walter

Walter

Walter is a tiny deployment pipeline template.

Overview

Walter automates the deployment process of applications or servers from configuration to software deployment.

Getting Started

Requirements

• Go 1.3 or greater
• Mercurial 2.9 or greater

How to Build

You can build Walter with the following commands.

$git clone git@github.com:walter-cd/walter.git
$cd walter
$./build

How to contribute

We welcome any contributions through Github pull requests. When you make changes such as new features and the add the tests, please run test before throw the pull request. You can run test with the test.sh script.

$sh test.sh

Configuration setting

Walter has one configuration file, which specifies a set of tasks needed to build or deploy target application or service. More specifically, users specify the order of the tasks for the deployment. Each task is called as stage, and the flow is called pipeline in Walter.

Pipeline setting

The configuration format of Walter is Yaml. The yaml configuration file need to have one pipeline block, which has more than one stage element.

The following is a sample configuration of Walter.

 pipeline:
      - name: command_stage_1
        type: command
        command: echo "hello, world"
      - name: command_stage_2
        type: command
        command: echo "hello, world, command_stage_2"
      - name: command_stage_3
        type: command
        command: echo "hello, world, command_stage_3"

As we see, the pipeline block has three stages and the stage type is command, each of which run echo command and has the stage name (such as command_stage_1). User can name arbitrary name of each stage. The commands are executed with the same order as the pipeline configuration.

Stage setting

Stage in pipeline has three elements, name, type and configurations. configuration elements are optional. The elements of configurations depend on the type. For example command_stage type has command configuration, which specify the shell command run in the stage. The following is the table on the type and the parameters.

Command stage

Command stage executes one command. Users specify Command stage adding command in type.

The following is the parameter of Command stage.

Shell script stage

Shell script stage executes specified shell script file. Users specify Shell script stage adding shell in type.

The following is the parameter of Shell script stage.

Cleanup pipeline

Walter configuraiton can have one cleanup block; cleanup is another pipeline which needs to be executed after a pipeline has either failed or passed. In the cleanup block, we can add command or shell script stages. The below example create a log file in pipeline and then cleanup the log file in the cleaup steps.

pipeline:
    -  name: start pipeline
       command: echo “pipeline” > log/log.txt
cleanup:
    -  name: cleanup
       command:  rm log/*

Reporting function

Walter supports to submits the messages to messaging services.

Report configuration

To submit a message, users need to add a messenger block into the configuration file. The following is a sample of the yaml block with HipChat.

messenger:
    type: hipchat
    room_id: ROOM_ID
    token: TOKEN
    from: USER_NAME

To report the full output of stage execution to the specified messenger service added with the above setting, users add report_full_output attribute with true into the stage they want to know the command outputs.

 pipeline:
    - name: command_stage_1
      type: command
      command: echo "hello, world"
      report_full_output: true # If you put this option, messenger sends the command output "hello, world"
    - name: command_stage_2
      type: command
      command: echo "hello, world, command_stage_2"
      # By default, report_full_output is false

Report types

Walter supports HipChat API v1 and v2 as the messenger type.

Report configuration

To activate the report function, we need to specify the properties for messenger type. The needed properties are different in each messenger type.

hipchat and hipchat2

slack

Service coordination

Walter provides a coordination function to a project hosting service, GitHub. Specifically the service function provides two roles

• Check if a new commit or pull requests from the repository
• Run pipeline to the latest commit and pull requests when there are newer ones than the last update

Service configuration

To activate service coordination function, we add a "service" block to the Walter configuration file. "service" block contains several elements (type, token, repo, from, update).

service:
    type: github
    token: ADD_YOUR_KEY
    repo: YOUR_REPOSITORY_NAME
    from: YOUR_ACCOUNT_OR_GROUP_NAME
    update: UPDATE_FILE_NAME

The following shows the description of each element.

Embedding Environment Variables

Users add environment variables in Walter configuration files. The names of environment variables are expanted into the the values of environment variables. Environment variables in the configuration files are valuable when we need to write the sensitive information such as tokens of messenger service or passwords of a external systems.

The following is the format of embedding of the environment variables.

 $ENV_NAME

We write the envrionment variable into ENV_NAME. The following configuration file specify the GitHub Token by embedding the environment variable, GITHUB_TOKEN.

service:
    type: github
    token: $GITHUB_TOKEN
    repo: my-service-repository
    from: service-group
    update: .walter