Markdown-run

Execute code blocks from your markdown files. Save results to a new code block appended after the initial code block. Do not rerun code blocks if result block is present.

Meant to be used from the terminal or from an editor with a keybinding.

Supported languages:

• Javascript
• Ruby
• sqlite3
• postgresql
• bash
• zsh
• mermaid (generates SVG diagrams)

gem install markdown-run

• Run specs markdown-run
• Run on a markdown file markdown-run your-filename

example vscode keybinding

  {
    "key": "ctrl+shift+b",
    "command": "runCommands",
    "args": {
      "commands": [
        {
          "command": "workbench.action.files.save"
        },
        {
          "command": "workbench.action.terminal.sendSequence",
          "args": {
            "text": "markdown-run \"${file}\"\n"
          }
        },
        {
          "command": "workbench.action.files.revert"
        }
      ]
    },
    "when": "editorTextFocus && editorLangId == 'markdown'"
  },

• run=true or run=false to control whether a code block should be executed at all. run=true is the default if not specified
• rerun=true or rerun=false to control whether a code block should be re-executed if a result block already exists. rerun=false is the default if not specified
• result=true or result=false to control whether the result block should be displayed after execution. result=true is the default if not specified. When result=false, the code still executes but the result block is hidden
• explain=true or explain=false for psql code blocks to generate query execution plans with Dalibo visualization links. explain=false is the default if not specified
• flamegraph=true or flamegraph=false for psql code blocks to generate PostgreSQL query execution plan flamegraphs as SVG images. flamegraph=false is the default if not specified

Options can be combined. If run=false is specified, the code block will not execute regardless of the rerun setting. The result option only affects display of the result block, not code execution.

Options can also be specified using standalone syntax without explicit =true:

• run is equivalent to run=true
• rerun is equivalent to rerun=true
• result is equivalent to result=true
• explain is equivalent to explain=true
• flamegraph is equivalent to flamegraph=true

Explicit assignments (e.g., run=false) take precedence over standalone options.

Examples:

console.log("This will not execute at all");

console.log("This will re-execute even if result exists");

console.log("This will execute only if no result exists");

puts "This executes but the result block is hidden"

SELECT * FROM users WHERE id = 1;

EXPLAIN (ANALYZE) SELECT * FROM large_table;

SELECT u.name, COUNT(o.id) as order_count
FROM users u
LEFT JOIN orders o ON u.id = o.user_id
WHERE u.created_at > '2024-01-01'
GROUP BY u.id, u.name
ORDER BY order_count DESC
LIMIT 10;

-- This will generate a flamegraph but hide the JSON result block
SELECT * FROM complex_query_with_joins;

SELECT * FROM large_table;
-- This will execute the explain query and show the Dalibo link but hide the result block

PostgreSQL flamegraph blocks generate interactive SVG flamegraphs from query execution plans:

SELECT users.*, orders.total
FROM users
JOIN orders ON users.id = orders.user_id
WHERE users.created_at > '2024-01-01';

This generates:

• An SVG flamegraph file in a directory named after the markdown file
• Filename format: my-document-flamegraph-20250118-143022-a1b2c3.svg
• Embedded image tag: ![PostgreSQL Query Flamegraph](my-document/my-document-flamegraph-20250118-143022-a1b2c3.svg)

Flamegraph features:

• Interactive: Hover over rectangles to see detailed timing information
• Color-coded: Different colors for operation types (red=seq scans, green=index scans, blue=joins, etc.)
• Hierarchical: Shows query plan structure visually
• Performance insights: Width represents execution time, making bottlenecks immediately visible

What flamegraphs help identify:

• Slow operations (widest rectangles)
• Query plan structure (nested relationships)
• Inefficient operations (color-coded by type)
• Execution time distribution across plan nodes

Mermaid blocks generate SVG files and insert markdown image tags:

graph TD
    A[Start] --> B[Process]
    B --> C[End]

This generates an SVG file in a directory named after the markdown file, with a filename that includes the markdown file's basename and a timestamp:

• Directory: my-document/ (if the markdown file is my-document.md)
• Filename: my-document-20250602-215507-a1289a799c29.svg
• Image tag: ![Mermaid Diagram](my-document/my-document-20250602-215507-a1289a799c29.svg)

Note: Requires @mermaid-js/mermaid-cli to be installed: npm install -g @mermaid-js/mermaid-cli

You can add a yaml frontmatter to redefine code block behavior.

For example sql blocks run by default against sqlite To have them run with postgres you can add at the top of your markdown file:

markdown-run:
  alias:
    - sql: psql

You can override the default behavior for code block options using frontmatter:

markdown-run:
  defaults:
    rerun: true
    result: false
  psql:
    explain: true
  ruby:
    rerun: false

Priority order (highest to lowest):

1. Explicit options in code blocks (e.g., rerun=true)
2. Language-specific defaults (e.g., psql: { explain: true })
3. Global defaults (e.g., defaults: { rerun: true })
4. Built-in application defaults

Available options for defaults:

• run: Control whether code blocks execute (default: true)
• rerun: Control whether to re-execute if result exists (default: false)
• result: Control whether to show result blocks (default: true)
• explain: For psql blocks, generate explain plans (default: false)
• flamegraph: For psql blocks, generate flamegraph SVGs (default: false)

Examples:

Make all code blocks rerun by default:

markdown-run:
  defaults:
    rerun: true

Hide result blocks by default but enable explain for psql:

markdown-run:
  defaults:
    result: false
  psql:
    explain: true

Enable flamegraphs by default for all psql blocks:

markdown-run:
  psql:
    flamegraph: true

Language-specific settings override global defaults:

markdown-run:
  defaults:
    rerun: false # Global default
  ruby:
    rerun: true # Ruby blocks will rerun, others won't

Just run the script with ./exe/markdown-run

Bug reports are welcome on GitHub at https://github.com/aurelienbottazini/markdown-run.

The gem is available as open source under the terms of the MIT License.