Walter is a tiny deployment pipeline template.
Walter automates the deployment process of applications or servers from configuration to software deployment.
- Go 1.3 or greater
- Mercurial 2.9 or greater
How to Build
You can build Walter with the following commands.
$ git clone firstname.lastname@example.org: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
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.
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 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 executes one command. Users specify Command stage adding command in type.
The following is the parameter of Command stage.
|command||false||shell command run in the stage|
|only_if||true||run specified command on when the condition written in only_if is satisfied|
|directory||true||the directory where walter runs the specified command|
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.
|file||false||shell script file run in the stage|
You can set child stages and run these stages in parallel like this.
pipeline: - name: parallel stages parallel: - name: parallel command 1 type: command command: parallel command 1 - name: parallel command 2 type: command command: parallel command 2 - name: parallel command 3 type: command command: parallel command 3
In the above setting,
parallel command 1,
parallel command 2 and
parallel command 3 are executed in parallel.
Import predefined stages
Walter provides the feature to import predefined stages in specified files.
To import stages to pipeline configuration file, we use require block and
add the list of file names into the block.
For example, the following example import the stages defined in conf/mystage.yml
require: - conf/mystages.yml pipeline: - call: mypackage::hello - call: mypackage::goodbye
In the above setting, the stages ("mypacakge::hello" and "mypackage::goodbye") which are defined in "mystage.yml" are specified.
The files specified in pipeline configuration file need to have two blocks namespace and stages.
In namespace, we add the package name, the package name is need to avoid collisions of the stage names in multiple required files.
The stages block contains the list of stage definitions. We can define the stages same as the stages in pipeline configurations.
For example, the following configuration is the content of conf/mystages.yml imported from the above pipeline configuration file.
namespace: mypackage stages: - def: name: hello command: echo "May I help you majesty!" - def: name: goodbye command: echo "Goobye majesty."
As we see that stages hello and goodbye are defined in the file.
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/*
Walter supports to submits the messages to messaging services.
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: hipchat2 base_url: BASE_URL 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
Walter supports HipChat API v1 and v2 as the messenger type.
|hipchat||HipChat (API v1)|
|hipchat2||HipChat (API v2)|
|slack||Slack Incoming Webhook integration|
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
|base_url||Base API URL (for private servers; hipchat2 only)|
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
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.
|type||Service type (currently Walter supports github only)|
|from||Account or organization name (if the repository is own by a organization)|
|update||Update file which contains the result and time of the last execution (default .walter)|
|branch||Branch name pattern (When this value is filled, Walter only checks the branches who name is matched with the filled regex pattern)|
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.
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
Reusing the results from stages
Walter stores the results of preceding stages. The stages can make use of the results of finished stages using the three special
variables (OUT, ERR, COMBINED and RESULT) in Walter configuration files.
- __OUT - output flushed to standard output
- __ERR - output flushed to standard error
- __COMBINED - combined output of stdout and stderr
- __RESULT - execution result (true or false)
The three variables are maps whose keys are stage names and the value are results of the stages. For example, we want the standard output
result of the stage named "stage1", we write __OUT["stage1"].
The following is a sample configuration with a specical value.
pipeline: - name: stage_1 command: echo "hello world" - name: stage_2 command: echo __OUT["stage_1"]
Walter with the above configuraiton outputs "hello world" twice, since the second stage (stage_2) flushes the standard output result of first stage (stage_1).
Wait running stages until the conditions are satisfied
Walter stage starts imidiately after the previous stage finish, but some stages need to wait for some action such as port is ready or file are created.
wait_for feature supports the actions which need to be ready before the stages begin.
wait_for is defined as a property of stage.
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
The wait_for property takes the key value pairs. Key has sevaral variations. The value depends on the key type. The following table shows the supported key value pairs and the description.
|Key||Value (value type)||Description|
|delay||second (float)||The second to wait after the previous stage finish|
|port||port number (int)||Port number|
|file||file name (string)||File to be created in the previous stages|
|host||host (string)||IP address or host name|
|state||state of the other key (string)||Four types of states are supported. The possible value is dependent to the other Keys.|
There are seveal state values and possible state values are depend on the other key.
|present / ready||Specified port is ready or file is created.|
|absent / unready||port is not active or file does not exist|