Feature add env by rousbound · Pull Request #425 · ferronweb/ferron

rousbound · 2026-01-17T20:46:16Z

Hi @DorianNiemiecSVRJS!

I've created this PR as a follow up of the discussion on issue #233 and the PR #236 .

I tried to follow the style of the previous PR on lookup_env_var.rs with the addition of:

Changes to kdl.rs adapter
Interpolation of env variables in lookup_env_var.rs

I appreciate any feedback.

Thanks in advance.

Signed-off-by: alex <alex@alex-tuxedoinfinitybooks1517gen7>

Signed-off-by: Alex <al-git001@none.at>

amejia1 · 2026-01-31T18:37:04Z

+use anyhow::bail;
+use std::env;
+
+pub fn lookup_env_value(conf_string: String) -> anyhow::Result<String> {


This can be done cleaner with the regex crate, see here for example.

@amejia1 I think procedural code is enough... Let's not over-use regexes...

amejia1 · 2026-01-31T18:41:10Z

+use std::env;
+
+pub fn lookup_env_value(conf_string: String) -> anyhow::Result<String> {
+  if !conf_string.contains("{env:") {


Ferron config files look a lot like caddy config files. How about using the same syntax like the caddyfile "env" placeholders? See https://caddyserver.com/docs/conventions#placeholders .

amejia1 · 2026-01-31T18:45:58Z

+  }
+}
+
+#[cfg(test)]


There should be a way to escape the placeholder, for example \{env.HOME} should render {env.HOME}.

amejia1 · 2026-01-31T19:02:18Z

  for kdl_entry in kdl_node.iter() {
    let value = match kdl_entry.value().to_owned() {
-      KdlValue::String(value) => ServerConfigurationValue::String(value),
+      KdlValue::String(value) => {


It will probably be best to render all placeholders first and then process the config files. Will this config work?

{env.HTTP_ADDRESS} { proxy "http://localhost:3000/" // Replace "http://localhost:3000" with the backend server URL }

rousbound · 2026-03-27T10:07:11Z

Hello @amejia1! Sorry for taking so long to catch up with your comments.

I found all of our points very reasonable.

Regarding the implementation of them:

1st suggestion (regex changes): straightforward to implement, but needs to add regex lib to Cargo.toml(currently there is fancy-regex)
2nd suggestion (Caddy-like env syntax): more impactful since it affects Ferron’s config ergonomics, so it would be good to get alignment on this
3rd suggestion (escaping of braces): also straightforward
4th suggestion (render order): reasonable, though the “render first” approach might have edge cases worth validating

@DorianNiemiecSVRJS do you have any position regarding @amejia1 suggestions, specifically the env syntax and the render-order approach?

In the meantime, I’m planning to prototype these changes in this PR.

DorianNiemiecSVRJS · 2026-03-27T10:17:01Z

@DorianNiemiecSVRJS do you have any position regarding @amejia1 suggestions, specifically the env syntax and the render-order approach?

I think procedural code (like it's in https://github.com/ferronweb/ferron/blob/48eda07699092a268382fcde041b18b7c6897ee0/ferron/src/util/log_placeholders.rs) is enough...

…placeholders.rs and log_placeholders.rs

rousbound · 2026-03-27T13:16:30Z

Hello again @DorianNiemiecSVRJS!

@DorianNiemiecSVRJS do you have any position regarding @amejia1 suggestions, specifically the env syntax and the render-order approach?

I think procedural code (like it's in https://github.com/ferronweb/ferron/blob/48eda07699092a268382fcde041b18b7c6897ee0/ferron/src/util/log_placeholders.rs) is enough...

I've adapted the parsing to match the style of log_placeholders.rs, could you review it?

Thanks in advance!

DorianNiemiecSVRJS · 2026-04-25T08:10:19Z

    let value = match kdl_entry.value().to_owned() {
-      KdlValue::String(value) => ServerConfigurationValue::String(value),
+      KdlValue::String(value) => {
+        let resolved_value = replace_placeholders(&value).expect("Failed to resolve environment variable in configuration");


If environment variable wouldn't be found (see https://github.com/ferronweb/ferron/pull/425/changes#diff-63c5becf3cec064da1306878c6a2ffe08a0e70be83a1d6c801b59e2b268339abR8), the web server would crash... Could this be handled more gracefully, like it's in:

ferron/ferron-common/src/util/header_placeholders.rs

Lines 3 to 118 in 9148eb9

pub fn replace_header_placeholders(

input: &str,

request_parts: &hyper::http::request::Parts,

socket_data: Option<&SocketData>,

) -> String {

let mut output = String::new();

let mut index_rb_saved = 0;

loop {

let index_lb = input[index_rb_saved..].find("{");

if let Some(index_lb) = index_lb {

let index_rb_afterlb = input[index_rb_saved + index_lb + 1..].find("}");

if let Some(index_rb_afterlb) = index_rb_afterlb {

let index_rb = index_rb_afterlb + index_lb + 1;

let placeholder_value = &input[index_rb_saved + index_lb + 1..index_rb_saved + index_rb];

output.push_str(&input[index_rb_saved..index_rb_saved + index_lb]);

match placeholder_value {

"path" => output.push_str(request_parts.uri.path()),

"path_and_query" => output.push_str(

request_parts

.uri

.path_and_query()

.map_or(request_parts.uri.path(), |p| p.as_str()),

),

"method" => output.push_str(request_parts.method.as_str()),

"version" => output.push_str(match request_parts.version {

hyper::Version::HTTP_09 => "HTTP/0.9",

hyper::Version::HTTP_10 => "HTTP/1.0",

hyper::Version::HTTP_11 => "HTTP/1.1",

hyper::Version::HTTP_2 => "HTTP/2.0",

hyper::Version::HTTP_3 => "HTTP/3.0",

_ => "HTTP/Unknown",

}),

"scheme" => {

if let Some(socket_data) = socket_data {

output.push_str(if socket_data.encrypted { "https" } else { "http" });

} else {

// No socket data, leave it as is

output.push_str("{scheme}");

}

}

"client_ip" => {

if let Some(socket_data) = socket_data {

output.push_str(&socket_data.remote_addr.ip().to_string());

} else {

// No socket data, leave it as is

output.push_str("{client_ip}");

}

}

"client_port" => {

if let Some(socket_data) = socket_data {

output.push_str(&socket_data.remote_addr.port().to_string());

} else {

// No socket data, leave it as is

output.push_str("{client_port}");

}

}

"client_ip_canonical" => {

if let Some(socket_data) = socket_data {

output.push_str(&socket_data.remote_addr.ip().to_canonical().to_string());

} else {

// No socket data, leave it as is

output.push_str("{client_ip_canonical}");

}

}

"server_ip" => {

if let Some(socket_data) = socket_data {

output.push_str(&socket_data.local_addr.ip().to_string());

} else {

// No socket data, leave it as is

output.push_str("{server_ip}");

}

}

"server_port" => {

if let Some(socket_data) = socket_data {

output.push_str(&socket_data.local_addr.port().to_string());

} else {

// No socket data, leave it as is

output.push_str("{server_port}");

}

}

"server_ip_canonical" => {

if let Some(socket_data) = socket_data {

output.push_str(&socket_data.local_addr.ip().to_canonical().to_string());

} else {

// No socket data, leave it as is

output.push_str("{server_ip_canonical}");

}

}

_ => {

if let Some(header_name) = placeholder_value.strip_prefix("header:") {

if let Some(header_value) = request_parts.headers.get(header_name) {

output.push_str(header_value.to_str().unwrap_or(""));

}

} else {

// Unknown placeholder, leave it as is

output.push('{');

output.push_str(placeholder_value);

output.push('}');

}

}

}

if index_rb < input.len() - 1 {

index_rb_saved += index_rb + 1;

} else {

break;

}

} else {

output.push_str(&input[index_rb_saved..]);

}

} else {

output.push_str(&input[index_rb_saved..]);

break;

}

}

output

}

DorianNiemiecSVRJS · 2026-04-25T08:11:23Z

Apologies for such a late review, I was working on a future major version of Ferron...

git001 and others added 7 commits October 25, 2025 10:27

Add lookup_env_var to get environment Variable

4cefae6

Signed-off-by: alex <alex@alex-tuxedoinfinitybooks1517gen7>

Add lookup_env_var to get environment Variable, after feedback

2b41f6d

Signed-off-by: Alex <al-git001@none.at>

Merge branch 'develop-2.x' into feature-add-ENV

adb102f

Env lookup working right now

fabaeef

env variable interpolation implemented

351b987

Panicked on failure to parse env variable in ferron.kdl

48375a3

Merge branch 'ferronweb:develop-2.x' into feature-add-ENV

79c048f

amejia1 reviewed Jan 31, 2026

View reviewed changes

krovuxdev mentioned this pull request Mar 10, 2026

How to migrate a Caddyfile with wildcard site and host matchers to Ferron? #455

Open

Geraldo Luiz added 3 commits March 27, 2026 09:13

Adopted more standard way of replacing placeholders based on headers_…

a208997

…placeholders.rs and log_placeholders.rs

Adapted tests to work with new functions

5bda26c

Improved tests

9b88283

DorianNiemiecSVRJS requested changes Apr 25, 2026

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Feature add env#425

Feature add env#425
rousbound wants to merge 10 commits intoferronweb:develop-2.xfrom
rousbound:feature-add-ENV

rousbound commented Jan 17, 2026 •

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	pub fn replace_header_placeholders(
	input: &str,
	request_parts: &hyper::http::request::Parts,
	socket_data: Option<&SocketData>,
	) -> String {
	let mut output = String::new();
	let mut index_rb_saved = 0;
	loop {
	let index_lb = input[index_rb_saved..].find("{");
	if let Some(index_lb) = index_lb {
	let index_rb_afterlb = input[index_rb_saved + index_lb + 1..].find("}");
	if let Some(index_rb_afterlb) = index_rb_afterlb {
	let index_rb = index_rb_afterlb + index_lb + 1;
	let placeholder_value = &input[index_rb_saved + index_lb + 1..index_rb_saved + index_rb];
	output.push_str(&input[index_rb_saved..index_rb_saved + index_lb]);
	match placeholder_value {
	"path" => output.push_str(request_parts.uri.path()),
	"path_and_query" => output.push_str(
	request_parts
	.uri
	.path_and_query()
	.map_or(request_parts.uri.path(), \|p\| p.as_str()),
	),
	"method" => output.push_str(request_parts.method.as_str()),
	"version" => output.push_str(match request_parts.version {
	hyper::Version::HTTP_09 => "HTTP/0.9",
	hyper::Version::HTTP_10 => "HTTP/1.0",
	hyper::Version::HTTP_11 => "HTTP/1.1",
	hyper::Version::HTTP_2 => "HTTP/2.0",
	hyper::Version::HTTP_3 => "HTTP/3.0",
	_ => "HTTP/Unknown",
	}),
	"scheme" => {
	if let Some(socket_data) = socket_data {
	output.push_str(if socket_data.encrypted { "https" } else { "http" });
	} else {
	// No socket data, leave it as is
	output.push_str("{scheme}");
	}
	}
	"client_ip" => {
	if let Some(socket_data) = socket_data {
	output.push_str(&socket_data.remote_addr.ip().to_string());
	} else {
	// No socket data, leave it as is
	output.push_str("{client_ip}");
	}
	}
	"client_port" => {
	if let Some(socket_data) = socket_data {
	output.push_str(&socket_data.remote_addr.port().to_string());
	} else {
	// No socket data, leave it as is
	output.push_str("{client_port}");
	}
	}
	"client_ip_canonical" => {
	if let Some(socket_data) = socket_data {
	output.push_str(&socket_data.remote_addr.ip().to_canonical().to_string());
	} else {
	// No socket data, leave it as is
	output.push_str("{client_ip_canonical}");
	}
	}
	"server_ip" => {
	if let Some(socket_data) = socket_data {
	output.push_str(&socket_data.local_addr.ip().to_string());
	} else {
	// No socket data, leave it as is
	output.push_str("{server_ip}");
	}
	}
	"server_port" => {
	if let Some(socket_data) = socket_data {
	output.push_str(&socket_data.local_addr.port().to_string());
	} else {
	// No socket data, leave it as is
	output.push_str("{server_port}");
	}
	}
	"server_ip_canonical" => {
	if let Some(socket_data) = socket_data {
	output.push_str(&socket_data.local_addr.ip().to_canonical().to_string());
	} else {
	// No socket data, leave it as is
	output.push_str("{server_ip_canonical}");
	}
	}
	_ => {
	if let Some(header_name) = placeholder_value.strip_prefix("header:") {
	if let Some(header_value) = request_parts.headers.get(header_name) {
	output.push_str(header_value.to_str().unwrap_or(""));
	}
	} else {
	// Unknown placeholder, leave it as is
	output.push('{');
	output.push_str(placeholder_value);
	output.push('}');
	}
	}
	}
	if index_rb < input.len() - 1 {
	index_rb_saved += index_rb + 1;
	} else {
	break;
	}
	} else {
	output.push_str(&input[index_rb_saved..]);
	}
	} else {
	output.push_str(&input[index_rb_saved..]);
	break;
	}
	}
	output
	}

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