Environment Variable Support #83
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…ome from environment variables
| template <typename T> | ||
| T derive_configuration(const char* key, | ||
| const toml::parse_result& settings, | ||
| T&& fallback) { | ||
| T result = settings[key].value_or(fallback); | ||
| std::string envar = toupper(std::string("ORC_") + key); | ||
| if (const char* enval = std::getenv(envar.c_str())) { | ||
| result = parse_enval<T>(enval); | ||
| } | ||
| return result; | ||
| } |
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This routine is the heart of the PR. Instead of taking values from the settings file directly, derive_configuration will also look at the associated environment variable and use that if found.
| @@ -32,7 +32,12 @@ jobs: | |||
| id: build-orc-orc_dogfood | |||
| continue-on-error: true | |||
| run: | | |||
| xcodebuild -project ./build/orc.xcodeproj -scheme orc_dogfood -configuration Debug | |||
| ORC_OUTPUT_FILE=./output.json ORC_OUTPUT_FILE_MODE=json xcodebuild -json -project ./build/orc.xcodeproj -scheme orc_dogfood -configuration Debug -hideShellScriptEnvironment | |||
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A new test that leverages the environment variables to cause a JSON file to get dumped when running orc_dogfood (which is a CMake target that uses ORC to build ORC). The JSON is then traversed with a couple jq queries to make sure some boilerplate keys are in there and filled in with something meaningful.
| T parse_enval(std::string&&) = delete; | ||
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| template <> | ||
| std::string parse_enval(std::string&& x) { |
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why move semantics instead of const std::string&?
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Good question. the value coming from getenv is a const char*, which is then converted to a std::string for this routine. For the std::string specialization of parse_enval, we can move the incoming string to the result with no additional changes. If the incoming string were const std::string&, it would cost us a copy to make a new one to return by value.
With this PR, ORC now uses environment variables to override its configuration values. The environment variables, if set, will usurp any defaults or values found in the
orc-configfile. Environment variables can be used to override any ORC configuration setting except those that take lists (symbol_ignore,violation_report, andviolation_ignore).For any given
orc-configsetting, the equivalent environment variable isORC_appended to the name of the setting in all caps. Sooutput_filecan be overridden byORC_OUTPUT_FILE,parallel_processingbyORC_PARALLEL_PROCESSING, etc.This PR also comes with additional tests that leverage this new capability.