fix(tools): allow using env vars in tools

When parsing `tools` section, add locally defined
environment variables to Tera context,
so they are available for templating.

Note that this only allows using the variables from the current file.
References to other files are not resolved.

Author: Anton Sergeyev

docs/dev-tools/index.md

@@ -22,6 +22,9 @@ It's also compatible
 with asdf `.tool-versions` files as well as [idiomatic version files](/configuration#idiomatic-version-files) like `.node-version` and
 `.ruby-version`. See [configuration](/configuration) for more details.
 
+When specifying tool versions, you can also refer to environment variables defined in the same file, but note
+that environment variables from referenced files are not resolved here.
+
 ::: info
 mise is inspired by [asdf](https://asdf-vm.com) and can leverage asdf's
 vast [plugin ecosystem](https://github.com/mise-plugins/registry)

docs/templates.md

@@ -20,8 +20,12 @@ Here is an example of a `mise.toml` file that uses templates:
 ```toml
 [env]
 PROJECT_NAME = "{{ cwd | basename }}"
+TERRAFORM_VERSION = "1.0.0"
 
 [tools]
+# refers to env variable defined in this file
+terraform = "{{ env.TERRAFORM_VERSION }}"
+# refers to external env variable
 node = "{{ get_env(name='NODE_VERSION', default='20') }}"
 ```
 

src/config/config_file/mise_toml.rs

@@ -22,7 +22,7 @@ use crate::config::config_file::{config_root, toml::deserialize_arr};
 use crate::config::env_directive::{AgeFormat, EnvDirective, EnvDirectiveOptions, RequiredValue};
 use crate::config::settings::SettingsPartial;
 use crate::config::{Alias, AliasMap, Config};
-use crate::file;
+use crate::env_diff::EnvMap;
 use crate::file::{create_dir_all, display_path};
 use crate::hooks::{Hook, Hooks};
 use crate::redactions::Redactions;
@@ -31,6 +31,7 @@ use crate::task::Task;
 use crate::tera::{BASE_CONTEXT, get_tera};
 use crate::toolset::{ToolRequest, ToolRequestSet, ToolSource, ToolVersionOptions};
 use crate::watch_files::WatchFile;
+use crate::{env, file};
 
 use super::{ConfigFileType, min_version::MinVersionSpec};
 
@@ -137,11 +138,13 @@ impl MiseToml {
             "config_root",
             config_root::config_root(path).to_str().unwrap(),
         );
-        Self {
+        let mut rf = Self {
             path: path.to_path_buf(),
             context,
             ..Default::default()
-        }
+        };
+        rf.update_context_env(env::PRISTINE_ENV.clone());
+        rf
     }
 
     pub fn from_file(path: &Path) -> eyre::Result<Self> {
@@ -166,6 +169,7 @@ impl MiseToml {
         rf.context = BASE_CONTEXT.clone();
         rf.context
             .insert("config_root", path.parent().unwrap().to_str().unwrap());
+        rf.update_context_env(env::PRISTINE_ENV.clone());
         rf.path = path.to_path_buf();
         let project_root = rf.project_root().map(|p| p.to_path_buf());
         for task in rf.tasks.0.values_mut() {
@@ -356,6 +360,23 @@ impl MiseToml {
         Ok(())
     }
 
+    // Merge base OS env vars with env sections from this file,
+    // so they are available for templating.
+    // Note this only merges regular key-value variables; referenced files are not resolved.
+    fn update_context_env(&mut self, mut base_env: EnvMap) {
+        let env_vars = self
+            .env
+            .0
+            .iter()
+            .filter_map(|e| match e {
+                EnvDirective::Val(key, value, _) => Some((key.clone(), value.clone())),
+                _ => None,
+            })
+            .collect::<IndexMap<_, _>>();
+        base_env.extend(env_vars);
+        self.context.insert("env", &base_env);
+    }
+
     fn parse_template(&self, input: &str) -> eyre::Result<String> {
         self.parse_template_with_context(&self.context, input)
     }
@@ -1731,6 +1752,30 @@ mod tests {
         });
     }
 
+    #[tokio::test]
+    async fn test_env_var_in_tool() {
+        let _config = Config::get().await.unwrap();
+        let p = CWD.as_ref().unwrap().join(".test.mise.toml");
+        file::write(
+            &p,
+            r#"
+        [env]
+        TERRAFORM_VERSION = '1.0.0'
+        JQ_PREFIX = '1.6'
+
+        [tools]
+        terraform = "{{env.TERRAFORM_VERSION}}"
+        jq = { prefix = "{{ env.JQ_PREFIX }}" }
+        "#,
+        )
+        .unwrap();
+        let cf = MiseToml::from_file(&p).unwrap();
+        assert_snapshot!(replace_path(&format!(
+            "{:#?}",
+            cf.to_tool_request_set().unwrap().tools
+        )));
+    }
+
     #[tokio::test]
     async fn test_env_array_valid() {
         let _config = Config::get().await.unwrap();

src/config/config_file/snapshots/mise__config__config_file__mise_toml__tests__env_var_in_tool.snap

@@ -0,0 +1,34 @@
+---
+source: src/config/config_file/mise_toml.rs
+expression: "replace_path(&format!(\"{:#?}\", cf.to_tool_request_set().unwrap().tools))"
+---
+{
+    BackendArg(terraform): [
+        Version {
+            backend: BackendArg(terraform),
+            version: "1.0.0",
+            options: ToolVersionOptions {
+                os: None,
+                install_env: {},
+                opts: {},
+            },
+            source: MiseToml(
+                "~/cwd/.test.mise.toml",
+            ),
+        },
+    ],
+    BackendArg(jq): [
+        Prefix {
+            backend: BackendArg(jq),
+            prefix: "1.6",
+            options: ToolVersionOptions {
+                os: None,
+                install_env: {},
+                opts: {},
+            },
+            source: MiseToml(
+                "~/cwd/.test.mise.toml",
+            ),
+        },
+    ],
+}