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Read all cgroup v2 metrics that can be read
This commit removes any arbitration of the cgroup v2 heirarchy for a given process. We instead read anything that can be read, looping over all cgroup files present but not following the heirarchy down. Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,2 @@ | ||
| /// Code to read cgroup information. | ||
| pub(crate) mod v2; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,93 @@ | ||
| use std::{io, path::PathBuf}; | ||
|
|
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| use metrics::gauge; | ||
| use tokio::fs; | ||
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|
||
| #[derive(thiserror::Error, Debug)] | ||
| pub enum Error { | ||
| #[error("IO error: {0}")] | ||
| Io(#[from] io::Error), | ||
| #[error("Parse int error: {0}")] | ||
| ParseInt(#[from] std::num::ParseIntError), | ||
| #[error("Parse float error: {0}")] | ||
| ParseFloat(#[from] std::num::ParseFloatError), | ||
| #[error("Cgroup v2 not found")] | ||
| CgroupV2NotFound, | ||
| } | ||
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| /// Determines the cgroup v2 path for a given PID. | ||
| pub(crate) async fn get_path(pid: i32) -> Result<PathBuf, Error> { | ||
| let path = format!("/proc/{pid}/cgroup"); | ||
| let content = fs::read_to_string(path).await?; | ||
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| for line in content.lines() { | ||
| let mut fields = line.split(':'); | ||
| let hierarchy_id = fields.next().ok_or(Error::CgroupV2NotFound)?; | ||
| let controllers = fields.next().ok_or(Error::CgroupV2NotFound)?; | ||
| let cgroup_path = fields.next().ok_or(Error::CgroupV2NotFound)?; | ||
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| if hierarchy_id == "0" && controllers.is_empty() { | ||
| // cgroup v2 detected | ||
| let cgroup_mount_point = "/sys/fs/cgroup"; // Default mount point | ||
| let full_cgroup_path = PathBuf::from(cgroup_mount_point) | ||
| .join(cgroup_path.strip_prefix('/').unwrap_or(cgroup_path)); | ||
| return Ok(full_cgroup_path); | ||
| } | ||
| } | ||
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| Err(Error::CgroupV2NotFound) | ||
| } | ||
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| /// Polls for any cgroup metrics that can be read, v2 version. | ||
| pub(crate) async fn poll(path: PathBuf) -> Result<(), Error> { | ||
| let mut entries = fs::read_dir(&path).await?; | ||
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| while let Some(entry) = entries.next_entry().await? { | ||
| let metadata = entry.metadata().await?; | ||
| if metadata.is_file() { | ||
| let file_name = entry.file_name(); | ||
| let metric_prefix = match file_name.to_str() { | ||
| Some(s) => String::from(s), | ||
| None => { | ||
| // Skip files with non-UTF-8 names | ||
| continue; | ||
| } | ||
| }; | ||
| let file_path = entry.path(); | ||
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| let content = fs::read_to_string(&file_path).await?; | ||
| let content = content.trim(); | ||
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| // Cgroup files that have values are either single-valued or | ||
| // key-value pairs. For single-valued files, we create a single | ||
| // metric and for key-value pairs, we create metrics with the same | ||
| // scheme as single-valued files but tack on the key to the metric | ||
| // name. | ||
| if let Ok(value) = content.parse::<f64>() { | ||
| // Single-valued | ||
| gauge!(metric_prefix).set(value); | ||
| } else { | ||
| // Key-value pairs | ||
| if kv_pairs(content, &metric_prefix).is_err() { | ||
| // File may fail to parse, for instance cgroup.controllers | ||
| // is a list of strings. | ||
| continue; | ||
| } | ||
| } | ||
| } | ||
| } | ||
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||
| Ok(()) | ||
| } | ||
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| fn kv_pairs(content: &str, metric_prefix: &str) -> Result<(), Error> { | ||
| for line in content.lines() { | ||
| let mut parts = line.split_whitespace(); | ||
| let key = parts.next().expect("malformed key-value pair"); | ||
| let value_str = parts.next().expect("malformed key-value pair"); | ||
| let value: f64 = value_str.parse()?; | ||
| let metric_name = format!("{metric_prefix}.{key}"); | ||
| gauge!(metric_name).set(value); | ||
| } | ||
| Ok(()) | ||
| } |