> ## Documentation Index
> Fetch the complete documentation index at: https://tally.wharflab.com/llms.txt
> Use this file to discover all available pages before exploring further.

# tally/no-trailing-spaces

> Disallows trailing whitespace at the end of lines.

Disallows trailing whitespace at the end of lines.

| Property | Value      |
| -------- | ---------- |
| Severity | Style      |
| Category | Style      |
| Default  | Enabled    |
| Auto-fix | Yes (safe) |

## Description

Trailing whitespace (spaces and tabs at the end of lines) is invisible noise that clutters diffs in version control. This rule detects and can
automatically remove trailing whitespace from all lines in a Dockerfile.

## Companion editor configuration

Use [EditorConfig integration](/integrations/editorconfig) to configure IDEs and editors to trim trailing whitespace before tally reports it.

## Examples

### Bad

```dockerfile theme={null}
FROM alpine:3.20···
RUN echo hello··
COPY . /app→
```

(where `·` = space, `→` = tab)

### Good

```dockerfile theme={null}
FROM alpine:3.20
RUN echo hello
COPY . /app
```

## Configuration

Default (no config needed):

```toml theme={null}
# Enabled by default with no special options
```

Skip blank lines that consist entirely of whitespace:

```toml theme={null}
[rules.tally.no-trailing-spaces]
skip-blank-lines = true
```

Ignore comment lines:

```toml theme={null}
[rules.tally.no-trailing-spaces]
ignore-comments = true
```

Both options:

```toml theme={null}
[rules.tally.no-trailing-spaces]
skip-blank-lines = true
ignore-comments = true
```

## Options

| Option             | Type    | Default | Description                                                                               |
| ------------------ | ------- | ------- | ----------------------------------------------------------------------------------------- |
| `skip-blank-lines` | boolean | `false` | Skip lines that are entirely whitespace                                                   |
| `ignore-comments`  | boolean | `false` | Skip any line starting with `#` (Dockerfile comments and `#` lines inside heredoc bodies) |

## Auto-fix

This rule provides a safe auto-fix that removes trailing whitespace from offending lines:

```bash theme={null}
tally lint --fix Dockerfile
```

Each trailing whitespace occurrence is removed independently, so the fix count equals the number of affected lines.