Variables

Variables provide template substitution in Units and reusable run definitions.

[[variable]]
name = "someservice"
default = { exec = "/bin/tcp", args = ["makano-test"], env = { PORT = "4533" } }

Field	Type	Purpose
name	string	Unique variable name
default	table	Inline { exec, args, env } definition
env	string	Environment variable name to source the definition from

Using Variables in Services

[[variable]]
name = "my-bin"
default = { exec = "/usr/bin/my-app", args = ["--port", "8080"] }
 
[[service]]
name = "app"
run.variable = "my-bin"        # references the variable above

Environment-Sourced Variables

[[variable]]
name = "custom-path"
env = "RIND_CUSTOM_BIN"        # read from daemon environment at load time

Default Structure

[[variable]]
name = "webserver"
default = {
    exec = "/usr/bin/httpd",
    args = ["-f", "/etc/httpd/httpd.conf"],
    env = { PORT = "80", LOG_DIR = "/var/log/httpd" },
}
 

VariableHeap

The runtime store for variables. Variables are registered from unit definitions, then resolved at runtime with environment variable fallbacks.

pub struct VariableHeap {
    values: HashMap<Ustr, toml::Value>,
    defaults: HashMap<Ustr, toml::Value>,
    env_mappings: HashMap<Ustr, Ustr>,
    path: PathBuf,
}
 
impl VariableHeap {
    pub const KEY: &str = "runtime:variable_heap";
    pub fn new(path: impl Into<PathBuf>) -> Self;
    pub fn register(&mut self, id: impl Into<Ustr>, default: Option<toml::Value>, env: Option<Ustr>);
    pub fn set(&mut self, id: impl Into<Ustr>, value: toml::Value);
    pub fn get(&self, id: &str) -> Option<toml::Value>;
    pub fn get_full(&self, name: &Ustr) -> Option<(toml::Value, toml::Value)>;
    pub fn all(&self) -> impl Iterator<Item = (&Ustr, &toml::Value, toml::Value)>;
    pub fn contains(&self, id: &str) -> bool;
    pub fn load(&mut self) -> Result<Void>;
    pub fn save(&self) -> Result<Void>;
}

Variable resolution order: runtime values > environment variable > defaults.

See also: Services, Units, Scopes, Orchestrators