Build and automated builds www.scmGalaxy.com scmGalaxy Author: Rajesh Kumar info@scmGalaxy.com

Build and automated builds

www.scmGalaxy.com scmGalaxy Build script A build process is expected to help create a single integrated unit that can be deployed on a target environment A build process can be a sequence of steps that helps in creating a unit Compilation - javac Integration – jar Creating one unit – war Deploy – put the war file into a particular directory The need for a build script arises once there is a need to build the unit multiple times and by multiple people Defining a build script to take care of the sequence of steps helps in faster build process and most importantly the ability to standardize on a build and deployment strategy across the team

www.scmGalaxy.com scmGalaxy Manual build process A manual build process is the one where each individual is expected to go through a set of steps based using his or her memory or a documented steps With time parts of steps will get side-stepped More often than not parts of the code will be deployed rather than the whole A properties file change and the related java class change should be released together. One without the other will not be of any use A manual build by a developer or a CM is too risky for the project Even addition of new steps (like adding code guards using a script before compilation) cannot be done unless a script is used

www.scmGalaxy.com scmGalaxy Build script Each software platform will provide a way to write a script and invoke a sequence of build steps Unix shell scripts, make files, windows batch files etc can be used to define a build script A framework / tool like ANT, helps in abstracting the script from a platform dependency and use simple XML file to define the build script Interestingly ANT itself is only a XML notation, that defines the sequence of steps. The steps themselves rely on the code base, framework binaries, SDK binaries etc. In summary using any suitable syntax a build script should be defined. The script itself should automate the sequence of steps that needs to be executed to create a single unit of software

www.scmGalaxy.com scmGalaxy Notes on build script Choose a language that can be used in multiple platforms (very important for a java project) Ensure that as many steps are automated. Begin with a full clean up and allow full build and deployment to the server Automate even server restart to increase developer efficiency Each build should ensure that it recompiles all classes and optionally fetches latest code from the repository Stale references to others code is the most frequent offense among developers. So use the build script to enforce some discipline too

www.scmGalaxy.com scmGalaxy Notes on build script During peak development, the number of builds and changes to a particular piece of code on a developers machine can be as high as 50 If the developer is made to build and deploy as many times even for small changes like JSP, simple Java class change then the productivity of the developer can be affected While writing a build script, one needs to take care of small short cuts that can help in a faster build and deployment Deploy only HTML and JSP Deploy only compiled java classes Do only a restart Deploy only properties files This is not a default option and one should not spend time at this in the beginning. This is a step more relevant to iterative improvement of the build script

www.scmGalaxy.com scmGalaxy Environment and build The unit created by the build is dependent on the environment it will run in A build is expected to modify environment related dependencies before it creates a integrated unit The build script can also modify the environment before it deploys the unit It is important to keep in mind the various environments in which a build will execute the parts of the environment that needs modifications during a build Typically a environment consists of A application server A web server A database

www.scmGalaxy.com scmGalaxy Environment and build A build could affects all parts of the environment App server – deploy the ear file Web server – deploy web assets Database – deploy DB scripts A strategy needs to be evolved to ensure that the automated deployment (or manual) affects all parts of the environment Recreation of the DB at regular intervals, redeploying web assets (images) with each deployment is an important practice to test the code sanity Ensure that the build script takes care of tagging, building and deploying all related parts of a project How often each of them should be refreshed differs from case-2-case, but, the build script should be capable of managing all deployments to all parts of an environment

www.scmGalaxy.com scmGalaxy Build script and dependencies Once an environment has multiple constituents it is important to understand the inter-dependencies between them A java code base often is dependent on the table names and column names A UI image path defined in a JSP is dependent on the existence of that asset in the web server The whole java code base depends on the existence of a data source defined in the app server More often than not parts of this will change without the other even being informed of the same

www.scmGalaxy.com scmGalaxy Non-related changes that break the build Case 1 DBA makes changes to the DB model based on the requests from the module leads But the code in the module will not need this change for another week Case 2 DBA modifies a column name of an existing column to resolve a review comment The existing java code needs to reflect this change Case 3 The Driver for a DB connectivity has changed The app server configuration needs to change

www.scmGalaxy.com scmGalaxy Non-related changes that break the build In all these case, a part of the environment has changed and the rest of the application get affected The key question is how can the build and release process be synchronized to reduce impact The answer is in bringing about a convention and a team level practice that when followed can reduce the impact First understand the individual parts and their dependency Measure risk of stale data Synchronize the deployments

www.scmGalaxy.com scmGalaxy Understand dependency First understand the dependency, the risk and the level of impact A web asset if not refreshed only results in an old image being shown – relatively low impact in a dev phase A DB column change can affect the way in which the java code accesses the DB and can result in an exception – high impact A new DB driver will result in a change in the data source configuration. The whole application needs to be tested – high risk

www.scmGalaxy.com scmGalaxy Synchronize the deployments The answer to all problems is in synchronizing the deployments Strategy 1 - Full deployments each time Strategy 2 - Full application deployment and partial deployments of dependent systems Strategy 3 - Full application deployments and dependent systems deployed at regular intervals

www.scmGalaxy.com scmGalaxy Synchronize deployments - Strategy 1 Full deployments each time Here the DB or other dependent systems are rebuilt with each code deployment Pros The dependent systems and the code base are refreshed each time and errors can be caught very early Reference to stale column names, images etc can be easily discovered Stale data is also refreshed each time Complete automation can be achieved Cons Needs thorough testing and automation of functional testing to ensure that the breaks can be discovered early Frequent builds can lead to high code breaks because the code cannot change at the same pace as a DB Team discipline needs to be very high with respect to code modifications and modifying the dependent assets Build and configuration management team has too many tasks to work with

www.scmGalaxy.com scmGalaxy Synchronize deployments - Strategy 2 Full application deployment and partial deployments of dependent systems The partial deployments to the dependent systems can be controlled and be executed on a need basis The team decides which script needs to be deployed and only those scripts are deployed with each build Pros The partial deployment helps in better scheduling of code modifications Testing can be targeted at a particular area where the highest amount of change has been delivered Cons Automation cannot be achieved due to human decision intervention Can lead to erroneous code being used till such time the new DB changes are introduced Bugs and errors are caught late in the cycle Coordination between the team could be a weak point

www.scmGalaxy.com scmGalaxy Synchronize deployments - Strategy 3 Full application deployments and complete deployment of dependent systems at regular intervals In this strategy the dependent systems is refreshed at regular intervals (every fortnight, ad-hoc but well announced dates) Pros A blended approach and helps teams schedule code deployments better The fact that the dependent systems are rebuilt regularly ensures that the bugs will surface with each rebuild Automation can be achieved. Cons Code breaks will be discovered late but it will be discovered Needs automation of functional test cases

www.scmGalaxy.com scmGalaxy Frequency of builds A build essentially brings an integrated unit of code and deploys the unit into an environment It is the first point of integration where compilation errors will automatically be discovered With a higher amount of integration and integrated builds the risk of integration level bugs will get lower Typically an integrated build can expect to find the following types of bugs Method signature incompatibility Incorrect reference to column / table names Some amount of testing can help in discovering flow continuity bugs

www.scmGalaxy.com scmGalaxy Frequency of builds The frequency of builds is dependent on the phase of the project During the initial phases, code incompatibility is definitely expected, so the builds can be less frequent and sometimes not even required Gradually the team begins to use each others code and the inter-dependency increases between individuals and modules Initiate a weekly build and then increase it to 3ce a week in a short period of time A daily build and a continuous integration build can be a goal once the build process stabilizes and lesser breaks occur

www.scmGalaxy.com scmGalaxy Environments in a project How many environments should a project have?

www.scmGalaxy.com scmGalaxy Environments in a project No correct answer. But it is a function of the various types of audience that the project needs to cater to For a project that is being developed and it is in the dev phase, the various environments could be Client QA environment Internal testers Integration unit for developers Developer For a project that is on production Production Production-like (can be dormant) QA for production A QA environment per release being worked upon (usually 1 or 2) Integration environment Developer Understand the need for a new environment and how to decide on the final count

www.scmGalaxy.com scmGalaxy Environments in a project Each environment should have a separate app and web server. It needs to have a separate DB instance The integration environment should be machine on which the build itself is executed It helps in ensuring that any target platform specific changes can also be done to the code base The propagation between some environments should also be thought through. Ideally a build that reached QA and once certified by the QA team as release candidate, should automatically be promoted to client and production environments Should a rebuild be done on the same tag or should the same code be propagated is a project specific question? As a CM understand the needs of each environment and the frequency of builds to estimate your own schedule

www.scmGalaxy.com scmGalaxy Automated build A build script itself is a good start point for automation It automates the sequence of steps to be executed per build However, with increasing need for integration and maintaining multiple environments, one needs to worry about the availability of bandwidth to perform such tasks Automating builds helps answer the following questions How often should the build be started? What event should trigger it off? On build breaks how should the feedback be routed to the team / individuals? How can an auto deploy be configured and managed?

www.scmGalaxy.com scmGalaxy Automated build Automated build can be configured to leverage existing build scripts Tools such as cruise control, bamboo etc. provide us the ability to define an automated build and monitor them using web consoles The data reported from such tools can be used to provide effective feedback on build breaks and code quality Automating builds is the next step after defining the build script Multiple builds can be defined to ensure a full build and a full application build are automated and kicked off based on different events Automated build helps in reducing the manual work of starting off a build

www.scmGalaxy.com scmGalaxy Note on continuous integration Continuous integration is a term used to describe the process of triggering a build for each incremental code modification The integration is a continuous process and not a big bang approach It advices the following rules single repository Event triggered build Commit code continuously (every day at least) Use a production like machine and deploy the integrated build Execute a fast build (take only modified code) Use these builds to tag and monitor the best version of the day Send feedback of breakages, test coverage reports , code reviews etc

www.scmGalaxy.com scmGalaxy Benefits of continuous integration The cost of fixing a bug early in the project is less than doing the same at a later stage in the project The key is to identify bugs early. CI helps in doing this on an incremental basis Ability to use automated builds and monitor the progress of build breaks, code coverage on continuous basis helps in making some decisions easier Project delivery risk is reduced

www.scmGalaxy.com scmGalaxy Tool integration with build A typical software project faces the following issues Lack of adherence to coding standards Lack of good programming practices, especially with novice programmers Lack of white box testing in many cases Using simple command line tools one can integrate a build script with 3rd party tools to obtain simple reports about the code quality If the build script is written using ant, then most tools provide a simple way to integrate with the ant tasks It is first important to understand the 3rd party tool and the type of report it generates. Most importantly, how often the tool should be run and the intent of the report

www.scmGalaxy.com scmGalaxy Tools integration with build PMD – automated code review, standards adherence, dead code, duplicate code etc. JUnit – Unit testing and regression test cases EMMA – unit test code coverage Code guards – adding conditional execution of log statements AndroMDA – model driven code generator .. http://www.javapowertools.com/cooltools In summary, each of these tools can be iteratively added to the build script in order to obtain a few reports about the code. The feedback on the quality of the code should be given to the team for continuous improvement

www.scmGalaxy.com scmGalaxy Reports and data analysis - demo PMD – code review JUnit and EMMA – code coverage

www.scmGalaxy.com Thank You ! Author: Rajesh Kumar rajeshkumar.raj06@gmail.com