feat: Adds configuration variables for dispenser.toml (#15)

* feat: Adds support for variables in dispenser.toml

* Closes #14

* chore: Adds CI unit testing

Author: andyquinterom

.github/workflows/test.yml

@@ -0,0 +1,20 @@
+name: Test
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+      - name: Run tests
+        run: cargo test

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "dispenser"
-version = "0.4.0"
+version = "0.5.0"
 edition = "2021"
 license = "MIT"
 
@@ -11,10 +11,12 @@ 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"
 rayon = "1.11.0"
 sd-notify = "0.4.2"
 serde = { version = "1.0.210", features = ["derive"] }
 serde_json = "1.0.128"
 signal-hook = "0.3.17"
+thiserror = "2.0.17"
 toml = "0.8.19"
 urlencoding = "2.1.3"

Cargo.toml

@@ -27,9 +27,9 @@ Download the latest `.deb` or `.rpm` package from the [releases page](https://gi
 
 ```sh
 # Download the .deb package
-# wget https://github.com/ixpantia/dispenser/releases/download/v0.3.0/dispenser-0.3-0.x86_64.deb
+# wget https://github.com/ixpantia/dispenser/releases/download/v0.5.0/dispenser-0.5-0.x86_64.deb
 
-sudo apt install ./dispenser-0.3-0.x86_64.deb
+sudo apt install ./dispenser-0.5-0.x86_64.deb
 ```
 
 ### RHEL / CentOS / Fedora
@@ -38,7 +38,7 @@ sudo apt install ./dispenser-0.3-0.x86_64.deb
 # Download the .rpm package
 # wget ...
 
-sudo dnf install ./dispenser-0.3-0.x86_64.rpm
+sudo dnf install ./dispenser-0.5-0.x86_64.rpm
 ```
 
 The installation process will:
@@ -170,7 +170,63 @@ initialize = "on-trigger"
 ```
 In this example, the service defined in the `backup-service` directory will only be started when the cron schedule is met. After its first run, it will continue to be managed by its cron schedule.
 
-### Step 6: Start and Verify the Deployment
+### 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.
+
+This is useful for reusing the same configuration in multiple deployments.
+
+1.  Create a `dispenser.vars` file in `/opt/dispenser`.
+
+    ```sh
+    vim dispenser.vars
+    ```
+
+2.  Define your variables in TOML format.
+
+    ```toml
+    registry_url = "ghcr.io"
+    app_version = "latest"
+    ```
+
+3.  Use these variables in your `dispenser.toml`.
+
+    ```toml
+    [[instance]]
+    path = "my-app"
+    images = [{ registry = "{{ registry_url }}", name = "my-org/my-app", tag = "{{ app_version }}" }]
+    ```
+
+### Step 7: Validating Configuration
+
+Before applying changes, you can validate your configuration files (including variable substitution) to ensure there are no syntax errors or missing variables.
+
+Run dispenser with the `--test` (or `-t`) flag:
+
+```sh
+dispenser --test
+```
+
+If the configuration is valid, it will output:
+```
+Dispenser config is ok.
+```
+
+If there's an error `dispenser` will show you a detailed error message.
+
+```
+---------------------------------- <string> -----------------------------------
+   2 |
+   3 | [[instance]]
+   4 | path = "nginx"
+   5 > images = [{ registry = "{{ missing }}", name = "nginx", tag = "latest" }]
+     i                            ^^^^^^^ undefined value
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+No referenced variables
+-------------------------------------------------------------------------------
+```
+
+### Step 8: Start and Verify the Deployment
 
 1.  Exit the `dispenser` user session to return to your regular user.
     ```sh

README.md

@@ -1,5 +1,5 @@
 Package: dispenser
-Version: 0.4
+Version: 0.5
 Maintainer: ixpantia S.A.
 Architecture: amd64
 Description: Continously Deploy services with Docker Compose

deb/DEBIAN/control

@@ -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

@@ -0,0 +1 @@
+docker_io="docker.io"

example/dispenser.vars

@@ -1,6 +1,6 @@
 # justfile for dispenser project
 
-DISPENSER_VERSION := "0.4"
+DISPENSER_VERSION := "0.5"
 TARGET_BIN := "target/x86_64-unknown-linux-musl/release/dispenser"
 USR_BIN_DEB := "deb/usr/local/bin/dispenser"
 USR_BIN_RPM := "rpm/usr/local/bin/dispenser"

justfile

@@ -1,5 +1,5 @@
 Name: dispenser
-Version: 0.4
+Version: 0.5
 Release: 0
 Summary: Continously Deploy services with Docker Compose
 License: see /usr/share/doc/dispenser/copyright

rpm/dispenser.spec

@@ -9,6 +9,13 @@ pub struct Args {
     /// Path to the config file.
     #[arg(short, long, default_value = "dispenser.toml")]
     pub config: PathBuf,
+    /// Path to the vars file.
+    #[arg(short, long, default_value = "dispenser.vars")]
+    pub vars: PathBuf,
+
+    /// Test the configuration file and exit.
+    #[arg(short, long)]
+    pub test: bool,
 }
 
 static ARGS: OnceLock<Args> = OnceLock::new();