Agent types (permanent, cloud) in Jenkins - Step-by-Step Execution

Process Flow - Agent types (permanent, cloud)

Start Jenkins Job

↓

Check Agent Type

↓

Permanent

↓

Use Existing

↓

Agent Node

↓

Run Job

↓

Job Complete

↓

Cloud Agent Cleanup

↓

End

Jenkins decides if the job runs on a permanent or cloud agent, then runs the job accordingly. Cloud agents are created and removed dynamically.

Execution Sample

Jenkins

node('permanent-agent') {
  echo 'Running on permanent agent'
}

node('cloud-agent') {
  echo 'Running on cloud agent'
}

Runs a Jenkins job on either a permanent or a cloud agent node.

Process Table

Step	Agent Type	Action	Agent State	Job State
1	Permanent	Select existing permanent agent	Agent ready	Job queued
2	Permanent	Run job on permanent agent	Agent busy	Job running
3	Permanent	Job completes	Agent ready	Job complete
4	Cloud	Provision new cloud agent	Agent provisioning	Job queued
5	Cloud	Cloud agent ready	Agent ready	Job queued
6	Cloud	Run job on cloud agent	Agent busy	Job running
7	Cloud	Job completes	Agent ready	Job complete
8	Cloud	Cloud agent cleanup	Agent removed	Job complete

💡 Job finishes on permanent agent or cloud agent; cloud agent is removed after job.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5	After Step 7	Final
Agent State	Not assigned	Busy (permanent)	Ready (permanent)	Ready (cloud)	Ready (cloud)	Removed (cloud)
Job State	Not started	Running	Complete	Queued	Complete	Complete

Key Moments - 2 Insights

Why does the cloud agent get removed after the job but the permanent agent stays?

Cloud agents are created dynamically for each job and removed after to save resources, as shown in steps 4 to 8 in the execution table. Permanent agents are always available and stay ready for new jobs.

What happens if the permanent agent is busy when a job starts?

The job waits in the queue until the permanent agent becomes ready, as indicated by the 'Agent ready' and 'Job queued' states in steps 1 and 2.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the cloud agent get provisioned?

A Step 2

B Step 6

C Step 4

D Step 8

💡 Hint

Check the 'Action' column for 'Provision new cloud agent' in the execution table.

According to the variable tracker, what is the agent state after step 7 for the cloud agent?

A Removed

B Ready

C Busy

D Provisioning

💡 Hint

Look at the 'Agent State' row under 'After Step 7' in the variable tracker.

If the permanent agent is busy, what happens to the job state at step 1?

A Job is queued

B Job runs immediately

C Job fails

D Agent is removed

💡 Hint

Refer to the 'Job State' column at step 1 in the execution table.

Concept Snapshot

Jenkins agents run jobs either on permanent or cloud nodes.
Permanent agents are always available.
Cloud agents are created and removed dynamically per job.
Jobs wait if agents are busy.
Cloud agents save resources by cleaning up after use.

Full Transcript

This visual execution shows how Jenkins handles two types of agents: permanent and cloud. When a job starts, Jenkins checks the agent type. For permanent agents, it uses an existing node that stays ready for jobs. For cloud agents, Jenkins provisions a new node, runs the job, then removes the node to save resources. The execution table traces each step, showing agent and job states. The variable tracker highlights how agent and job states change over time. Key moments clarify why cloud agents are removed and how jobs queue if agents are busy. The quiz tests understanding of provisioning steps, agent states, and job queuing behavior.