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@vfarcic
Last active Jun 23, 2021
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# Source: https://gist.github.com/17f57ba2a076bcd5335424575f55d6bd
##########################################################
# How to do database schema migration inside Kubernetes? #
# https://youtu.be/SofQxb4CDQQ #
##########################################################
# Referenced videos:
# - K3d - How to run Kubernetes cluster locally using Rancher k3s: https://youtu.be/mCesuGk-Fks
# - Argo CD - Applying GitOps Principles To Manage Production Environment In Kubernetes: https://youtu.be/vpWQeoaiRM4
# - Flux CD v2 With GitOps Toolkit - Kubernetes Deployment And Sync Mechanism (Second Review): https://youtu.be/R6OeIgb7lUI
# - Bitnami Sealed Secrets - How To Store Kubernetes Secrets In Git Repositories: https://youtu.be/xd2QoV6GJlc
#########
# Setup #
#########
git clone https://github.com/vfarcic/schemahero-demo
cd schemahero-demo
# Please watch https://youtu.be/mCesuGk-Fks if you are not familiar with k3d.
# It could be any other Kubernetes cluster. It does not have to be k3d.
k3d cluster create --config k3d.yaml
helm repo add bitnami \
https://charts.bitnami.com/bitnami
helm upgrade --install \
postgresql bitnami/postgresql \
--namespace postgresql \
--create-namespace \
--wait
export PGPASSWORD=$(\
kubectl --namespace postgresql \
get secret postgresql \
--output jsonpath="{.data.postgresql-password}" \
| base64 --decode)
cat db-orig.yaml \
| sed -e "s@password@$PGPASSWORD@g" \
| tee db.yaml
kubectl krew install schemahero
#########################
# Installing SchemaHero #
#########################
kubectl schemahero install
kubectl --namespace postgresql \
run postgresql-client \
--rm -ti --restart='Never' \
--image docker.io/bitnami/postgresql:11.12.0-debian-10-r23 \
--env PGPASSWORD=$PGPASSWORD \
--command -- psql --host postgresql -U postgres -d postgres -p 5432
\l
CREATE DATABASE devopstoolkit;
\l
exit
###################################
# Configuring database connection #
###################################
# Open https://schemahero.io/databases/
cat db.yaml
kubectl --namespace postgresql \
apply --filename db.yaml
kubectl --namespace postgresql get databases
###################
# Creating tables #
###################
cat table.yaml
kubectl --namespace postgresql \
apply --filename table.yaml
kubectl --namespace postgresql get tables
kubectl schemahero \
--namespace postgresql \
get migrations
# Replace `[...]` with the migration ID
kubectl schemahero \
--namespace postgresql \
describe migration [...]
kubectl --namespace postgresql \
run postgresql-client \
--rm -ti --restart='Never' \
--image docker.io/bitnami/postgresql:11.12.0-debian-10-r23 \
--env PGPASSWORD=$PGPASSWORD \
--command -- psql --host postgresql -U postgres -d devopstoolkit -p 5432
\d videos
exit
###################
# Altering tables #
###################
cat table2.yaml
diff table.yaml table2.yaml
kubectl --namespace postgresql \
apply --filename table2.yaml
kubectl schemahero \
--namespace postgresql \
get migrations
# Replace `[...]` with the migration ID
kubectl schemahero \
--namespace postgresql \
describe migration [...]
kubectl --namespace postgresql \
run postgresql-client \
--rm -ti --restart='Never' \
--image docker.io/bitnami/postgresql:11.12.0-debian-10-r23 \
--env PGPASSWORD=$PGPASSWORD \
--command -- psql --host postgresql -U postgres -d devopstoolkit -p 5432
\d videos
exit
##############################
# Rolling back table changes #
##############################
kubectl --namespace postgresql \
apply --filename table.yaml
kubectl --namespace postgresql \
run postgresql-client \
--rm -ti --restart='Never' \
--image docker.io/bitnami/postgresql:11.12.0-debian-10-r23 \
--env PGPASSWORD=$PGPASSWORD \
--command -- psql --host postgresql -U postgres -d devopstoolkit -p 5432
\d videos
exit
###########
# Destroy #
###########
k3d cluster delete devops-toolkit
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