From 045ad9ff3f7ce6f0b555fcbeb32574fd8927a5af Mon Sep 17 00:00:00 2001
From: Jonas Bushart <jonas@bushart.org>
Date: Mon, 13 Feb 2023 20:44:18 +0100
Subject: [PATCH] Only set env vars if they are unset.

---
 CHANGELOG.md |  5 +++++
 action.yml   | 24 ++++++++++++++++++------
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 378b373..941ccf8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+* Only set environment variables, if they are not set before.
+    This allows setting environment variables before using this action and keeping their values.
+    
 ## [1.3.7] - 2023-01-31
 
 ### Fixed
diff --git a/action.yml b/action.yml
index 1ad2ed4..b96a000 100644
--- a/action.yml
+++ b/action.yml
@@ -57,15 +57,27 @@ runs:
     # The environment variables always need to be set before the caching action
     - name: "Setting Environment Variables"
       run: |
-        echo "CARGO_INCREMENTAL=0" >> $GITHUB_ENV
-        echo "CARGO_PROFILE_DEV_DEBUG=0" >> $GITHUB_ENV
-        echo "CARGO_TERM_COLOR=always" >> $GITHUB_ENV
-        echo "RUST_BACKTRACE=short" >> $GITHUB_ENV
-        echo "RUSTFLAGS=-D warnings" >> $GITHUB_ENV
+        if [[ ! -v CARGO_INCREMENTAL ]]; then
+          echo "CARGO_INCREMENTAL=0" >> $GITHUB_ENV
+        fi
+        if [[ ! -v CARGO_PROFILE_DEV_DEBUG ]]; then
+          echo "CARGO_PROFILE_DEV_DEBUG=0" >> $GITHUB_ENV
+        fi
+        if [[ ! -v CARGO_TERM_COLOR ]]; then
+          echo "CARGO_TERM_COLOR=always" >> $GITHUB_ENV
+        fi
+        if [[ ! -v RUST_BACKTRACE ]]; then
+          echo "RUST_BACKTRACE=short" >> $GITHUB_ENV
+        fi
+        if [[ ! -v RUSTFLAGS ]]; then
+          echo "RUSTFLAGS=-D warnings" >> $GITHUB_ENV
+        fi
         # Enable faster sparse index on nightly
         # The value is ignored on stable and causes no problems
         # https://internals.rust-lang.org/t/call-for-testing-cargo-sparse-registry/16862
-        echo "CARGO_UNSTABLE_SPARSE_REGISTRY=true" >> $GITHUB_ENV
+        if [[ ! -v CARGO_UNSTABLE_SPARSE_REGISTRY ]]; then
+          echo "CARGO_UNSTABLE_SPARSE_REGISTRY=true" >> $GITHUB_ENV
+        fi
         # Enable sparse index after stabilization
         # This causes warnings on stable 1.67, e.g., when using "cargo add"
         # https://github.com/rust-lang/cargo/pull/11224