feat: implement kernel / initrd oci image support (#103)

* feat: implement kernel / initrd oci image support

* fix: implement image urls more faithfully

crates/oci/src/name.rs

@@ -2,33 +2,39 @@ use anyhow::Result;
 use std::fmt;
 use url::Url;
 
-const DOCKER_HUB_MIRROR: &str = "mirror.gcr.io";
-const DEFAULT_IMAGE_TAG: &str = "latest";
-
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct ImageName {
     pub hostname: String,
     pub port: Option<u16>,
     pub name: String,
-    pub reference: String,
+    pub reference: Option<String>,
+    pub digest: Option<String>,
 }
 
 impl fmt::Display for ImageName {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if DOCKER_HUB_MIRROR == self.hostname && self.port.is_none() {
+        let mut suffix = String::new();
+
+        if let Some(ref reference) = self.reference {
+            suffix.push(':');
+            suffix.push_str(reference);
+        }
+
+        if let Some(ref digest) = self.digest {
+            suffix.push('@');
+            suffix.push_str(digest);
+        }
+
+        if ImageName::DOCKER_HUB_MIRROR == self.hostname && self.port.is_none() {
             if self.name.starts_with("library/") {
-                write!(f, "{}:{}", &self.name[8..], self.reference)
+                write!(f, "{}{}", &self.name[8..], suffix)
             } else {
-                write!(f, "{}:{}", self.name, self.reference)
+                write!(f, "{}{}", self.name, suffix)
             }
         } else if let Some(port) = self.port {
-            write!(
-                f,
-                "{}:{}/{}:{}",
-                self.hostname, port, self.name, self.reference
-            )
+            write!(f, "{}:{}/{}{}", self.hostname, port, self.name, suffix)
         } else {
-            write!(f, "{}/{}:{}", self.hostname, self.name, self.reference)
+            write!(f, "{}/{}{}", self.hostname, self.name, suffix)
         }
     }
 }
@@ -41,13 +47,21 @@ impl Default for ImageName {
 }
 
 impl ImageName {
+    pub const DOCKER_HUB_MIRROR: &'static str = "registry.docker.io";
+    pub const DEFAULT_IMAGE_TAG: &'static str = "latest";
+
     pub fn parse(name: &str) -> Result<Self> {
         let full_name = name.to_string();
         let name = full_name.clone();
         let (mut hostname, mut name) = name
             .split_once('/')
             .map(|x| (x.0.to_string(), x.1.to_string()))
-            .unwrap_or_else(|| (DOCKER_HUB_MIRROR.to_string(), format!("library/{}", name)));
+            .unwrap_or_else(|| {
+                (
+                    ImageName::DOCKER_HUB_MIRROR.to_string(),
+                    format!("library/{}", name),
+                )
+            });
 
         // heuristic to find any docker hub image formats
         // that may be in the hostname format. for example:
@@ -55,7 +69,7 @@ impl ImageName {
         // and neither will abc/hello/xyz:latest
         if !hostname.contains('.') && full_name.chars().filter(|x| *x == '/').count() == 1 {
             name = format!("{}/{}", hostname, name);
-            hostname = DOCKER_HUB_MIRROR.to_string();
+            hostname = ImageName::DOCKER_HUB_MIRROR.to_string();
         }
 
         let (hostname, port) = if let Some((hostname, port)) = hostname
@@ -66,15 +80,54 @@ impl ImageName {
         } else {
             (hostname, None)
         };
-        let (name, reference) = name
-            .split_once(':')
-            .map(|x| (x.0.to_string(), x.1.to_string()))
-            .unwrap_or((name.to_string(), DEFAULT_IMAGE_TAG.to_string()));
+
+        let name_has_digest = if name.contains('@') {
+            let digest_start = name.chars().position(|c| c == '@');
+            let ref_start = name.chars().position(|c| c == ':');
+            if let (Some(digest_start), Some(ref_start)) = (digest_start, ref_start) {
+                digest_start < ref_start
+            } else {
+                true
+            }
+        } else {
+            false
+        };
+
+        let (name, digest) = if name_has_digest {
+            name.split_once('@')
+                .map(|(name, digest)| (name.to_string(), Some(digest.to_string())))
+                .unwrap_or_else(|| (name, None))
+        } else {
+            (name, None)
+        };
+
+        let (name, reference) = if name.contains(':') {
+            name.split_once(':')
+                .map(|(name, reference)| (name.to_string(), Some(reference.to_string())))
+                .unwrap_or((name, None))
+        } else {
+            (name, None)
+        };
+
+        let (reference, digest) = if let Some(reference) = reference {
+            if let Some(digest) = digest {
+                (Some(reference), Some(digest))
+            } else {
+                reference
+                    .split_once('@')
+                    .map(|(reff, digest)| (Some(reff.to_string()), Some(digest.to_string())))
+                    .unwrap_or_else(|| (Some(reference), None))
+            }
+        } else {
+            (None, digest)
+        };
+
         Ok(ImageName {
             hostname,
             port,
             name,
             reference,
+            digest,
         })
     }