Datatype that represents YAML with substituted variables.
If YAML has value that starts with an $, then such value is treated as a variable from config_vars. For example if config_vars contains variable: 42 and the YAML is following:
some_element:
some: $variable
)");
EXPECT_EQ(yaml["some_element"]["some"].As<int>(), 42);
EXPECT_EQ(yaml["some_element"]["some"].GetPath(), "some_element.some");
Then the result of yaml["some_element"]["some"].As<int>() is 42.
If YAML key ends on #env and the mode is YamlConfig::Mode::kEnvAllowed or YamlConfig::Mode::kEnvAndFileAllowed, then the value of the key is searched in environment variables of the process and returned as a value. For example:
some_element:
some#env: ENV_VARIABLE_NAME
)");
::setenv("ENV_VARIABLE_NAME", "100", 1);
EXPECT_EQ(yaml["some_element"]["some"].As<int>(), 100);
If YAML key ends on #file and the mode is YamlConfig::Mode::kEnvAndFileAllowed, then the value of the key is the content of specified YAML parsed file. For example:
const auto yaml_content = fmt::format("some#file: {}", path_to_file);
EXPECT_EQ(yaml["some"]["some_key"][0].As<std::string>(), "a");
If YAML key ends on #fallback, then the value of the key is used as a fallback for environment, file and $ variables. For example for the following YAML with YamlConfig::Mode::kEnvAndFileAllowed:
# yaml
some_element:
some: $variable
some#file: /some/path/to/the/file.yaml
some#env: SOME_ENV_VARIABLE
some#fallback: 100500
The result of yaml["some_element"]["some"].As<int>() is the value of variable from config_vars if it exists; otherwise the value is the contents of the environment variable SOME_ENV_VARIABLE if it exists; otherwise the value is the content of the file with name file.yaml; otherwise the value is 100500, from the fallback.
Another example:
# yaml
some_element:
some#env: ENV_NAME
some#fallback: 5
With YamlConfig::Mode::kEnvAllowed the result of yaml["some_element"]["some"].As<int>() is the value of ENV_NAME environment variable if it exists; otherwise it is 5.
- Note
#env, #file and #fallback also work for keys inside config_vars.
- Warning
- YamlConfig::Mode::kEnvAllowed or YamlConfig::Mode::kEnvAndFileAllowed should be used only on configs that come from trusted environments. Otherwise, an attacker could create a config and read any of your environment variables of files, including variables that contain passwords and other sensitive data.
- Examples
- samples/grpc_middleware_service/src/middlewares/server/meta_filter.cpp, and samples/grpc_middleware_service/src/middlewares/server/meta_filter.hpp.
Definition at line 72 of file yaml_config.hpp.
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| YamlConfig (formats::yaml::Value yaml, formats::yaml::Value config_vars, Mode mode=Mode::kSecure) |
| | YamlConfig = config + config_vars.
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| YamlConfig | operator[] (std::string_view key) const |
| | Access member by key for read.
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| YamlConfig | operator[] (size_t index) const |
| | Access member by index for read.
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| std::size_t | GetSize () const |
| | Returns array size or object members count.
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bool | IsMissing () const noexcept |
| | Returns true if *this holds nothing. When IsMissing() returns true any attempt to get the actual value or iterate over *this will throw MemberMissingException.
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bool | IsNull () const noexcept |
| | Returns true if *this holds 'null'.
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bool | IsBool () const noexcept |
| | Returns true if *this is convertible to bool.
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bool | IsInt () const noexcept |
| | Returns true if *this is convertible to int.
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bool | IsInt64 () const noexcept |
| | Returns true if *this is convertible to int64_t.
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bool | IsUInt64 () const noexcept |
| | Returns true if *this is convertible to uint64_t.
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bool | IsDouble () const noexcept |
| | Returns true if *this is convertible to double.
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bool | IsString () const noexcept |
| | Returns true if *this is convertible to std::string.
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bool | IsArray () const noexcept |
| | Returns true if *this is an array (Type::kArray).
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bool | IsObject () const noexcept |
| | Returns true if *this is a map (Type::kObject).
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| void | CheckNotMissing () const |
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| void | CheckArray () const |
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| void | CheckArrayOrNull () const |
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| void | CheckObjectOrNull () const |
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| void | CheckObject () const |
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| void | CheckString () const |
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| void | CheckObjectOrArrayOrNull () const |
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| template<typename T> |
| auto | As () const |
| | Returns value of *this converted to T.
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| template<typename T, typename First, typename... Rest> |
| auto | As (First &&default_arg, Rest &&... more_default_args) const |
| | Returns value of *this converted to T or T(args) if this->IsMissing().
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| template<typename T> |
| auto | As (DefaultConstructed) const |
| | Returns value of *this converted to T or T() if this->IsMissing().
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| bool | HasMember (std::string_view key) const |
| | Returns true if *this holds a key.
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std::string | GetPath () const |
| | Returns full path to this value.
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| const_iterator | begin () const |
| | Returns an iterator to the beginning of the held array or map.
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| const_iterator | end () const |
| | Returns an iterator to the end of the held array or map.
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| formats::yaml::Value | GetRawYamlWithoutConfigVars () const |
| | Get the plain Yaml without substitutions. It may contain raw references.
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Inheritance diagram for yaml_config::YamlConfig: