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//! `[plugins]`: the WebAssembly plugin sandbox and the ceilings an operator
//! sets on it.
//!
//! A plugin requests nothing. Every limit below is the host's, and a
//! per-plugin override may only reduce one — an author who needs more asks
//! the operator, which is the conversation these numbers exist to force.
//! Off by default: `enabled = false` preserves the pre-plugin behaviour
//! exactly, and a stored plugin row on a node with plugins disabled
//! quarantines the workflows that name its functions rather than aborting.
use serde::{Deserialize, Serialize};
use super::validation::{reduce_only, require_nonzero};
use crate::errors::OrionError;
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default, deny_unknown_fields)]
pub struct PluginsConfig {
/// Whether this node loads and runs plugins at all.
pub enabled: bool,
/// Reserved for an on-disk cache of compiled artifacts. Not supported
/// yet: a non-empty value is refused at startup, so nothing is silently
/// ignored (in-memory only until an on-disk cache is measured worth its lifecycle).
pub cache_dir: String,
/// Largest component an upload may carry.
pub max_component_bytes: usize,
/// Linear memory ceiling per invocation. Also sizes the pooling
/// allocator's per-instance reservation, so the process reserves
/// `max_live_instances × max_memory_bytes` of *virtual* address space at
/// startup — count it when a container limits virtual memory.
pub max_memory_bytes: usize,
/// Largest evaluated `function.input`, serialised, handed to a guest.
pub max_request_bytes: usize,
/// Largest JSON a guest may return.
pub max_response_bytes: usize,
/// Wall-clock ceiling per invocation. The task's own deadline applies
/// too; the shorter wins.
pub max_timeout_ms: u64,
/// Invocations of one function that may run at once. Beyond it a task
/// waits for a permit until its deadline and then fails as a limit.
pub max_concurrency_per_function: u32,
/// Instances the pooling allocator can hold at once, across every
/// function. Under-sizing it surfaces as instantiation failures under
/// load, so it must be at least `max_concurrency_per_function`.
pub max_live_instances: u32,
/// Fuel per invocation — a backstop against a guest that spins without
/// touching the clock, not a contract: fuel cost moves between Wasmtime
/// versions, so operators reason in `max_timeout_ms`. Sized well above
/// what `max_timeout_ms` admits (a tight loop burns roughly 5e9 units a
/// second), so the deadline is what stops a runaway guest and fuel only
/// catches one the clock somehow missed.
pub fuel_backstop: u64,
pub trust: PluginTrustConfig,
/// Per-plugin ceilings, each at most the host's.
pub overrides: Vec<PluginOverride>,
}
/// Optional hardening: when `public_keys` is non-empty, an upload must carry
/// a signature over the component digest by one of them, verified again at
/// every load.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(default, deny_unknown_fields)]
pub struct PluginTrustConfig {
pub public_keys: Vec<String>,
}
/// A ceiling lowered for one plugin. Any field left unset keeps the host's.
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
#[serde(default, deny_unknown_fields)]
pub struct PluginOverride {
pub id: String,
pub timeout_ms: Option<u64>,
pub max_memory_bytes: Option<usize>,
pub max_concurrency: Option<u32>,
pub max_request_bytes: Option<usize>,
pub max_response_bytes: Option<usize>,
}
impl Default for PluginsConfig {
fn default() -> Self {
Self {
enabled: false,
cache_dir: String::new(),
max_component_bytes: 16 * 1024 * 1024,
max_memory_bytes: 64 * 1024 * 1024,
max_request_bytes: 1024 * 1024,
max_response_bytes: 1024 * 1024,
max_timeout_ms: 5_000,
max_concurrency_per_function: 64,
max_live_instances: 256,
fuel_backstop: 100_000_000_000,
trust: PluginTrustConfig::default(),
overrides: Vec::new(),
}
}
}
impl PluginsConfig {
pub(crate) fn validate(&self) -> Result<(), OrionError> {
if !self.cache_dir.is_empty() {
return Err(OrionError::Config {
message: "plugins.cache_dir is reserved and not supported yet: leave it empty"
.to_string(),
});
}
require_nonzero(
self.max_component_bytes as u64,
"plugins.max_component_bytes",
)?;
require_nonzero(self.max_memory_bytes as u64, "plugins.max_memory_bytes")?;
require_nonzero(self.max_request_bytes as u64, "plugins.max_request_bytes")?;
require_nonzero(self.max_response_bytes as u64, "plugins.max_response_bytes")?;
require_nonzero(self.max_timeout_ms, "plugins.max_timeout_ms")?;
require_nonzero(
u64::from(self.max_concurrency_per_function),
"plugins.max_concurrency_per_function",
)?;
require_nonzero(
u64::from(self.max_live_instances),
"plugins.max_live_instances",
)?;
require_nonzero(self.fuel_backstop, "plugins.fuel_backstop")?;
// A key that does not decode would make every upload fail to verify
// with a message about the signature, when the mistake is in the
// config; refused here, where it can be named.
for (i, key) in self.trust.public_keys.iter().enumerate() {
if let Err(reason) = crate::plugin::trust::parse_public_key(key) {
return Err(OrionError::Config {
message: format!(
"plugins.trust.public_keys[{i}] is not an Ed25519 public key: {reason}"
),
});
}
}
if self.max_live_instances < self.max_concurrency_per_function {
return Err(OrionError::Config {
message: format!(
"plugins.max_live_instances ({}) must be at least \
plugins.max_concurrency_per_function ({}): one function alone could \
otherwise exhaust the instance pool",
self.max_live_instances, self.max_concurrency_per_function
),
});
}
let mut seen: Vec<&str> = Vec::new();
for (i, o) in self.overrides.iter().enumerate() {
let at = format!("plugins.overrides[{i}]");
if o.id.trim().is_empty() {
return Err(OrionError::Config {
message: format!("{at}.id must name a plugin"),
});
}
if seen.contains(&o.id.as_str()) {
return Err(OrionError::Config {
message: format!("{at}.id '{}' appears twice", o.id),
});
}
seen.push(&o.id);
reduce_only(&at, "timeout_ms", o.timeout_ms, self.max_timeout_ms)?;
reduce_only(
&at,
"max_memory_bytes",
o.max_memory_bytes.map(|v| v as u64),
self.max_memory_bytes as u64,
)?;
reduce_only(
&at,
"max_concurrency",
o.max_concurrency.map(u64::from),
u64::from(self.max_concurrency_per_function),
)?;
reduce_only(
&at,
"max_request_bytes",
o.max_request_bytes.map(|v| v as u64),
self.max_request_bytes as u64,
)?;
reduce_only(
&at,
"max_response_bytes",
o.max_response_bytes.map(|v| v as u64),
self.max_response_bytes as u64,
)?;
}
Ok(())
}
/// The override for `plugin_id`, if the operator wrote one.
pub fn override_for(&self, plugin_id: &str) -> Option<&PluginOverride> {
self.overrides.iter().find(|o| o.id == plugin_id)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn the_defaults_validate() {
PluginsConfig::default()
.validate()
.expect("defaults are valid");
}
#[test]
fn the_cache_dir_is_refused_until_it_exists() {
let c = PluginsConfig {
cache_dir: "/var/cache/orion".to_string(),
..PluginsConfig::default()
};
let err = c.validate().expect_err("reserved");
assert!(err.to_string().contains("cache_dir"));
}
#[test]
fn a_pool_smaller_than_one_functions_concurrency_is_refused() {
let c = PluginsConfig {
max_live_instances: 8,
..PluginsConfig::default()
};
let err = c.validate().expect_err("pool");
assert!(err.to_string().contains("max_live_instances"));
}
#[test]
fn an_override_may_only_reduce() {
let mut c = PluginsConfig::default();
c.overrides.push(PluginOverride {
id: "acme.codec".to_string(),
timeout_ms: Some(100),
..Default::default()
});
c.validate().expect("a lower timeout is fine");
c.overrides[0].timeout_ms = Some(6_000);
let err = c.validate().expect_err("raised");
assert!(
err.to_string().contains("exceeds the host ceiling"),
"{err}"
);
c.overrides[0].timeout_ms = Some(0);
assert!(c.validate().is_err());
c.overrides[0].timeout_ms = None;
c.overrides.push(PluginOverride {
id: "acme.codec".to_string(),
..Default::default()
});
let err = c.validate().expect_err("dup");
assert!(err.to_string().contains("appears twice"));
}
}