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new(unit_tests,userspace): properly support env var expansions in all scalar values of yaml file.

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Signed-off-by: Federico Di Pierro <nierro92@gmail.com>
This commit is contained in:
Federico Di Pierro
2023-12-05 09:11:19 +01:00
committed by poiana
parent 3b095a5eda
commit cbbcb61153
2 changed files with 120 additions and 79 deletions
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175
userspace/falco/yaml_helper.h
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@@ -31,13 +31,46 @@ limitations under the License.
#include <set>
#include <iostream>
#include <fstream>
#include <type_traits>
#include "config_falco.h"
#include "event_drops.h"
#include "falco_outputs.h"
class yaml_helper;
class yaml_visitor {
private:
using Callback = std::function<void(YAML::Node&)>;
yaml_visitor(Callback cb): seen(), cb(std::move(cb)) {}
void operator()(YAML::Node &cur) {
seen.push_back(cur);
if (cur.IsMap()) {
for (YAML::detail::iterator_value pair : cur) {
descend(pair.second);
}
} else if (cur.IsSequence()) {
for (YAML::detail::iterator_value child : cur) {
descend(child);
}
} else if (cur.IsScalar()) {
cb(cur);
}
}
void descend(YAML::Node &target) {
if (std::find(seen.begin(), seen.end(), target) == seen.end()) {
(*this)(target);
}
}
std::vector<YAML::Node> seen;
Callback cb;
friend class yaml_helper;
};
/**
* @brief An helper class for reading and editing YAML documents
*/
@@ -50,6 +83,7 @@ public:
void load_from_string(const std::string& input)
{
m_root = YAML::Load(input);
pre_process_env_vars();
}
/**
@@ -58,6 +92,7 @@ public:
void load_from_file(const std::string& path)
{
m_root = YAML::LoadFile(path);
pre_process_env_vars();
}
/**
@@ -78,79 +113,8 @@ public:
get_node(node, key);
if(node.IsDefined())
{
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 >> std::boolalpha >> result) return result;
return default_value;
};
auto start_pos = value.find('$');
while (start_pos != std::string::npos)
{
auto substr = value.substr(start_pos);
// Case 1 -> ${}
if (substr.rfind("${", 0) == 0)
{
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;
}
}
// 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("$", start_pos);
}
return convert_str_to_t(value);
return node.as<T>(default_value);
}
return default_value;
}
@@ -189,6 +153,71 @@ public:
private:
YAML::Node m_root;
/*
* When loading a yaml file,
* we immediately pre process all scalar values through a visitor private API,
* and resolve any "${env_var}" to its value;
* moreover, any "$${str}" is resolved to simply "${str}".
*/
void pre_process_env_vars()
{
yaml_visitor([](YAML::Node &scalar) {
auto value = scalar.as<std::string>();
auto start_pos = value.find('$');
while (start_pos != std::string::npos)
{
auto substr = value.substr(start_pos);
// Case 1 -> ${}
if (substr.rfind("${", 0) == 0)
{
auto end_pos = substr.find('}');
if (end_pos != std::string::npos)
{
// Eat "${" and "}" when getting the env var name
auto env_str = substr.substr(2, end_pos - 2);
const char* env_value = std::getenv(env_str.c_str()); // Get the environment variable value
if(env_value)
{
// env variable name + "${}"
value.replace(start_pos, env_str.length() + 3, env_value);
}
else
{
value.erase(start_pos, env_str.length() + 3);
}
}
else
{
// There are no "}" chars anymore; just break leaving rest of value untouched.
break;
}
}
// Case 2 -> $${}
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);
}
scalar = value;
})(m_root);
}
/**
* Key is a string representing a node in the YAML document.
* The provided key string can navigate the document in its