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chore(unit_test,userspace): allow env var to get expanded in yaml eve…
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…n when part of a string.

Moreover, support env variable embedding another env variable.

Signed-off-by: Federico Di Pierro <[email protected]>
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@FedeDP
FedeDP committed Nov 20, 2023
1 parent 66a122d commit 00343d4
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Showing 2 changed files with 110 additions and 42 deletions.
70 changes: 51 additions & 19 deletions unit_tests/falco/test_configuration.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -114,11 +114,14 @@ TEST(Configuration, configuration_environment_variables)
// Set an environment variable for testing purposes
std::string env_var_value = "envVarValue";
std::string env_var_name = "ENV_VAR";
std::string default_value = "default";
SET_ENV_VAR(env_var_name.c_str(), env_var_value.c_str());
yaml_helper conf;

std::string sample_yaml =
std::string embedded_env_var_value = "${ENV_VAR}";
std::string embedded_env_var_name = "ENV_VAR_EMBEDDED";
SET_ENV_VAR(embedded_env_var_name.c_str(), embedded_env_var_value.c_str());

std::string default_value = "default";
std::string env_var_sample_yaml =
"base_value:\n"
" id: $ENV_VAR\n"
" name: '${ENV_VAR}'\n"
Expand All @@ -133,52 +136,81 @@ TEST(Configuration, configuration_environment_variables)
" sample_list:\n"
" - ${ENV_VAR}\n"
" - ' ${ENV_VAR}'\n"
" - $UNSED_XX_X_X_VAR\n";
conf.load_from_string(sample_yaml);
" - '${ENV_VAR} '\n"
" - $UNSED_XX_X_X_VAR\n"
"paths:\n"
" - ${ENV_VAR}/foo\n"
" - $ENV_VAR/foo\n"
" - /foo/${ENV_VAR}/\n"
" - /${ENV_VAR}/${ENV_VAR}${ENV_VAR}/foo\n"
" - ${ENV_VAR_EMBEDDED}/foo\n";
yaml_helper conf;
conf.load_from_string(env_var_sample_yaml);

/* Check if the base values are defined */
ASSERT_TRUE(conf.is_defined("base_value"));
ASSERT_TRUE(conf.is_defined("base_value_2"));
ASSERT_TRUE(conf.is_defined("paths"));
ASSERT_FALSE(conf.is_defined("unknown_base_value"));

/* Test fetching of a regular string without any environment variable */
std::string base_value_string = conf.get_scalar<std::string>("base_value.string", default_value);
auto base_value_string = conf.get_scalar<std::string>("base_value.string", default_value);
ASSERT_EQ(base_value_string, "my_string");

/* Test fetching of escaped environment variable format. Should return the string as-is after stripping the leading `$` */
std::string base_value_invalid = conf.get_scalar<std::string>("base_value.invalid", default_value);
auto base_value_invalid = conf.get_scalar<std::string>("base_value.invalid", default_value);
ASSERT_EQ(base_value_invalid, "${ENV_VAR}");

/* Test fetching of invalid escaped environment variable format. Should return the string as-is */
std::string base_value_invalid_env = conf.get_scalar<std::string>("base_value.invalid_env", default_value);
/* Test fetching of invalid escaped environment variable format. Should return the string as-is */
auto base_value_invalid_env = conf.get_scalar<std::string>("base_value.invalid_env", default_value);
ASSERT_EQ(base_value_invalid_env, "$$ENV_VAR");

/* Test fetching of strings that contain environment variables */
std::string base_value_id = conf.get_scalar<std::string>("base_value.id", default_value);
auto base_value_id = conf.get_scalar<std::string>("base_value.id", default_value);
ASSERT_EQ(base_value_id, "$ENV_VAR"); // Does not follow the `${VAR}` format, so it should be treated as a regular string

std::string base_value_name = conf.get_scalar<std::string>("base_value.name", default_value);
auto base_value_name = conf.get_scalar<std::string>("base_value.name", default_value);
ASSERT_EQ(base_value_name, env_var_value); // Proper environment variable format

std::string base_value_escaped = conf.get_scalar<std::string>("base_value.escaped", default_value);
auto base_value_escaped = conf.get_scalar<std::string>("base_value.escaped", default_value);
ASSERT_EQ(base_value_escaped, env_var_value); // Environment variable within quotes

/* Test fetching of an undefined environment variable. Expected to return the default value.*/
std::string unknown_boolean = conf.get_scalar<std::string>("base_value.subvalue.subvalue2.boolean", default_value);
auto unknown_boolean = conf.get_scalar<std::string>("base_value.subvalue.subvalue2.boolean", default_value);
ASSERT_EQ(unknown_boolean, default_value);

/* Test fetching of environment variables from a list */
std::string base_value_2_list_0 = conf.get_scalar<std::string>("base_value_2.sample_list[0]", default_value);
auto base_value_2_list_0 = conf.get_scalar<std::string>("base_value_2.sample_list[0]", default_value);
ASSERT_EQ(base_value_2_list_0, env_var_value); // Proper environment variable format

std::string base_value_2_list_1 = conf.get_scalar<std::string>("base_value_2.sample_list[1]", default_value);
ASSERT_EQ(base_value_2_list_1, " ${ENV_VAR}"); // Environment variable preceded by a space, hence treated as a regular string
auto base_value_2_list_1 = conf.get_scalar<std::string>("base_value_2.sample_list[1]", default_value);
ASSERT_EQ(base_value_2_list_1, " " + env_var_value); // Environment variable preceded by a space, still extracted env var with leading space

auto base_value_2_list_2 = conf.get_scalar<std::string>("base_value_2.sample_list[2]", default_value);
ASSERT_EQ(base_value_2_list_2, env_var_value + " "); // Environment variable proceeded by a space, still extracted env var with trailing space

std::string base_value_2_list_2 = conf.get_scalar<std::string>("base_value_2.sample_list[2]", default_value);
ASSERT_EQ(base_value_2_list_2, "$UNSED_XX_X_X_VAR"); // Does not follow the `${VAR}` format, so should be treated as a regular string
auto base_value_2_list_3 = conf.get_scalar<std::string>("base_value_2.sample_list[3]", default_value);
ASSERT_EQ(base_value_2_list_3, "$UNSED_XX_X_X_VAR"); // Does not follow the `${VAR}` format, so should be treated as a regular string

/* Test expansion of environment variables within strings */
auto path_list_0 = conf.get_scalar<std::string>("paths[0]", default_value);
ASSERT_EQ(path_list_0, env_var_value + "/foo"); // Even if env var is part of bigger string, it gets expanded

auto path_list_1 = conf.get_scalar<std::string>("paths[1]", default_value);
ASSERT_EQ(path_list_1, "$ENV_VAR/foo"); // Does not follow the `${VAR}` format, so should be treated as a regular string

auto path_list_2 = conf.get_scalar<std::string>("paths[2]", default_value);
ASSERT_EQ(path_list_2, "/foo/" + env_var_value + "/"); // Even when env var is in the middle of a string. it gets expanded

auto path_list_3 = conf.get_scalar<std::string>("paths[3]", default_value);
ASSERT_EQ(path_list_3, "/" + env_var_value + "/" + env_var_value + env_var_value + "/foo"); // Even when the string contains multiple env vars they are correctly expanded

auto path_list_4 = conf.get_scalar<std::string>("paths[4]", default_value);
ASSERT_EQ(path_list_4, env_var_value + "/foo"); // Even when the env var contains another env var, it gets correctly double-expanded

/* Clear the set environment variable after testing */
SET_ENV_VAR(env_var_name.c_str(), env_var_value.c_str());
SET_ENV_VAR(env_var_name.c_str(), "");
SET_ENV_VAR(embedded_env_var_name.c_str(), "");
}

TEST(Configuration, configuration_webserver_ip)
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82 changes: 59 additions & 23 deletions userspace/falco/yaml_helper.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ limitations under the License.
#include <set>
#include <iostream>
#include <fstream>
#include <type_traits>

#include "config_falco.h"

Expand Down Expand Up @@ -77,42 +78,77 @@ class yaml_helper
get_node(node, key);
if(node.IsDefined())
{
std::string value = node.as<std::string>();
auto value = node.as<std::string>();

// Helper function to convert string to the desired type T
auto convert_str_to_t = [&default_value](const std::string& str) -> T {
if (str.empty())
{
return default_value;
}

if constexpr (std::is_same_v<T, std::string>)
{
return str;
}
std::stringstream ss(str);
T result;
if (ss >> result) return result;
return default_value;
};

// If the value starts with `$$`, check for a subsequent `{...}`
if (value.size() >= 3 && value[0] == '$' && value[1] == '$')
auto start_pos = value.find('$');
while (start_pos != std::string::npos)
{
// If after stripping the first `$`, the string format is like `${VAR}`, treat it as a plain string and don't resolve.
if (value[2] == '{' && value[value.size() - 1] == '}')
auto substr = value.substr(start_pos);
// Case 1 -> ${}
if (substr.rfind("${", 0) == 0)
{
value = value.substr(1);
return convert_str_to_t(value);
auto end_pos = substr.find('}');
if (end_pos != std::string::npos)
{
// Eat "${" and "}" when getting the env var name
auto env_str = substr.substr(2, end_pos - 2);
const char* env_value = std::getenv(env_str.c_str()); // Get the environment variable value
if(env_value)
{
// env variable name + "${}"
value.replace(start_pos, env_str.length() + 3, env_value);
}
else
{
value.erase(start_pos, env_str.length() + 3);
}
}
else
{
// There are no "}" chars anymore; just break leaving rest of value untouched.
break;
}
}
else return convert_str_to_t(value);
}

// Check if the value is an environment variable reference
if(value.size() >= 2 && value[0] == '$' && value[1] == '{' && value[value.size() - 1] == '}')
{
// Format: ${ENV_VAR_NAME}
std::string env_var = value.substr(2, value.size() - 3);

const char* env_value = std::getenv(env_var.c_str()); // Get the environment variable value
if(env_value) return convert_str_to_t(env_value);

return default_value;
// Case 2 -> $${}
else if (substr.rfind("$${", 0) == 0)
{
auto end_pos = substr.find('}');
if (end_pos != std::string::npos)
{
// Consume first "$" token
value.erase(start_pos, 1);
}
else
{
// There are no "}" chars anymore; just break leaving rest of value untouched.
break;
}
start_pos++; // consume the second '$' token
}
else
{
start_pos += substr.length();
}
start_pos = value.find("$", start_pos);
}

// If it's not an environment variable reference, return the value as is
return node.as<T>();
return convert_str_to_t(value);
}

return default_value;
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