cglue

CuriousGlue "cglue" is an operations and management tool for configuring and executing an application runtime that enables you to launch one or more server processes using a simple set of commands.

cglue solves the challenge of providing a lifecycle around applications that is consistent across environments: from development on to production. A simple set of files placed in a location within the application artifact is all that is required to make use of the cglue command line interface - while the Maven plugin goals provide hooks to implement and test your app lifecycle.

An "app" could consist of any sort of process - a database server, a tomcat instance, a local file processing daemon, etc..

Composition

cglue-api

Provides a set of interfaces that can be used in implementing your App. The responsibility of an app is to instantiate the Server which wraps around the process being managed by the framework.

An Application

An app originates from an Artifact where cglue will be able to find the META-INF/cglue/app.properties file that configures the runtime to execute the lifecycle of your App implementation.

    @Log
    class MyWebApp implements cglue.App {

        final Go go

        MyWebApp(Go go) {
           this.go = go
        }

        Server initialize() {
           return new TomcatServer(go)
        }
        void starting() {
            ...
            log.info("Configuring the dispatcher.xml file ...")
            go.config.bind(go.docBase.read('META-INF/cglue/myapp/dispatcher.xml'), go.docBase.write('WEB-INF/classes/dispatcher.xml'))
        }
        void stopping() {
            log.info("Making a backup of the app home directory ...")
            go.ant.copy(dir: go.appHome, dest: new File(go.config.props['myapp.backupDir']))
        }

    }

Configuration

Configuration is sourced from the app.properties file of your artifact. This file contains the "default" configuration that will resolved on a per attribute basis by the Config interface using this order:

• Environment
• System Property
• Command line switch or Maven configuration override
• META-INF/cglue/app.properties

The configuration is used to make decisions within the App implementation. Another common use is to write the elements out to a file that can be accessed by your runtime application.

Usage

Command line

$ export CGLUE_HOME=/opt/cglue

$ cglue exampleapp start
-----> [Main] CuriousGlue 1.0, artifact: cglue/artifacts/exampleapp.war
-----> [Glue] Initializing example.app.ExampleApp
-----> [ExampleApp] Initializing cglue.server.tomcat.TomcatServer
-----> [TomcatServer] Checking for running server on control port 8099
-----> [Glue] Expanding cglue/artifacts/exampleapp.war into cglue/work/exampleapp/f34fd334sd4f
-----> [Glue] Calling ExampleApp#starting()
-----> [ExampleApp] Configuring cglue/app/exampleapp/myconfiguration.properties
-----> [ExampleApp] Acquiring connection to jdbc:mysql://localhost:3306/sakila?profileSQL=true
-----> [ExampleApp] Updating database tables ...
-----> [TomcatServer] Dispatching to external process

$ cglue exampleapp status
-----> [Main] CuriousGlue 1.0, artifact: cglue/artifacts/exampleapp.war
-----> [Glue] Initializing example.app.ExampleApp
-----> [ExampleApp] Initializing cglue.server.tomcat.TomcatServer
-----> [TomcatServer] Checking for running server on control port 8099
-----> [Glue] Server is running on port 8080

$ cglue exampleapp stop
-----> [Main] CuriousGlue 1.0, artifact: cglue/artifacts/exampleapp.war
-----> [Glue] Initializing example.app.ExampleApp
-----> [ExampleApp] Initializing cglue.server.tomcat.TomcatServer
-----> [TomcatServer] Stopping external process

From Maven

mvn cglue:prepare

Running the prepare goal will "instrument" your Maven module artifact with the contents of the src/main/go directory that contains the application App implementation and your app.properties like so:

exampleapp/
    src/main/cglue
        ExampleApp.groovy
        app.properties

License

Copyright 2012 Jason Stiefel jason@stiefel.io

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.