Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

apiserver: use direct paths for ephemeral storage #133

Merged
merged 1 commit into from
Sep 9, 2024
Merged

apiserver: use direct paths for ephemeral storage #133

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
61 changes: 25 additions & 36 deletions sources/api/apiserver/src/server/ephemeral_storage.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,10 @@ static FINDMNT: &str = "/usr/bin/findmnt";

/// Name of the array (if created) and filesystem label. Selected to be 12 characters so it
/// fits within both the xfs and ext4 volume label limit.
static EPHEMERAL: &str = ".ephemeral";
static EPHEMERAL_MNT: &str = ".ephemeral";
/// Name of the device and its path from the MD driver
static RAID_DEVICE_DIR: &str = "/dev/md/";
static RAID_DEVICE_NAME: &str = "ephemeral";

/// initialize prepares the ephemeral storage for formatting and formats it. For multiple disks
/// preparation is the creation of a RAID0 array, for a single disk this is a no-op. The array or disk
Expand Down Expand Up @@ -70,11 +73,14 @@ pub fn initialize(fs: Option<Filesystem>, disks: Option<Vec<String>>) -> Result<
let scan_output = mdadm_scan()?;
// no previously configured array found, so construct a new one
if scan_output.is_empty() {
info!("creating array named {:?} from {:?}", EPHEMERAL, disks);
mdadm_create(EPHEMERAL, disks.iter().map(|x| x.as_str()).collect())?;
info!(
"creating array named {:?} from {:?}",
RAID_DEVICE_NAME, disks
);
mdadm_create(RAID_DEVICE_NAME, disks.iter().map(|x| x.as_str()).collect())?;
yeazelm marked this conversation as resolved.
Show resolved Hide resolved
}
// can't lookup the array until it's created
resolve_array_by_id()?
// Once it is built, it will be available in `/dev/md/`
format!("{}{}", RAID_DEVICE_DIR, RAID_DEVICE_NAME)
}
};

Expand All @@ -95,14 +101,18 @@ pub fn initialize(fs: Option<Filesystem>, disks: Option<Vec<String>>) -> Result<
/// binds the specified directories to the pre-configured array, creating those directories if
/// they do not exist.
pub fn bind(variant: &str, dirs: Vec<String>) -> Result<()> {
// handle the no local instance storage case
if ephemeral_devices()?.is_empty() {
info!("no ephemeral disks found, skipping ephemeral storage binding");
return Ok(());
}
let device_name = match ephemeral_devices()?.len() {
// handle the no local instance storage case
0 => {
info!("no ephemeral disks found, skipping ephemeral storage binding");
return Ok(());
}
// If there is only one device, use that
1 => ephemeral_devices()?.first().expect("non-empty").clone(),
_ => format!("{}{}", RAID_DEVICE_DIR, RAID_DEVICE_NAME),
};

let device_name = resolve_device_by_label()?;
let mount_point = format!("/mnt/{}", EPHEMERAL);
let mount_point = format!("/mnt/{}", EPHEMERAL_MNT);
let mount_point = Path::new(&mount_point);
let allowed_dirs = allowed_bind_dirs(variant);
for dir in &dirs {
Expand Down Expand Up @@ -202,34 +212,16 @@ fn is_mounted(path: &String) -> Result<bool> {
Ok(status.success())
}

/// resolve_device_by_label resolves the by-label link for the raid array or single disk to the device name
fn resolve_device_by_label() -> Result<String> {
canonical_name(format!("/dev/disk/by-label/{}", EPHEMERAL))
}

/// resolve_array_by_name resolves the by-id link for the raid array
fn resolve_array_by_id() -> Result<String> {
canonical_name(format!("/dev/disk/by-id/md-name-{}", EPHEMERAL))
}

/// canonical_name will create the canonical, absolute form of a path with all intermediate
/// components normalized and symbolic links resolved
fn canonical_name(name: String) -> Result<String> {
Ok(std::fs::canonicalize(OsString::from(name))
.context(error::CanonicalizeFailureSnafu {})?
.to_string_lossy()
.to_string())
}

/// creates the array with the given name from the specified disks
fn mdadm_create<T: AsRef<str>>(name: T, disks: Vec<T>) -> Result<()> {
let mut device_name = OsString::from("/dev/md/");
let mut device_name = OsString::from(RAID_DEVICE_DIR);
device_name.push(name.as_ref());

let mut cmd = Command::new(MDADM);
cmd.arg("--create");
cmd.arg("--force");
cmd.arg("--verbose");
cmd.arg("--homehost=any");
cmd.arg(device_name);
cmd.arg("--level=0");
// By default, mdadm uses a 512KB chunk size. mkfs.xfs attempts to match some of its settings to
Expand Down Expand Up @@ -332,7 +324,7 @@ pub fn format_device<S: AsRef<OsStr>>(device: S, format: &Filesystem) -> Result<
mkfs.arg(device.as_ref());
// labeled, XFS has a max of 12 characters, EXT4 allows 16
mkfs.arg("-L");
mkfs.arg(EPHEMERAL);
mkfs.arg(RAID_DEVICE_NAME);

let output = mkfs
.output()
Expand Down Expand Up @@ -405,9 +397,6 @@ pub mod error {

#[snafu(display("Failed to create directory, {}", source))]
Mkdir { source: std::io::Error },

#[snafu(display("Failed to canonicalize path, {}", source))]
CanonicalizeFailure { source: std::io::Error },
}
}

Expand Down