Refactoring for Show/Delete handlers

Refactor the existing code architecture to be a little flatter to support adding the show and delete handlers.  Currently these two handlers are just stubbed functions, but the CLI looks about right.

src/api.rs

@@ -92,3 +92,70 @@ fn parse_rfc5988(header_value: Option<&http::HeaderValue>) -> Result<Option<Stri
 
     Ok(None)
 }
+
+/// Parse the response according to the API Documentation.
+///
+/// If a 200 OK response is returned, the registry implements the V2(.1)
+/// registry API and the client may proceed safely with other V2 operations.
+/// Optionally, the response may contain information about the supported
+/// paths in the response body. The client should be prepared to ignore this data.
+///
+/// If a 401 Unauthorized response is returned, the client should take action
+/// based on the contents of the "WWW-Authenticate" header and try the endpoint
+/// again. Depending on access control setup, the client may still have to
+/// authenticate against different resources, even if this check succeeds.
+///
+/// If 404 Not Found response status, or other unexpected status, is returned,
+/// the client should proceed with the assumption that the registry does not
+/// implement V2 of the API.
+///
+/// When a 200 OK or 401 Unauthorized response is returned, the
+/// "Docker-Distribution-API-Version" header should be set to "registry/2.0".
+/// Clients may require this header value to determine if the endpoint serves
+/// this API. When this header is omitted, clients may fallback to an older
+/// API version.
+///
+/// # Errors:
+///
+/// Returns an `ApiError` on the following conditions:
+///
+/// * There is an error parsing the "Docker-Distribution-API-Version" header.
+/// * The value of the above header is not the expected result.
+/// * The above header is missing from the response.
+/// * A non 200 HTTP response status code is returned.
+pub fn parse_response_status(response: &reqwest::Response) -> Result<(), ApiError> {
+    match response.status() {
+        http::StatusCode::OK => {
+            let headers = response.headers();
+            if let Some(header_value) = headers.get("Docker-Distribution-API-Version") {
+                if header_value.to_str()? != "registry/2.0" {
+                    Err(ApiError::UnsupportedVersion(header_value.to_str()?.into()))
+                } else {
+                    Ok(())
+                }
+            } else {
+                Err(ApiError::UnexpectedResponse(
+                    "Missing version header".into(),
+                ))
+            }
+        }
+        http::StatusCode::UNAUTHORIZED => {
+            let headers = response.headers();
+            if let Some(header_value) = headers.get("Docker-Distribution-API-Version") {
+                if header_value.to_str()? != "registry/2.0" {
+                    Err(ApiError::UnsupportedVersion(header_value.to_str()?.into()))
+                } else {
+                    Err(ApiError::AuthorizationFailed)
+                }
+            } else {
+                Err(ApiError::UnexpectedResponse(
+                    "Missing version header".into(),
+                ))
+            }
+        }
+        http::StatusCode::NOT_FOUND => Err(ApiError::NotFound),
+        _ => Err(ApiError::UnexpectedResponse(
+            "Undocumented status code".into(),
+        )),
+    }
+}

src/cli.rs

@@ -78,8 +78,21 @@ pub enum Commands {
     Catalog,
 
     /// Fetch the list of tags for a given image.
+    #[command(arg_required_else_help = true)]
     Tags { name: String },
 
+    /// Show detailed information about a particular image.
+    #[command(arg_required_else_help = true)]
+    Show {
+        image: String,
+        #[arg(default_missing_value = "latest")]
+        tag: Option<String>,
+    },
+
+    /// Delete a tagged image from the registry.
+    #[command(arg_required_else_help = true)]
+    Delete { image: String, tag: String },
+
     /// Perform a simple API Version check towards the configured registry
     /// endpoint.
     Check,

src/commands.rs

@@ -14,6 +14,117 @@
  *    limitations under the License.
  */
 
-pub mod catalog;
+use crate::api;
-pub mod tags;
+use crate::config::Config;
-pub mod version;
+use crate::error::ApiError;
+use serde::Deserialize;
+
+/// Handler for the `Catalog` endpoint
+///
+/// Fetch the list of repository names from the Docker Registry API, and
+/// simply print the resulting names to stdout.
+///
+/// # Errors:
+///
+/// Returns an `ApiError` if there is a problem fetching or parsing the
+/// responses from the Docker Registry API.  
+pub async fn catalog_handler(config: &Config) -> Result<(), ApiError> {
+    #[derive(Deserialize)]
+    struct Response {
+        repositories: Vec<String>,
+    }
+
+    log::trace!("catalog_handler()");
+    let path = "v2/_catalog";
+
+    let responses: Vec<Response> = api::fetch_all(config, path).await?;
+    let repository_list: Vec<&str> = responses
+        .iter()
+        .flat_map(|r| r.repositories.iter().map(String::as_str))
+        .collect();
+
+    for repository in repository_list {
+        println!("{repository}");
+    }
+
+    Ok(())
+}
+
+/// Handler for the `Tags` endpoint
+///
+/// Fetch the list of tags names for a given image from the Docker Registry API, and
+/// simply print the resulting names to stdout.
+///
+/// # Errors:
+///
+/// Returns an `ApiError` if there is a problem fetching or parsing the
+/// responses from the Docker Registry API.  
+pub async fn tags_handler(config: &Config, name: &str) -> Result<(), ApiError> {
+    #[derive(Deserialize)]
+    struct Response {
+        tags: Vec<String>,
+    }
+
+    log::trace!("tags_handler(name: {name})");
+    let path = format!("/v2/{name}/tags/list");
+
+    let responses: Vec<Response> = api::fetch_all(config, &path).await?;
+    let tag_list: Vec<&str> = responses
+        .iter()
+        .flat_map(|r| r.tags.iter().map(String::as_str))
+        .collect();
+
+    for tag in tag_list {
+        println!("{tag}");
+    }
+
+    Ok(())
+}
+
+/// Handler function for showing manifest details
+///
+/// # Errors:
+///
+/// Returns an `ApiError` if there is a problem fetching the manifest or if there
+/// is a problem parsing the response from the Docker Registry API.
+pub async fn show_handler(config: &Config, image: &str, tag: &str) -> Result<(), ApiError> {
+    log::trace!("show_handler(image: {image}, tag: {tag})");
+    let base = config.registry_url.to_owned();
+    let path = format!("/v2/{image}/manifests/{tag}");
+    let _url = base.join(&path)?;
+    Ok(())
+}
+
+/// Handler function for deleting a manifest for a given tagged image.
+///
+/// # Errors:
+///
+/// Returns and `ApiError` if there is a problem converting the given tag to a
+/// manifest digest, or if there is a problem deleting the manifest from the
+/// Docker Registry API.
+pub async fn delete_handler(_config: &Config, image: &str, tag: &str) -> Result<(), ApiError> {
+    log::trace!("delete_handler(image: {image}, tag: {tag})");
+    todo!()
+}
+
+// Path to the Docker Registry APIs "api version check" endpoint.
+
+/// Handler for the API Version Check.
+///
+/// # Errors:
+///
+/// Returns an `ApiError` if there is a problem communicating with the
+/// endpoint or if the required version is not supported.
+pub async fn check_handler(config: &Config) -> Result<(), ApiError> {
+    log::trace!("check_handler()");
+
+    let base = config.registry_url.to_owned();
+    let path = "/v2";
+    let url = base.join(path)?;
+
+    let response = reqwest::get(url).await?;
+
+    api::parse_response_status(&response)?;
+    println!("Ok");
+    Ok(())
+}

src/commands/catalog.rs

@@ -1,59 +0,0 @@
-/*
- *    Copyright 2023 Anthony Oteri
- *
- *    Licensed under the Apache License, Version 2.0 (the "License");
- *    you may not use this file except in compliance with the License.
- *    You may obtain a copy of the License at
- *
- *        http://www.apache.org/licenses/LICENSE-2.0
- *
- *    Unless required by applicable law or agreed to in writing, software
- *    distributed under the License is distributed on an "AS IS" BASIS,
- *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *    See the License for the specific language governing permissions and
- *    limitations under the License.
- */
-
-//! Command module responsible for handling the "catalog" command.
-//!
-//! The "catalog" command works with the Docker Registry APIs "catalog"
-//! entity available at /v2/_catalog.
-//!
-use serde::Deserialize;
-
-use crate::api;
-use crate::config::Config;
-use crate::error::ApiError;
-
-/// Path to the Docker Registry APIs "catalog" entity.
-const BASE_CATALOG_URI: &str = "/v2/_catalog";
-
-/// Handler for the `Catalog` endpoint
-///
-/// Fetch the list of repository names from the Docker Registry API, and
-/// simply print the resulting names to stdout.
-///
-/// # Errors:
-///
-/// Returns an `ApiError` if there is a problem fetching or parsing the
-/// responses from the Docker Registry API.  
-pub async fn handler(config: &Config) -> Result<(), ApiError> {
-    #[derive(Deserialize)]
-    struct Response {
-        repositories: Vec<String>,
-    }
-
-    log::trace!("handler()");
-
-    let responses: Vec<Response> = api::fetch_all(config, BASE_CATALOG_URI).await?;
-    let repository_list: Vec<&str> = responses
-        .iter()
-        .flat_map(|r| r.repositories.iter().map(String::as_str))
-        .collect();
-
-    for repository in repository_list {
-        println!("{repository}");
-    }
-
-    Ok(())
-}

src/commands/tags.rs

@@ -1,60 +0,0 @@
-/*
- *    Copyright 2023 Anthony Oteri
- *
- *    Licensed under the Apache License, Version 2.0 (the "License");
- *    you may not use this file except in compliance with the License.
- *    You may obtain a copy of the License at
- *
- *        http://www.apache.org/licenses/LICENSE-2.0
- *
- *    Unless required by applicable law or agreed to in writing, software
- *    distributed under the License is distributed on an "AS IS" BASIS,
- *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *    See the License for the specific language governing permissions and
- *    limitations under the License.
- */
-
-//! Command module responsible for handling the "tags" command.
-//!
-//! The "tags" command works with the Docker Registry APIs "tags"
-//! entity available at /v2/<name>/tags/list.
-//!
-use serde::Deserialize;
-
-use crate::api;
-use crate::config::Config;
-use crate::error::ApiError;
-
-/// Path to the Docker Registry APIs "catalog" entity.
-const BASE_TAGS_URI: &str = "/v2/{name}/tags/list";
-
-/// Handler for the `Tags` endpoint
-///
-/// Fetch the list of tags names for a given image from the Docker Registry API, and
-/// simply print the resulting names to stdout.
-///
-/// # Errors:
-///
-/// Returns an `ApiError` if there is a problem fetching or parsing the
-/// responses from the Docker Registry API.  
-pub async fn handler(config: &Config, name: &str) -> Result<(), ApiError> {
-    #[derive(Deserialize)]
-    struct Response {
-        tags: Vec<String>,
-    }
-
-    log::trace!("handler()");
-
-    let url = BASE_TAGS_URI.replace("{name}", name);
-    let responses: Vec<Response> = api::fetch_all(config, &url).await?;
-    let tag_list: Vec<&str> = responses
-        .iter()
-        .flat_map(|r| r.tags.iter().map(String::as_str))
-        .collect();
-
-    for tag in tag_list {
-        println!("{name}:{tag}");
-    }
-
-    Ok(())
-}

src/commands/version.rs

@@ -1,110 +0,0 @@
-/*
- *    Copyright 2023 Anthony Oteri
- *
- *    Licensed under the Apache License, Version 2.0 (the "License");
- *    you may not use this file except in compliance with the License.
- *    You may obtain a copy of the License at
- *
- *        http://www.apache.org/licenses/LICENSE-2.0
- *
- *    Unless required by applicable law or agreed to in writing, software
- *    distributed under the License is distributed on an "AS IS" BASIS,
- *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *    See the License for the specific language governing permissions and
- *    limitations under the License.
- */
-
-//! Command module responsible for handling the API Version check.
-//!
-//! This is a minimal endpoint suitable for ensuring that the configured
-//! Docker Registry API supports the correct API version.
-//!
-use crate::config::Config;
-use crate::error::ApiError;
-
-/// Path to the Docker Registry APIs "api version check" endpoint.
-const BASE_URL: &str = "/v2";
-
-/// Handler for the API Version Check.
-///
-/// # Errors:
-///
-/// Returns an `ApiError` if there is a problem communicating with the
-/// endpoint or if the required version is not supported.
-pub async fn handler(config: &Config) -> Result<(), ApiError> {
-    log::trace!("handler()");
-
-    let url = config.registry_url.join(BASE_URL)?;
-    let response = reqwest::get(url).await?;
-
-    parse_response_status(&response)?;
-    println!("Ok");
-    Ok(())
-}
-
-/// Parse the response according to the API Documentation.
-///
-/// If a 200 OK response is returned, the registry implements the V2(.1)
-/// registry API and the client may proceed safely with other V2 operations.
-/// Optionally, the response may contain information about the supported
-/// paths in the response body. The client should be prepared to ignore this data.
-///
-/// If a 401 Unauthorized response is returned, the client should take action
-/// based on the contents of the "WWW-Authenticate" header and try the endpoint
-/// again. Depending on access control setup, the client may still have to
-/// authenticate against different resources, even if this check succeeds.
-///
-/// If 404 Not Found response status, or other unexpected status, is returned,
-/// the client should proceed with the assumption that the registry does not
-/// implement V2 of the API.
-///
-/// When a 200 OK or 401 Unauthorized response is returned, the
-/// "Docker-Distribution-API-Version" header should be set to "registry/2.0".
-/// Clients may require this header value to determine if the endpoint serves
-/// this API. When this header is omitted, clients may fallback to an older
-/// API version.
-///
-/// # Errors:
-///
-/// Returns an `ApiError` on the following conditions:
-///
-/// * There is an error parsing the "Docker-Distribution-API-Version" header.
-/// * The value of the above header is not the expected result.
-/// * The above header is missing from the response.
-/// * A non 200 HTTP response status code is returned.
-fn parse_response_status(response: &reqwest::Response) -> Result<(), ApiError> {
-    match response.status() {
-        http::StatusCode::OK => {
-            let headers = response.headers();
-            if let Some(header_value) = headers.get("Docker-Distribution-API-Version") {
-                if header_value.to_str()? != "registry/2.0" {
-                    Err(ApiError::UnsupportedVersion(header_value.to_str()?.into()))
-                } else {
-                    Ok(())
-                }
-            } else {
-                Err(ApiError::UnexpectedResponse(
-                    "Missing version header".into(),
-                ))
-            }
-        }
-        http::StatusCode::UNAUTHORIZED => {
-            let headers = response.headers();
-            if let Some(header_value) = headers.get("Docker-Distribution-API-Version") {
-                if header_value.to_str()? != "registry/2.0" {
-                    Err(ApiError::UnsupportedVersion(header_value.to_str()?.into()))
-                } else {
-                    Err(ApiError::AuthorizationFailed)
-                }
-            } else {
-                Err(ApiError::UnexpectedResponse(
-                    "Missing version header".into(),
-                ))
-            }
-        }
-        http::StatusCode::NOT_FOUND => Err(ApiError::NotFound),
-        _ => Err(ApiError::UnexpectedResponse(
-            "Undocumented status code".into(),
-        )),
-    }
-}

src/main.rs

@@ -103,9 +103,13 @@ async fn main() -> Result<(), DredgeError> {
 
     let config = Config::try_from(config_file.as_ref())?;
     match args.command {
-        Commands::Catalog => commands::catalog::handler(&config).await?,
+        Commands::Catalog => commands::catalog_handler(&config).await?,
-        Commands::Tags { name } => commands::tags::handler(&config, &name).await?,
+        Commands::Tags { name } => commands::tags_handler(&config, &name).await?,
-        Commands::Check => commands::version::handler(&config).await?,
+        Commands::Show { image, tag } => {
+            commands::show_handler(&config, &image, &tag.unwrap_or("latest".to_string())).await?
+        }
+        Commands::Delete { image, tag } => commands::delete_handler(&config, &image, &tag).await?,
+        Commands::Check => commands::check_handler(&config).await?,
     }
 
     Ok(())