add builtin docker-hub support

src/hub.rs

@@ -0,0 +1,42 @@
+use color_eyre::eyre::WrapErr;
+use color_eyre::{eyre::ensure, Result};
+use reqwest::Client;
+use serde::Deserialize;
+use time::OffsetDateTime;
+
+pub async fn tags(client: &Client, user: &str, repo: &str) -> Result<Vec<HubTag>> {
+    let result = client
+        .get(format!(
+            "https://hub.docker.com/v2/repositories/{}/{}/tags",
+            user, repo
+        ))
+        .send()
+        .await
+        .wrap_err("error with sending docker hub request")?;
+    ensure!(
+        !result.status().is_client_error(),
+        "error with sending docker hub request"
+    );
+    ensure!(
+        !result.status().is_server_error(),
+        "docker hub request returned an error"
+    );
+    Ok(result
+        .json::<HubTagResponse>()
+        .await
+        .wrap_err("failed to parse hub response")?
+        .results)
+}
+
+#[derive(Debug, Deserialize)]
+pub struct HubTagResponse {
+    results: Vec<HubTag>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct HubTag {
+    pub id: u64,
+    #[serde(with = "time::serde::rfc3339")]
+    pub last_updated: OffsetDateTime,
+    pub name: String,
+}

src/main.rs

@@ -1,4 +1,5 @@
 mod config;
+mod hub;
 
 use crate::config::{Config, FeedConfig};
 use color_eyre::{
@@ -107,6 +108,25 @@ impl FeedFetcher {
     }
 
     async fn get_feed_key(&self, feed: &str) -> Result<u64> {
+        if let Some(hub) = feed.strip_prefix("docker-hub://") {
+            if let Some((user, repo)) = hub.split_once('/') {
+                let tags = hub::tags(&self.client, user, repo).await?;
+                let mut hasher = DefaultHasher::new();
+                for tag in tags {
+                    tag.id.hash(&mut hasher);
+                    tag.last_updated.hash(&mut hasher);
+                }
+
+                Ok(hasher.finish())
+            } else {
+                return Err(eyre!("Invalid hub format {}", feed))
+            }
+        } else {
+            self.get_rss_feed_key(feed).await
+        }
+    }
+
+    async fn get_rss_feed_key(&self, feed: &str) -> Result<u64> {
         let content = self
             .client
             .get(feed)