fix: output .env file is now relative to project root, not cwd

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 # UNRELEASED
 
+=== fix: output_env_file is now considered relative to project root
+
+The .env file location, whether specified as `output_env_file` in dfx.json
+or `--output-env-file <file>` on the commandline, is now considered relative
+to the project root, rather than relative to the current working directory.
+
 === feat: Read dfx canister install argument from a file
 
 Enables passing large arguments that cannot be passed directly in the command line using the `--argument-file` flag. For example `dfx canister install --argument-file ./my/argument/file.txt my_canister_name`.

e2e/tests-dfx/dotenv.bash

@@ -14,6 +14,43 @@ teardown() {
   standard_teardown
 }
 
+
+@test "puts .env in project root" {
+  dfx_start
+  jq '.canisters["e2e_project_backend"].post_install="echo post install backend"' dfx.json | sponge dfx.json
+  jq '.canisters["e2e_project_frontend"].post_install="echo post install frontend"' dfx.json | sponge dfx.json
+
+  mkdir subdir
+  mkdir subdir/canister-install-all subdir/canister-install-single
+  mkdir subdir/build-all subdir/build-single
+  mkdir subdir/deploy-single subdir/deploy-all
+  dfx canister create --all
+  ( cd subdir/build-single && dfx build e2e_project_frontend )
+  ( cd subdir/build-all && dfx build --all )
+  ( cd subdir/canister-install-single && dfx canister install e2e_project_backend )
+  dfx canister uninstall-code e2e_project_backend
+  ( cd subdir/canister-install-all && dfx canister install --all )
+  rm -rf .dfx
+  ( cd subdir/deploy-single && dfx deploy e2e_project_backend)
+  ( cd subdir/deploy-all && dfx deploy )
+
+  assert_command find . -name .env
+  assert_eq "./.env"
+}
+
+@test "the output_env_file must be contained within project" {
+  dfx_start
+  mkdir ../outside
+
+  assert_command_fail dfx deploy --output-env-file nonexistent/.env
+  assert_contains "failed to canonicalize output_env_file"
+  assert_contains "working-dir/e2e_project/nonexistent: No such file or directory"
+  assert_command_fail dfx deploy --output-env-file /etc/passwd
+  assert_contains "The output_env_file must be a relative path, but is /etc/passwd"
+  assert_command_fail dfx deploy --output-env-file ../outside/.env
+  assert_match "The output_env_file must be within the project root, but is .*/working-dir/e2e_project/../outside/.env"
+}
+
 @test "writes environment variables to .env" {
   dfx_start
   dfx canister create --all

src/dfx-core/src/config/model/dfinity.rs

@@ -3,6 +3,7 @@
 use crate::config::directories::get_user_dfx_config_dir;
 use crate::config::model::bitcoin_adapter::BitcoinAdapterLogLevel;
 use crate::config::model::canister_http_adapter::HttpAdapterLogLevel;
+use crate::error::config::GetOutputEnvFileError;
 use crate::error::dfx_config::AddDependenciesError::CanisterCircularDependency;
 use crate::error::dfx_config::GetCanisterNamesWithDependenciesError::AddDependenciesFailed;
 use crate::error::dfx_config::GetComputeAllocationError::GetComputeAllocationFailed;
@@ -1013,6 +1014,35 @@ impl Config {
         )
     }
 
+    // returns the path to the output env file if any, guaranteed to be
+    // a child relative to the project root
+    pub fn get_output_env_file(
+        &self,
+        from_cmdline: Option<PathBuf>,
+    ) -> Result<Option<PathBuf>, GetOutputEnvFileError> {
+        from_cmdline
+            .or(self.config.output_env_file.clone())
+            .map(|p| {
+                if p.is_relative() {
+                    let p = self.get_project_root().join(p);
+
+                    // cannot canonicalize a path that doesn't exist, but the parent should exist
+                    let env_parent =
+                        crate::fs::parent(&p).map_err(GetOutputEnvFileError::Parent)?;
+                    let env_parent = crate::fs::canonicalize(&env_parent)
+                        .map_err(GetOutputEnvFileError::Canonicalize)?;
+                    if !env_parent.starts_with(self.get_project_root()) {
+                        Err(GetOutputEnvFileError::OutputEnvFileMustBeInProjectRoot(p))
+                    } else {
+                        Ok(self.get_project_root().join(p))
+                    }
+                } else {
+                    Err(GetOutputEnvFileError::OutputEnvFileMustBeRelative(p))
+                }
+            })
+            .transpose()
+    }
+
     pub fn save(&self) -> Result<(), StructuredFileError> {
         save_json_file(&self.path, &self.json)
     }

src/dfx-core/src/error/config.rs

@@ -1,5 +1,6 @@
 use crate::error::fs::FsError;
 use crate::error::get_user_home::GetUserHomeError;
+use std::path::PathBuf;
 use thiserror::Error;
 
 #[derive(Error, Debug)]
@@ -13,3 +14,18 @@ pub enum ConfigError {
     #[error("Failed to determine shared network data directory: {0}")]
     DetermineSharedNetworkDirectoryFailed(GetUserHomeError),
 }
+
+#[derive(Error, Debug)]
+pub enum GetOutputEnvFileError {
+    #[error("failed to canonicalize output_env_file")]
+    Canonicalize(#[source] FsError),
+
+    #[error("The output_env_file must be within the project root, but is {}", .0.display())]
+    OutputEnvFileMustBeInProjectRoot(PathBuf),
+
+    #[error("The output_env_file must be a relative path, but is {}", .0.display())]
+    OutputEnvFileMustBeRelative(PathBuf),
+
+    #[error(transparent)]
+    Parent(FsError),
+}

src/dfx/src/commands/build.rs

@@ -40,9 +40,7 @@ pub fn exec(env: &dyn Environment, opts: CanisterBuildOpts) -> DfxResult {
 
     // Read the config.
     let config = env.get_config_or_anyhow()?;
-    let env_file = opts
-        .output_env_file
-        .or_else(|| config.get_config().output_env_file.clone());
+    let env_file = config.get_output_env_file(opts.output_env_file)?;
 
     // Check the cache. This will only install the cache if there isn't one installed
     // already.

src/dfx/src/commands/canister/install.rs

@@ -155,9 +155,7 @@ pub async fn exec(
         } else {
             let canister_info = canister_info?;
             let config = config.unwrap();
-            let env_file = opts
-                .output_env_file
-                .or_else(|| config.get_config().output_env_file.clone());
+            let env_file = config.get_output_env_file(opts.output_env_file)?;
             let idl_path = canister_info.get_constructor_idl_path();
             let init_type = get_candid_init_type(&idl_path);
             let install_args = || blob_from_arguments(arguments, None, arg_type, &init_type);
@@ -182,9 +180,7 @@ pub async fn exec(
     } else if opts.all {
         // Install all canisters.
         let config = env.get_config_or_anyhow()?;
-        let env_file = opts
-            .output_env_file
-            .or_else(|| config.get_config().output_env_file.clone());
+        let env_file = config.get_output_env_file(opts.output_env_file)?;
         if let Some(canisters) = &config.get_config().canisters {
             for canister in canisters.keys() {
                 if pull_canisters_in_config.contains_key(canister) {

src/dfx/src/commands/deploy.rs

@@ -115,9 +115,7 @@ pub fn exec(env: &dyn Environment, opts: DeployOpts) -> DfxResult {
         .map_err(|err| anyhow!(err))
         .context("Failed to parse InstallMode.")?;
     let config = env.get_config_or_anyhow()?;
-    let env_file = opts
-        .output_env_file
-        .or_else(|| config.get_config().output_env_file.clone());
+    let env_file = config.get_output_env_file(opts.output_env_file)?;
 
     let with_cycles = opts.with_cycles;
 

src/dfx/src/lib/builders/mod.rs

@@ -448,18 +448,18 @@ fn write_environment_variables(vars: &[Env<'_>], write_path: &Path) -> DfxResult
                 // the section is correctly formed
                 let end_pos = end_pos + END_TAG.len() + start_pos + START_TAG.len();
                 existing_file.replace_range(start_pos..end_pos, &write_string);
-                fs::write(write_path, existing_file)?;
+                dfx_core::fs::write(write_path, existing_file)?;
                 return Ok(());
             } else {
                 // the file has been edited, so we don't know how much to delete, so we append instead
             }
         }
         // append to the existing file
         existing_file.push_str(&write_string);
-        fs::write(write_path, existing_file)?;
+        dfx_core::fs::write(write_path, existing_file)?;
     } else {
         // no existing file, okay to clobber
-        fs::write(write_path, write_string)?;
+        dfx_core::fs::write(write_path, write_string)?;
     }
     Ok(())
 }
@@ -501,7 +501,7 @@ impl BuildConfig {
             idl_root: canister_root.join("idl/"), // TODO: possibly move to `network_root.join("idl/")`
             lsp_root: network_root.join("lsp/"),
             canisters_to_build: None,
-            env_file: config_intf.output_env_file.clone(),
+            env_file: config.get_output_env_file(None)?,
         })
     }