feat: Add Kubernetes Module (starship#404)

Adds a Kubernetes module, which works by parsing kubeconfig.

Author: andytom

Cargo.lock

@@ -85,6 +85,7 @@ The prompt shows information you need while you're working, while staying sleek
   - `✘` — deleted files
 - Execution time of the last command if it exceeds the set threshold
 - Indicator for jobs in the background (`✦`)
+- Current Kubernetes Cluster and Namespace (`☸`)
 
 ## 🚀 Installation
 

README.md

@@ -85,6 +85,7 @@ The default `prompt_order` is used to define the order in which modules are show
 prompt_order = [
     "username",
     "hostname",
+    "kubernetes",
     "directory",
     "git_branch",
     "git_state",
@@ -528,6 +529,35 @@ symbol = "+ "
 threshold = 4
 ```
 
+
+## Kubernetes
+
+Displays the current Kubernetes context name and, if set, the namespace from
+the kubeconfig file. The namespace needs to be set in the kubeconfig file, this
+can be done via `kubectl config set-context starship-cluster --namespace
+astronaut`. If the `$KUBECONFIG` env var is set the module will use that if
+not it will use the `~/.kube/config`.
+
+### Options
+
+| Variable   | Default       | Description                                         |
+| ---------- | ------------- | --------------------------------------------------- |
+| `symbol`   | `"☸ "`       | The symbol used before displaying the Cluster info. |
+| `style`    | `"bold blue"` | The style for the module.                           |
+| `disabled` | `false`       | Disables the `kubernetes` module                    |
+
+### Example
+
+```toml
+# ~/.config/starship.toml
+
+[kubernetes]
+symbol = "⛵ "
+style = "dim green"
+disabled = true
+```
+
+
 ## Line Break
 
 The `line_break` module separates the prompt into two lines.

docs/config/README.md

@@ -45,6 +45,7 @@ chrono = "0.4"
 sysinfo = "0.9.5"
 byte-unit = "3.0.3"
 starship_module_config_derive = { version = "0.20", path = "../starship_module_config_derive" }
+yaml-rust = "0.4"
 
 [dev-dependencies]
 tempfile = "3.1.0"

starship/Cargo.toml

@@ -20,6 +20,7 @@ pub const ALL_MODULES: &[&str] = &[
     "hostname",
     "java",
     "jobs",
+    "kubernetes",
     "line_break",
     "memory_usage",
     "nix_shell",

starship/src/module.rs

@@ -0,0 +1,182 @@
+use ansi_term::Color;
+use dirs;
+use yaml_rust::YamlLoader;
+
+use std::env;
+use std::path;
+
+use super::{Context, Module};
+use crate::utils;
+
+const KUBE_CHAR: &str = "☸ ";
+
+fn get_kube_context(contents: &str) -> Option<(String, String)> {
+    let yaml_docs = YamlLoader::load_from_str(&contents).ok()?;
+    if yaml_docs.is_empty() {
+        return None;
+    }
+    let conf = &yaml_docs[0];
+
+    let current_ctx = conf["current-context"].as_str()?;
+
+    if current_ctx.is_empty() {
+        return None;
+    }
+
+    let ns = conf["contexts"]
+        .as_vec()
+        .and_then(|contexts| {
+            contexts
+                .iter()
+                .filter_map(|ctx| Some((ctx, ctx["name"].as_str()?)))
+                .find(|(_, name)| *name == current_ctx)
+                .and_then(|(ctx, _)| ctx["context"]["namespace"].as_str())
+        })
+        .unwrap_or("");
+
+    Some((current_ctx.to_string(), ns.to_string()))
+}
+
+pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
+    let filename = match env::var("KUBECONFIG") {
+        Ok(path) => path::PathBuf::from(path),
+        Err(_) => dirs::home_dir()?.join(".kube").join("config"),
+    };
+
+    let contents = utils::read_file(filename).ok()?;
+
+    match get_kube_context(&contents) {
+        Some(kube_cfg) => {
+            let (kube_ctx, kube_ns) = kube_cfg;
+
+            let mut module = context.new_module("kubernetes");
+
+            let module_style = module
+                .config_value_style("style")
+                .unwrap_or_else(|| Color::Cyan.bold());
+            module.set_style(module_style);
+            module.get_prefix().set_value("on ");
+
+            module.new_segment("symbol", KUBE_CHAR);
+            module.new_segment("context", &kube_ctx);
+            if kube_ns != "" {
+                module.new_segment("namespace", &format!(" ({})", kube_ns));
+            }
+            Some(module)
+        }
+        None => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_empty_config() {
+        let input = "";
+        let result = get_kube_context(&input);
+        let expected = None;
+
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn parse_no_config() {
+        let input = r#"
+apiVersion: v1
+clusters: []
+contexts: []
+current-context: ""
+kind: Config
+preferences: {}
+users: []
+"#;
+        let result = get_kube_context(&input);
+        let expected = None;
+
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn parse_only_context() {
+        let input = r#"
+apiVersion: v1
+clusters: []
+contexts:
+- context:
+    cluster: test_cluster
+    user: test_user
+  name: test_context
+current-context: test_context
+kind: Config
+preferences: {}
+users: []
+"#;
+        let result = get_kube_context(&input);
+        let expected = Some(("test_context".to_string(), "".to_string()));
+
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn parse_context_and_ns() {
+        let input = r#"
+apiVersion: v1
+clusters: []
+contexts:
+- context:
+    cluster: test_cluster
+    user: test_user
+    namespace: test_namespace
+  name: test_context
+current-context: test_context
+kind: Config
+preferences: {}
+users: []
+"#;
+        let result = get_kube_context(&input);
+        let expected = Some(("test_context".to_string(), "test_namespace".to_string()));
+
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn parse_multiple_contexts() {
+        let input = r#"
+apiVersion: v1
+clusters: []
+contexts:
+- context:
+    cluster: another_cluster
+    user: another_user
+    namespace: another_namespace
+  name: another_context
+- context:
+    cluster: test_cluster
+    user: test_user
+    namespace: test_namespace
+  name: test_context
+current-context: test_context
+kind: Config
+preferences: {}
+users: []
+"#;
+        let result = get_kube_context(&input);
+        let expected = Some(("test_context".to_string(), "test_namespace".to_string()));
+
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn parse_broken_config() {
+        let input = r#"
+---
+dummy_string
+"#;
+        let result = get_kube_context(&input);
+        let expected = None;
+
+        assert_eq!(result, expected);
+    }
+}

starship/src/modules/kubernetes.rs

@@ -11,6 +11,7 @@ mod golang;
 mod hostname;
 mod java;
 mod jobs;
+mod kubernetes;
 mod line_break;
 mod memory_usage;
 mod nix_shell;
@@ -44,6 +45,7 @@ pub fn handle<'a>(module: &str, context: &'a Context) -> Option<Module<'a>> {
         "git_branch" => git_branch::module(context),
         "git_state" => git_state::module(context),
         "git_status" => git_status::module(context),
+        "kubernetes" => kubernetes::module(context),
         "username" => username::module(context),
         #[cfg(feature = "battery")]
         "battery" => battery::module(context),