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GitOps: Drive operations through git

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Tirumarai Selvan

@Tirumarai

We’re making it blazing fast for developers to build their backends.

Blazingly fastest, lightest GraphQL engine on postgres.
Blazingly setup GitOps on Docker/Kubernetes.

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Git - Source of Truth

Infrastructure as Code

Terraform, CloudFormation

System Configuration as Code

Ansible
Chef
Puppet

Application Configuration as Code

Kubernetes
Hasura

Application Source Code

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Declarative tools ❤ Git

Declarative X (Infra, config etc)

Kubernetes, terraform, ansible etc.

YAML files, version controlled

Collaboration, rollbacks

Declarative means that configuration is guaranteed by a set of facts instead of by a set of instructions, for example, “there are ten redis servers”, rather than “start ten redis servers, and tell me if it worked or not”.

By using declarative tools, the entire set of configuration files can be version controlled in Git. This means that Git is the source of truth. And it also means you get code reviews, comments in the configuration files, and links to any issues in commit messages and PRs. All of this makes the system (and the reasons behind it!) discoverable and easier to operate, recover, and observe. You can even include version-controlled product user stories to help understand the evolution of intent as well as the implementation.

In the case of Kubernetes, we use version control not only for code but also for the YAML files that define the Kubernetes Deployments, Services, DaemonSets, etc. We also use Terraform and Ansible to provision Kubernetes on Amazon, and these are also version controlled in Git.

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Ops

Configure, build, test, deploy
CI/CD
Monitor, fix
Upgrades
Rollbacks
Automation

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GitOps

Ops practices using Git
Use Git as source of truth
Drive operations through git repo
Get version control, history, peer review, and rollback
Githooks/Webhooks: push to trigger build/test
PRs & merge branch to deploy

What exactly is GitOps? By using Git as our source of truth, we can operate almost everything. For example, version control, history, peer review, and rollback happen through Git without needing to poke around with tools like kubectl.

Our provisioning of AWS resources and deployment of k8s is declarative
Our entire system state is under version control and described in a single Git repository
Operational changes are made by pull request (plus build & release pipelines)
Diff tools detect any divergence and notify us via Slack alerts; and sync tools enable convergence
Rollback and audit logs are also provided via Git

Diff and Sync

GitOps is a way to manage systems like Kubernetes

Recovery from total wipeout of your system

Git has moved the state of the art forward in development. A decade of best practices says that config is code, and code should be stored in version control. Now it is paying that benefit forward to Ops

(https://www.weave.works/blog/gitops-operations-by-pull-request)

https://www.weave.works/blog/category/gitops/

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GitOps - Patterns

Use declarative configuration to define application and services
All changes go through git review process, none using kubectl
Use an operator in the cluster to drive observed state to desired state, as declared by the configuration in git

pre-push hook to create manifests

Render templates for correct env
Secrets

pre-receive hook or webhooks to build artifacts and do kubectl set-image
Power to developer
Own tooling

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Gitkube

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Gitkube - Architecture

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Demo

Gitkube

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Tirumarai Selvan

tiru@hasura.io

@Tirumarai

Thanks for listening! Questions?