Walter

Walter is a tiny deployment pipeline tool.

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Blogs

• http://ainoya.io/walter
• http://walter-cd.net

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Overview

Walter is a simple command line tool that automates build, test and deployment of applications or servers.

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Getting Started

How to install

Get a binary file from GitHub Releases and place it in $PATH.

Writing your pipeline

Write your command pipeline in pipeline.yml.

build:
  tasks:
    - name: setup build
      command: echo "setting up ..."
    - name: run build
      command: echo "building ..."
  cleanup:
    - name: cleanup build
      command: echo "cleanup build ..."

deploy:
  tasks:
    - name: run deploy
      command: echo "deploying ..."
  cleanup:
    - name: cleanup
      command: echo "cleanup deploy ..."

Run walter

$ walter -build -deploy
INFO[0000] Build started
INFO[0000] [setup build] Start task
INFO[0000] [setup build] setting up ...
INFO[0000] [setup build] End task
INFO[0000] [run build] Start task
INFO[0000] [run build] building ...
INFO[0000] [run build] End task
INFO[0000] Build succeeded
INFO[0000] Build cleanup started
INFO[0000] [cleanup build] Start task
INFO[0000] [cleanup build] cleanup build ...
INFO[0000] [cleanup build] End task
INFO[0000] Build cleanup succeeded
INFO[0000] Deploy started
INFO[0000] [run deploy] Start task
INFO[0000] [run deploy] deploying ...
INFO[0000] [run deploy] End task
INFO[0000] Deploy succeeded
INFO[0000] [cleanup] Start task
INFO[0000] [cleanup] cleanup deploy ...
INFO[0000] [cleanup] End task
INFO[0000] Deploy cleanup succeeded

That's it.

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Other features

Environment variables

You can use environment variables.

deploy:
  tasks:
    - name: release files
      command: ghr -token $GITHUB_TOKEN $VERSION pkg/dist/$VERSION

Working directory

You can specify a working directory of a task.

build:
  tasks:
    - name: list files under /tmp
      command: ls
      directory: /tmp

Conditions to run tasks

build:
  tasks:
    - name: list files under /tmp
      command: ls
      only_if: test -d /tmp

Get stdout of a previous task

Tasks get stdout of a previous task through a pipe.

build:
  tasks:
    - name: setup build
      command: echo "setting up"
    - name: run build
      command: cat

The second "run build" task outputs "setting up".

Parallel tasks

You can define parallel tasks.

build:
   tasks:
     - name: parallel tasks
       parallel:
           - name: task 1
             command: echo task 1
           - name: task 2
             command: echo task 2
           - name: task 3
             command: echo task 3

You can also mix serial tasks in parallel tasks.

build:
   tasks:
     - name: parallel tasks
       parallel:
           - name: task 1
             command: echo task 1
           - name: task 2
             serial:
               - name: task 2-1
                 command: echo task 2-1
               - name: task 2-2
                 command: echo task 2-2
           - name: task 3
             command: echo task 3

Split pipeline definitions and include them

You can split pipeline definitions in other files and include them.

pipeline.yml

build:
  tasks:
    - include: task1.yml
    - include: task2.yml

task1.yml

- name: task1
  command: echo task1

task2.yaml

- name: task2
  command: echo task2

You can also run single definition file.

$ walter -build -config task2.yml

Wait for some conditions

You can make tasks wait for some conditions.

build:
  tasks:
    - name: launch solr
      command: bin/solr start
    - name: post data to solr index
      command: bin/post -d ~/tmp/foobar.js
      wait_for:
        host: localhost
        port: 8983
        state: ready

Available keys and values are these:

Key	Value (value type)	Description
delay	second (float)	Seconds to wait after the previous stage finish
host	host (string)	IP address or host name
port	port number (int)	Port number
file	file name (string)	File name
state	state of the other key (string)	Two types(present/ready or absent/unready) of states are supported.

Notification

Walter supports notification of task results to Slack.

notify:
  - type: slack
    channel: serverspec
    url: $SLACK_WEBHOOK_URL
    icon_url: http://example.jp/walter.jpg
    username: walter

Other services(ex. HipChat) are not supported currently.

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Changes in v2

Pipeline definition format

Pipeline definition in v1:

pipeline:
  - name: setup build
    type: command
    command: echo "setting up ..."
  - name: run build
    type: command
    command: echo "building ..."
cleanup:
  - name: cleanup build
    type: command
    command: echo "cleanup build ..."

In v2:

build:
  tasks:
    - name: setup build
      command: echo "setting up ..."
    - name: run build
      command: echo "building ..."
  cleanup:
    - name: cleanup build
      command: echo "cleanup build ..."

Separate build and deploy phase

You can separate build and deploy phases in v2:

build:
  tasks:
    - name: setup build
      command: echo "setting up ..."
    - name: run build
      command: echo "building ..."
  cleanup:
    - name: cleanup build
      command: echo "cleanup build ..."

deploy:
  tasks:
    - name: run deploy
      command: echo "deploying ..."
  cleanup:
    - name: cleanup
      command: echo "cleanup deploy ..."

You can run both phases at once or each phase separately.

# Run build and deploy phases
$ walter -build -deploy

# Run build phase only
$ walter -build

# Run deploy phase only
$ walter -deploy

Format of wait_for

You must define parameters for wait_for in one line in v1:

pipeline:
  - name: launch solr
    command: bin/solr start
  - name: post data to solr index
    command: bin/post -d ~/tmp/foobar.js
    wait_for: host=localhost port=8983 state=ready

In v2, you must define parameters for wait_for with mapping of yaml.

build:
  tasks:
    - name: launch solr
      command: bin/solr start
    - name: post data to solr index
      command: bin/post -d ~/tmp/foobar.js
      wait_for:
        host: localhost
        port: 8983
        state: ready

Definition of notification

In v1:

messenger:
  type: slack
  channel: serverspec
  url: $SLACK_WEBHOOK_URL
  icon_url: http://example.jp/walter.jpg
  username: walter

In v2:

notify:
  - type: slack
    channel: serverspec
    url: $SLACK_WEBHOOK_URL
    icon_url: http://example.jp/walter.jpg
    username: walter

The key messenger was changed to notify and you can define multiple notification definitions in v2.

Special variables

Special variables like __OUT, __ERR, __COMBINED and __RESULT are obsoleted in v2.

Tasks get stdout of a previous task through a pipe.

build:
  tasks:
    - name: setup build
      command: echo "setting up"
    - name: run build
      command: cat

The second "run build" task outputs "setting up".

I think this is suffient for defining pipelines. Special variables bring complexity for pipelines.

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Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request