# Local backend

:::danger
The local backend will execute the pipelines on the local system without any isolation of any kind.
:::

:::note
This backend is still pretty new and cannot be treated as stable. Its
implementation and configuration can change at any time.
:::

Since the code runs directly in the same context as the agent (same user, same
filesystem), a malicious pipeline could be used to access the agent
configuration especially the `WOODPECKER_AGENT_SECRET` variable.

It is recommended to use this backend only for private setup where the code and
pipeline can be trusted. You shouldn't use it for a public facing CI where
anyone can submit code or add new repositories. You shouldn't execute the agent
as a privileged user (root).

The local backend will use a random directory in $TMPDIR to store the cloned
code and execute commands.

In order to use this backend, you need to download (or build) the
[binary](https://github.com/woodpecker-ci/woodpecker/releases/latest) of the
agent, configure it and run it on the host machine.

## Configuration

### Server

Enable connection to the server from the outside of the docker environment by
exposing the port 9000:

```yaml title="docker-compose.yml" for the server
version: '3'

services:
  woodpecker-server:
  [...]
    ports:
      - 9000:9000
      [...]
    environment:
      - [...]
```

### Agent

You can use the `.env` file to store environmental variables for configuration.
At the minimum you need the following information:

```ini
# .env for the agent
WOODPECKER_AGENT_SECRET=replace_with_your_server_secret
WOODPECKER_SERVER=replace_with_your_server_address:9000
```

## Running the agent

Start the agent from the directory with the `.env` file:

`woodpecker-agent`

:::note
When using the `local` backend, the
[plugin-git](https://github.com/woodpecker-ci/plugin-git) binary must be in
your `$PATH` for the default clone step to work. If not, you can still write a
manual clone step.
:::

## Further configuration

### Specify the shell to be used for a pipeline step

The `image` entry is used to specify the shell, such as Bash or Fish, that is
used to run the commands.

```yaml title=".woodpecker.yml"
steps:
  build:
    image: bash
    commands: [...]
```

### Plugins as Executable Binaries

```yaml
steps:
  build:
    image: /usr/bin/tree
```

If no commands are provided, we treat them as plugins in the usual manner.
In the context of the local backend, plugins are simply executable binaries, which can be located using their name if they are listed in `$PATH`, or through an absolute path.

### Using labels to filter tasks

You can use the [agent configuration options](../15-agent-config.md#woodpecker_filter_labels)
and the [pipeline syntax](../../20-usage/20-workflow-syntax.md#labels) to only run certain
pipelines on certain agents. Example:

Define a `label` `type` with value `exec` for a particular agent:

```ini
# .env for the agent

WOODPECKER_FILTER_LABELS=type=exec
```

Then, use this `label` `type` with value `exec` in the pipeline definition, to
only run on this agent:

```yaml title=".woodpecker.yml"
labels:
  type: exec

steps: [...]
```

### Change temp directory

We use the default temp directory to create folders for workflows.
This directory can be changed by:

```env
WOODPECKER_BACKEND_LOCAL_TEMP_DIR=/some/other/dir
```
