In this chapter, we will show how to use and store sensitive and non-sensitive application configurations properly.
In previous chapters, we added the configuration directly to containers during the build or used the container’s environment variables to pass parameters during the deployment.
Now, you will learn how to store application parameters in ConfigMaps and Secrets for security and flexibility. We will show how you can use Helm chart values and werf secrets and discuss parameterization and configuration reuse approaches. In addition, you will learn how to store sensitive data along with the code in the application’s Git repository.
The application described in this chapter is not intended for use in production environments as-is. Note that successful completion of this entire guide is required to create a production-ready application.
Preparing the environment
If you haven’t prepared your environment during previous steps, please, do it using the instructions provided in the “Preparing the environment” chapter.
If your environment has stopped working or instructions in this chapter don’t work, please, refer to these hints:
Let’s launch Docker Desktop. It takes some time for this application to start Docker. If there are no errors during the startup process, check that Docker is running and is properly configured:
docker run hello-world
You will see the following output if the command completes successfully:
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
Should you have any problems, please refer to the Docker documentation.
Let’s launch the Docker Desktop application. It takes some time for the application to start Docker. If there are no errors during the startup process, then check that Docker is running and is properly configured:
docker run hello-world
You will see the following output if the command completes successfully:
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
Should you have any problems, please refer to the Docker documentation.
Start Docker:
sudo systemctl restart docker
Make sure that Docker is running:
sudo systemctl status docker
If the Docker start is successful, you will see the following output:
● docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2021-06-24 13:05:17 MSK; 13s ago
TriggeredBy: ● docker.socket
Docs: https://docs.docker.com
Main PID: 2013888 (dockerd)
Tasks: 36
Memory: 100.3M
CGroup: /system.slice/docker.service
└─2013888 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
dockerd[2013888]: time="2021-06-24T13:05:16.936197880+03:00" level=warning msg="Your kernel does not support CPU realtime scheduler"
dockerd[2013888]: time="2021-06-24T13:05:16.936219851+03:00" level=warning msg="Your kernel does not support cgroup blkio weight"
dockerd[2013888]: time="2021-06-24T13:05:16.936224976+03:00" level=warning msg="Your kernel does not support cgroup blkio weight_device"
dockerd[2013888]: time="2021-06-24T13:05:16.936311001+03:00" level=info msg="Loading containers: start."
dockerd[2013888]: time="2021-06-24T13:05:17.119938367+03:00" level=info msg="Loading containers: done."
dockerd[2013888]: time="2021-06-24T13:05:17.134054120+03:00" level=info msg="Daemon has completed initialization"
systemd[1]: Started Docker Application Container Engine.
dockerd[2013888]: time="2021-06-24T13:05:17.148493957+03:00" level=info msg="API listen on /run/docker.sock"
Now let’s check if Docker is available and its configuration is correct:
docker run hello-world
You will see the following output if the command completes successfully:
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
Should you have any problems, please refer to the Docker documentation.
Let’s start the minikube cluster we have already configured in the “Preparing the environment” chapter:
minikube start
Set the default Namespace so that you don’t have to specify it every time you invoke kubectl:
kubectl config set-context minikube --namespace=werf-guide-app
You will see the following output if the command completes successfully:
😄 minikube v1.20.0 on Ubuntu 20.04
✨ Using the docker driver based on existing profile
👍 Starting control plane node minikube in cluster minikube
🚜 Pulling base image ...
🎉 minikube 1.21.0 is available! Download it: https://github.com/kubernetes/minikube/releases/tag/v1.21.0
💡 To disable this notice, run: 'minikube config set WantUpdateNotification false'
🔄 Restarting existing docker container for "minikube" ...
🐳 Preparing Kubernetes v1.20.2 on Docker 20.10.6 ...
🔎 Verifying Kubernetes components...
▪ Using image gcr.io/google_containers/kube-registry-proxy:0.4
▪ Using image k8s.gcr.io/ingress-nginx/controller:v0.44.0
▪ Using image registry:2.7.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎 Verifying registry addon...
🔎 Verifying ingress addon...
🌟 Enabled addons: storage-provisioner, registry, default-storageclass, ingress
🏄 Done! kubectl is now configured to use "minikube" cluster and "werf-guide-app" namespace by default
Make sure that the command output contains the following line:
Restarting existing docker container for "minikube"
Its absence means that a new minikube cluster was created instead of using the old one. In this case, repeat all the steps required to install the environment using minikube.
Now run the command in the background PowerShell terminal (do not close its window):
minikube tunnel --cleanup=true
Let’s start the minikube cluster we have already configured in the “Preparing the environment” chapter:
minikube start --namespace werf-guide-app
Set the default Namespace so that you don’t have to specify it every time you invoke kubectl:
kubectl config set-context minikube --namespace=werf-guide-app
You will see the following output if the command completes successfully:
😄 minikube v1.20.0 on Ubuntu 20.04
✨ Using the docker driver based on existing profile
👍 Starting control plane node minikube in cluster minikube
🚜 Pulling base image ...
🎉 minikube 1.21.0 is available! Download it: https://github.com/kubernetes/minikube/releases/tag/v1.21.0
💡 To disable this notice, run: 'minikube config set WantUpdateNotification false'
🔄 Restarting existing docker container for "minikube" ...
🐳 Preparing Kubernetes v1.20.2 on Docker 20.10.6 ...
🔎 Verifying Kubernetes components...
▪ Using image gcr.io/google_containers/kube-registry-proxy:0.4
▪ Using image k8s.gcr.io/ingress-nginx/controller:v0.44.0
▪ Using image registry:2.7.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎 Verifying registry addon...
🔎 Verifying ingress addon...
🌟 Enabled addons: storage-provisioner, registry, default-storageclass, ingress
🏄 Done! kubectl is now configured to use "minikube" cluster and "werf-guide-app" namespace by default
Make sure that the command output contains the following line:
Restarting existing docker container for "minikube"
Its absence means that a new minikube cluster was created instead of using the old one. In this case, repeat all the steps required to install the environment from scratch using minikube.
If you have inadvertently deleted Namespace of the application, you must run the following commands to proceed with the guide:
kubectl create namespace werf-guide-app
kubectl create secret docker-registry registrysecret \
--docker-server='https://index.docker.io/v1/' \
--docker-username='<Docker Hub username>' \
--docker-password='<Docker Hub password>'
You will see the following output if the command completes successfully:
namespace/werf-guide-app created
secret/registrysecret created
If nothing worked, repeat all the steps described in the “Preparing the environment” chapter and create a new environment from scratch. If creating an environment from scratch did not help either, please, tell us about your problem in our Telegram chat or create an issue on GitHub. We will be happy to help you!
Preparing the repository
Update the existing repository containing the application:
Run the following commands in PowerShell:
cd ~/werf-guide/app
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/django/080_configuration/* .
git add .
git commit -m WIP
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Run the following commands in Bash:
cd ~/werf-guide/app
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/django/080_configuration/. .
git add .
git commit -m WIP
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Doesn’t work? Try the instructions on the “I am just starting from this chapter” tab above.
Prepare a new repository with the application:
Run the following commands in PowerShell:
# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
if (-not (Test-Path ~/werf-guide/guides)) {
git clone https://github.com/werf/website $env:HOMEPATH/werf-guide/guides
}
# Copy the (unchanged) application files to ~/werf-guide/app.
rm -Recurse -Force ~/werf-guide/app
cp -Recurse -Force ~/werf-guide/guides/examples/django/050_s3 ~/werf-guide/app
# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/django/080_configuration/* .
git add .
git commit -m WIP
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Run the following commands in Bash:
# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
test -e ~/werf-guide/guides || git clone https://github.com/werf/website ~/werf-guide/guides
# Copy the (unchanged) application files to ~/werf-guide/app.
rm -rf ~/werf-guide/app
cp -rf ~/werf-guide/guides/examples/django/050_s3 ~/werf-guide/app
# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/django/080_configuration/. .
git add .
git commit -m WIP
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
ConfigMap and Secret
ConfigMap and Secret Kubernetes resources allow you to separate environment-dependent and context-specific configuration from container images.
Both objects store data in key-value pairs and provide them to Pods as environment variables, command-line arguments, or configuration files mounted in a selected container.
ConfigMap stores non-confidential data, while Secret stores confidential data (various secret types).
You can learn more about these resource types in the official Kubernetes documentation (ConfigMaps, Secrets). This chapter discusses various use cases for ConfigMaps and Secrets using our application as an example.
Storing application’s config files in the ConfigMap
Currently, the nginx.conf config file gets copied into the image during the build. As a result, the image is rebuilt, and Pods are restarted each time the file is modified. In addition, there is no easy way to benefit from templating in our nginx.conf.
You can get around these obstacles by moving .werf/nginx.conf into a dedicated ConfigMap. This way, you can mount nginx.conf when deploying instead of adding the file during the build:
apiVersion: v1
kind: ConfigMap
metadata:
name: nginx-conf
data:
nginx.conf: |
user nginx;
worker_processes 1;
pid /run/nginx.pid;
events {
worker_connections 1024;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
upstream backend {
server 127.0.0.1:8000 fail_timeout=0;
}
server {
listen 80;
server_name _;
root /app;
client_max_body_size 100M;
keepalive_timeout 10s;
# For the /static path, serve the assets directly from the NGINX container file system.
location /static {
expires 1y;
add_header Cache-Control public;
add_header Last-Modified "";
add_header ETag "";
# If possible, serve pre-compressed files (instead of compressing them on the fly).
gzip_static on;
access_log off;
try_files $uri =404;
}
# Serve media assets (images, etc.) directly from the NGINX container file system,
# but turn off gzip compression.
location /static/images {
expires 1y;
add_header Cache-Control public;
add_header Last-Modified "";
add_header ETag "";
access_log off;
try_files $uri =404;
}
# All requests, except for asset requests, are sent to the Spring Boot backend.
location / {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_pass http://backend;
}
}
}
Now, let’s add our ConfigMap to the Deployment — we will mount it as a file in the frontend container:
...
volumeMounts:
- mountPath: /etc/nginx/nginx.conf
subPath: nginx.conf
name: nginx-conf
volumes:
- name: nginx-conf
configMap:
name: nginx-conf
We also need to delete the no longer needed .werf/nginx.conf as well as a command to copy this file to an image during the build. The Dockerfile for the frontend image will look as follows:
...
FROM nginx:stable-alpine as frontend
WORKDIR /app
COPY app/static /app/static
Handling ConfigMap and Secret changes
Note that by default, changes in ConfigMaps or Secrets mounted in a Deployment, StatefulSet, or DaemonSet will not trigger Pod restarts for the new configuration to take effect. To trigger Pod restart, you need to add annotations with checksums of all ConfigMaps and Secrets used by this Pod. In this case, the annotations will change in response to ConfigMap and Secret modifications, leading to the Pod restart. Below is an example of an annotation that includes the checksum of the nginx.conf ConfigMap:
...
template:
metadata:
labels:
app: werf-guide-app
annotations:
checksum/configmap-nginx: '{{ include (print $.Template.BasePath "/configmap-nginx.yaml") . | sha256sum }}'
Note that you will need a unique annotation for each mounted ConfigMap/Secret.
The authors of this tutorial prefer to use operators like stakater/Reloader instead of checksum-containing annotations because they are simpler, more flexible, and easier to work with.
Values
Using a Helm chart to deploy an application has many advantages — for example, you can create manifest templates with Helm charts. Values is the key built-in templating object. With it, you can access values passed to the chart from various sources.
When using werf, all data passed to the chart can be grouped into several categories:
- User-defined regular values:
values.yamlparameters and corresponding options. - User-defined secret values: parameters from the
secret-values.yamlfile. - Service values: information about the project, release, built images, etc.
Reusing configuration with Values and ConfigMaps
Frequently used parameters can be put into .helm/values.yaml:
...
mysql:
storageSize: "100Mi"
envs:
MYSQL_DATABASE: "django"
… to make manifest configuration easier:
...
volumeClaimTemplates:
- metadata:
name: mysql-data
spec:
accessModes: ["ReadWriteOnce"]
resources:
requests:
storage: "{{ .Values.mysql.storageSize }}"
This way, you can adjust the parameters to the specific environment (we will discuss this in more detail in the following tutorial chapters).
Probably, the most useful feature is the ability to place repetitive configuration snippets into .helm/values.yaml. For example, you can store in this file environment variables used in multiple places:
...
app:
envs:
MYSQL_HOST: mysql
MINIO_ENDPOINT: "http://minio:9000"
BUCKET_NAME: "storage"
The environment variables from .Values.app.envs can be inserted either into the container manifest as env values (as we did before), or you can put them into the ConfigMap and load it into the container via envFrom.
The first option is easier to do, but the ConfigMap option is more convenient if you have a large number of shared environment variables. This way, you will avoid duplicating them between controllers. Your ConfigMap may look like this:
apiVersion: v1
kind: ConfigMap
metadata:
name: app-envs
data:
{{- range $key, $val := .Values.app.envs }}
"{{ $key }}": "{{ $val }}"
{{- end }}
Now you can use envFrom in the Deployment to define ConfigMap’s data as container environment variables:
...
envFrom:
- configMapRef:
name: app-envs
Don’t forget to add checksum-containing annotations to trigger Pod re-deployment in response to ConfigMap changes:
...
template:
metadata:
labels:
app: werf-guide-app
annotations:
checksum/configmap-nginx: '{{ include (print $.Template.BasePath "/configmap-nginx.yaml") . | sha256sum }}'
checksum/configmap-app-envs: '{{ include (print $.Template.BasePath "/configmap-app-envs.yaml") . | sha256sum }}'
Similarly, you can load this ConfigMap into other resources that use the same environment variables.
Handling confidential data using Values and Secrets
To start working with secrets, you first need to generate a symmetric encryption key. You can use the following command to do this: werf helm secret generate-secret-key. However, since we have already prepared/encrypted the secrets for you, the encryption key that will be used in this chapter is generated as well. This encryption key is stored in the repository in the .werf_secret_key file; werf uses it automatically.
Caution! You MUST NOT store the key in the repository when working with real-life applications. We recommend keeping it in a safe place and passing via the
WERF_SECRET_KEYenvironment variable. You can read more about using encryption keys in the werf documentation.
The application configuration contains data that should not be stored in unencrypted form in the repository (e.g., the database login and password). Thus, we won’t store the login and password in plain text
in the deployment’s environment variables.
Instead, we will store them encrypted in the .helm/secret-values.yaml file along with other confidential parameters:
app:
secretEnvs:
MYSQL_USERNAME: 1000b46a9eb2f5673975c1170663e43e10929943e6be2a66415223ac3fb8b7130637
MYSQL_PASSWORD: 100053791b2a03d1b14a31fe071e7e916286f436cd3846429e7dbb7d11ecd31ca498
minio:
secretEnvs:
MINIO_ACCESS_KEY: 1000918cc905f82c734c23af6bb4145ba3b4e374a99c6578755ce5e057f2fceb7dd2
MINIO_SECRET_KEY: 100040102dcb1c51995040e7d9900265a1d84d4052acff9456484a2dbebb6e46694d
mysql:
secretEnvs:
MYSQL_USER: 1000b4c64a2225733825456bc5a435dca72f44734ee378d6fe9a28d94f059b0a41cb
MYSQL_PASSWORD: 1000774b6581770befabf32342484adadf44f89b24d69bdadf4195fc7bcb3b05c86e
MYSQL_ROOT_PASSWORD: 1000437887b0b12bd28f4ab218c6919817af71f50e8b3ee6c2cbb8014bf3c90880df
Use the command below to decrypt the secrets stored in .helm/secret-values.yaml:
werf helm secret values decrypt .helm/secret-values.yaml
You should see the following output:
app:
secretEnvs:
MYSQL_USERNAME: django
MYSQL_PASSWORD: django
minio:
secretEnvs:
MINIO_ACCESS_KEY: minio
MINIO_SECRET_KEY: password
mysql:
secretEnvs:
MYSQL_USER: django
MYSQL_PASSWORD: django
MYSQL_ROOT_PASSWORD: django
Now, you need to pass the secrets contained in .helm/secret-values.yaml back to the application config. To do this, let’s first pass them to the Secret resource:
apiVersion: v1
kind: Secret
metadata:
name: app-envs
type: Opaque
data:
{{- range $key, $val := .Values.app.secretEnvs }}
"{{ $key }}": "{{ $val | b64enc }}"
{{- end }}
… and then load this resource’s data as a set of environment variables by mounting it in containers:
...
- secretRef:
name: app-envs
- secretRef:
name: minio-envs
- configMapRef:
name: db-envs
- secretRef:
name: db-envs
You have to make similar changes to the rest of the .helm/templates files (we won’t delve into details here; you can take a look at their contents in the repository.)
You can also use Secrets to store and mount complete secret configuration files. This is similar to using ConfigMap to mount non-secret configuration files (as described above), except that the Secret contents must be stored encrypted in .helm/secret/... or .helm/secret-values.yaml. You can read more about this in the werf documentation.
Note: learn more about working with secrets in the werf documentation.
Checking whether the application runs as expected
Let’s make sure the configuration changes did not affect the application performance:
werf converge --repo <DOCKER HUB USERNAME>/werf-guide-app
You should see the following output:
┌ Concurrent builds plan (no more than 5 images at the same time)
│ Set #0:
│ - ⛵ image backend
│ - ⛵ image frontend
└ Concurrent builds plan (no more than 5 images at the same time)
┌ ⛵ image backend
│ Use cache image for backend/dockerfile
│ name: <DOCKER HUB USERNAME>/werf-guide-app:384636338cad8c70b70c4e530032aa930f32b91b8d476aa5cf8219a7-1661359407179
│ id: d9865e6aa43c
│ created: 2022-08-24 19:43:25 +0000 UTC
│ size: 143.3 MiB
└ ⛵ image backend (0.00 seconds)
┌ ⛵ image frontend
│ Use cache image for frontend/dockerfile
│ name: <DOCKER HUB USERNAME>/werf-guide-app:c546302ec08085df109e165e201928b2de7b8989b4494f8b4df8b5ab-1661406370479
│ id: 8254c2a08186
│ created: 2022-08-25 08:45:31 +0000 UTC
│ size: 9.7 MiB
└ ⛵ image frontend (0.00 seconds)
┌ Waiting for resources to become ready
│ ┌ job/setup-and-migrate-db-rev3 po/setup-and-migrate-db-rev3-s8fpn container/setup-and-migrate-db logs
│ │ Operations to perform:
│ │ Apply all migrations: admin, auth, contenttypes, sessions, talkers
│ │ Running migrations:
│ │ No migrations to apply.
│ └ job/setup-and-migrate-db-rev3 po/setup-and-migrate-db-rev3-s8fpn container/setup-and-migrate-db logs
│
│ ┌ Status progress
│ │ DEPLOYMENT REPLICAS AVAILABLE UP-TO-DATE
│ │ werf-guide-app 1/1 1 1
│ │ STATEFULSET REPLICAS READY UP-TO-DATE
│ │ minio 1/1 1 1
│ │ mysql 1/1 1 1
│ │ JOB ACTIVE DURATION SUCCEEDED/FAILED
│ │ setup-and-migrate-db-rev3 0 2s 1/0
│ │ │ POD READY RESTARTS STATUS
│ │ └── and-migrate-db-rev3-s8fpn 0/1 0 Completed
│ └ Status progress
└ Waiting for resources to become ready (1.87 seconds)
┌ Waiting for resources elimination: jobs/setup-and-migrate-db-rev1, jobs/setup-and-migrate-db-rev2
└ Waiting for resources elimination: jobs/setup-and-migrate-db-rev1, jobs/setup-and-migrate-db-rev2 (0.21 seconds)
Release "werf-guide-app" has been upgraded. Happy Helming!
NAME: werf-guide-app
LAST DEPLOYED: Thu Aug 25 08:59:27 2022
LAST PHASE: rollout
LAST STAGE: 0
NAMESPACE: werf-guide-app
STATUS: deployed
REVISION: 3
TEST SUITE: None
Running time 13.47 seconds
Check if the application is available:
curl http://werf-guide-app.test/ping
You should see the following output:
pong
In this chapter, you learned how to securely store the confidential application parameters, minimize duplicate configuration, and turn application configs into templates (thus, no re-builds are necessary when changes are made).
