Monthly Archives: November 2014

Checkout branch from git server to local

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This is command to show remote branches:

$ git remote
origin

$ git remote show origin
user@example.com's password:
* remote origin
  Fetch URL: user@example.com:/home/user/git/project.git
  Push  URL: user@example:/home/user/git/project.git
  HEAD branch: master
  Remote branches:
    develop                tracked
    feature/feature1       tracked
    master                 tracked
    release                tracked
  Local branches configured for 'git pull':
    develop                merges with remote develop
    feature/feature1       merges with remote feature/feature1
    master                 rebases onto remote master
    release                merges with remote release
  Local refs configured for 'git push':
    develop                pushes to develop                (up to date)
    feature/feature1       pushes to feature/feature1       (up to date)
    master                 pushes to master                 (up to date)
    release                pushes to release                (up to date)

This is command to checkout remote branch to local, and set the local branch to track remote branch:
git checkout --track origin/branchname

Configuring LogBack

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When default configuration does not exists (logback.groovy, logback-test.xml, logback.xml), LogBack will read system property to get the configuration file location:

java -Dlogback.configurationFile=/path/to/config.xml com.stefanauwyang.ApplicationClass

 

LogBack can be configured to automatically detect the change in configuration file:

<configuration scan="true" scanPeriod="30 seconds" >
  ...
</configuration>

Without the scanPeriod attribute, default period 60 seconds will be set automatically.

LogBack provides a servlet to check the LogBack logging status:

<servlet>
  <servlet-name>ViewStatusMessages</servlet-name>
  <servlet-class>ch.qos.logback.classic.ViewStatusMessagesServlet</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>ViewStatusMessages</servlet-name>
  <url-pattern>/lbClassicStatus</url-pattern>
</servlet-mapping>

We can also print LogBack status to console by configuring this listener through Java code.

LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory(); 
StatusManager statusManager = lc.getStatusManager();
OnConsoleStatusListener onConsoleListener = new OnConsoleStatusListener();
statusManager.add(onConsoleListener);

… or from config file …

<configuration>
  <statusListener class="ch.qos.logback.core.status.OnConsoleStatusListener" />
  ...
</configuration>

Pushing git project to server

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It is often that we started a project in our local laptop, and we want this project secured in our server. I know, it may not possible to execute git clone command from server to clone the project from your local computer due to firewall or at that moment your laptop does not have public IP like your server does.

Before pushing the project to server, I assumed that we have created git repository in the server:

$ mkdir projectname.git
$ cd projectname.git
$ git init --bare

Or just:

$ git init --bare projectname.git

From our local, execute these command to push the git local repository to the server:

$ git remote add origin ssh://user@server.com:port/path/to/projectname.git
$ git push origin master

Now we have our project safe in the server. We can safely continue our work in local laptop, we can clone to other laptop if required, and push the changes to server anytime we want.

Configure application to load its libraries first before websphere libraries

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When deploying our application in IBM WebSphere application server, sometimes there are some libraries which we are using in our application, get conflicted with the one being used by WebSphere.

Follow this instruction to configure WebSphere to load our application libraries first before it loads the WebSphere libraries.

1. Install the application in WebSphere

2. Once the application installed, go to this path:

Enterprise Applications > [ear application name] > Manage Modules > [war application name]

3. Set Class loader order to Classes loaded with parent class loader first

4. Start the application.

Our application will be started by loading application libraries first, before then it loads WebSphere libraries.

Setting iptables to allow port connection from localhost only

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Most of the time, we don’t want to allow direct access to the port from outside our server.
We can configure this through iptables command.

In this example we want to configure port 8080 to be accessible from localhost only. These are the steps:
1. Execute this command to accept connection from localhost.

iptables -A INPUT -p tcp -s localhost --dport 8080 -j ACCEPT

2. Execute this command to drop any connection from other hosts.

iptables -A INPUT -p tcp --dport 8080 -j DROP

If we want to undo this changes, we can execute the same command by replacing -A with -D. From here we may reverse proxy our 8080 port using our apache http server.