Revision management in GCP - Step-by-Step Execution

Process Flow - Revision management

Create initial revision

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Deploy revision to service

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Make changes to config/code

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Create new revision

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Deploy new revision

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Traffic shifts to new revision

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Optionally rollback to previous revision

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Manage multiple revisions

Revision management tracks versions of deployed code/configuration, allowing updates and rollbacks safely.

Execution Sample

GCP

gcloud run deploy myservice --image gcr.io/myproject/myimage:v1
# Deploys revision-1

gcloud run deploy myservice --image gcr.io/myproject/myimage:v2
# Deploys revision-2

gcloud run services update-traffic myservice --to-revisions revision-1=100
# Rollback traffic to revision-1

Deploys two revisions of a Cloud Run service and rolls back traffic to the first revision.

Process Table

Step	Action	Revision Created	Traffic Allocation	Result
1	Deploy service with image:v1	revision-1	revision-1=100%	Service running revision-1
2	Deploy service with image:v2	revision-2	revision-2=100%	Service updated to revision-2
3	Update traffic to revision-1	none	revision-1=100%	Traffic rolled back to revision-1
4	Deploy service with image:v3	revision-3	revision-3=100%	Service updated to revision-3
5	Split traffic between revision-3 and revision-1	none	revision-3=50%, revision-1=50%	Traffic split between revisions
6	Delete old revision-2	none	unchanged	revision-2 removed
7	No further changes	none	unchanged	Stable traffic and revisions

💡 No more changes; revisions managed with traffic control and cleanup

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
Revisions	none	[revision-1]	[revision-1, revision-2]	[revision-1, revision-2]	[revision-1, revision-2, revision-3]	[revision-1, revision-2, revision-3]	[revision-1, revision-3]	[revision-1, revision-3]
Traffic	none	revision-1=100%	revision-2=100%	revision-1=100%	revision-3=100%	revision-3=50%, revision-1=50%	revision-3=50%, revision-1=50%	revision-3=50%, revision-1=50%

Key Moments - 3 Insights

Why does deploying a new image create a new revision instead of replacing the old one?

Each deployment creates a new revision to keep history and allow rollback, as shown in steps 1, 2, and 4 where new revisions are created without deleting old ones.

How does traffic shifting work between revisions?

Traffic can be split or shifted fully between revisions without redeploying, as in step 5 where traffic is split 50/50 between revision-3 and revision-1.

What happens if you delete a revision that still has traffic?

Deleting a revision with traffic is not allowed or causes errors; traffic must be shifted away first, as shown in step 6 where revision-2 is deleted only after traffic moved away.

Visual Quiz - 3 Questions

Look at the execution table, at which step is traffic rolled back to revision-1?

A Step 3

B Step 2

C Step 5

D Step 6

💡 Hint

Check the 'Traffic Allocation' column for 100% traffic to revision-1

According to variable_tracker, how many revisions exist after step 4?

A 1

B 3

C 2

D 4

💡 Hint

Look at the 'Revisions' row after step 4

If traffic was not shifted before deleting revision-2, what would happen?

A Revision-2 would be deleted successfully

B Traffic would automatically move to revision-1

C Deletion would fail or cause errors

D Revision-3 would be deleted instead

💡 Hint

Refer to key_moments about deleting revisions with traffic

Concept Snapshot

Revision management in GCP Cloud Run:
- Each deploy creates a new revision
- Traffic can be shifted or split between revisions
- Rollbacks done by shifting traffic back
- Old revisions can be deleted after traffic moves
- Enables safe updates and quick recovery

Full Transcript

Revision management in Google Cloud Platform involves creating new versions called revisions each time you deploy a service update. These revisions keep a history of your service states. You can control which revision receives user traffic, allowing you to shift traffic gradually or rollback to a previous version if needed. Deleting old revisions is possible only after traffic is moved away from them. This process ensures safe updates and easy recovery from issues.