable should have
const prefix = 'VIETER_'
// The suffix an environment variable in order for it to be loaded from a file
// instead
const file_suffix = '_FILE'
pub struct ServerConfig {
pub:
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log_level string [default: WARN]
log_file string [default: 'vieter.log']
pkg_dir string
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download_dir string
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api_key string
repo_dir string
repos_file string
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}
pub struct BuildConfig {
pub:
api_key string
address string
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}
fn get_env_var(field_name string) ?string {
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env_var_name := '$env.prefix$field_name.to_upper()'
env_file_name := '$env.prefix$field_name.to_upper()$env.file_suffix'
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env_var := os.getenv(env_var_name)
env_file := os.getenv(env_file_name)
// If both aren't set, we report them missing
if env_var == '' && env_file == '' {
return error('Either $env_var_name or $env_file_name is required.')
}
// If they're both set, we report a conflict
if env_var != '' && env_file != '' {
return error('Only one of $env_var_name or $env_file_name can be defined.')
}
// If it's the env var itself, we return it.
// I'm pretty sure this also prevents variable ending in _FILE (e.g.
// VIETER_LOG_FILE) from being mistakingely read as an _FILE suffixed env
// var.
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if env_var != '' {
return env_var
}
// Otherwise, we process the file
return os.read_file(env_file) or {
error('Failed to read file defined in $env_file_name: ${err.msg}.')
}
}
// load<T> attempts to create the given type from environment variables. For
// each field, the corresponding env var is its name in uppercase prepended
// with the hardcoded prefix. If this one isn't present, it looks for the env
// var with the file_suffix suffix.
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pub fn load<T>() ?T {
res := T{}
$for field in T.fields {
res.$(field.name) = get_env_var(field.name) or {
// We use the default instead, if it's present
mut default := ''
for attr in field.attrs {
if attr.starts_with('default: ') {
default = attr[9..]
break
}
}
if default == '' {
return err
}
default
}
}
return res
}