Add tomlload function to tera templating engine

Floki templates can use `tomlload(file="<filepath>")` in order to load values.

Signed-off-by: Max Dymond <max.dymond@microsoft.com>

Author: Max Dymond

CHANGELOG.md

@@ -18,6 +18,8 @@ Status: Available for use
   can use `yamlload(file="<filepath>")` in order to load values.
 - Add `jsonload` function to tera templating engine so that floki templates
   can use `jsonload(file="<filepath>")` in order to load values.
+- Add `tomlload` function to tera templating engine so that floki templates
+  can use `tomlload(file="<filepath>")` in order to load values.
 
 ### Fixed
 

Cargo.lock

@@ -30,6 +30,7 @@ anyhow = "1.0.71"
 thiserror = "1.0.40"
 tera = "1"
 serde_json = "1.0.100"
+toml = "0.5.11"
 
 [dev-dependencies]
 tempfile = "3.6.0"

Cargo.toml

@@ -99,28 +99,32 @@ pub(crate) struct FlokiConfig {
     pub(crate) entrypoint: Entrypoint,
 }
 
-fn yamlloader(args: &HashMap<String, tera::Value>) -> tera::Result<tera::Value> {
+fn path_from_args(args: &HashMap<String, tera::Value>) -> tera::Result<String> {
     let file = match args.get("file") {
         Some(file) => file,
         None => return Err("file parameter is required".into()),
     };
+    Ok(from_value::<String>(file.clone())?)
+}
 
-    let path = from_value::<String>(file.clone())?;
+fn yamlloader(args: &HashMap<String, tera::Value>) -> tera::Result<tera::Value> {
+    let path = path_from_args(args)?;
     let f = std::fs::File::open(path)?;
     serde_yaml::from_reader(f).map_err(|_| "Failed to read file".into())
 }
 
 fn jsonloader(args: &HashMap<String, tera::Value>) -> tera::Result<tera::Value> {
-    let file = match args.get("file") {
-        Some(file) => file,
-        None => return Err("file parameter is required".into()),
-    };
-
-    let path = from_value::<String>(file.clone())?;
+    let path = path_from_args(args)?;
     let f = std::fs::File::open(path)?;
     serde_json::from_reader(f).map_err(|_| "Failed to read file".into())
 }
 
+fn tomlloader(args: &HashMap<String, tera::Value>) -> tera::Result<tera::Value> {
+    let path = path_from_args(args)?;
+    let contents = std::fs::read_to_string(path)?;
+    toml::from_str(&contents).map_err(|_| "Failed to read file".into())
+}
+
 // Renders a template from a given string.
 pub fn render_template(template: &str, source_filename: &Path) -> Result<String, Error> {
     let template_path = source_filename.display().to_string();
@@ -130,9 +134,10 @@ pub fn render_template(template: &str, source_filename: &Path) -> Result<String,
     // Read the template using tera
     let mut tera = Tera::default();
 
-    // Allow templates to load yaml and json files as Values.
+    // Allow templates to load variables files as Values.
     tera.register_function("yamlload", yamlloader);
     tera.register_function("jsonload", jsonloader);
+    tera.register_function("tomlload", tomlloader);
 
     tera.add_raw_template(&template_path, template)
         .map_err(|e| errors::FlokiError::ProblemRenderingTemplate {
@@ -328,4 +333,13 @@ mod test {
         assert_eq!(config, "shell: bar");
         Ok(())
     }
+
+    #[test]
+    fn test_tera_tomlload() -> Result<(), Box<dyn std::error::Error>> {
+        let template =
+            r#"{% set values = tomlload(file="Cargo.toml") %}floki: {{ values.package.name }}"#;
+        let config = render_template(template, Path::new("floki"))?;
+        assert_eq!(config, "floki: floki");
+        Ok(())
+    }
 }