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k8s-handle

Easy CI/CD for Kubernetes clusters with python and jinja2

k8s-handle is a command line tool that facilitates continuous delivery for Kubernetes applications. Also k8s-handle supports environments, so you can use same deployment templates for different environments like staging and production. k8s-handle is a helm alternative, but without package manager

Table of contents

Features

  • Easy to use command line interface
  • Configure any variables in one configuration file (config.yaml)
  • Templating for kubernetes resource files (jinja2) with includes, loops, if-else and so on.
  • Loading variables from environment
  • Includes for configuration (includes in config.yaml) for big deploys
  • Async and sync mode for deploy (wait for deployment, statefulset, daemonset ready)
  • Strict mode, stop deploy if any warning appear
  • Easy integration with CI pipeline (gitlab ci for example)
  • Ability to destroy resources (deploy and destroy from git branches, gitlab environments)

k8s-handle vs helm

  • k8s-handle acts like template parser and provisioning tool, but not package manager included like in helm
  • k8s-handle don't need in cluster tools like The Tiller Server, you need only ServiceAccount for deploy
  • k8s-handle secure by default, you don't need to generate any certificates for deploying application, k8s-handle uses kubernetes REST API with https, like kubectl

Deploy process

Before you begin

$ cat > ~/.kube/kubernetes.ca.crt << EOF
> <paste your cluster CA here>
>EOF
cat > ~/.kube/config << EOF
apiVersion: v1
kind: Config
preferences: {}
clusters:
- cluster:
    certificate-authority: kubernetes.ca.crt
    server: < protocol://masterurl:port >
  name: my-cluster
contexts:
- context:
    cluster: my-cluster
    namespace: my-namespace
    user: my-user
  name: my-context
current-context: my-context
users:
- name: my-user
  user:
    token: <your token>
EOF

Installation with pip

Required python 3.4 or higher

$ pip install k8s-handle
 -- or --
$ pip install --user k8s-handle

Usage with docker

$ cd $WORKDIR
$ git clone https://github.com/2gis/k8s-handle-example.git
$ cd k8s-handle-example
$ docker run --rm -v $(pwd):/tmp/ -v "$HOME/.kube:/root/.kube" 2gis/k8s-handle k8s-handle deploy -s staging --use-kubeconfig
INFO:templating:File "/tmp/k8s-handle/configmap.yaml" successfully generated
INFO:templating:Trying to generate file from template "secret.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/secret.yaml" successfully generated
INFO:templating:Trying to generate file from template "deployment.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/deployment.yaml" successfully generated
INFO:k8s.resource:ConfigMap "k8s-starter-kit-nginx-conf" already exists, replace it
INFO:k8s.resource:Secret "k8s-starter-kit-secret" already exists, replace it
INFO:k8s.resource:Deployment "k8s-starter-kit" does not exist, create it

                         _(_)_                          wWWWw   _
             @@@@       (_)@(_)   vVVVv     _     @@@@  (___) _(_)_
            @@()@@ wWWWw  (_)\    (___)   _(_)_  @@()@@   Y  (_)@(_)
             @@@@  (___)     `|/    Y    (_)@(_)  @@@@   \|/   (_)
              /      Y       \|    \|/    /(_)    \|      |/      |
           \ |     \ |/       | / \ | /  \|/       |/    \|      \|/
            \|//    \|///    \|//  \|/// \|///    \|//    |//    \|//
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Usage with CI/CD tools

If you are using Gitlab CI, TeamCity or something else, you can use docker runner/agent, script will be slightly different:

$ k8s-handle deploy -s staging

Configure checkout for https://github.com/2gis/k8s-handle-example.git and specific branch without-kubeconfig Also you need to setup next env vars:

  • K8S_NAMESPACE
  • K8S_MASTER_URI
  • K8S_CA_BASE64 (optional)
  • K8S_TOKEN

use image 2gis/k8s-handle:

Notice: If you use Gitlab CI, you can configure Kubernetes integration and just use --use-kubeconfig flag.

Usage

$ k8s-handle deploy -s staging --use-kubeconfig
INFO:templating:Trying to generate file from template "configmap.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/configmap.yaml" successfully generated
INFO:templating:Trying to generate file from template "secret.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/secret.yaml" successfully generated
INFO:templating:Trying to generate file from template "deployment.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/deployment.yaml" successfully generated
INFO:k8s.resource:ConfigMap "k8s-starter-kit-nginx-conf" already exists, replace it
INFO:k8s.resource:Secret "k8s-starter-kit-secret" already exists, replace it
INFO:k8s.resource:Deployment "k8s-starter-kit" does not exist, create it

                         _(_)_                          wWWWw   _
             @@@@       (_)@(_)   vVVVv     _     @@@@  (___) _(_)_
            @@()@@ wWWWw  (_)\    (___)   _(_)_  @@()@@   Y  (_)@(_)
             @@@@  (___)     `|/    Y    (_)@(_)  @@@@   \|/   (_)
              /      Y       \|    \|/    /(_)    \|      |/      |
           \ |     \ |/       | / \ | /  \|/       |/    \|      \|/
            \|//    \|///    \|//  \|/// \|///    \|//    |//    \|//
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
$ kubectl get configmap 
NAME                         DATA      AGE
k8s-starter-kit-nginx-conf   1         1m
$ kubectl get secret | grep starter-kit
k8s-starter-kit-secret   Opaque                                1         1m
$ kubectl get deploy
NAME              DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
k8s-starter-kit   1         1         1            1           3m

Now set replicas_count in config.yaml to 3, and run again in sync mode

$ k8s-handle deploy -s staging --use-kubeconfig --sync-mode
...
INFO:k8s.resource:Deployment "k8s-starter-kit" already exists, replace it
INFO:k8s.resource:desiredReplicas = 3, updatedReplicas = 3, availableReplicas = 1
INFO:k8s.resource:Deployment not completed on 1 attempt, next attempt in 5 sec.
INFO:k8s.resource:desiredReplicas = 3, updatedReplicas = 3, availableReplicas = 2
INFO:k8s.resource:Deployment not completed on 2 attempt, next attempt in 5 sec.
INFO:k8s.resource:desiredReplicas = 3, updatedReplicas = 3, availableReplicas = 3
INFO:k8s.resource:Deployment completed on 3 attempt
...
$ kubectl get deploy
NAME              DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
k8s-starter-kit   3         3         3            3           7m

Example

You can start by example https://github.com/2gis/k8s-handle-example. There are nginx with index.html and all needed kubernetes resources for deploy them.

$ cd $WORKDIR
$ git clone https://github.com/2gis/k8s-handle-example.git
$ cd k8s-handle-example
$ k8s-handle deploy -s staging --use-kubeconfig --sync-mode
INFO:__main__:Using default namespace k8s-handle-test
INFO:templating:Trying to generate file from template "configmap.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/configmap.yaml" successfully generated
INFO:templating:Trying to generate file from template "deployment.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/deployment.yaml" successfully generated
INFO:templating:Trying to generate file from template "service.yaml.j2" in "/tmp/k8s-handle"
INFO:templating:File "/tmp/k8s-handle/service.yaml" successfully generated
INFO:k8s.resource:ConfigMap "example-nginx-conf" does not exist, create it
INFO:k8s.resource:Deployment "example" does not exist, create it
INFO:k8s.resource:desiredReplicas = 1, updatedReplicas = 1, availableReplicas = None
INFO:k8s.resource:Deployment not completed on 1 attempt, next attempt in 5 sec.
INFO:k8s.resource:desiredReplicas = 1, updatedReplicas = 1, availableReplicas = None
INFO:k8s.resource:Deployment not completed on 2 attempt, next attempt in 5 sec.
INFO:k8s.resource:desiredReplicas = 1, updatedReplicas = 1, availableReplicas = 1
INFO:k8s.resource:Deployment completed on 3 attempt
INFO:k8s.resource:Service "example" does not exist, create it
$ kubectl -n k8s-handle-test get svc 
NAME      TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
example   NodePort   10.100.132.168   <none>        80:31153/TCP   52s
$ curl http://<any node>:31153
<h1>Hello world!</h1>
Deployed with k8s-handle.

Docs

Configuration structure

k8s-handle works with 2 components:

  • config.yaml (or any other yaml file through -c argument) that stores all configuration for deploy
  • templates catalog, where your can store all required templates for kubernetes resource files (can be changed through TEMPLATES_DIR env var)

Environments

If your have testing, staging, production-zone-1, production-zone-2, etc, you can easily cover all environments with one set of templates for your application without duplication.

Common section

In the common section you can specify variables that you want to combine with the variables of the selected section:

common:
    app_name: my-shiny-app
    app_port: 8080

Both of these example variables will be added to variables of the selected section. Common section is optional and can be omitted.

Any other sections

Let's specify testing environment

testing:
    replicas: 1
    request_cpu: 100m 
    request_memory: 128M
    some_option: disabled

In testing in most cases we don't want performance from our application so we can keep 1 replica and small amount of resources for it. Also you can set some options to disabled state, in case when you don't want to affect any integrated systems during testing during testing.

staging:
    replicas: 2
    request_cpu: 200m 
    request_memory: 512M

Some teams use staging for integration and demo, so we can increase replicas and resources for our service.

production-zone-1:
    replicas: 50
    request_cpu: 1000m
    request_memory: 1G
    production: "true"
    never_give_up: "true"

In production we need to process n thousand RPS, so set replicas to 50, increase resources and set all production variables to ready for anything values.

Deploy specific environment

In your CI/CD script you can deploy any environment

$ k8s-handle deploy -s staging # Or testing or production-zone-1

In Gitlab CI for example you can create manual job for each environment

Templates

Templates in k8s-handle use jinja2 syntax and support all standard filters + some special

Filters

  • {{ my_var | b64encode }} - encode value of my_var to base64
  • {{ my_var | b64decode }} - decode value of my_var from base64
  • {{ my_var | hash_sha256 }} - encode value of my_var to sha256sum
  • {{ my_var | to_yaml(flow_style=True, width=99999) }} - Tries to render yaml representation of given variable(flow_style=True - render in one line, False multiline. width - max line width for rendered yaml lines)

Warning: You can use filters only for templates and can't for config.yaml

Functions

  • {{ include_file('my_file.txt') }} - include my_file.txt to resulting resource w/o parsing it, useful for include configs to configmap. my_file.txt will be searched in parent directory of templates dir(most of the time - k8s-handle project dir):
$ ls -1
config.yaml
templates
my_file.txt
...
  • {{ list_files('dir/or/glob*') }} - returns list of files in specified directory. Useful for including all files in folder to configmap. You specify directory path relative to parent of templates folder.

Note, both fuctions support unix glob. You can import all files from directory conf.d/*.conf for example.

You can put *.j2 templates in 'templates' directory and specify it in config.yaml

testing:
    replicas: 1
    request_cpu: 100m 
    request_memory: 128M
    some_option: disabled
    templates:
    - template: my-deployment.yaml.j2

the same template you can use in each section you want:

staging:
    ...
    templates:
    - template: my-deployment.yaml.j2
    
production-zone-1:
  ...
  templates:
  - template: my-deployment.yaml.j2

You can use regular expressions (not glob) for templates selection in TEMPLATES_DIR:

cluster-1:
  ...
  templates:
  - template: dir-1/.* # All files at TEMPLATES_DIR/dir-1 will be recognised as template and rendered

Template loader path

k8s-handle uses jinja2 template engine and initializes it with base folder specified in the TEMPLATES_DIR env variable. Jinja environment considers template paths as specified relatively to its base init directory.

Therefore, users must specify paths in {% include %} (and other) blocks relatively to the base (TEMPLATES_DIR) folder, not relative to the importer template location.

Example

We have the following templates dir content layout:

templates /
     subdirectory /
         template_A.yaml
         template_B.yaml

In that scheme, if template_A contains jinja2 import of the template_B, that import statement must be

{% include "subdirectory/template_B.yaml" %}

despite that included template lies as the same level as the template where include is used.

Tags

If you have a large deployment with many separate parts (for ex. main application and migration job), you can want to deploy them independently. In this case you have two options:

  • Use multiple isolated sections (like production_app, production_migration, etc.)
  • Use one section and tag yours templates. For example:
    production:
      templates:
      - template: my-job.yaml.j2
        tags: migration
      - template: my-configmap.yaml.j2
        tags: ['app', 'config']
      - template: my-deployment.yaml.j2
        tags:
        - app
        - deployment
      - template: my-service.yaml.j2
        tags: "app,service"

Since you templates are tagged you can use --tags/--skip-tags keys to partial deploy. For example, you can delete only a migration job:

k8s-handle destroy --section production --tags migration

Command line keys --tags and --skip-tags can be specified multiple times, for ex.:

k8s-handle deploy --section production --tags=tag1 --tags=tag2 --tags=tag3

Groups

You can make groups for templates. For example:

production:
  templates:
  - group:
    - template: my-configmap.yaml.j2
    - template: my-deployment.yaml.j2
    - template: my-service.yaml.j2
    tags: service-one
  - group:
    - template: my-job.yaml.j2

It is useful for creating different sets of templates for other environments, or tag a bunch of templates at once

Variables

Required parameters

k8s-handle needs several parameters to be set in order to connect to k8s, such as:

  • K8S master uri
  • K8S CA base64
  • K8S token

Each of these parameters can be set in various ways in any combination and are applied with the following order (from highest to lowest precedence):

  1. From the command line via corresponding keys
  2. From the config.yaml section, lowercase, underscore-delimited, e.g. k8s_master_uri
  3. From environment, uppercase, underscore-delimited, e.g K8S_MASTER_URI

If the --use-kubeconfig flag is used, these explicitly specified parameters are ignored.

In addition, the K8S namespace parameter also must be specified. k8s-handle uses namespace specified in metadata: namespace block of a resource. If it is not present, the default namespace is used, which is evaluated in the following order (from highest to lowest precedence):

  1. From the config.yaml k8s_namespace key
  2. From the kubeconfig current-context field, if --use-kubeconfig flag is used
  3. From the environment K8S_NAMESPACE variable

If the namespace is not specified in the resource spec, and the default namespace is also not specified, this will lead to a provisioning error.

The one of the common ways is to specify connection parameters and/or k8s_namespace in the common section of your config.yaml, but you can do it in another way if necessary.

Thus, the k8s-handle provides flexible ways to set the required parameters.

Merging with common

All variables defined in common will be merged with deployed section and available as context dict in templates rendering, for example:

common:
  common_var: common_value 
testing:
  testing_variable: testing_value

After the rendering of this template some-file.txt.j2:

common_var = {{ common_var }}
testing_variable = {{ testing_variable }}

file some-file.txt will be generated with the following content:

common_var = common_value
testing_variable = testing_value

If the variable is declared both in common section and the selected one, the value from the selected section will be chosen.

If the particular variable is a dictionary in both (common and the selected one) sections, resulting variable will contain merge of these two dictionaries.

Load variables from environment

If you want to use environment variables in your templates(for docker image tag generated by build for example), you can use next construction in config.yaml:

common:
  image_version: "{{ env='TAG' }}"

Load variables from yaml file

common:
  test: "{{ file='include.yaml' }}"

include.yaml:

- 1
- 2 
- 3

template:

{{ test[0] }}
{{ test[1] }}
{{ test[2] }}

After rendering you get:

1
2
3

How to use in CI/CD

Gitlab CI

Native integration

Use Gitlab CI integration with Kubernetes (https://docs.gitlab.com/ee/user/project/clusters/index.html#adding-an-existing-kubernetes-cluster) .gitlab-ci.yaml:

deploy:
  image: 2gis/k8s-handle:latest
  script:
    - k8s-handle deploy --section <section_name> --use-kubeconfig

Through variables

Alternatively you can setup Gitlab CI variables:

  • K8S_TOKEN_STAGING = < serviceaccount token for staging >
  • K8S_TOKEN_PRODUCTION = < serviceaccount token for production >

Don't forget mark variables as protected

then add next lines to config.yaml

staging:
  k8s_master_uri: <kubenetes staging master uri>
  k8s_token: "{{ env='K8S_TOKEN_STAGING' }}"
  k8s_ca_base64: <kubernetes staging ca>
  
production:
  k8s_master_uri: <kubenetes production master uri>
  k8s_token: "{{ env='K8S_TOKEN_PRODUCTION' }}"
  k8s_ca_base64: <kubernetes production ca>

Now just run proper gitlab job(without --use-kubeconfig option):

deploy:
  image: 2gis/k8s-handle:latest
  script:
    - k8s-handle deploy --section <section_name>

Working modes

Sync mode

Works only with Deployment, Job, StatefulSet and DaemonSet

By default k8s-handle just apply resources to kubernetes and exit. In sync mode k8s-handle wait for resources up and running

$ k8s-handle deploy --section staging  --sync-mode
...
INFO:k8s.resource:Deployment "k8s-starter-kit" already exists, replace it
INFO:k8s.resource:desiredReplicas = 3, updatedReplicas = 3, availableReplicas = 1
INFO:k8s.resource:Deployment not completed on 1 attempt, next attempt in 5 sec.
INFO:k8s.resource:desiredReplicas = 3, updatedReplicas = 3, availableReplicas = 2
INFO:k8s.resource:Deployment not completed on 2 attempt, next attempt in 5 sec.
INFO:k8s.resource:desiredReplicas = 3, updatedReplicas = 3, availableReplicas = 3
INFO:k8s.resource:Deployment completed on 3 attempt
...

You can specify number of tries before k8s-handle exit with non zero exit code and delay before checks:

--tries <tries> (360 by default)
--retry-delay <retry-delay in seconds> (5 by default)

Strict mode

In some cases k8s-handle warn you about ambiguous situations and keep working. With --strict mode k8s-handle warn and exit with non zero code. For example when some used environment variables is empty.

$ k8s-handle-os deploy -s staging --use-kubeconfig --strict
ERROR:__main__:RuntimeError: Environment variable "IMAGE_VERSION" is not set
$ echo $?
1

Destroy

In some cases you need to destroy early created resources(demo env, deploy from git branches, testing etc.), k8s-handle support destroy subcommand for you. Just use destroy instead of deploy. k8s-handle process destroy as deploy, but call delete kubernetes api calls instead of create or replace.

Sync mode is available for destroy as well.

Operating without config.yaml

The most common way for the most of use cases is to operate with k8s-handle via config.yaml, specifying connection parameters, targets (sections and tags) and variables in one file. The deploy command that runs after that, at first will trigger templating process: filling your spec templates with variables, creating resource spec files. That files become a targets for the provisioner module, which does attempts to create K8S resources.

But in some cases, such as the intention to use your own templating engine or, probably, necessity to make specs beforehand and to deploy them separately and later, there may be a need to divide the process into the separate steps:

  1. Templating
  2. Direct, kubectl apply-like provisioning without config.yaml context.

For this reason, k8s-handle render, k8s-handle apply, k8s-handle delete commands are implemented.

Render

render command is purposed for creating specs from templates without their subsequent deployment.

Another purpose is to check the generation of the templates: previously, this functionality was achieved by using the --dry-run optional flag. The support of --dry-run in deploy and destroy commands remains at this time for the sake of backward compatibility but it's discouraged for the further usage.

Just like with deploy command, -s/--section and --tags/--skip-tags targeting options are provided to make it handy to render several specs. Connection parameters are not needed to be specified cause no k8s cluster availability checks are performed.

Templates directory path is taken from env TEMPLATES_DIR and equal to 'templates' by default. Resources generated by this command can be obtained in directory that set in TEMP_DIR env variable with default value '/tmp/k8s-handle'. Users that want to preserve generated templates might need to change this default to avoid loss of the generated resources.

TEMP_DIR="/home/custom_dir" k8s-handle render -s staging
2019-02-15 14:44:44 INFO:k8s_handle.templating:Trying to generate file from template "service.yaml.j2" in "/home/custom_dir"
2019-02-15 14:44:44 INFO:k8s_handle.templating:File "/home/custom_dir/service.yaml" successfully generated

Apply

apply command with the -r/--resource required flag starts the process of provisioning of separate resource spec to k8s.

The value of -r key is considered as absolute path if it's started with slash. Otherwise, it's considered as relative path from directory specified in TEMP_DIR env variable.

No config.yaml-like file is required (and not taken into account even if exists). The connection parameters can be set via --use-kubeconfig mode which is available and the most handy, or via the CLI/env flags and variables. Options related to output and syncing, like --sync-mode, --tries and --show-logs are available as well.

$ k8s-handle apply -r /tmp/k8s-handle/service.yaml --use-kubeconfig
2019-02-15 14:22:58 INFO:k8s_handle:Default namespace "test"
2019-02-15 14:22:58 INFO:k8s_handle.k8s.resource:Using namespace "test"
2019-02-15 14:22:58 INFO:k8s_handle.k8s.resource:Service "k8s-handle-example" does not exist, create it

Delete

delete command with the -r/--resource required flag acts similarly to destroy command and does a try to delete the directly specified resource from k8s if any.

$ k8s-handle delete -r service.yaml --use-kubeconfig

2019-02-15 14:24:06 INFO:k8s_handle:Default namespace "test"
2019-02-15 14:24:06 INFO:k8s_handle.k8s.resource:Using namespace "test"
2019-02-15 14:24:06 INFO:k8s_handle.k8s.resource:Trying to delete Service "k8s-handle-example"
2019-02-15 14:24:06 INFO:k8s_handle.k8s.resource:Service "k8s-handle-example" deleted

Custom resource definitions and custom resources

Since version 0.5.5 k8s-handle supports Custom resource definition (CRD) and custom resource (CR) kinds. If your deployment involves use of such kinds, make sure that CRD was deployed before CR and check correctness of the CRD's scope.

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