Add support for expanding .env quoted values. (#180)

Switch from the dotenvy crate to dotenvs to achieve this. A patched
version is used to ensure we maintain support for hard failure when
invalid `.env` files are read.

Fixes #166
Fixes #167

CHANGES.md

@@ -1,5 +1,11 @@
 # Release Notes
 
+## 0.14.0
+
+Change `.env` parsing libraries to gain support for double quoted values with variable
+substitution; e.g.: the `.env` line `PYTHONPATH="/Users/A. Space:$PYTHONPATH"` now has the
+`$PYTHONPATH` portion of the value substituted.
+
 ## 0.13.3
 
 Ensure liblzma is statically linked.

Cargo.toml

@@ -5,7 +5,7 @@ members = [
 
 [package]
 name = "scie-jump"
-version = "0.13.3"
+version = "0.14.0"
 description = "The self contained interpreted executable launcher."
 authors = [
     "John Sirois <[email protected]>",

docs/packaging.md

@@ -114,9 +114,31 @@ In the "lift" manifest, there are 3 required fields:
 
 ### Optional fields
 
-A scie "lift" can opt in to loading `.env` files via the "load_dotenv" boolean field. The [dotenv](
-https://crates.io/crates/dotenv) crate handles this loading. A lift's files and commands can also
-have additional configuration metadata described.
+A scie "lift" can opt in to loading `.env` files via the "load_dotenv" boolean field. The [dotenvs](
+https://crates.io/crates/dotenvs) crate handles this loading and the following behavior is
+guaranteed:
+
+Parsing rules:
+
+- `BASIC=basic` and `export BASIC=basic` both export an environment variable named `BASIC` with
+  value `basic`.
+- Empty lines are skipped.
+- Lines beginning with `#` are treated as comments.
+- A `#` marks the beginning of a comment (unless the value is wrapped in quotes).
+- Empty values become empty strings.
+- Inner quotes are maintained.
+- Whitespace is removed from both ends of unquoted values.
+- Single and double quoted values maintain whitespace from both ends.
+
+Expanding rules:
+
+- `$KEY` or `${KEY}` will expand to the ambient environment value of `KEY` (unless the value is
+  wrapped in single quotes). If there is no ambient environment value for `KEY`, the expanded value
+  will be an empty string.
+- `${KEY:-default}` will first attempt to expand `KEY` subject to the rules above. If `KEY` is not
+  defined, then it will return `default`.
+- `\$KEY` will escape the `$KEY` rather than expand when not wrapped with quotes or wrapped with
+  double quotes.
 
 A scie "lift" can also establish a custom `nce` cache directory via the "base" string field. Any
 placeholders  present in the custom value will be expanded save for the `{scie.lift}` placeholder
@@ -400,4 +422,4 @@ analyze and measure your use case for applicability when considering making a sc
 creates an extra file called the `scie-tote` that is a zip that stores all the files above it inside
 as STORED (uncompressed) entries. You need not be aware of this, the scie still functions like you'd
 expect. Its only when using a tool like `zipinfo` to inspect your scie executable that you'll notice
-a zip file entry for each of the files you specified.
+a zip file entry for each of the files you specified.

examples/load/test.sh

@@ -36,8 +36,20 @@ source .env
 grep "${GET_CONFIG}" "${GET_LOG_CONFIG}"
 
 # Motivated by: https://github.com/pantsbuild/scie-pants/issues/307
+# And ammended by: https://github.com/a-scie/jump/issues/166
 # shellcheck disable=SC2016 # We with this text to be included verbatim in the .env file.
 echo 'PYTHONPATH="/foo/bar:$PYTHONPATH"' >> .env
+./cowsay "Should succeed!"
+
+# See motivating case here: https://github.com/arniu/dotenvs-rs/issues/4
+cat << EOF >> .env
+A=foo bar
+B="notenough
+C='toomany''
+D=valid
+export NOT_SET
+E=valid
+EOF
 if ./cowsay "Should fail!"; then
   die "The expected .env file loading failure did not happen."
 else

jump/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "jump"
-version = "0.13.3"
+version = "0.14.0"
 description = "The bulk of the scie-jump binary logic."
 authors = [
     "John Sirois <[email protected]>",
@@ -13,7 +13,6 @@ bstr = { workspace = true }
 byteorder = "1.4"
 bzip2 = "0.4"
 dirs = "4.0"
-dotenvy = "0.15"
 fd-lock = "3.0"
 flate2 = "1.0"  # For gz support.
 indexmap = { version = "1.9", features = ["serde"] }
@@ -35,6 +34,10 @@ zip = { workspace = true }
 zstd = "0.12"
 walkdir = "2.3"
 
+[dependencies.dotenvs]
+git = "https://github.com/jsirois/dotenvs-rs"
+rev = "b2276ef3fd039ed8565b4c1cbedb7a5aeeca734e"
+
 [dev-dependencies]
 ctor = "0.2"
 env_logger = { workspace = true }

jump/src/lib.rs

@@ -180,20 +180,27 @@ pub fn prepare_boot() -> Result<BootAction, String> {
 
     if lift.load_dotenv {
         let _timer = timer!(Level::Debug; "jump::load_dotenv");
-        match dotenvy::dotenv() {
-            Ok(dotenv_file) => debug!("Loaded env file from {path}", path = dotenv_file.display()),
-            Err(err) if err.not_found() => {
+        match dotenv::from_filename(".env") {
+            Ok(env) => {
+                let mut iter = env.iter();
+                while let Some((key, value)) = iter.try_next().map_err(|err| {
+                    format!(
+                        "This scie requested .env files be loaded but there was an error doing so: \
+                        {err}"
+                    )
+                })? {
+                    if std::env::var(key).is_err() {
+                        std::env::set_var(key, value);
+                    }
+                }
+            }
+            Err(_) => {
                 debug!(
                     "No .env files found for invocation of {current_exe} from cwd of {cwd:?}",
                     current_exe = current_exe.exe.display(),
                     cwd = env::current_dir()
                 )
             }
-            Err(err) => {
-                return Err(format!(
-                "This scie requested .env files be loaded but there was an error doing so: {err}"
-            ))
-            }
         }
     }
     let payload = &data[jump.size..data.len() - lift.size];