Templates

Templates are snippets of predefined code that people can use to replace a job definition in a screwdriver.yaml. A template contains a series of predefined steps along with a selected Docker image.

Using a template

To use a template, define a screwdriver.yaml:

jobs:
    main:
        template: myNamespace/template_name@1.3.0

Screwdriver takes the template configuration and plugs it in, so that the screwdriver.yaml becomes:

jobs:
    main:
        image: node:6
        requires: [~pr, ~commit]
        steps:
          - install: npm install
          - test: npm test
          - echo: echo $FOO
        environment:
           FOO: bar
        secrets:
          - NPM_TOKEN

Wrap

Wrapping is when you add commands to run before and/or after an existing step. To wrap a step from a template, add a pre or post in front of the step name.

Example:

jobs:
    main:
        requires: [~pr, ~commit]
        template: myNamespace/template_name@1.3.0
        steps:
            - preinstall: echo pre-install
            - postinstall: echo post-install

This will run the command echo pre-install before the template’s install step, and echo post-install after the template’s install step.

Replace

To replace a step from a template, add your command with the same template’s step name.

Example:

jobs:
    main:
        requires: [~pr, ~commit]
        template: myNamespace/template_name@1.3.0
        steps:
            - install: echo skip installing

This will run the command echo skip installing for the install step.

You can also replace the image defined in the template. Some of the steps in the template could assume commands or environment invariants that your image may not have, so use this replacement judiciously.

Example:

jobs:
    main:
        requires: [~pr, ~commit]
        image: my_org/my_image:latest
        template: myNamespace/template_name@1.3.0

Creating a template

Writing a template yaml

To create a template, create a new repo with a sd-template.yaml file. The file should contain a namespace, name, version, description, maintainer email, and a config with an image and steps. If no namespace is specified, a ‘default’ namespace will be applied. An optional images directive can be defined to list supported images with a descriptive label.

Example sd-template.yaml:

namespace: myNamespace
name: template_name
version: '1.3'
description: template for testing
maintainer: foo@bar.com
images:
    stable-image: node:6
    latest-image: node:7
config:
    image: node:6
    steps:
        - install: npm install
        - test: npm test
        - echo: echo $FOO
    environment:
        FOO: bar
    secrets:
        - NPM_TOKEN

Writing a screwdriver.yaml for your template repo

To validate your template, run the template-validate script from the screwdriver-template-main npm module in your main job to validate your template. This means the build image must have NodeJS and NPM properly installed to use it. To publish your template, run the template-publish script from the same module in a separate job.

To remove your template, run the template-remove script. You will need to provide the template name as an argument.

By default, the file at ./sd-template.yaml will be read. However, a user can specify a custom path using the env variable: SD_TEMPLATE_PATH.

Tagging templates

You can optionally tag a specific template version by running the template-tag script from the screwdriver-template-main npm package. This must be done by the same pipeline that your template is created by. You will need to provide arguments to the script: template name and tag. You can optionally specify a version; the version needs to be an exact version. If the version is omitted, the most recent version will be tagged.

To remove a template tag, run the template-remove-tag script. You will need to provide the template name and tag as arguments.

Example screwdriver.yaml:

shared:
    image: node:6
jobs:
    main:
        requires: [~pr, ~commit]
        steps:
            - install: npm install screwdriver-template-main
            - validate: ./node_modules/.bin/template-validate
        environment:
            SD_TEMPLATE_PATH: ./path/to/template.yaml
    publish:
        requires: [main]
        steps:
            - install: npm install screwdriver-template-main
            - publish: ./node_modules/.bin/template-publish
            - autotag: ./node_modules/.bin/template-tag --name myNamespace/template_name --tag latest
            - tag: ./node_modules/.bin/template-tag --name myNamespace/template_name --version 1.3.0 --tag stable
        environment:
            SD_TEMPLATE_PATH: ./path/to/template.yaml
    remove:
        steps:
            - install: npm install screwdriver-template-main
            - remove: ./node_modules/.bin/template-remove --name myNamespace/template_name
    remove_tag:
        steps:
            - install: npm install screwdriver-template-main
            - remove_tag: ./node_modules/.bin/template-remove-tag --name myNamespace/template_name --tag stable

Create a Screwdriver pipeline with your template repo and start the build to validate and publish it.

To update a Screwdriver template, make changes in your SCM repository and rerun the pipeline build.

Finding templates

To figure out which templates already exist, you can make a GET call to the /templates endpoint. See the API documentation for more information. There is also a /templates endpoint in the UI.