# mermaid-cli

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This is a command-line interface (CLI) for [mermaid](https://mermaid.js.org/). It takes a mermaid definition file as input and generates an SVG/PNG/PDF file as output.

## Installation

```sh
npm install -g @mermaid-js/mermaid-cli
```

## Usage

Convert Mermaid mmd Diagram File To SVG

```sh
mmdc -i input.mmd -o output.svg
```

> **Note**
>
> See [Alternative installations](#alternative-installations) if you don't want to install the package globally.
>
> Locate how to call the mmdc executable for your preferred method
> i.e. Docker, Yarn, NPM, local install, etc.

## Examples

### Create A PNG With A Dark Theme And Transparent Background

```sh
mmdc -i input.mmd -o output.png -t dark -b transparent
```

### Animating an SVG file with custom CSS

The `--cssFile` option can be used to inline some custom CSS.

Please see [./test-positive/flowchart1.css](test-positive/flowchart1.css) for an example of a CSS file that has animations.

**Warning**: If you want to override `mermaid`'s [`themeCSS`](https://mermaid.js.org/config/schema-docs/config.html#themecss), we recommend instead adding `{"themeCSS": "..."})` to your mermaid `--configFile`. You may also need to use [`!important`](https://developer.mozilla.org/en-US/docs/Web/CSS/important) to override mermaid's `themeCSS`.

**Warning**: Inline CSS files may be blocked by your browser, depending on the [HTTP Content-Security-Policy header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy) of the website that hosts your SVG.

```sh
mmdc --input test-positive/flowchart1.mmd --cssFile test-positive/flowchart1.css -o docs/animated-flowchart.svg
```

<details>
  <summary>Example output: docs/animated-flowchart.svg</summary>

![docs/animated-flowchart.svg](docs/animated-flowchart.svg)

</details>

### Transform a markdown file with mermaid diagrams

```sh
mmdc -i readme.template.md -o readme.md
```

This command transforms a markdown file itself. The mermaid-cli will find the mermaid diagrams, create SVG files from them and refer to those in the markdown output.

This:

````md
### Some markdown

```mermaid
graph
   [....]
```

### Some more markdown

```mermaid
sequenceDiagram
   [....]
```

### Mermaid with custom title/desc

```mermaid
graph
   accTitle: My title here
   accDescr: My description here
   A-->B
```
````

Becomes:

```md
### Some markdown

![diagram](./readme-1.svg)

### Some more markdown

![diagram](./readme-2.svg)

### Mermaid with custom title/desc

![My description here](./readme-3.svg "My title here")
```

### Piping from stdin

You can easily pipe input from stdin. This example shows how to use a heredoc to
send a diagram as stdin to mermaid-cli (mmdc).

```sh
cat << EOF  | mmdc --input -
    graph TD
    A[Client] --> B[Load Balancer]
EOF
```

### See All Available Options

```sh
mmdc -h
```

# Alternative installations

## Use Docker/Podman:

```sh
docker pull minlag/mermaid-cli
```

or pull from Github Container Registry

```sh
docker pull ghcr.io/mermaid-js/mermaid-cli/mermaid-cli
```

or e.g. version 8.8.0

```sh
docker pull minlag/mermaid-cli:8.8.0
```

The container looks for input files in `/data`. So for example, if you have a
diagram defined on your system in `/path/to/diagrams/diagram.mmd`, you can use
the container to generate an SVG file as follows:

```sh
docker run --rm -u `id -u`:`id -g` -v /path/to/diagrams:/data minlag/mermaid-cli -i diagram.mmd
```

Or, if using [Podman](https://podman.io/), instead do:

```sh
podman run --userns keep-id --user ${UID} --rm -v /path/to/diagrams:/data:z ghcr.io/mermaid-js/mermaid-cli/mermaid-cli -i diagram.mmd
```

The key differences in the podman command versus the docker command are:

- The addition of the `--userns keep-id` argument. This allows the container to keep the same UID as the current user's UID in the container namespace instead of mapping to a subuid. To learn more, see the [`userns=mode` documentation](https://docs.podman.io/en/v4.4/markdown/options/userns.container.html).
- The addition of `:z` to the end of the volume mapping. This instructs podman to relabel the files in the volume with the SELinux label `container_file_t`, which allows processes in the container to access the files. See the "Labeling Volume Mounts" section of [podman-run (1)](https://docs.podman.io/en/latest/markdown/podman-run.1.html#volume-v-source-volume-host-dir-container-dir-options) for more info.

In previous version, the input files were mounted in `/home/mermaidcli`. You can
restore this behaviour with the `--workdir` option:

```sh
docker run [...] --workdir=/home/mermaidcli minlag/mermaid-cli [...]
```

## Use Node.JS API

It's possible to call `mermaid-cli` via a Node.JS API.
Please be aware that **the NodeJS API is not covered by semver**, as `mermaid-cli` follows
`mermaid`'s versioning.

```js
import { run } from "@mermaid-js/mermaid-cli";

await run(
    "input.mmd",
    "output.svg", // {optional options},
);
```

## Install locally

Some people are [having issues](https://github.com/mermaidjs/mermaid.cli/issues/15)
installing this tool globally. Installing it locally is an alternative solution:

```
npm install @mermaid-js/mermaid-cli
./node_modules/.bin/mmdc -h
```

### Run with npx

[`npx`](https://www.npmjs.com/package/npx) is installed by default with NPM. It
downloads and runs commands at the same time. To use Mermaid CLI with npx, you
need to use the `-p` flag because the package name is different than the command
it installs (`mmdc`). `npx -p @mermaid-js/mermaid-cli mmdc -h`

## Install with [brew](https://brew.sh)

> **Warning**
>
> This method of installation is no longer supported.
> For more details, see the [discussion](https://github.com/mermaid-js/mermaid-cli/issues/288).
> An old version of mermaid-cli can be installed with brew.
>
> ```sh
> brew install mermaid-cli
> ```

## Known issues

1. [Linux sandbox issue](docs/linux-sandbox-issue.md)
2. [Docker permission denied issue](docs/docker-permission-denied.md)
3. [How to setup up mermaid to use already installed chromium?](docs/already-installed-chromium.md)

## For contributors

Contributions are welcome. See the [contribution guide](CONTRIBUTING.md).
