Add 'apiclient get' for simple API retrieval

README.md

@@ -248,7 +248,7 @@ Here we'll describe the settings you can configure on your Bottlerocket instance
 
 You can see the current settings with an API request:
 ```
-apiclient -u /settings
+apiclient get settings
 ```
 
 This will return all of the current settings in JSON format.

sources/api/apiclient/README.md

@@ -14,18 +14,17 @@ It can be pointed to another socket using `--socket-path`, for example for local
 The most important use is probably checking your current settings:
 
 ```
-apiclient -u /settings
+apiclient get settings
 ```
 
-You can also request the values of specific settings using `keys`:
+`get` will request all settings whose names start with the given prefix, so you can drill down into specific areas of interest:
 ```
-apiclient -u /settings?keys=settings.motd,settings.kernel.lockdown
+apiclient get settings.host-containers.admin
 ```
 
-Or, request all settings whose names start with a given `prefix`.
-(Note: here, the prefix should not start with "settings." since it's assumed.)
+Or, request some specific settings:
 ```
-apiclient -u /settings?prefix=host-containers.admin
+apiclient get settings.motd settings.kernel.lockdown
 ```
 
 ### Set mode
@@ -193,8 +192,8 @@ For example, if you want the name "FOO", you can `PATCH` to `/settings?tx=FOO` a
 ## apiclient library
 
 The apiclient library provides high-level methods to interact with the Bottlerocket API.  See
-the documentation for submodules [`apply`], [`exec`], [`reboot`], [`set`], and [`update`] for
-high-level helpers.
+the documentation for submodules [`apply`], [`exec`], [`get`], [`reboot`], [`set`], and
+[`update`] for high-level helpers.
 
 For more control, and to handle APIs without high-level wrappers, there are also 'raw' methods
 to query an HTTP API over a Unix-domain socket.

sources/api/apiclient/README.tpl

@@ -14,18 +14,17 @@ It can be pointed to another socket using `--socket-path`, for example for local
 The most important use is probably checking your current settings:
 
 ```
-apiclient -u /settings
+apiclient get settings
 ```
 
-You can also request the values of specific settings using `keys`:
+`get` will request all settings whose names start with the given prefix, so you can drill down into specific areas of interest:
 ```
-apiclient -u /settings?keys=settings.motd,settings.kernel.lockdown
+apiclient get settings.host-containers.admin
 ```
 
-Or, request all settings whose names start with a given `prefix`.
-(Note: here, the prefix should not start with "settings." since it's assumed.)
+Or, request some specific settings:
 ```
-apiclient -u /settings?prefix=host-containers.admin
+apiclient get settings.motd settings.kernel.lockdown
 ```
 
 ### Set mode

sources/api/apiclient/src/get.rs

@@ -0,0 +1,72 @@
+use snafu::{OptionExt, ResultExt};
+use std::path::Path;
+
+mod merge_json;
+use merge_json::merge_json;
+
+/// Fetches the given prefixes from the API and merges them into a single Value.  (It's not
+/// expected that given prefixes would overlap, but if they do, later ones take precedence.)
+pub async fn get_prefixes<P>(socket_path: P, prefixes: Vec<String>) -> Result<serde_json::Value>
+where
+    P: AsRef<Path>,
+{
+    let mut results: Vec<serde_json::Value> = Vec::with_capacity(prefixes.len());
+
+    // Fetch all given prefixes into separate Values.
+    for prefix in prefixes {
+        let uri = format!("/?prefix={}", prefix);
+        let method = "GET";
+        let (_status, body) = crate::raw_request(&socket_path, &uri, method, None)
+            .await
+            .context(error::Request { uri, method })?;
+        let value = serde_json::from_str(&body).context(error::ResponseJson { body })?;
+        results.push(value);
+    }
+
+    // Merge results together.
+    results
+        .into_iter()
+        .reduce(|mut merge_into, merge_from| {
+            merge_json(&mut merge_into, merge_from);
+            merge_into
+        })
+        .context(error::NoPrefixes)
+}
+
+/// Fetches the given URI from the API and returns the result as an untyped Value.
+pub async fn get_uri<P>(socket_path: P, uri: String) -> Result<serde_json::Value>
+where
+    P: AsRef<Path>,
+{
+    let method = "GET";
+    let (_status, body) = crate::raw_request(&socket_path, &uri, method, None)
+        .await
+        .context(error::Request { uri, method })?;
+    serde_json::from_str(&body).context(error::ResponseJson { body })
+}
+
+mod error {
+    use snafu::Snafu;
+
+    #[derive(Debug, Snafu)]
+    #[snafu(visibility = "pub(super)")]
+    pub enum Error {
+        #[snafu(display("Must give prefixes to query"))]
+        NoPrefixes,
+
+        #[snafu(display("Failed {} request to '{}': {}", method, uri, source))]
+        Request {
+            method: String,
+            uri: String,
+            source: crate::Error,
+        },
+
+        #[snafu(display("Response contained invalid JSON '{}' - {}", body, source))]
+        ResponseJson {
+            body: String,
+            source: serde_json::Error,
+        },
+    }
+}
+pub use error::Error;
+pub type Result<T> = std::result::Result<T, error::Error>;

sources/api/apiclient/src/get/merge_json.rs

@@ -0,0 +1,96 @@
+use serde_json::{map::Entry, Value};
+
+/// This modifies the first given JSON Value by inserting any values from the second Value.
+///
+/// This is done recursively.  Any time a scalar or array is seen, the left side is set to match
+/// the right side.  Any time an object is seen, we iterate through the keys of the objects; if the
+/// left side does not have the key from the right side, it's inserted, otherwise we recursively
+/// merge the values in each object for that key.
+// Logic and tests taken from storewolf::merge-toml, modified for serde_json.
+pub(super) fn merge_json(merge_into: &mut Value, merge_from: Value) {
+    match (merge_into, merge_from) {
+        // If we see objects, we recursively merge each key.
+        (Value::Object(merge_into), Value::Object(merge_from)) => {
+            for (merge_from_key, merge_from_val) in merge_from.into_iter() {
+                // Check if the left has the same key as the right.
+                match merge_into.entry(merge_from_key) {
+                    // If not, we can just insert the value.
+                    Entry::Vacant(entry) => {
+                        entry.insert(merge_from_val);
+                    }
+                    // If so, we need to recursively merge; we don't want to replace an entire
+                    // table, for example, because the left may have some distinct inner keys.
+                    Entry::Occupied(ref mut entry) => {
+                        merge_json(entry.get_mut(), merge_from_val);
+                    }
+                }
+            }
+        }
+
+        // If we see a scalar, we replace the left with the right.  We treat arrays like scalars so
+        // behavior is clear - no question about whether we're appending right onto left, etc.
+        (merge_into, merge_from) => {
+            *merge_into = merge_from;
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::merge_json;
+    use serde_json::json;
+
+    #[test]
+    fn recursion() {
+        let mut left = json! {{
+            "top1": "left top1",
+            "top2": "left top2",
+            "settings": {
+                "inner": {
+                    "inner_setting1": "left inner_setting1",
+                    "inner_setting2": "left inner_setting2"
+                }
+            }
+        }};
+        let right = json! {{
+            "top1": "right top1",
+            "settings": {
+                "setting": "right setting",
+                "inner": {
+                    "inner_setting1": "right inner_setting1",
+                    "inner_setting3": "right inner_setting3"
+                }
+            }
+        }};
+        let expected = json! {{
+            // "top1" is being overwritten from right.
+            "top1": "right top1",
+            // "top2" is only in the left and remains.
+            "top2": "left top2",
+            "settings": {
+                // "setting" is only in the right side.
+                "setting": "right setting",
+                // "inner" tests that recursion works.
+                "inner": {
+                    // inner_setting1 is replaced.
+                    "inner_setting1": "right inner_setting1",
+                    // 2 is untouched.
+                    "inner_setting2": "left inner_setting2",
+                    // 3 is new.
+                    "inner_setting3": "right inner_setting3"
+                }
+            }
+        }};
+        merge_json(&mut left, right);
+        assert_eq!(left, expected);
+    }
+
+    #[test]
+    fn array() {
+        let mut left = json!({"a": [1, 2, 3]});
+        let right = json!({"a": [4, 5]});
+        let expected = json!({"a": [4, 5]});
+        merge_json(&mut left, right);
+        assert_eq!(left, expected);
+    }
+}

sources/api/apiclient/src/lib.rs

@@ -1,8 +1,8 @@
 #![deny(rust_2018_idioms)]
 
 //! The apiclient library provides high-level methods to interact with the Bottlerocket API.  See
-//! the documentation for submodules [`apply`], [`exec`], [`reboot`], [`set`], and [`update`] for
-//! high-level helpers.
+//! the documentation for submodules [`apply`], [`exec`], [`get`], [`reboot`], [`set`], and
+//! [`update`] for high-level helpers.
 //!
 //! For more control, and to handle APIs without high-level wrappers, there are also 'raw' methods
 //! to query an HTTP API over a Unix-domain socket.
@@ -23,6 +23,7 @@ use std::path::Path;
 
 pub mod apply;
 pub mod exec;
+pub mod get;
 pub mod reboot;
 pub mod set;
 pub mod update;