b4n

b4n is a terminal user interface (TUI) for the Kubernetes API, created mainly for learning the Rust programming language. It is heavily based on the k9s project and built using the kube-rs and ratatui crates.

The Cascadia Code font, or any other font with Nerd Font symbols, is required for proper display of the user interface in the terminal.

To build b4n ensure you have a recent Rust toolchain installed (1.95+). Clone the repository and navigate into the project directory:

git clone https://github.com/fioletoven/b4n.git
cd b4n

Then compile the project in release mode for the best performance:

cargo build --release

The resulting binary will be available at ./target/release/b4n.

• View and filter a list of Kubernetes resources.
• Create, read, update, and delete Kubernetes resources.
• View events for the highlighted resource.
• View logs for the highlighted pod or container.
• Open a shell session or attach to the highlighted container's main process.
• Enable port forwarding for the highlighted container.
• Inject an ephemeral container into the highlighted pod.
• Transfer files to and from containers (requires tar executable on the container).
• Run external binaries configured in a simple plugin system.
• Support mouse interactions in all views.

The resources and port forwards views support advanced filtering with prefixes:

• ns: - filter by namespace (e.g., ns:kube-system)
• n: - filter by resource name (e.g., n:nginx)
• a: - filter by annotations (e.g., a:app.kubernetes.io/name=nginx)
• l: - filter by labels (e.g., l:app=frontend)

Filters can be combined using logical operators: & (and), | (or), ! (negation), and parentheses ().

Example: ns:default & (l:app=web | l:app=api)

Note: CTRL + p keeps the active filter pinned when you switch resources.

When viewing logs for a single container, you can fetch earlier entries by pressing ↑ (up arrow). This works only when you are already scrolled to the top of the current log output and earlier entries are still available.

Note: This functionality works only in single container logs view, not when viewing combined logs for all containers in a pod.

When mouse support is enabled, you can:

• Select text by clicking and dragging in the YAML, logs, shell, and attach views
• Select whole words by double-clicking
• Select whole lines by triple-clicking
• Copy selected text to clipboard using standard key bindings

In edit mode, the following shortcuts are available:

• CTRL + c - copy selected text
• CTRL + x - cut selected text
• CTRL + v - paste text from clipboard
• CTRL + a - select all text
• CTRL + d - delete current line
• CTRL + z - undo
• CTRL + y - redo
• ALT + ↑ - move current line up
• ALT + ↓ - move current line down

Feature requires a tar executable on the container where files are uploaded to or downloaded from.

If Overwrite files is unchecked before the transfer, a check will be executed on the remote container that requires the presence of sh and test commands (if the container does not have these commands, as a workaround the checkbox can be checked, but be aware that files may be overwritten).

If the destination path (To (dir): textbox) contains ~, there will be an attempt to resolve it to the home directory (this requires sh and echo commands to be present on the container). To bypass this, simply provide the full path without ~.

Note: Currently, the upload feature supports only uploading a single file.

Configuration files are stored in the $HOME/.b4n directory. The layout looks like this:

.b4n/
├─ logs/
├─ plugins/
├─ themes/
│  └─ default.yaml
├─ config.yaml
└─ history.yaml

This directory contains application logs, with one file created per day.

This folder contains custom command definitions that appear in the command palette in the resources view (the main b4n screen). Store each command in a separate .yaml file.

name: plugin-name
aliases: []          # additional aliases recognised by the command palette
description: "plugin description"
shortcut: Ctrl+Y
command: dive
args: []             # command arguments; see the available variables below
scopes:
  - pods             # scopes where the plugin will be visible; empty means all (format: 'plural[.group/version]')
excluded_scopes: []  # scopes where the plugin will be hidden; empty means none
confirm: false       # show run confirmation dialog
interactive: true    # run the command as an interactive terminal application; otherwise run it in the background
keep_output: false   # do not close terminal on command exit
keep_error: true     # do not close terminal if command exited with error (if keep_output: false)
output_type: plain   # highlight output as `plain`, `yaml` or `describe` (if keep_output: true and interactive: false)
auto_mouse: false    # automatically enable mouse support if app asks for it
pin_to_top: false    # stay at the beginning of the command output
highlighted: true    # allow running the plugin only when a resource in the list is highlighted
selected: false      # allow running the plugin only when at least one resource is selected
for_each: false      # run each selected resource separately (if interactive: false)

Example plugins are available in the plugins folder.

This folder stores all TUI themes.
If default.yaml does not exist, the application will create it automatically.

You can add more theme files here by copying the ones from the repository themes folder or by creating your own.

This file contains settings that control how b4n behaves.
Example structure:

logs:
  lines: 800
  timestamps: true
mouse: true
terminal:
  system_cursor: false
  scrollback_lines: 1000
theme: light
debug_images:
- busybox
- alpine
- nicolaka/netshoot
contexts:
  test-cluster: '#43464f:#8aad81'
  production: '#d8d8d8:#e1140a'
aliases:
  daemonsets: ds,dms
  namespace: nn
  namespaces: ns,na,nam
  services: svc
key_bindings:
  action.name: list of key bindings for that action
  command-palette.open: :, >, Shift+:, Shift+>
  [...]

• logs.lines - Number of log lines to retrieve from the Kubernetes API for the selected container.
• logs.timestamps - Whether timestamps are enabled by default for logs. You can still toggle this while viewing logs.
• mouse - Whether mouse support is enabled when the application starts. You can also toggle it while the app is running.
• terminal.system_cursor - If true all terminal views will stop drawing its own cursor and start using the system one.
• terminal.scrollback_lines - A configurable maximum size limit of the terminal scrollback buffer.
• theme - The name of the currently selected theme. This should match a file in the themes directory (without the .yaml extension).
• debug_images - List of container images that are displayed during ephemeral container injection.
• contexts - (Optional) A map of context names to their corresponding colors. Useful for highlighting important Kubernetes clusters with distinct header colors.
• aliases - Command palette aliases.
• key_bindings - Defines custom key bindings for various application actions.
  Example key bindings: Ctrl+C, Ctrl+Alt+A, F7, Z, Left, Enter.

Note: If config.yaml does not exist, the application will create it automatically with default values.

This file stores the history for filters, search patterns, and the last selected resource for each Kubernetes context. To remove entries for a specific context, or to clear the file entirely, you can edit or delete it manually.
You can also delete history entries from the UI by highlighting one and pressing Ctrl+D.

MIT