Branch indexing and scanning in Jenkins - Step-by-Step Execution

Process Flow - Branch indexing and scanning

Start Jenkins Multibranch Pipeline

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Trigger Branch Indexing

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Scan SCM for Branches

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Identify New/Deleted/Updated Branches

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Create/Update/Delete Jenkins Jobs

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Schedule Builds for New/Updated Branches

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End

Jenkins scans the source code repository to find branches, then creates or updates jobs for each branch automatically.

Execution Sample

Jenkins

1. Start Multibranch Pipeline job
2. Jenkins triggers branch indexing
3. Jenkins scans SCM repository
4. Jenkins detects branches and changes
5. Jenkins creates or updates jobs
6. Builds are scheduled for branches

This sequence shows Jenkins scanning branches and managing jobs accordingly.

Process Table

Step	Action	SCM State	Branches Found	Jenkins Jobs Created/Updated	Builds Scheduled
1	Start Multibranch Pipeline	Repo with branches: main, feature1	None yet	None	None
2	Trigger Branch Indexing	Repo unchanged	None yet	None	None
3	Scan SCM for branches	Branches: main, feature1	main, feature1	None	None
4	Identify new branches	Branches: main, feature1	main, feature1	Create jobs for main, feature1	None
5	Schedule builds	Branches: main, feature1	main, feature1	Jobs exist	Builds scheduled for main, feature1
6	Later scan detects new branch feature2	Branches: main, feature1, feature2	feature2 new	Create job for feature2	Build scheduled for feature2
7	Branch feature1 deleted	Branches: main, feature2	feature1 missing	Delete job for feature1	No build for feature1
8	End	Branches: main, feature2	main, feature2	Jobs for main, feature2	Builds scheduled as needed

💡 Branch indexing completes after scanning all branches and updating jobs accordingly.

Status Tracker

Variable	Start	After Step 3	After Step 4	After Step 6	After Step 7	Final
SCM Branches	main, feature1	main, feature1	main, feature1	main, feature1, feature2	main, feature2	main, feature2
Jenkins Jobs	None	None	main, feature1	main, feature1, feature2	main, feature2	main, feature2
Builds Scheduled	None	None	None	main, feature1, feature2	main, feature2	main, feature2

Key Moments - 3 Insights

Why does Jenkins create new jobs during branch indexing?

Because Jenkins detects new branches in the SCM (see execution_table step 4 and 6), it creates jobs to build those branches automatically.

What happens when a branch is deleted from the SCM?

Jenkins deletes the corresponding job to keep the pipeline clean (see execution_table step 7), so no builds run for deleted branches.

Does Jenkins schedule builds immediately after indexing?

Yes, after creating or updating jobs for branches, Jenkins schedules builds for them (see execution_table step 5 and 6).

Visual Quiz - 3 Questions

Look at the execution_table at step 4. What action does Jenkins take?

A Deletes jobs for all branches

B Schedules builds for deleted branches

C Creates jobs for new branches

D Stops the pipeline

💡 Hint

Check the 'Jenkins Jobs Created/Updated' column at step 4.

At which step does Jenkins detect a new branch 'feature2'?

A Step 3

B Step 6

C Step 5

D Step 7

💡 Hint

Look at the 'SCM State' and 'Branches Found' columns for new branches.

If the branch 'feature1' is deleted, what happens to its Jenkins job?

A It is deleted

B It is updated

C It remains unchanged

D It is renamed

💡 Hint

See the 'Jenkins Jobs Created/Updated' column at step 7.

Concept Snapshot

Branch indexing in Jenkins scans the source code repository for branches.
It creates, updates, or deletes Jenkins jobs based on branch changes.
Builds are scheduled automatically for new or updated branches.
This keeps CI/CD pipelines in sync with the repository branches.

Full Transcript

Branch indexing and scanning in Jenkins is the process where Jenkins looks at the source code repository to find all branches. It then creates or updates jobs for each branch automatically. When a new branch appears, Jenkins creates a job and schedules builds. If a branch is deleted, Jenkins removes the corresponding job. This process keeps the Jenkins pipeline aligned with the current state of the repository branches.