# Run builds and builds steps conditionally

> Configure conditions when build or build step should be run



In addition to the triggers specified in the [triggering section](/yaml/yaml-getting-started/#triggering) of `codemagic.yaml`, it is possible to define custom conditions for more control over when to run builds and build steps.

## Skip building a specific commit

Include `[skip ci]` or `[ci skip]` in your commit message, if you do not wish Codemagic to build a particular commit.

## Using `when` to run or skip builds

Add the `when` key to the workflow root to either skip or run it depending on the specified `changeset` and `condition`.

### Using `changeset` inside `when`

You can avoid unnecessary builds when functional components of your repository were not modified. Use conditional workflow triggering to skip building the workflow if the watched files were not updated since the last successful build.

You should specify the files to watch in `changeset` by using the `includes` and `excludes` keys.

```yaml
workflows:
  build-app:
    name: Build App
    triggering:
      events:
        - push
    when:
      changeset:
        includes:
          - '.'
        excludes:
          - '**/*.md'
```

In this case, the build would be skipped if there were changes only to Markdown files `.md`.

Both keys `includes` and `excludes` in `changeset` are *optional*. If the `includes` key is not specified, its value will default to `'.'`. The `excludes` key defaults to no exclusions.

If you use a monorepo, each workflow can be responsible for building a part of your application. Use conditional workflow triggering and specify the path to the application in the changeset as in the example below.

```yaml
workflows:
  build-android:
    name: Build Android
    triggering:
      events:
        - push
    when:
      changeset:
        includes:
          - 'android/'
```

As a result, commits with changes outside of the `android` folder will not trigger a build.



> 
> Note that **`codemagic.yaml`** is always included in the changeset by default.
> 



### Using `condition` inside `when`

Use `condition` for checking values of environment variables or webhook payload values to either run or skip build.

The `condition` you specify will be evaluated during the build. The build will be skipped if the condition evaluates to `false`.

You can use logical operators in condition, e.g. `==`, `not`, `and`, `or`.

Environment variables are available under the `env` variable. You can check [built-in](https://docs.codemagic.io/variables/environment-variables/) or other environment variables.

Webhook payload is available under the `event` variable. You can check the structure of the webhook payloads that your git provider sends on the **Webhooks** tab in application settings. Note that `event` is not available if the build is started manually from the UI or by a schedule.

For example, the build will continue if the triggering event was *not* a draft pull request update:

```yaml
workflows:
  build:
    name: Build on PR update
    triggering:
      events:
        - pull_request
    when:
      condition: not event.pull_request.draft
```

## Using `when` to run or skip build steps

You may want to either run or skip some specific build steps in your workflow when building your application.


```yaml

  scripts:
    - name: Run unit tests
      script: |
        flutter test
      when:
        condition: env.RUN_TEST == "true"

```


Both `changeset` and `condition` are supported for build steps.