When running Jenkins CI on Debian Squeeze, you might notice that the system displays UTC time despite your machine being configured for local time (e.g., 'America/Toronto'). This happens because Jenkins defaults to the Etc/UTC timezone, ignoring system settings.

First, check your system's current timezone configuration:

$ date
Mon Jul  9 16:00:57 EDT 2012
$ cat /etc/timezone
America/Toronto

Jenkins inherits its timezone from the JVM environment. Even with UTC=no in /etc/default/rcS, Jenkins may still use UTC. Check Jenkins' system information:

System.getProperty("user.timezone") = Etc/UTC

There are two reliable methods to make Jenkins use local time:

Method 1: Java System Property

Edit Jenkins' startup configuration (usually in /etc/default/jenkins):

JAVA_ARGS="-Duser.timezone=America/Toronto"

Then restart Jenkins:

sudo service jenkins restart

Method 2: Global Environment Variable

Alternatively, set the timezone globally for all Java applications:

echo "export TZ=America/Toronto" | sudo tee -a /etc/profile
source /etc/profile
sudo service jenkins restart

After applying either solution, verify the change:

$ curl -s http://localhost:8080/systemInfo | grep timezone
user.timezone = America/Toronto

• Ensure your Debian system has the correct timezone package: sudo apt-get install tzdata
• Check for multiple timezone configurations in /etc/timezone, /etc/localtime, and /etc/sysconfig/clock
• For Docker-based Jenkins installations, you'll need to set the timezone in both the container and Jenkins configuration

For more flexibility, consider installing the Timezone Plugin:

Manage Jenkins → Manage Plugins → Available → Search for "Timezone"

Then configure it in Manage Jenkins → Configure System.

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When running Jenkins on Debian systems, you might notice that timestamps in build logs and system information show UTC time despite your server being configured with a local timezone. This happens because Jenkins defaults to UTC for consistency across distributed builds.

First, confirm your system's timezone settings:

$ date
Mon Jul  9 16:00:57 EDT 2012
$ cat /etc/timezone
America/Toronto

The /etc/default/rcS setting (UTC=no) only affects how the hardware clock is interpreted during boot - it doesn't control Java applications like Jenkins.

There are several approaches to make Jenkins honor your local timezone:

1. Java System Property

Modify Jenkins startup parameters by editing the init script (usually /etc/default/jenkins):

JAVA_ARGS="-Duser.timezone=America/Toronto"

Restart Jenkins after making changes:

$ sudo systemctl restart jenkins

2. Global Jenkins Configuration

Alternatively, set the timezone through Jenkins' system configuration:

1. Go to Manage Jenkins → System Configuration
2. Add a global environment variable:

   TZ=America/Toronto
   

3. Containerized Environments

For Docker installations, pass the timezone through environment variables:

docker run -e TZ=America/Toronto -p 8080:8080 jenkins/jenkins

Check the system information page in Jenkins (/systemInfo) to confirm:

user.timezone   America/Toronto

• If using Tomcat, set the timezone in setenv.sh
• For systemd services, add Environment=TZ=America/Toronto to the service file
• Remember that build timestamps in archive files will still use UTC for consistency

Consider installing the Timezone Plugin for per-user timezone preferences:

$ jenkins-plugin-cli --plugins timezone