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Rollout Deployment Chart - v5.1

1. Yaml File -

Container Ports

This defines ports on which application services will be exposed to other services

ContainerPort:
  - envoyPort: 8799
    idleTimeout:
    name: app
    port: 8080
    servicePort: 80
    nodePort: 32056
    supportStreaming: true
    useHTTP2: true
Key Description
envoyPort envoy port for the container.
idleTimeout the duration of time that a connection is idle before the connection is terminated.
name name of the port.
port port for the container.
servicePort port of the corresponding kubernetes service.
nodePort nodeport of the corresponding kubernetes service.
supportStreaming Used for high performance protocols like grpc where timeout needs to be disabled.
useHTTP2 Envoy container can accept HTTP2 requests.

EnvVariables

EnvVariables: []

To set environment variables for the containers that run in the Pod.

EnvVariablesFromSecretKeys

EnvVariablesFromSecretKeys: 
  - name: ENV_NAME
    secretName: SECRET_NAME
    keyName: SECRET_KEY

It is use to get the name of Environment Variable name, Secret name and the Key name from which we are using the value in that corresponding Environment Variable.

EnvVariablesFromConfigMapKeys

EnvVariablesFromConfigMapKeys: 
  - name: ENV_NAME
    configMapName: CONFIG_MAP_NAME
    keyName: CONFIG_MAP_KEY

It is use to get the name of Environment Variable name, Config Map name and the Key name from which we are using the value in that corresponding Environment Variable.

Liveness Probe

If this check fails, kubernetes restarts the pod. This should return error code in case of non-recoverable error.

LivenessProbe:
  Path: ""
  port: 8080
  initialDelaySeconds: 20
  periodSeconds: 10
  successThreshold: 1
  timeoutSeconds: 5
  failureThreshold: 3
  httpHeaders:
    - name: Custom-Header
      value: abc
  scheme: ""
  tcp: true
Key Description
Path It define the path where the liveness needs to be checked.
initialDelaySeconds It defines the time to wait before a given container is checked for liveliness.
periodSeconds It defines the time to check a given container for liveness.
successThreshold It defines the number of successes required before a given container is said to fulfil the liveness probe.
timeoutSeconds It defines the time for checking timeout.
failureThreshold It defines the maximum number of failures that are acceptable before a given container is not considered as live.
httpHeaders Custom headers to set in the request. HTTP allows repeated headers,You can override the default headers by defining .httpHeaders for the probe.
scheme Scheme to use for connecting to the host (HTTP or HTTPS). Defaults to HTTP.
tcp The kubelet will attempt to open a socket to your container on the specified port. If it can establish a connection, the container is considered healthy.

MaxUnavailable

  MaxUnavailable: 0

The maximum number of pods that can be unavailable during the update process. The value of "MaxUnavailable: " can be an absolute number or percentage of the replicas count. The default value of "MaxUnavailable: " is 25%.

MaxSurge

MaxSurge: 1

The maximum number of pods that can be created over the desired number of pods. For "MaxSurge: " also, the value can be an absolute number or percentage of the replicas count. The default value of "MaxSurge: " is 25%.

Min Ready Seconds

MinReadySeconds: 60

This specifies the minimum number of seconds for which a newly created Pod should be ready without any of its containers crashing, for it to be considered available. This defaults to 0 (the Pod will be considered available as soon as it is ready).

Readiness Probe

If this check fails, kubernetes stops sending traffic to the application. This should return error code in case of errors which can be recovered from if traffic is stopped.

ReadinessProbe:
  Path: ""
  port: 8080
  initialDelaySeconds: 20
  periodSeconds: 10
  successThreshold: 1
  timeoutSeconds: 5
  failureThreshold: 3
  httpHeaders:
    - name: Custom-Header
      value: abc
  scheme: ""
  tcp: true
Key Description
Path It define the path where the readiness needs to be checked.
initialDelaySeconds It defines the time to wait before a given container is checked for readiness.
periodSeconds It defines the time to check a given container for readiness.
successThreshold It defines the number of successes required before a given container is said to fulfill the readiness probe.
timeoutSeconds It defines the time for checking timeout.
failureThreshold It defines the maximum number of failures that are acceptable before a given container is not considered as ready.
httpHeaders Custom headers to set in the request. HTTP allows repeated headers,You can override the default headers by defining .httpHeaders for the probe.
scheme Scheme to use for connecting to the host (HTTP or HTTPS). Defaults to HTTP.
tcp The kubelet will attempt to open a socket to your container on the specified port. If it can establish a connection, the container is considered healthy.

Pod Disruption Budget

You can create PodDisruptionBudget for each application. A PDB limits the number of pods of a replicated application that are down simultaneously from voluntary disruptions. For example, an application would like to ensure the number of replicas running is never brought below the certain number.

podDisruptionBudget: 
     minAvailable: 1

or

podDisruptionBudget: 
     maxUnavailable: 50%

You can specify either maxUnavailable or minAvailable in a PodDisruptionBudget and it can be expressed as integers or as a percentage

Key Description
minAvailable Evictions are allowed as long as they leave behind 1 or more healthy pods of the total number of desired replicas.
maxUnavailable Evictions are allowed as long as at most 1 unhealthy replica among the total number of desired replicas.

Ambassador Mappings

You can create ambassador mappings to access your applications from outside the cluster. At its core a Mapping resource maps a resource to a service.

ambassadorMapping:
  ambassadorId: "prod-emissary"
  cors: {}
  enabled: true
  hostname: devtron.example.com
  labels: {}
  prefix: /
  retryPolicy: {}
  rewrite: ""
  tls:
    context: "devtron-tls-context"
    create: false
    hosts: []
    secretName: ""
Key Description
enabled Set true to enable ambassador mapping else set false.
ambassadorId used to specify id for specific ambassador mappings controller.
cors used to specify cors policy to access host for this mapping.
weight used to specify weight for canary ambassador mappings.
hostname used to specify hostname for ambassador mapping.
prefix used to specify path for ambassador mapping.
labels used to provide custom labels for ambassador mapping.
retryPolicy used to specify retry policy for ambassador mapping.
corsPolicy Provide cors headers on flagger resource.
rewrite used to specify whether to redirect the path of this mapping and where.
tls used to create or define ambassador TLSContext resource.
extraSpec used to provide extra spec values which not present in deployment template for ambassador resource.

Autoscaling

This is connected to HPA and controls scaling up and down in response to request load.

autoscaling:
  enabled: false
  MinReplicas: 1
  MaxReplicas: 2
  TargetCPUUtilizationPercentage: 90
  TargetMemoryUtilizationPercentage: 80
  extraMetrics: []
Key Description
enabled Set true to enable autoscaling else set false.
MinReplicas Minimum number of replicas allowed for scaling.
MaxReplicas Maximum number of replicas allowed for scaling.
TargetCPUUtilizationPercentage The target CPU utilization that is expected for a container.
TargetMemoryUtilizationPercentage The target memory utilization that is expected for a container.
extraMetrics Used to give external metrics for autoscaling.

Fullname Override

fullnameOverride: app-name

fullnameOverride replaces the release fullname created by default by devtron, which is used to construct Kubernetes object names. By default, devtron uses {app-name}-{environment-name} as release fullname.

Image

image:
  pullPolicy: IfNotPresent

Image is used to access images in kubernetes, pullpolicy is used to define the instances calling the image, here the image is pulled when the image is not present,it can also be set as "Always".

imagePullSecrets

imagePullSecrets contains the docker credentials that are used for accessing a registry.

imagePullSecrets:
  - regcred

regcred is the secret that contains the docker credentials that are used for accessing a registry. Devtron will not create this secret automatically, you'll have to create this secret using dt-secrets helm chart in the App store or create one using kubectl. You can follow this documentation Pull an Image from a Private Registry https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/ .

Ingress

This allows public access to the url, please ensure you are using right nginx annotation for nginx class, its default value is nginx

ingress:
  enabled: false
  # For K8s 1.19 and above use ingressClassName instead of annotation kubernetes.io/ingress.class:
  className: nginx
  annotations: {}
  hosts:
      - host: example1.com
        paths:
            - /example
      - host: example2.com
        paths:
            - /example2
            - /example2/healthz
  tls: []

Legacy deployment-template ingress format

ingress:
  enabled: false
  # For K8s 1.19 and above use ingressClassName instead of annotation kubernetes.io/ingress.class:
  ingressClassName: nginx-internal
  annotations: {}
  path: ""
  host: ""
  tls: []
Key Description
enabled Enable or disable ingress
annotations To configure some options depending on the Ingress controller
path Path name
host Host name
tls It contains security details

additionalBackends

This defines additional backend path in the ingress .

    hosts:
    - host: chart-example2.local
      pathType: "ImplementationSpecific"
      paths:
        - /example2
        - /example2/healthz
      additionalBackends: 
        - path: /example1
          pathType: "ImplementationSpecific"
          backend:
            service:
              name: test-service
              port:
                number: 80

Ingress Internal

This allows private access to the url, please ensure you are using right nginx annotation for nginx class, its default value is nginx

ingressInternal:
  enabled: false
  # For K8s 1.19 and above use ingressClassName instead of annotation kubernetes.io/ingress.class:
  ingressClassName: nginx-internal
  annotations: {}
  hosts:
      - host: example1.com
        paths:
            - /example
      - host: example2.com
        paths:
            - /example2
            - /example2/healthz
  tls: []
Key Description
enabled Enable or disable ingress
annotations To configure some options depending on the Ingress controller
path Path name
host Host name
tls It contains security details

Init Containers

initContainers: 
  - reuseContainerImage: true
    securityContext:
      runAsUser: 1000
      runAsGroup: 3000
      fsGroup: 2000
    volumeMounts:
     - mountPath: /etc/ls-oms
       name: ls-oms-cm-vol
   command:
     - flyway
     - -configFiles=/etc/ls-oms/flyway.conf
     - migrate

  - name: nginx
    image: nginx:1.14.2
    securityContext:
      privileged: true
    ports:
    - containerPort: 80
    command: ["/usr/local/bin/nginx"]
    args: ["-g", "daemon off;"]

Specialized containers that run before app containers in a Pod. Init containers can contain utilities or setup scripts not present in an app image. One can use base image inside initContainer by setting the reuseContainerImage flag to true.

Istio

Istio is a service mesh which simplifies observability, traffic management, security and much more with it's virtual services and gateways.

istio:
  enable: true
  gateway:
    annotations: {}
    enabled: false
    host: example.com
    labels: {}
    tls:
      enabled: false
      secretName: example-tls-secret
  virtualService:
    annotations: {}
    enabled: false
    gateways: []
    hosts: []
    http:
      - corsPolicy:
          allowCredentials: false
          allowHeaders:
            - x-some-header
          allowMethods:
            - GET
          allowOrigin:
            - example.com
          maxAge: 24h
        headers:
          request:
            add:
              x-some-header: value
        match:
          - uri:
              prefix: /v1
          - uri:
              prefix: /v2
        retries:
          attempts: 2
          perTryTimeout: 3s
        rewriteUri: /
        route:
          - destination:
              host: service1
              port: 80
        timeout: 12s
      - route:
          - destination:
              host: service2
    labels: {}

Pause For Seconds Before Switch Active

pauseForSecondsBeforeSwitchActive: 30

To wait for given period of time before switch active the container.

Winter-Soldier

Winter Soldier can be used to

  • cleans up (delete) Kubernetes resources
  • reduce workload pods to 0

NOTE: After deploying this we can create the Hibernator object and provide the custom configuration by which workloads going to delete, sleep and many more. for more information check the main repo

Given below is template values you can give in winter-soldier:

winterSoilder:
  enable: false
  apiVersion: pincher.devtron.ai/v1alpha1
  action: sleep
  timeRangesWithZone:
    timeZone: "Asia/Kolkata"
    timeRanges: []
  targetReplicas: []
  fieldSelector: []

Here,

Key values Description
enable fasle,true decide the enabling factor
apiVersion pincher.devtron.ai/v1beta1, pincher.devtron.ai/v1alpha1 specific api version
action sleep,delete, scale This specify the action need to perform.
timeRangesWithZone:timeZone eg:- "Asia/Kolkata","US/Pacific" It use to specify the timeZone used. (It uses standard format. please refer this)
timeRangesWithZone:timeRanges array of [ timeFrom, timeTo, weekdayFrom, weekdayTo] It use to define time period/range on which the user need to perform the specified action. you can have multiple timeRanges.
These settings will take action on Sat and Sun from 00:00 to 23:59:59,
targetReplicas [n] : n - number of replicas to scale. These is mandatory field when the action is scale
Defalut value is [].
fieldSelector - AfterTime(AddTime( ParseTime({{metadata.creationTimestamp}}, '2006-01-02T15:04:05Z'), '5m'), Now()) These value will take a list of methods to select the resources on which we perform specified action .

here is an example,

winterSoilder:
  apiVersion: pincher.devtron.ai/v1alpha1 
  enable: true
  annotations: {}
  labels: {}
  timeRangesWithZone:
    timeZone: "Asia/Kolkata"
    timeRanges: 
      - timeFrom: 00:00
        timeTo: 23:59:59
        weekdayFrom: Sat
        weekdayTo: Sun
      - timeFrom: 00:00
        timeTo: 08:00
        weekdayFrom: Mon
        weekdayTo: Fri
      - timeFrom: 20:00
        timeTo: 23:59:59
        weekdayFrom: Mon
        weekdayTo: Fri
  action: scale
  targetReplicas: [1,1,1]
  fieldSelector: 
    - AfterTime(AddTime( ParseTime({{metadata.creationTimestamp}}, '2006-01-02T15:04:05Z'), '10h'), Now())

Above settings will take action on Sat and Sun from 00:00 to 23:59:59, and on Mon-Fri from 00:00 to 08:00 and 20:00 to 23:59:59. If action:sleep then runs hibernate at timeFrom and unhibernate at timeTo. If action: delete then it will delete workloads at timeFrom and timeTo. Here the action:scale thus it scale the number of resource replicas to targetReplicas: [1,1,1]. Here each element of targetReplicas array is mapped with the corresponding elments of array timeRangesWithZone/timeRanges. Thus make sure the length of both array is equal, otherwise the cnages cannot be observed.

The above example will select the application objects which have been created 10 hours ago across all namespaces excluding application's namespace. Winter soldier exposes following functions to handle time, cpu and memory.

  • ParseTime - This function can be used to parse time. For eg to parse creationTimestamp use ParseTime({{metadata.creationTimestamp}}, '2006-01-02T15:04:05Z')
  • AddTime - This can be used to add time. For eg AddTime(ParseTime({{metadata.creationTimestamp}}, '2006-01-02T15:04:05Z'), '-10h') ll add 10h to the time. Use d for day, h for hour, m for minutes and s for seconds. Use negative number to get earlier time.
  • Now - This can be used to get current time.
  • CpuToNumber - This can be used to compare CPU. For eg any({{spec.containers.#.resources.requests}}, { MemoryToNumber(.memory) < MemoryToNumber('60Mi')}) will check if any resource.requests is less than 60Mi.

Resources

These define minimum and maximum RAM and CPU available to the application.

resources:
  limits:
    cpu: "1"
    memory: "200Mi"
  requests:
    cpu: "0.10"
    memory: "100Mi"

Resources are required to set CPU and memory usage.

Limits

Limits make sure a container never goes above a certain value. The container is only allowed to go up to the limit, and then it is restricted.

Requests

Requests are what the container is guaranteed to get.

Service

This defines annotations and the type of service, optionally can define name also.

  service:
    type: ClusterIP
    annotations: {}

Volumes

volumes:
  - name: log-volume
    emptyDir: {}
  - name: logpv
    persistentVolumeClaim:
      claimName: logpvc

It is required when some values need to be read from or written to an external disk.

Volume Mounts

volumeMounts:
  - mountPath: /var/log/nginx/
    name: log-volume 
  - mountPath: /mnt/logs
    name: logpvc
    subPath: employee

It is used to provide mounts to the volume.

Affinity and anti-affinity

Spec:
  Affinity:
    Key:
    Values:

Spec is used to define the desire state of the given container.

Node Affinity allows you to constrain which nodes your pod is eligible to schedule on, based on labels of the node.

Inter-pod affinity allow you to constrain which nodes your pod is eligible to be scheduled based on labels on pods.

Key

Key part of the label for node selection, this should be same as that on node. Please confirm with devops team.

Values

Value part of the label for node selection, this should be same as that on node. Please confirm with devops team.

Tolerations

tolerations:
 - key: "key"
   operator: "Equal"
   value: "value"
   effect: "NoSchedule|PreferNoSchedule|NoExecute(1.6 only)"

Taints are the opposite, they allow a node to repel a set of pods.

A given pod can access the given node and avoid the given taint only if the given pod satisfies a given taint.

Taints and tolerations are a mechanism which work together that allows you to ensure that pods are not placed on inappropriate nodes. Taints are added to nodes, while tolerations are defined in the pod specification. When you taint a node, it will repel all the pods except those that have a toleration for that taint. A node can have one or many taints associated with it.

Arguments

args:
  enabled: false
  value: []

This is used to give arguments to command.

Command

command:
  enabled: false
  value: []

It contains the commands for the server.

Key Description
enabled To enable or disable the command.
value It contains the commands.

Containers

Containers section can be used to run side-car containers along with your main container within same pod. Containers running within same pod can share volumes and IP Address and can address each other @localhost. We can use base image inside container by setting the reuseContainerImage flag to true.

    containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
        command: ["/usr/local/bin/nginx"]
        args: ["-g", "daemon off;"]
      - reuseContainerImage: true
        securityContext:
          runAsUser: 1000
          runAsGroup: 3000
          fsGroup: 2000
        volumeMounts:
        - mountPath: /etc/ls-oms
          name: ls-oms-cm-vol
        command:
          - flyway
          - -configFiles=/etc/ls-oms/flyway.conf
          - migrate

Prometheus

  prometheus:
    release: monitoring

It is a kubernetes monitoring tool and the name of the file to be monitored as monitoring in the given case.It describes the state of the prometheus.

rawYaml

rawYaml: 
  - apiVersion: v1
    kind: Service
    metadata:
      name: my-service
    spec:
      selector:
        app: MyApp
      ports:
        - protocol: TCP
          port: 80
          targetPort: 9376
      type: ClusterIP

Accepts an array of Kubernetes objects. You can specify any kubernetes yaml here and it will be applied when your app gets deployed.

Grace Period

GracePeriod: 30

Kubernetes waits for the specified time called the termination grace period before terminating the pods. By default, this is 30 seconds. If your pod usually takes longer than 30 seconds to shut down gracefully, make sure you increase the GracePeriod.

A Graceful termination in practice means that your application needs to handle the SIGTERM message and begin shutting down when it receives it. This means saving all data that needs to be saved, closing down network connections, finishing any work that is left, and other similar tasks.

There are many reasons why Kubernetes might terminate a perfectly healthy container. If you update your deployment with a rolling update, Kubernetes slowly terminates old pods while spinning up new ones. If you drain a node, Kubernetes terminates all pods on that node. If a node runs out of resources, Kubernetes terminates pods to free those resources. It’s important that your application handle termination gracefully so that there is minimal impact on the end user and the time-to-recovery is as fast as possible.

Server

server:
  deployment:
    image_tag: 1-95a53
    image: ""

It is used for providing server configurations.

Deployment

It gives the details for deployment.

Key Description
image_tag It is the image tag
image It is the URL of the image

Service Monitor

servicemonitor:
      enabled: true
      path: /abc
      scheme: 'http'
      interval: 30s
      scrapeTimeout: 20s
      metricRelabelings:
        - sourceLabels: [namespace]
          regex: '(.*)'
          replacement: myapp
          targetLabel: target_namespace

It gives the set of targets to be monitored.

Db Migration Config

dbMigrationConfig:
  enabled: false

It is used to configure database migration.

KEDA Autoscaling

KEDA is a Kubernetes-based Event Driven Autoscaler. With KEDA, you can drive the scaling of any container in Kubernetes based on the number of events needing to be processed. KEDA can be installed into any Kubernetes cluster and can work alongside standard Kubernetes components like the Horizontal Pod Autoscaler(HPA).

Example for autosccaling with KEDA using Prometheus metrics is given below:

kedaAutoscaling:
  enabled: true
  minReplicaCount: 1
  maxReplicaCount: 2
  idleReplicaCount: 0
  pollingInterval: 30
  advanced:
    restoreToOriginalReplicaCount: true
    horizontalPodAutoscalerConfig:
      behavior:
        scaleDown:
          stabilizationWindowSeconds: 300
          policies:
          - type: Percent
            value: 100
            periodSeconds: 15
  triggers: 
    - type: prometheus
      metadata:
        serverAddress:  http://<prometheus-host>:9090
        metricName: http_request_total
        query: envoy_cluster_upstream_rq{appId="300", cluster_name="300-0", container="envoy",}
        threshold: "50"
  triggerAuthentication:
    enabled: false
    name:
    spec: {}
  authenticationRef: {}

Example for autosccaling with KEDA based on kafka is given below :

kedaAutoscaling:
  enabled: true
  minReplicaCount: 1
  maxReplicaCount: 2
  idleReplicaCount: 0
  pollingInterval: 30
  advanced: {}
  triggers: 
    - type: kafka
      metadata:
        bootstrapServers: b-2.kafka-msk-dev.example.c2.kafka.ap-southeast-1.amazonaws.com:9092,b-3.kafka-msk-dev.example.c2.kafka.ap-southeast-1.amazonaws.com:9092,b-1.kafka-msk-dev.example.c2.kafka.ap-southeast-1.amazonaws.com:9092
        topic: Orders-Service-ESP.info
        lagThreshold: "100"
        consumerGroup: oders-remove-delivered-packages
        allowIdleConsumers: "true"
  triggerAuthentication:
    enabled: true
    name: keda-trigger-auth-kafka-credential
    spec:
      secretTargetRef:
        - parameter: sasl
          name: keda-kafka-secrets
          key: sasl
        - parameter: username
          name: keda-kafka-secrets
          key: username
  authenticationRef: 
    name: keda-trigger-auth-kafka-credential

Security Context

A security context defines privilege and access control settings for a Pod or Container.

To add a security context for main container:

containerSecurityContext:
  allowPrivilegeEscalation: false

To add a security context on pod level:

podSecurityContext:
  runAsUser: 1000
  runAsGroup: 3000
  fsGroup: 2000

Topology Spread Constraints

You can use topology spread constraints to control how Pods are spread across your cluster among failure-domains such as regions, zones, nodes, and other user-defined topology domains. This can help to achieve high availability as well as efficient resource utilization.

topologySpreadConstraints:
  - maxSkew: 1
    topologyKey: zone
    whenUnsatisfiable: DoNotSchedule
    autoLabelSelector: true
    customLabelSelector: {}

Deployment Metrics

It gives the realtime metrics of the deployed applications

Key Description
Deployment Frequency It shows how often this app is deployed to production
Change Failure Rate It shows how often the respective pipeline fails.
Mean Lead Time It shows the average time taken to deliver a change to production.
Mean Time to Recovery It shows the average time taken to fix a failed pipeline.

2. Show application metrics

If you want to see application metrics like different HTTP status codes metrics, application throughput, latency, response time. Enable the Application metrics from below the deployment template Save button. After enabling it, you should be able to see all metrics on App detail page. By default it remains disabled.

Once all the Deployment template configurations are done, click on Save to save your deployment configuration. Now you are ready to create Workflow to do CI/CD.

Helm Chart Json Schema

Helm Chart json schema is used to validate the deployment template values.

Other Validations in Json Schema

The values of CPU and Memory in limits must be greater than or equal to in requests respectively. Similarly, In case of envoyproxy, the values of limits are greater than or equal to requests as mentioned below.

resources.limits.cpu >= resources.requests.cpu
resources.limits.memory >= resources.requests.memory
envoyproxy.resources.limits.cpu >= envoyproxy.resources.requests.cpu
envoyproxy.resources.limits.memory >= envoyproxy.resources.requests.memory