Environment file injector for Kubernetes resources
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README.md

kenv

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kenv is an environment file injector for Kubernetes resources.

kenv injects variables into Kubernetes resource documents by loading a list of files containing variables and modifying the resource document to include those values. This way, you can dynamically set environment variables without having to template your resource documents.

kenv Example

kenv supports referencing environment variables as:

Getting Started

Download kenv and run by passing a resource doc (YAML or JSON) to:

STDIN:

cat fixtures/deployment.yaml | ./kenv -v fixtures/vars.env
./kenv -v fixtures/vars.env < fixtures/deployment.yaml

or as a CLI Arg:

./kenv -v fixtures/vars.env fixtures/deployment.yaml

Usage

Usage: kenv [options] file

Examples:

  kenv -v fixtures/vars.env fixtures/deployment.yaml
  kenv -name nginx -v fixtures/vars.env -s fixtures/secrets.yml fixtures/deployment.yaml
  cat fixtures/deployment.yaml | kenv -v fixtures/vars.env

Options:
  -c value
    	Files containing variables to inject as ConfigMaps (repeatable)
  -convert-keys
    	Convert ConfigMap keys to support k8s version < 1.4
  -name string
    	Name to give the ConfigMap and Secret resources
  -namespace string
    	Namespace to create the ConfigMap in (default "default")
  -s value
    	Files containing variables to inject as Secrets (repeatable)
  -v value
    	Files containing variables to inject as environment variables (repeatable)
  -yaml
    	Output as YAML

Variables

Variables are stored in files either as simple key=value pairs, or YAML pairs (key: value). Multiple variable files can be specified by repeating the -v (inject directly as plaintext variables), -c (create and map as ConfigMaps), and -s (create and map as Secrets) flags. These flags are not mutually exclusive, meaning you can specify plaintext, ConfigMaps, and Secrets within the same command:

./kenv \
  -v fixtures/vars.env \
  -c fixtures/configmap.env \
  -s fixtures/secrets.yml \
  fixtures/deployment.yaml

YAML Format

YAML files must be in the following format (nested data types are not currently supported):

key1: value1
key2: value2

KV Format

A key=value format is also supported, for example:

key1=value1
key2=value2

Injection

Variables are injected into the resource doc specified by the user as either plaintext environment variables, ConfigMaps, or Secrets. When specifying ConfigMaps and/or Secrets, you must also set a -name for the ConfigMap/Secret resource being created.

kenv injects the variables into the PodSpec for the following resources:

  • DaemonSet
  • Deployment
  • ReplicaSet
  • ReplicationController

Conversion and Support for K8S < 1.4

When using ConfigMap and/or Secret resources in Kubernetes version < 1.4, keys must adhere to the following regex:

\.?[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*

As a convenience, you can pass -convert-keys, which will replace underscores with dashes and convert uppercase strings to lower.

Examples

Plaintext K/V Injection

Variables can be injected as plaintext, directly tied to the containers in the resource document by using the -v flag.

Given the variable file below (fixtures/plaintext.env):

ptkey1=ptvalue1
ptkey2=ptvalue2

Running the following command injecting as plaintext would result in:

$ kenv -yaml -v fixtures/plaintext.env fixtures/deployment.yaml
---
apiVersion: extensions/v1beta1
kind: Deployment
... snip ...
    spec:
      containers:
      - env:
        - name: ptkey1
          value: ptvalue1
        - name: pykey2
          value: ptvalue2
        image: nginx:latest
... snip ...

ConfigMap Injection

Variables can be injected as ConfigMaps references by specifying variable files with the flag -c. This will both print a ConfigMap resource to be created and modify the specified resource to use the ConfigMap.

Given the variable file below (fixtures/configmap.env):

cmkey1=cmvalue1
cmkey2=cmvalue2

Running the following command injecting as a ConfigMap would result in:

$ kenv -yaml -name nginx -c fixtures/plaintext.env fixtures/deployment.yaml
---
apiVersion: v1
data:
  cmkey1: cmvalue1
  cmkey2: cmvalue2
kind: ConfigMap
metadata:
  name: nginx
  namespace: default
---
apiVersion: extensions/v1beta1
kind: Deployment
... snip ...
    spec:
      containers:
      - env:
        - name: cmkey1
          valueFrom:
            configMapKeyRef:
              key: cmkey1
              name: nginx
        - name: cmkey2
          valueFrom:
            configMapKeyRef:
              key: cmkey2
              name: nginx
        image: nginx:latest
... snip ...

Secret Injection

Variables can be injected as Secret references by specifying variable files with the flag -s. This will both print a Secret resource to be created and modify the specified resource to use the Secret.

Given the variable file below (fixtures/secrets.yml):

secretkey1: secretvalue1
secretkey2: secretvalue2

Running the following command injecting as a ConfigMap would result in:

$ kenv -yaml -name nginx -s fixtures/secrets.yml fixtures/deployment.yaml
---
apiVersion: v1
data:
  secretkey1: YzJWamNtVjBkbUZzZFdVeA==
  secretkey2: YzJWamNtVjBkbUZzZFdVeQ==
kind: Secret
metadata:
  creationTimestamp: null
  name: nginx
  namespace: default
---
apiVersion: extensions/v1beta1
kind: Deployment
... snip ...
    spec:
      containers:
      - env:
        - name: secretkey1
          valueFrom:
            secretKeyRef:
              key: secretkey1
              name: nginx
        - name: secretkey2
          valueFrom:
            secretKeyRef:
              key: secretkey2
              name: nginx
        image: nginx:latest
... snip ...

Plaintext, ConfigMaps, and Secrets

Combining the examples above into one command, you would get the following output:

$ kenv -yaml -name nginx -v fixtures/plaintext.env -c fixtures/configmap.env -s fixtures/secrets.yml fixtures/deployment.yaml
---
apiVersion: v1
data:
  secretkey1: YzJWamNtVjBkbUZzZFdVeA==
  secretkey2: YzJWamNtVjBkbUZzZFdVeQ==
kind: Secret
metadata:
  name: nginx
  namespace: default
---
apiVersion: v1
data:
  cmkey1: cmvalue1
  cmkey2: cmvalue2
kind: ConfigMap
metadata:
  name: nginx
  namespace: default
---
apiVersion: extensions/v1beta1
kind: Deployment
... snip ...
    spec:
      containers:
      - env:
        - name: ptkey1
          value: ptvalue1
        - name: pykey2
          value: ptvalue2
        - name: secretkey1
          valueFrom:
            secretKeyRef:
              key: secretkey1
              name: nginx
        - name: secretkey2
          valueFrom:
            secretKeyRef:
              key: secretkey2
              name: nginx
        - name: cmkey1
          valueFrom:
            configMapKeyRef:
              key: cmkey1
              name: nginx
        - name: cmkey2
          valueFrom:
            configMapKeyRef:
              key: cmkey2
              name: nginx
        image: nginx:latest
... snip ...

Building

govendor sync
go test -v .