Gitops Hands On

Hands on Gitops
January 2019 – Cloud Native Wales
Brice Fernandes – @fractallambda – brice@weave.works
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I’m Brice
I work for Weaveworks.
You can find Weaveworks at https://www.weave.works
or @weaveworks
Team at Weaveworks is behind the GitOps model
You can find me online at @fractallambda

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Login to your cluster – Weave Cloud & C9
1. Go to tinyurl.com/cnw-gitops-2019
2. Add your name and email
3. You can log into your cluster using the username and password

Q: Why this talk?
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A: New ideas. Inspire change.

What’s this Gitops business anyway?
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GitOps is...
An operation model

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GitOps is...
An operation model
Derived from CS and operation knowledge

10
GitOps is...
An operation model
Technology agnostic (name notwithstanding)

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GitOps is...
An operation model
A set of principles (Why instead of How)

12
GitOps is...
An operation model
Although
Weaveworks
can help
with how

13
GitOps is...
An operation model
A way to speed up your team

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1 The entire system is described declaratively.

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Beyond code, data ⇒
Implementation independent
Easy to abstract in simple ways
Easy to validate for correctness
Easy to generate & manipulate from code

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Beyond code, data ⇒
Implementation independent
Easy to abstract in simple ways
Easy to validate for correctness
Easy to generate & manipulate from code

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How is that different from
Infrastructure as code?

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How is that different from
Infrastructure as code?
It’s about consistency in the
failure case.

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It’s about consistency in the
failure case.
When imperative systems
fail, the system ends up in
an unknown, inconsistent
state.

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fail, the system ends up in
an unknown, inconsistent
state.
Declarative changes let you
think of changes as
transactions.

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Declarative changes let you
think of changes as
transactions.
This is a very good thing.

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The canonical desired system state is versioned
(with Git)
2

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The canonical desired system state is versioned
(with Git)
Canonical Source of Truth (DRY)
With declarative definition, trivialises rollbacks
Excellent security guarantees for auditing
Sophisticated approval processes (& existing workflows)
Great Software ↔ Human collaboration point
2

25
Changes to the desired state are
automatically applied to the system
3

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Changes to the desired state are
Significant velocity gains
Privileged operators don’t cross security boundaries
Separates What and How.
3

27
Software agents ensure correctness
and alert on divergence
4

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Software agents ensure correctness
4
Continuously checking that desired state is met
System can self heal
Recovers from errors without intervention (PEBKAC)
It’s the control loop for your operations

29
2 The canonical desired system state is versioned
(with Git)
3 Changes to the desired state are
4 Software agents ensure correctness

Gitops is Functional Reactive Programming…
...for your infrastructure.
Like React, but for servers and applications.

What should be GitOps’ed?
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What should be GitOps’ed?
32
I’m o r
so y

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Canonical
source of truth
People
Software
Agents
Software
Agents

Dashboards
Alerts
Playbook
Kubernetes Manifests
Application configuration
Provisioning scripts
35
Application checklists
Recording Rules
Sealed Secrets

Getting started with your environment
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38
Login to your cluster – Weave Cloud & C9
1. Go to tinyurl.com/cnw-gitops-2019
2. Add your name and email
3. You can log into your cluster using the username and password

Your Cluster
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pod
Icon by Freepik from www.flaticon.com

Your Cluster
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pod
Cloud Source
Repositories Container
Builder
Cloud
Registry

GitOps hands-on 1/10Kick the tires on your cluster 💻
1. Start with a simple command:
➤ kubectl version
2. Look at what’s running on the cluster with
Weave Cloud Explore

“DevOps Console”
Tooling for deployment,
visualisation and
observability
Weave Cloud
45

GitOps hands-on 1/10
Ask Kubernetes what’s running on the cluster:
➤ kubectl get pods --all-namespaces
Query Kubernetes 💻

[Only do this step if you didn’t do it in your cluster earlier]
Create the namespace we will use for this exercise:
kubectl create namespace dev
Shortly, the Deploy agent will notice this change, and sync the Deployment and
Service files.
Watch for this happening in Weave Cloud or via:
watch kubectl -n dev get all
Gitops Hands On 1/12 💻

We’re going to make a code change and see it flow through CI, then
deploy that change.
Call the version endpoint on the service to see what is running:
curl podinfo.dev:9898/version

In the editor, open podinfo/pkg/version/version.go, increment the
version number and save:
var VERSION = "0.3.1"
Commit your changes and push to master:
cd /workspace/podinfo
git pull
git add pkg/version/version.go
git commit -m "release v0.3.1 to dev"
git push

The CI pipeline will create an image tagged the same as the git commit
Git said something like [master 89b8396]; the tag will be like
master-89b8396
Check by listing image tags (replace user with your username):
gcloud container images list-tags gcr.io/dx-training/USER-podinfo
USER should be of the form “training-user-<number>”.

Navigate in the editor to workspace/cluster/un-workshop/dev and open
podinfo-dep.yaml.
Where it says image:
replace quay.io/stefanprodan/podinfo with gcr.io/dx-training/USER-podinfo
replace the tag 0.3.0 with your tag master-TAG
Save the file and commit your changes and push to master:
cd /workspace/cluster/un-workshop/dev
git add podinfo-dep.yaml
git commit -m "my first deploy"
git push
NO : Her co g u w ar n

Call the version endpoint on the service to see if it changed:
curl podinfo.dev:9898/version

Editing the YAML file was tedious.
Let’s automate it!
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Let’s automate by adding an annotation to your deployment file:
annotations:
flux.weave.works/automated: 'true'
flux.weave.works/tag.podinfo: glob:*
Create a commit (In the control repository) and push it up to the remote to
trigger automation:
cd /worskpace/cluster/un-workshop/dev/
git add podinfo-dep.yaml
git commit -m "automate releases of podinfo"
git push

Open podinfo/pkg/version/version.go, increment the version number
again, and save:
var VERSION = "0.3.2"
Commit your changes and push to master:
git add pkg/version.version.go
git commit -m "release v0.3.2"
git push

Watch for the CI/CD to upgrade the app to 0.3.2:
watch curl podinfo.dev:9898/version

Suppose we don’t like the latest version: we want to roll back.
1. Deautomate by reverting your automate commit
git revert <sha of automation commit>
2. Set the version back to the previous version
3. Check again which version is running:
watch curl podinfo.dev:9898/version

We can flow the version number through the pipeline with a git tag, to
show more meaningful versions
Create and push a git tag:
git tag 0.3.2
git push origin 0.3.2
This will trigger another CI build, and when that is finished you should
have an image tagged 0.3.2

All done :)

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● Having separate pipelines for CI and CD enables better security
● It’s also easier to deal with if a deployment goes wrong
● We built a few versions of a simple app, using a demo CI pipeline
● Deployed those versions to Kubernetes using Weave Cloud
● Automated the deployment
● Deployments, rollback and lock are all done via git
● Git is our single source of truth.
Recap: GitOps CI/CD

Where to find out more
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Search for “Weaveworks GitOps” in your favourite search engine
Take a look at our opensource work on https://github.com/weaveworks
Questions?
Weaveworks
@weaveworks
https://weave.works
Brice Fernandes
@fractallambda
brice@weave.works

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Declare
Implement
Monitor /
Observe
Modify

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Declare
ImplementModify
Continuous
Deployment
Default
dashboards
Automated by
software
agents
Monitor /
Observe

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Declare
ImplementModify
Continuous
Deployment
Default
dashboards
Automated by
software
agents
Monitor /
Observe
Software
making
commits

70
Declare
ImplementModify
Continuous
Deployment
Default
dashboards
Automated by
software
agents
Monitor /
Observe
Safe and
reversible
changes

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Declare
ImplementModify
Continuous
Deployment
Default
dashboards
Automated by
software
agents
Monitor /
Observe
Automated,
templated
dashboards

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Feedback loop.
This is what matters.

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Kubernetes operator (Flux, Open Source)
Multiple clusters (staging and prod)
CD into staging
Promotion from staging to prod
Kubernetes
Automated diff tools
(*diff operators, Open Source)
Dashboard definitions in Git
(Grafanalib, Open Source)
Alert definitions in git
Read-only access to production
for all developers
Gated, PR-driven changes to
production
*“stress-reduced”

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CD into staging
Kubernetes
for all developers
production

77
CD into staging
Kubernetes
for all developers
production

78
CD into staging
Kubernetes
for all developers
production

79
CD into staging
Kubernetes
for all developers
production

81
CD into staging
Kubernetes
for all developers
production

83
CD into staging
Kubernetes
for all developers
production

86
CD into staging
Kubernetes
for all developers
production

93
CD into staging
Kubernetes
for all developers
production

94
CD into staging
Kubernetes
for all developers
production

95
CD into staging
Kubernetes
for all developers
production
⇒

96
CD into staging
Kubernetes
for all developers
production
⇒
< 30 minute total cluster recovery

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CD into staging
Kubernetes
for all developers
production
⇒
Dozens of changes per day
with a very small team

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CD into staging
Kubernetes
for all developers
production
⇒
Incredibly fast
regression response

99
CD into staging
Kubernetes
for all developers
production
⇒
Incredibly fast
regression response
Permissive approach
to production access

10
0
CD into staging
Kubernetes
for all developers
production
⇒
Incredibly fast
regression response
Permissive approach
Excellent developer experience

10
1
CD into staging
Kubernetes
for all developers
production
⇒
Incredibly fast
regression response
Permissive approach
Stress-free on-call*

10
2
CD into staging
Kubernetes
for all developers
production
⇒
Incredibly fast
regression response
Permissive approach
Stress-free on-call*

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