Quickstart

Test the application

The pipeline in the previous example was illustrative - you wouldn't ever use it in the real world! So let's write a Dagger pipeline to do something more useful, like running an application's tests.

The code listing below demonstrates a Dagger pipeline that runs tests for the example application, by executing the npm run test command.

tip

The npm run test command is appropriate for a React application, but other applications are likely to use different commands. Modify your Dagger pipeline accordingly.

Go

This code listing does the following:

• It creates a Dagger client with Connect() as before.
• It uses the client's Container().From() method to initialize a new container from a base image - again, the node:16-slim image. This base image is the Node.js version to use for testing. The From() method returns a new Container object with the result.
• It uses the Container.WithDirectory() method to mount the source code directory on the host at the /src mount point in the container, and the Container.WithWorkdir() method to set the working directory to that mount point.
  • Notice that the Container.WithDirectory() accepts additional options to exclude (or include) specific files from the mount. In this case, it excludes the node_modules (locally-installed dependencies) and ci (pipeline code) directories.
• It uses the Container.WithExec() method to define the commands to install dependencies and run tests in the container - in this case, the commands npm install and npm test -- --watchAll=false.
• It uses the Container.Stderr() method to return the error stream of the last executed command. No error output implies successful execution (all tests pass).
  • Failure, indicated by error output, will cause the pipeline to terminate.

Run the pipeline by executing the command below from the application directory:

dagger run go run ci/main.go

tip

The From(), WithDirectory(), WithWorkdir() and WithExec() methods all return a Container, making it easy to chain method calls together and create a pipeline that is intuitive to understand.

Node.js

This code listing does the following:

• It creates a Dagger client with connect() as before.
• It uses the client's container().from() method to initialize a new container from a base image - again, the node:16-slim image. This base image is the Node.js version to use for testing. The from() method returns a new Container object with the result.
• It uses the Container.withDirectory() method to mount the source code directory on the host at the /src mount point in the container, and the Container.withWorkdir() method to set the working directory to that mount point.
  • Notice that the Container.withDirectory() accepts additional options to exclude (or include) specific files from the mount. In this case, it excludes the node_modules (locally-installed dependencies) and ci (pipeline code) directories.
• It uses the Container.withExec() method to define the commands to install dependencies and run tests in the container - in this case, the commands npm install and npm test -- --watchAll=false.
• It uses the Container.stderr() method to return the error stream of the last executed command. No error output implies successful execution (all tests pass).
  • Failure, indicated by error output, will cause the pipeline to terminate.

Run the pipeline by executing the command below from the application directory:

dagger run node ci/index.mjs

tip

The from(), withDirectory(), withWorkdir() and withExec() methods all return a Container, making it easy to chain method calls together and create a pipeline that is intuitive to understand.

Python

This code listing does the following:

• It creates a Dagger client with with dagger.Connection() as before.
• It uses the client's container().from_() method to initialize a new container from a base image - again, the node:16-slim image. This base image is the Node.js version to use for testing. The from_() method returns a new Container object with the result.
• It uses the Container.with_directory() method to mount the source code directory on the host at the /src mount point in the container, and the Container.with_workdir() method to set the working directory to that mount point.
  • Notice that the Container.with_directory() accepts additional options to exclude (or include) specific files from the mount. In this case, it excludes the node_modules (locally-installed dependencies) and ci (pipeline code) directories.
• It uses the Container.with_exec() method to define the commands to install dependencies and run tests in the container - in this case, the commands npm install and npm test -- --watchAll=false.
• It uses the Container.stderr() method to return the error stream of the last executed command. No error output implies successful execution (all tests pass).
  • Failure, indicated by error output, will cause the pipeline to terminate.

Run the pipeline by executing the command below from the application directory:

dagger run python ci/main.py

tip

The from_(), with_directory(), with_workdir() and with_exec() methods all return a Container, making it easy to chain method calls together and create a pipeline that is intuitive to understand.

Go

Node.js

Python