Compare commits

...

7 Commits
0.0.6 ... 0.0.8

Author SHA1 Message Date
stakater-user
64d12a7c31 Bump Version to 0.0.8 2018-08-01 19:11:12 +00:00
Faizan Ahmad
078fc034d2 Add doc how to verify reloader working (#20)
* Add doc how to verify reloader working

* fix the text
2018-08-01 20:49:43 +02:00
stakater-user
a3125e876c Bump Version to 0.0.7 2018-08-01 10:27:17 +00:00
Faizan Ahmad
2f56d5c05b Move How it works section from readme to How it works doc (#15) 2018-08-01 11:58:39 +02:00
Faizan Ahmad
003eaee887 [STK-322] Add reloader vs k8s-trigger-controller doc (#13)
* Add reloader vs k8s-trigger-controller doc

* Fix kubectl command in readme
2018-08-01 11:41:45 +02:00
Faizan Ahmad
3030ddebf1 [STK-322] Add How it works doc (#12)
* Add How it works doc

* Update How-it-works.md

* Update how it works

* Add how it works reference in Readme
2018-08-01 11:41:26 +02:00
Faizan Ahmad
aa8b415fd4 [STK-322] Update readme to resolve any confusions (#9)
* Update readme to resolve any confusions

* Add new heading

* Remove unnecessary deployment commands from readme

* Set watch globally to true for jumbo manifest

* Update chart version to resolve conflicts

* Update readme with deploy with helm
2018-08-01 11:41:11 +02:00
11 changed files with 202 additions and 60 deletions

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@@ -1 +1 @@
0.0.6
0.0.8

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@@ -2,11 +2,11 @@
## Problem
We would like to watch if some change happens in `ConfigMap` and `Secret` objects and then perform certain upgrade on relevant `Deployment`, `Deamonset` and `Statefulset`
We would like to watch if some change happens in `ConfigMap` and `Secret` objects and then perform rolling upgrade on relevant `Deployment`, `Deamonset` and `Statefulset`
## Solution
Reloader can watch any changes in `ConfigMap` and `Secret` objects and update or recreate Pods for their associated `Deployments`, `Deamonsets` and `Statefulsets`. In this way Pods can get the latest changes in `ConfigMap` or `Secret` objects.
Reloader can watch changes in `ConfigMap` and `Secret` and do rolling upgrades on Pods with their associated `Deployments`, `Deamonsets` and `Statefulsets`.
**NOTE:** This controller has been inspired from [configmapController](https://github.com/fabric8io/configmapcontroller)
@@ -30,39 +30,33 @@ metadata:
secret.reloader.stakater.com/reload: "foo"
```
Then, providing `Reloader` is running, whenever you edit the `ConfigMap` or `Secret` called `foo` the Reloader will update the `Deployment` by adding the environment variable:
```
STAKATER_FOO_REVISION=${reloaderRevision}
```
This then triggers a rolling upgrade of your deployment's pods to use the new configuration.
Same procedure can be followed to perform rolling upgrade on `Deamonsets` and `Statefulsets` as well.
## Deploying to Kubernetes
You can deploy Reloader by running the following kubectl commands:
```bash
kubectl apply -f rbac.yaml -n <namespace>
kubectl apply -f deployment.yaml -n <namespace>
```
You can deploy Reloader by following methods:
### Vanilla Manifests
You can apply vanilla manifests by running the following command
```bash
kubecl apply -f https://raw.githubusercontent.com/stakater/Reloader/master/deployments/kubernetes/reloader.yaml
kubectl apply -f https://raw.githubusercontent.com/stakater/Reloader/master/deployments/kubernetes/reloader.yaml
```
### Helm Charts
Or alternatively if you configured `helm` on your cluster, you can deploy Reloader via helm chart located under `deployments/kubernetes/chart/reloader` folder.
Alternatively if you have configured helm on your cluster, you can add reloader to helm from our public chart repository and deploy it via helm using below mentioned commands
### Monitor All namespaces
You can monitor all namespaces in cluster by setting the `watchGlobally` flag to `true` in manifest file.
```bash
helm repo add stakater https://stakater.github.io/stakater-charts
helm repo update
helm install stakater/reloader
```
## Monitor All namespaces
By default Reloader gets deployed in `default` namespace and watches changes `secrets` and `configmaps` in all namespaces.
## Help

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@@ -3,7 +3,7 @@
apiVersion: v1
name: reloader
description: Reloader chart that runs on kubernetes
version: 0.0.6
version: 0.0.8
keywords:
- Reloader
- kubernetes

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@@ -7,9 +7,9 @@ reloader:
labels:
provider: stakater
group: com.stakater.platform
version: 0.0.6
version: 0.0.8
image:
name: stakater/reloader
tag: "0.0.6"
tag: "0.0.8"
pullPolicy: IfNotPresent
watchGlobally: false
watchGlobally: true

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@@ -7,8 +7,8 @@ metadata:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader
@@ -29,11 +29,7 @@ spec:
spec:
containers:
- env:
- name: KUBERNETES_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
image: "stakater/reloader:0.0.6"
image: "stakater/reloader:0.0.8"
imagePullPolicy: IfNotPresent
name: reloader
serviceAccountName: reloader

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@@ -7,21 +7,21 @@ metadata:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
kind: ClusterRole
metadata:
labels:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader-role
@@ -51,21 +51,21 @@ rules:
- patch
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
kind: ClusterRoleBinding
metadata:
labels:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader-role-binding
namespace: default
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
kind: ClusterRole
name: reloader-role
subjects:
- kind: ServiceAccount

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@@ -7,8 +7,8 @@ metadata:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader
@@ -29,11 +29,7 @@ spec:
spec:
containers:
- env:
- name: KUBERNETES_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
image: "stakater/reloader:0.0.6"
image: "stakater/reloader:0.0.8"
imagePullPolicy: IfNotPresent
name: reloader
serviceAccountName: reloader
@@ -47,21 +43,21 @@ metadata:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
kind: ClusterRole
metadata:
labels:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader-role
@@ -91,21 +87,21 @@ rules:
- patch
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
kind: ClusterRoleBinding
metadata:
labels:
app: reloader
group: com.stakater.platform
provider: stakater
version: 0.0.6
chart: "reloader-0.0.6"
version: 0.0.8
chart: "reloader-0.0.8"
release: "RELEASE-NAME"
heritage: "Tiller"
name: reloader-role-binding
namespace: default
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
kind: ClusterRole
name: reloader-role
subjects:
- kind: ServiceAccount

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@@ -12,4 +12,4 @@ reloader:
name: {{ getenv "DOCKER_IMAGE" }}
tag: "{{ getenv "VERSION" }}"
pullPolicy: IfNotPresent
watchGlobally: false
watchGlobally: true

77
docs/How-it-works.md Normal file
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@@ -0,0 +1,77 @@
# How it works?
Reloader watches for `ConfigMap` and `Secret` and detects if there are changes in data of these objects. After change detection reloader performs rolling upgrade on relevant Pods via associated `Deployment`, `Deamonset` and `Statefulset`.
## How change detection works
Reloader watches changes in `configmaps` and `secrets` data. As soon as it detects a change in these. It forwards these objects to an update handler which decides if and how to perform the rolling upgrade.
## Requirements for rolling upgrade
To perform rolling upgrade a `deployment`, `daemonset` or `statefulset` must have
- support for rolling upgrade strategy
- specific annotation for `configmaps` or `secrets`
The annotation value is comma separated list of `configmaps` or `secrets`. If a change is detected in data of these `configmaps` or `secrets`, reloader will perform rolling upgrades on their associated `deployments`, `daemonsets` or `statefulsets`.
### Annotation for Configmap
For a `Deployment` called `foo` have a `ConfigMap` called `foo`. Then add this annotation to your `Deployment`
```yaml
metadata:
annotations:
configmap.reloader.stakater.com/reload: "foo"
```
### Annotation for Secret
For a `Deployment` called `foo` have a `Secret` called `foo`. Then add this annotation to your `Deployment`
```yaml
metadata:
annotations:
secret.reloader.stakater.com/reload: "foo"
```
Above mentioned annotation are also work for `Daemonsets` and `Statefulsets`
## How Rolling upgrade works?
When reloader detects changes in configmap. It gets two objects of configmap. First object is an old configmap object which has a state before the latest change. Second object is new configmap object which contains latest changes. Reloader compares both objects and see whether any change in data occurred or not. If reloader finds any change in new configmap object, only then, it move forward with rolling upgrade.
After that, reloader gets the list of all deployments, daemonsets and statefulset and looks for above mentioned annotation for configmap. If the annotation value contains the configmap name, it then looks for an environment variable which can contain the configmap or secret data change hash.
### Environment variable for Configmap
If configmap name is foo then
```yaml
STAKATER_FOO_CONFIGMAP
```
### Environment variable for Secret
If Secret name is foo then
```yaml
STAKATER_FOO_SECRET
```
If the environment variable is found then it gets its value and compares it with new configmap hash value. If old value in environment variable is different from new hash value then reloader updates the environment variable. If the environment variable does not exist then it creates a new environment variable with latest hash value from configmap and updates the relevant `deployment`, `daemonset` or `statefulset`
Note: Rolling upgrade also works in the same way for secrets.
### Hash value Computation
Reloader uses SHA1 to compute hash value. SHA1 is used because it is efficient and less prone to collision.
## Monitor All Namespaces
By default reloader deploys in default namespace and monitors changes in all namespaces. To monitor changes in a specific namespace deploy the reloader in that namespace and set the `watchGlobally` flag to `false` in values file located under `deployments/kubernetes/chart/reloader`
And render manifest file using helm command
```bash
helm --namespace {replace this with namespace name} template . > reloader.yaml
```
The output file can then be used to deploy reloader in specific namespace.

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@@ -0,0 +1,28 @@
# Reloader vs k8s-trigger-controller
Reloader and k8s-trigger-controller are both built for same purpose. So there are quite a few similarities and differences between these.
## Similarities
- Both controllers support change detection in configmap and secrets
- Both controllers support deployment rollout
- Both controllers use SHA1 for hashing
- Both controllers have end to end as well as unit test cases.
## Differences
### Support for Daemonsets and Statefulsets.
#### k8s-trigger-controller:
k8s-trigger-controller only support for deployment rollout. It does not support daemonsets and statefulsets rollout.
#### Reloader:
Reloader supports deployment rollout as well as daemonsets and statefulsets rollout.
### Hashing usage
#### k8s-trigger-controller:
k8s-trigger-controller stores the hash value in an annotation `trigger.k8s.io/[secret|configMap]-NAME-last-hash`
#### Reloader:
Reloader stores the hash value in an environment variable `STAKATER_NAME_[SECRET|CONFIGMAP]`

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@@ -0,0 +1,51 @@
# Verify Reloader's Working
Reloader's working can be verified by two ways.
## Verify from logs
Check the logs of reloader and verify that you can see logs looks like below, if you are able to find these logs then it means reloader is working.
```text
Changes Detected in test-object of type 'SECRET' in namespace: test-reloader
Updated test-resource of type Deployment in namespace: test-reloader
```
Below are the details that explain these logs:
### test-object
`test-object` is the name of a `secret` or a `deployment` in which change has been detected.
### SECRET
`SECRET` is the type of `test-object`. It can either be `SECRET` or `CONFIGMAP`
### test-reloader
`test-reloader` is the name of namespace in which reloader has detected the change.
### test-resource
`test-resource` is the name of resource which is going to be updated
### Deployment
`Deployment` is the type of `test-resource`. It can either be a `Deployment`, `Daemonset` or `Statefulset`
## Verify by checking the age of Pod
A pod's age can tell whether reloader is working correctly or not. If you know that a change in a `secret` or `configmap` has occurred, then check the relevant Pod's age immediately. It should be newly created few moments ago.
### Verify from kubernetes Dashboard
`kubernetes dashboard` can be used to verify the working of Reloader. After a change in `secret` or `configmap`, check the relevant Pod's age from dashboard. It should be newly created few moments ago.
### Verify from command line
After a change in `secret` or `configmap`. Run the below mentioned command and verify that the pod is newly created.
```bash
kubectl get pods <pod name> -n <namespace name>
```