With templates dir

Part of the configuration can be moved in separate template files and then included into werf.yaml. Template files should live in the .werf directory with .tmpl extension (any nesting is supported).

Tip: templates can be generated or downloaded before running werf. For example, for sharing common logic between projects

werf parses all files in one environment, thus described define of one template file becomes available in other files, including werf.yaml.

werf.yaml 
{{ $_ := set . "RubyVersion" "2.3.4" }}
{{ $_ := set . "BaseImage" "alpine" }}

project: my-project
configVersion: 1
---

image: rails
from: {{ .BaseImage }}
ansible:
  beforeInstall:
  {{- include "(component) mysql client" . }}
  {{- include "(component) ruby" . }}
  install:
  {{- include "(component) Gemfile dependencies" . }}
.werf/ansible/components.tmpl 
{{- define "(component) Gemfile dependencies" }}
  - file:
      path: /root/.ssh
      state: directory
      owner: root
      group: root
      recurse: yes
  - name: "Setup ssh known_hosts used in Gemfile"
    shell: |
      set -e
      ssh-keyscan github.com >> /root/.ssh/known_hosts
      ssh-keyscan mygitlab.myorg.com >> /root/.ssh/known_hosts
    args:
      executable: /bin/bash
  - name: "Install Gemfile dependencies with bundler"
    shell: |
      set -e
      source /etc/profile.d/rvm.sh
      cd /app
      bundle install --without development test --path vendor/bundle
    args:
      executable: /bin/bash
{{- end }}

{{- define "(component) mysql client" }}
  - name: "Install mysql client"
    apt:
      name: "{{`{{ item }}`}}"
      update_cache: yes
    with_items:
    - libmysqlclient-dev
    - mysql-client
    - g++
{{- end }}

{{- define "(component) ruby" }}
  - command: gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
  - get_url:
      url: https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer
      dest: /tmp/rvm-installer
  - name: "Install rvm"
    command: bash -e /tmp/rvm-installer
  - name: "Install ruby {{ .RubyVersion }}"
    raw: bash -lec {{`{{ item | quote }}`}}
    with_items:
    - rvm install {{ .RubyVersion }}
    - rvm use --default {{ .RubyVersion }}
    - gem install bundler --no-ri --no-rdoc
    - rvm cleanup all
{{- end }}

If there are templates with the same name werf will use template defined in werf.yaml or the latest described in templates files

If need to use the whole template file, use template file path relative to .werf directory as a template name in include function.

werf.yaml 
project: my-project
configVersion: 1
---
image: app
from: java:8-jdk-alpine
shell:
  beforeInstall:
  - mkdir /app
  - adduser -Dh /home/gordon gordon
import:
- artifact: appserver
  add: '/usr/src/atsea/target/AtSea-0.0.1-SNAPSHOT.jar'
  to: '/app/AtSea-0.0.1-SNAPSHOT.jar'
  after: install
- artifact: storefront
  add: /usr/src/atsea/app/react-app/build
  to: /static
  after: install
docker:
  ENTRYPOINT: ["java", "-jar", "/app/AtSea-0.0.1-SNAPSHOT.jar"]
  CMD: ["--spring.profiles.active=postgres"]
---
{{ include "artifact/appserver.tmpl" . }}
---
{{ include "artifact/storefront.tmpl" . }}
.werf/artifact/appserver.tmpl 
artifact: appserver
from: maven:latest
git:
- add: '/app'
  to: '/usr/src/atsea'
shell:
  install:
  - cd /usr/src/atsea
  - mvn -B -f pom.xml -s /usr/share/maven/ref/settings-docker.xml dependency:resolve
  - mvn -B -s /usr/share/maven/ref/settings-docker.xml package -DskipTests
.werf/artifact/storefront.tmpl 
artifact: storefront
from: node:latest
git:
- add: /app/react-app
  to: /usr/src/atsea/app/react-app
shell:
  install:
  - cd /usr/src/atsea/app/react-app
  - npm install
  - npm run build

With tpl function

The tpl function allows the user to evaluate strings as Go templates inside a template. Thus, werf partials can be located anywhere in the project and be included in werf.yaml.

It is worth noting that these files can use anything defined in werf.yaml and templates in .werf (templates dir).

werf.yaml backend/werf-partial.yaml frontend/werf-partial.yaml 
{{ $_ := set . "BaseImage" "node:14.3" }}

project: app
configVersion: 1
---

{{ range $path, $content := .Files.Glob "**/werf-partial.yaml" }}
{{ tpl $content $ }}
{{ end }}

{{- define "common install commands" }}
- npm install
- npm run build
{{- end }}

image: backend
from: {{ .BaseImage }}
git:
- add: /backend
  to: /app/backend
shell:
  install:
  - cd /app/backend
{{- include "common install commands" . | indent 2 }}

image: frontend
from: {{ .BaseImage }}
git:
- add: /frontend
  to: /app/frontend
shell:
  install:
  - cd /app/frontend
{{- include "common install commands" . | indent 2 }}