feat: Adds compatible syntax for docker-compose interpolation

Author: andyquinterom

Cargo.lock

@@ -11,7 +11,7 @@ clap = { version = "4.5.18", features = ["derive"] }
 cron = { version = "0.15.0", features = ["serde"] }
 env_logger = "0.11.5"
 log = "0.4.22"
-minijinja = "2.12.0"
+minijinja = { version = "2.12.0", features = ["custom_syntax"] }
 rayon = "1.11.0"
 sd-notify = "0.4.2"
 serde = { version = "1.0.210", features = ["derive"] }

Cargo.toml

@@ -172,7 +172,11 @@ In this example, the service defined in the `backup-service` directory will only
 
 ### Step 6: Using Variables (Optional)
 
-Dispenser supports using variables in your configuration file via `dispenser.vars`. This file allows you to define values that can be reused inside `dispenser.toml` using `{{ VARIABLE }}` syntax.
+Dispenser supports using variables in your configuration file via `dispenser.vars`. This file allows you to define values that can be reused inside `dispenser.toml` using `${VARIABLE}` syntax.
+
+**Note:** While Dispenser uses the `${}` syntax similar to Docker Compose, it does not support all [Docker Compose interpolation features](https://docs.docker.com/compose/how-tos/environment-variables/variable-interpolation/) (such as default values `:-` or error messages `:?`) within `dispenser.toml`.
+
+However, variables defined in `dispenser.vars` are passed as environment variables to the underlying `docker compose` commands. This allows you to use them in your `docker-compose.yaml` files, where full Docker Compose interpolation is supported.
 
 This is useful for reusing the same configuration in multiple deployments.
 
@@ -194,7 +198,18 @@ This is useful for reusing the same configuration in multiple deployments.
     ```toml
     [[instance]]
     path = "my-app"
-    images = [{ registry = "{{ registry_url }}", name = "my-org/my-app", tag = "{{ app_version }}" }]
+    images = [{ registry = "${registry_url}", name = "my-org/my-app", tag = "${app_version}" }]
+    ```
+
+4.  Use these variables in your `docker-compose.yaml`.
+
+    ```yaml
+    services:
+      my-app:
+        # You can use the variables defined in dispenser.vars here
+        image: ${registry_url}/my-org/my-app:${app_version}
+        ports:
+          - "8080:80"
     ```
 
 ### Step 7: Validating Configuration
@@ -219,8 +234,8 @@ If there's an error `dispenser` will show you a detailed error message.
    2 |
    3 | [[instance]]
    4 | path = "nginx"
-   5 > images = [{ registry = "{{ missing }}", name = "nginx", tag = "latest" }]
-     i                            ^^^^^^^ undefined value
+   5 > images = [{ registry = "${missing}", name = "nginx", tag = "latest" }]
+     i                         ^^^^^^^^^^ undefined value
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 No referenced variables
 -------------------------------------------------------------------------------

README.md

@@ -4,7 +4,7 @@ delay = 60
 path = "nginx"
 # This service will be started immediately on startup, which is the default behavior.
 # It will be updated if a new 'nginx:latest' image is detected.
-images = [{ registry = "{{docker_io}}", name = "nginx", tag = "latest" }]
+images = [{ registry = "${docker_io}", name = "nginx", tag = "latest" }]
 
 [[instance]]
 path = "hello-world"

example/dispenser.toml

@@ -1,6 +1,6 @@
 version: "3.8"
 services:
   nginx:
-    image: nginx:latest
+    image: ${docker_io}/nginx:latest
     ports:
       - "8080:80"

example/nginx/docker-compose.yaml

@@ -1,6 +1,8 @@
 use rayon::prelude::*;
+use serde::Serialize;
 
 use std::{
+    collections::HashMap,
     num::NonZeroU64,
     path::PathBuf,
     sync::{Arc, Mutex},
@@ -13,6 +15,27 @@ use crate::{
     manifests::DockerWatcher,
 };
 
+#[derive(Debug, Default, PartialEq, Eq)]
+pub struct DispenserVars {
+    pub inner: Arc<HashMap<String, String>>,
+}
+
+impl Clone for DispenserVars {
+    fn clone(&self) -> Self {
+        let inner = Arc::clone(&self.inner);
+        Self { inner }
+    }
+}
+
+impl Serialize for DispenserVars {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        self.inner.serialize(serializer)
+    }
+}
+
 pub struct ContposeConfig {
     pub delay: NonZeroU64,
     pub instances: Vec<ContposeInstanceConfig>,
@@ -52,6 +75,7 @@ pub struct ContposeInstanceConfig {
     /// - `Immediately` (default): The service is started as soon as the application starts.
     /// - `OnTrigger`: The service is started only when a trigger occurs (e.g., a cron schedule or a detected image update).
     pub initialize: Initialize,
+    pub vars: DispenserVars,
 }
 
 #[derive(Clone)]

src/config.rs

@@ -2,11 +2,11 @@ use minijinja::Environment;
 use rayon::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use std::{collections::HashMap, num::NonZeroU64, path::PathBuf};
+use std::{collections::HashMap, num::NonZeroU64, path::PathBuf, sync::Arc};
 
 use cron::Schedule;
 
-#[derive(Debug, Default)]
+#[derive(Debug, Default, Clone)]
 pub struct DispenserVars {
     inner: HashMap<String, String>,
 }
@@ -49,12 +49,19 @@ impl DispenserVars {
 }
 
 #[derive(Debug, serde::Deserialize)]
-pub struct DispenserConfigFile {
+pub struct DispenserConfigFileSerde {
     pub delay: NonZeroU64,
     #[serde(default)]
     pub instance: Vec<DispenserInstanceConfigEntry>,
 }
 
+#[derive(Debug)]
+pub struct DispenserConfigFile {
+    pub delay: NonZeroU64,
+    pub instance: Vec<DispenserInstanceConfigEntry>,
+    pub vars: DispenserVars,
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum DispenserConfigError {
     #[error("IO error: {0}")]
@@ -68,14 +75,28 @@ pub enum DispenserConfigError {
 impl DispenserConfigFile {
     fn try_init_from_string(
         mut config: String,
-        vars: &DispenserVars,
+        vars: DispenserVars,
     ) -> Result<Self, DispenserConfigError> {
         let mut env = Environment::new();
+
+        let syntax = minijinja::syntax::SyntaxConfig::builder()
+            .variable_delimiters("${", "}")
+            .build()
+            .expect("This really should not fail. If this fail something has gone horribly wrong.");
+
+        env.set_syntax(syntax);
+
         env.set_undefined_behavior(minijinja::UndefinedBehavior::Strict);
         let template = env.template_from_str(&config)?;
         config = template.render(&vars)?;
 
-        Ok(toml::from_str(&config)?)
+        let config_toml: DispenserConfigFileSerde = toml::from_str(&config)?;
+
+        Ok(DispenserConfigFile {
+            delay: config_toml.delay,
+            instance: config_toml.instance,
+            vars,
+        })
     }
     pub fn try_init() -> Result<Self, DispenserConfigError> {
         use std::io::Read;
@@ -84,7 +105,7 @@ impl DispenserConfigFile {
         // Use handle vars to replace strings with handlevars
         let vars = DispenserVars::try_init()?;
 
-        Self::try_init_from_string(config, &vars)
+        Self::try_init_from_string(config, vars)
     }
 }
 
@@ -138,6 +159,9 @@ struct Image {
 
 impl DispenserConfigFile {
     pub fn into_config(self) -> crate::config::ContposeConfig {
+        let vars = crate::config::DispenserVars {
+            inner: Arc::new(self.vars.inner),
+        };
         let instances = self
             .instance
             .into_par_iter()
@@ -154,6 +178,7 @@ impl DispenserConfigFile {
                     .collect(),
                 cron: instance.cron,
                 initialize: instance.initialize.into(),
+                vars: vars.clone(),
             })
             .collect();
 
@@ -190,18 +215,18 @@ mod tests {
         let vars = DispenserVars::try_init_from_string(vars_input).unwrap();
 
         let config_input = r#"
-            delay = {{ delay_ms }}
+            delay = ${ delay_ms }
             [[instance]]
-            path = "{{ base_path }}/service"
+            path = "${ base_path }/service"
             initialize = "on-trigger"
 
             [[instance.images]]
             registry = "hub"
             name = "service"
-            tag = "{{ img_version }}"
+            tag = "${ img_version }"
         "#;
 
-        let config = DispenserConfigFile::try_init_from_string(config_input.to_string(), &vars)
+        let config = DispenserConfigFile::try_init_from_string(config_input.to_string(), vars)
             .expect("Failed to parse config");
 
         assert_eq!(config.delay.get(), 500);
@@ -228,7 +253,8 @@ mod tests {
             path = "."
         "#;
         let cfg =
-            DispenserConfigFile::try_init_from_string(default_config.to_string(), &vars).unwrap();
+            DispenserConfigFile::try_init_from_string(default_config.to_string(), vars.clone())
+                .unwrap();
         assert_eq!(cfg.instance[0].initialize, Initialize::Immediately);
 
         // Test aliases
@@ -251,7 +277,7 @@ mod tests {
             "#,
                 alias
             );
-            let cfg = DispenserConfigFile::try_init_from_string(toml, &vars).unwrap();
+            let cfg = DispenserConfigFile::try_init_from_string(toml, vars.clone()).unwrap();
             assert_eq!(cfg.instance[0].initialize, expected);
         }
     }
@@ -264,9 +290,9 @@ mod tests {
         let config = r#"
             delay = 1
             [[instance]]
-            path = "{{ non_existent }}"
+            path = "${ non_existent }"
         "#;
-        let res = DispenserConfigFile::try_init_from_string(config.to_string(), &vars);
+        let res = DispenserConfigFile::try_init_from_string(config.to_string(), vars.clone());
         assert!(
             matches!(res, Err(DispenserConfigError::Template(_))),
             "{:?}",

src/config_file.rs

@@ -50,6 +50,7 @@ impl Instance {
         let master = Arc::new(DockerComposeMaster::initialize(
             &config.path,
             config.initialize,
+            config.vars.clone(),
         ));
         let watchers = config.get_watchers();
         Self {

src/instance.rs

@@ -34,6 +34,8 @@ fn main() -> ExitCode {
         return ExitCode::SUCCESS;
     }
 
+    log::info!("Dispenser running with PID: {}", std::process::id());
+
     if let Err(e) = rayon::ThreadPoolBuilder::new()
         .num_threads(NUM_THREADS)
         .build_global()

src/main.rs

@@ -9,7 +9,7 @@ use std::{
     thread::JoinHandle,
 };
 
-use crate::config::Initialize;
+use crate::config::{DispenserVars, Initialize};
 
 #[derive(Clone, Copy, Eq, PartialEq)]
 #[repr(u32)]
@@ -90,7 +90,7 @@ impl DockerComposeMaster {
     pub fn send_msg(&self, msg: MasterMsg) {
         let _ = self.update_msg.send(msg);
     }
-    pub fn initialize(path: impl AsRef<Path>, initialize: Initialize) -> Self {
+    pub fn initialize(path: impl AsRef<Path>, initialize: Initialize, vars: DispenserVars) -> Self {
         let status_shared = Arc::new(AtomicMasterStatus::new(MasterStatus::Stopped));
         let status = Arc::clone(&status_shared);
         let (update_msg, update_recv) = std::sync::mpsc::channel::<MasterMsg>();
@@ -117,6 +117,7 @@ impl DockerComposeMaster {
                             .args(action.flags())
                             .arg("-d")
                             .current_dir(&path)
+                            .envs(vars.inner.iter())
                             .stdin(Stdio::null())
                             .stdout(Stdio::null())
                             .stderr(Stdio::null())
@@ -139,7 +140,7 @@ impl DockerComposeMaster {
                         log::warn!("Received stop signal for instace {path:?}");
                         let _ = Command::new("docker")
                             .arg("compose")
-                            .arg("down")
+                            .arg("stop")
                             .current_dir(&path)
                             .stdin(Stdio::null())
                             .stdout(Stdio::null())