1
I create a script called kubectl_apply. It loads variables from .env, replace ${CUSTOMVAR} in yml and pass it to kubectl command
#!/bin/bash
set -a
source .env
set +a
eval "cat <<EOF
$(<$1)
EOF
" | kubectl apply -f -cat $app/deployment.yaml | envsubst | kubectl apply ...This kind of thing is painfully easy with ytt:
deployment.yml
#@ load("@ytt:data", "data")
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: guestbook
spec:
replicas: 2
template:
metadata:
labels:
app: guestbook
spec:
container:
- name: guestbook
image: #@ data.values.image
values.yml
#@data/values
image: nginx@sha256:fe2fa7bb1ceb86c6d9c935bc25c3dd8cbd64f2e95ed5b894f93ae7ffbd1e92bb
Then...
$ ytt -f deployment.yml -f values.yml | kubectl apply -f -
or even better, use ytt's cousin, kapp for a high-control deployment experience:
$ ytt -f deployment.yml -f values.yml | kapp deploy -a guestbook -f -I have been using kubetpl (https://github.com/shyiko/kubetpl)
It has three different template flavors and supports ConfigMap/Secret freezing.#!/bin/bash
# sample value for your variables
MYVARVALUE="nginx:latest"
# read the yml template from a file and substitute the string
# {{MYVARNAME}} with the value of the MYVARVALUE variable
template=`cat "deploy.yml.template" | sed "s/{{MYVARNAME}}/$MYVARVALUE/g"`
# apply the yml with the substituted value
echo "$template" | kubectl apply -f -envsubst < deployment.yaml | kubectl apply -f -
My approach:
tools/jinja2-cli.py:
#!/usr/bin/env python3
import os
import sys
from jinja2 import Environment, FileSystemLoader
sys.stdout.write(Environment(loader=FileSystemLoader('templates/')).from_string(sys.stdin.read()).render(env=os.environ) + "\n")
Make rule:
_GENFILES = $(basename $(TEMPLATES))
GENFILES = $(_GENFILES:templates/%=%)
$(GENFILES): %: templates/%.j2 $(MKFILES) tools/jinja2-cli.py .env
env $$(cat .env | xargs) tools/jinja2-cli.py < $< > $@ || (rm -f $@; false)
Inside the .j2 template file you can use any jinja syntax construct, e.g. {{env.GUEST}} will be replaced by the value of GUEST defined in .env
So your templates/deploy.yaml.j2 would look like:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: guestbook
spec:
replicas: 2
template:
metadata:
labels:
app: guestbook
spec:
container:
- name: guestbook
image: {{env.GUEST}}
Another approach (using just bash builtins and xargs) might be
env $(cat .env | xargs) cat <<EOF | kubectl create -f -
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: guestbook
spec:
replicas: 2
template:
metadata:
labels:
app: guestbook
spec:
container:
- name: guestbook
image: ${GUEST}
EOF