What is Immutable Infrastructure

My name is Nikita and I am a systems engineer at SEMrush. And in this article I will tell you what Immutable Infrastructure is, what advantages and disadvantages this approach has, and how we use it in the company.

If you have never heard such a phrase, then sit back, it will be interesting.

What it is

Immutable Infrastructure — . , . , , Kubernetes, .

, "" . , — . , "" . , .

, .

GCP, “”, . GCP API SaaS , Immutable . KVM-, , . (Openstack, AWS, Azure ..), . , , , POST-, .

Immutable

, Docker Kubernetes, , :

1. 
   
   , . - , “ ” : - , security , . “” . . Immutable Infrastructure , --. : , . , .
2. 
   
   Immutable infrastructure , () , CI/CD. .
3. 
   
   Docker , . - configuration management unattended upgrades, . . , , , . , .
4. configuration drift
   
   , 100 , , - . , . unattended upgrade, , - , - . Immutable , , , .
5. 
   
   , . , . Immutable . , . failure point , , - production VM. , , , , .
6. 
   
   Immutable "" , , . — .
7. 
   
   , .
8. 
   
   , CPU RAM, . , GCP: Load balancers, GCS , Autoscaler, Cloud SQL ..
9. 
   
   , , — , . , immutable. "" . , .
10. 
    
    , . , . Docker .
11. 
    
    , . .
12. 
    
    Dev . , ( provisioner) Prod .

, , . Immutable . , , , , , .. Immutable.

1. 
   
   Immutable , , . ( , , ..). . .
2. 
   
   , - , , : , , , . , ( , , , Immutable ). : storage. , (, ), storage ( downgrade ). . Stateless , . , , SLA, .
3. 
   
   , Immutable — , security .., . , .

. Immutable , , , , , .. - ( ), . Immutable Immutable. , . .

Push Pull

, . :

Push

, , , . , — , , CI/CD , . — .

Pull

, ( ). , , CI. . — ( ).

- CI/CD .

:

1. Packer — Hashicorp, , . Packer , , , , .
2. Terraform — Hashicorp, , , . , , .
3. Ansible — , . , provision — .
4. Gitlab CI — Gitlab, .
5. GCP — , , , .

Immutable Images

VM . , Google, , - , (nginx, mysql, mongodb ..), . ( , -, ). , - . ( ) Ansible — , one-shot .

, . , , (, ), . .

Image Family

GCP , , , - Image Family.

Image Family — , "". — , , , .., image family, , . latest .

, Image Family , Image Name , ( ). latest , family .

Image Family :

image-v1 — . my-image-family

gcloud compute images create image-v1 \
    --source-disk disk-1 \
    --source-disk-zone us-central1-f \
    --family my-image-family

gcloud compute images describe-from-family my-image-family
family: my-image-family
id: '50116072863057736'
kind: compute#image
name: image-v1

image-v2, my-image-family .

gcloud compute images create image-v2 \
    --source-disk disk-2 \
    --source-disk-zone us-central1-f \
    --family my-image-family

gcloud compute images describe-from-family my-image-family
family: my-image-family
id: '50116072863057756'
kind: compute#image
name: image-v2

- , my-image-family image-v1:

gcloud compute images deprecate image-v2 \
    --state DEPRECATED \
    --replacement image-v1

gcloud compute images describe-from-family my-image-family
family: my-image-family
id: '50116072863057736'
kind: compute#image
name: image-v1

. , ? , , .. - , .

GCP :

READY —

DEPRECATED — deprecated. - -, gcloud terraform. .

OBSOLETE — .

DELETED — , .

REALLY_DELETED — , , DELETED, -.

, . .

. , . , image-family . , image-family.

image-rotator, ( ). :

1. , --image-family. ,
2. , Image Family, , Image Family
3. :
   
   
   • READY DEPRECATED , OBSOLETE
   • DEPRECATED , obsolete , OBSOLETE , DELETED
   • OBSOLETE DEPRECATED
   • DELETED. DELETED ,

, , , .

, , .

, Dev- Master- ( ), . , Prod- — stable, Merge Request.

. , , , :

• Hashicorp Vault
• Prod- Dev
• CloudSQL (: Google (MySQL, PostgreSQL)) Prod- Dev-
• Dev- ( , )

Terraform Dev-, , .1. , . “” Prod’ :)

. ( , ), , , , , . , /, , : , CI/CD . .

Immutable Infrastructure — , . , . , , . , . - , .

, , , , , . , , .