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Running targets

The run command is used in order to run a target on a selection of projects.

How to run a target​

Here is a basic example which runs a target called build on a single project called webapp.

blaze run -t build -p webapp
  • The -t (or --target) option is used in order to provide the target name
  • The -p (or --projects) option is used in order to select projects using their names (as declared in your workspace configuration at the projects key).

When you are launching the target for only one project, you can use a simplified syntax.

This example produces the same result as the last one :

blaze run webapp:build

Project selectors​

There are many different ways to select eligible projects to run a target.

Multiple named projects​

You can use the -p / --projects flag in order to select multiple projects by their names.

Just provide as a comma-separated list of project names.

blaze run -p project1,project2,project3 -t some-target

Any non-existing project within the list will result in an error.

Using a regular expression​

You can select projects which names match on a regular expression using the -r / --regex flag.

The expression is compiled and matched against using the regex Rust crate.

blaze run -r '^[a-zA-Z0-9]+$' -t build

All projects​

You can also select all projects using the -a / --all flag.

blaze run -a -t build

Using tags​

You can select projects that match some tags.

blaze run --tags tag1,tag2,tag3 -t build

Using named selectors​

You can have project selectors declared at the workspace level :

workspace.json
{
    "settings": {
        "selectors": {
            "apps": ["app-1", "app-2", "app-3"]
        }
    }
}

The -s, or --selector is used to specify the name of the selector :

blaze run -s apps -t build

This will run the build target on 3 different projects: app-1, app-2 and app-3.

Checkout this link if you want to know more about named selectors.

Default projects​

If you don't specify any project selector, projects declared in your workspace settings at the defaultSelector key will be selected.

blaze run -t build

This will run the build target using a default selector, or fail if there is no defaut selector.

The defaultSelector setting can take any project selector. Checkout this documentation in order to know more.

Parallelism​

By default, Blaze executes targets sequentially.

You can override this behavior using the --parallelism option.

# run the `build` target on all projects, with at most two tasks in parallel.  
blaze -t build -a --parallelism 2

# run the `build` target on all projects, with as many tasks in parallel as possible.  
blaze -t build -a --parallelism All

# run the `build` target on all projects, with at most one task per available processing unit on your system.
blaze -t build -a --parallelism Cores
 
# run the `build` target on all projects, sequentially.
blaze -t build -a --parallelism None

Check the execution graph before running​

It is possible to preview the execution graph before actually running the targets.

You can do so by using the --dry-run flag :

blaze --dry-run my-app:build

The run command will then do everything except actually executing the targets. Please note that executors will still be resolved even when using the --dry-run flag.