How to create kubernetes secret as json object and load the same in kubernetes environment as json - json

Question

I need to pass a JWK as kubernetes environment variable to my app.
I created a file to store my key like so:
cat deploy/keys/access-signature-public-jwk
{
algorithm = "RS256"
jwk = {"kty":"RSA","e":"AQAB","n":"ghhDZxuUo6TaSvAlD23mLP6n_T9pQuJsFY4JWdBYTjtcp_8Q3QeR477jou4cScPGczWw2JMGnx-Ao_b7ewagSl7VHpECBFHgcnlAgs5j6jfnd3M9ADKD2Yc756iXlIMT9xKDblIcXQQYlXalqxGvnLRLv1KAgVVVpVWzQd6Iz8WdTnexVrh7L9N87QQbOWcAVWGHCWCLCBsVE7JbC-XDt9h9P1g1sMqMV-qp7HjSXUKWuF2NwOnL2VeFSED7gdefs2Za1UYqhfwxdGl7aaPDXhjib0cfg4NvbcXMzxDEVkeJqhdDfD82wHOs4qFvnFMVxq9n6VVExSxsJq8gBJ7Z2AmfoXpmZC1L1ZwULB2KKpFXDCzgBELPLrfyIf8mNnk2nuuLT-aaMsqy2uB-ea3du4lyWo9MLk6x-L5g-n1oADKFKBY9aP2QQwruCG92XSd7jA9yLtbgr9OGVCYezxIxFp4vW6KcmPwJQjozWtwkZjeo4hv-zhRac73WDox2hDkif7WPTuEvC21fRy3GvyPIUPKPJA8pJjb2TXT7DXknR97CTnOWicuh3HMoRlVIwUzM5SVLGSXex0VjHZKgLYwQYukg5O2rab_4NxpD6LqLHx1bbPssC7BedCIfWX1Vcae40tlfvJAM09MiwQPZjWRahW_fK_9X5F5_rtUhCznm32M"}
}
Which is then used to create a kubernetes secret like so:
kubectl create secret generic intimations-signature-public-secret --from-file=./deploy/keys/access-signature-public-jwk
Which is then retrived in the kubernetes environment variable as:
- name: ACCESS_SIGNATURE_PUBLIC_JWK
valueFrom:
secretKeyRef:
name: intimations-signature-public-secret
key: access-signature-public-jwk
And passed to the application.conf of the application likeso:
pac4j.lagom.jwt.authenticator {
signatures = [
${ACCESS_SIGNATURE_PUBLIC_JWK}
]
}
The pac4j library expects the config pac4j.lagom.jwt.authenticator as a json object. But get the following exception when I run this app:
com.typesafe.config.ConfigException$WrongType: env variables: signatures has type list of STRING rather than list of OBJECT
at com.typesafe.config.impl.SimpleConfig.getHomogeneousWrappedList(SimpleConfig.java:452)
at com.typesafe.config.impl.SimpleConfig.getObjectList(SimpleConfig.java:460)
at com.typesafe.config.impl.SimpleConfig.getConfigList(SimpleConfig.java:465)
at org.pac4j.lagom.jwt.JwtAuthenticatorHelper.parse(JwtAuthenticatorHelper.java:84)
at com.codingkapoor.holiday.impl.core.HolidayApplication.jwtClient$lzycompute(HolidayApplication.scala
POD Description
Name: holiday-deployment-55b86f955d-9klk2
Namespace: default
Priority: 0
Node: minikube/192.168.99.103
Start Time: Thu, 28 May 2020 12:42:50 +0530
Labels: app=holiday
pod-template-hash=55b86f955d
Annotations: <none>
Status: Running
IP: 172.17.0.5
IPs:
IP: 172.17.0.5
Controlled By: ReplicaSet/holiday-deployment-55b86f955d
Containers:
holiday:
Container ID: docker://18443cfedc7fd39440f5fa6f038f36c58cec1660a2974e6432500e8c7d51f5e6
Image: codingkapoor/holiday-impl:latest
Image ID: docker://sha256:6e0ddcf41e0257755b7e865424671970091d555c4bad88b5d896708ded139eb7
Port: 8558/TCP
Host Port: 0/TCP
State: Terminated
Reason: Error
Exit Code: 255
Started: Thu, 28 May 2020 22:49:24 +0530
Finished: Thu, 28 May 2020 22:49:29 +0530
Last State: Terminated
Reason: Error
Exit Code: 255
Started: Thu, 28 May 2020 22:44:15 +0530
Finished: Thu, 28 May 2020 22:44:21 +0530
Ready: False
Restart Count: 55
Liveness: http-get http://:management/alive delay=20s timeout=1s period=10s #success=1 #failure=10
Readiness: http-get http://:management/ready delay=20s timeout=1s period=10s #success=1 #failure=10
Environment:
JAVA_OPTS: -Xms256m -Xmx256m -Dconfig.resource=prod-application.conf
APPLICATION_SECRET: <set to the key 'secret' in secret 'intimations-application-secret'> Optional: false
MYSQL_URL: jdbc:mysql://mysql/intimations_holiday_schema
MYSQL_USERNAME: <set to the key 'username' in secret 'intimations-mysql-secret'> Optional: false
MYSQL_PASSWORD: <set to the key 'password' in secret 'intimations-mysql-secret'> Optional: false
ACCESS_SIGNATURE_PUBLIC_JWK: <set to the key 'access-signature-public-jwk' in secret 'intimations-signature-public-secret'> Optional: false
REFRESH_SIGNATURE_PUBLIC_JWK: <set to the key 'refresh-signature-public-jwk' in secret 'intimations-signature-public-secret'> Optional: false
REQUIRED_CONTACT_POINT_NR: 1
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-kqmmv (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
default-token-kqmmv:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-kqmmv
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Pulled 5m21s (x23 over 100m) kubelet, minikube Container image "codingkapoor/holiday-impl:latest" already present on machine
Warning BackOff 27s (x466 over 100m) kubelet, minikube Back-off restarting failed container
I was wondering if there is any way to pass the environment variable as a json object instead of string. Please suggest. TIA.

Answer 1

First, the file access-signature-public-jwk is not a valid JSON file. You should update it as a valid one.
{
"algorithm" : "RS256",
"jwk" : {"kty":"RSA","e":"AQAB","n":"ghhDZxuUo6TaSvAlD23mLP6n_T9pQuJsFY4JWdBYTjtcp_8Q3QeR477jou4cScPGczWw2JMGnx-Ao_b7ewagSl7VHpECBFHgcnlAgs5j6jfnd3M9ADKD2Yc756iXlIMT9xKDblIcXQQYlXalqxGvnLRLv1KAgVVVpVWzQd6Iz8WdTnexVrh7L9N87QQbOWcAVWGHCWCLCBsVE7JbC-XDt9h9P1g1sMqMV-qp7HjSXUKWuF2NwOnL2VeFSED7gdefs2Za1UYqhfwxdGl7aaPDXhjib0cfg4NvbcXMzxDEVkeJqhdDfD82wHOs4qFvnFMVxq9n6VVExSxsJq8gBJ7Z2AmfoXpmZC1L1ZwULB2KKpFXDCzgBELPLrfyIf8mNnk2nuuLT-aaMsqy2uB-ea3du4lyWo9MLk6x-L5g-n1oADKFKBY9aP2QQwruCG92XSd7jA9yLtbgr9OGVCYezxIxFp4vW6KcmPwJQjozWtwkZjeo4hv-zhRac73WDox2hDkif7WPTuEvC21fRy3GvyPIUPKPJA8pJjb2TXT7DXknR97CTnOWicuh3HMoRlVIwUzM5SVLGSXex0VjHZKgLYwQYukg5O2rab_4NxpD6LqLHx1bbPssC7BedCIfWX1Vcae40tlfvJAM09MiwQPZjWRahW_fK_9X5F5_rtUhCznm32M"}
}
Steps I followed to validate.
kubectl create secret generic token1 --from-file=jwk.json
Mount the secret into the pod.
env:
- name: JWK
valueFrom:
secretKeyRef:
name: token
key: jwk.json
exec to the pod and check the env variable JWK
$ echo $JWK
{ "algorithm" : "RS256", "jwk" : {"kty":"RSA","e":"AQAB","n":"ghhDZxuUo6TaSvAlD23mLP6n_T9pQuJsFY4JWdBYTjtcp_8Q3QeR477jou4cScPGczWw2JMGnx-Ao_b7ewagSl7VHpECBFHgcnlAgs5j6jfnd3M9ADKD2Yc756iXlIMT9xKDblIcXQQYlXalqxGvnLRLv1KAgVVVpVWzQd6Iz8WdTnexVrh7L9N87QQbOWcAVWGHCWCLCBsVE7JbC-XDt9h9P1g1sMqMV-qp7HjSXUKWuF2NwOnL2VeFSED7gdefs2Za1UYqhfwxdGl7aaPDXhjib0cfg4NvbcXMzxDEVkeJqhdDfD82wHOs4qFvnFMVxq9n6VVExSxsJq8gBJ7Z2AmfoXpmZC1L1ZwULB2KKpFXDCzgBELPLrfyIf8mNnk2nuuLT-aaMsqy2uB-ea3du4lyWo9MLk6x-L5g-n1oADKFKBY9aP2QQwruCG92XSd7jA9yLtbgr9OGVCYezxIxFp4vW6KcmPwJQjozWtwkZjeo4hv-zhRac73WDox2hDkif7WPTuEvC21fRy3GvyPIUPKPJA8pJjb2TXT7DXknR97CTnOWicuh3HMoRlVIwUzM5SVLGSXex0VjHZKgLYwQYukg5O2rab_4NxpD6LqLHx1bbPssC7BedCIfWX1Vcae40tlfvJAM09MiwQPZjWRahW_fK_9X5F5_rtUhCznm32M"} }
Copy the content to a file
echo $JWK > jwk.json
Validate the file
$ jsonlint-php jwk.json
Valid JSON (jwk.json)
If I use the file you are given and followed the same steps. It gives an json validation error. Also, env variables are always strings. You have to convert them into the required types in your code.
$ echo $JWK
{ algorithm = "RS256" jwk = {"kty":"RSA","e":"AQAB","n":"ghhDZxuUo6TaSvAlD23mLP6n_T9pQuJsFY4JWdBYTjtcp_8Q3QeR477jou4cScPGczWw2JMGnx-Ao_b7ewagSl7VHpECBFHgcnlAgs5j6jfnd3M9ADKD2Yc756iXlIMT9xKDblIcXQQYlXalqxGvnLRLv1KAgVVVpVWzQd6Iz8WdTnexVrh7L9N87QQbOWcAVWGHCWCLCBsVE7JbC-XDt9h9P1g1sMqMV-qp7HjSXUKWuF2NwOnL2VeFSED7gdefs2Za1UYqhfwxdGl7aaPDXhjib0cfg4NvbcXMzxDEVkeJqhdDfD82wHOs4qFvnFMVxq9n6VVExSxsJq8gBJ7Z2AmfoXpmZC1L1ZwULB2KKpFXDCzgBELPLrfyIf8mNnk2nuuLT-aaMsqy2uB-ea3du4lyWo9MLk6x-L5g-n1oADKFKBY9aP2QQwruCG92XSd7jA9yLtbgr9OGVCYezxIxFp4vW6KcmPwJQjozWtwkZjeo4hv-zhRac73WDox2hDkif7WPTuEvC21fRy3GvyPIUPKPJA8pJjb2TXT7DXknR97CTnOWicuh3HMoRlVIwUzM5SVLGSXex0VjHZKgLYwQYukg5O2rab_4NxpD6LqLHx1bbPssC7BedCIfWX1Vcae40tlfvJAM09MiwQPZjWRahW_fK_9X5F5_rtUhCznm32M"} }
$ echo $JWK > jwk.json
$ jsonlint-php jwk.json
jwk.json: Parse error on line 1:
{ algorithm = "RS256"
-^
Expected one of: 'STRING', '}'

Answer 2

Although not a direct answer but an alternate solution to this problem.
As #hariK pointed out environment variables are always strings and in order to consume them as json we would need to convert the env var read as string into json.
However, in my case, this was not a viable solution because I was using a lib that was expecting a Config object and not a json object directly which would have meant a lot of work. Converting string -> json -> Config. Plus this approach is inconsistent with how Config object was being built in the developement scenarios i.e., json -> Config. See here.
The framework I am using to build this app is based on Play Framework which allows to modularize application configs in separate files and then club the required pieces together in a desired config file, as shown below. You can read it more in detail here.
application.conf
include "/opt/conf/app1.conf"
include "/opt/conf/app2.conf"
This allowed me to make use of Using Secrets as files from a Pod
feature from kubernetes.
Basically, I created a small config file that contains a part of my main application configuration file, as shown below:
cat deploy/keys/signature-public-jwk
pac4j.lagom.jwt.authenticator {
signatures = [
{
algorithm = "RS256"
jwk = {"kty":"RSA","e":"AQAB","n":"ghhDZxuUo6TaSvAlD23mLP6n_T9pQuJsFY4JWdBYTjtcp_8Q3QeR477jou4cScPGczWw2JMGnx-Ao_b7ewagSl7VHpECBFHgcnlAgs5j6jfnd3M9ADKD2Yc756iXlIMT9xKDblIcXQQYlXalqxGvnLRLv1KAgVVVpVWzQd6Iz8WdTnexVrh7L9N87QQbOWcAVWGHCWCLCBsVE7JbC-XDt9h9P1g1sMqMV-qp7HjSXUKWuF2NwOnL2VeFSED7gdefs2Za1UYqhfwxdGl7aaPDXhjib0cfg4NvbcXMzxDEVkeJqhdDfD82wHOs4qFvnFMVxq9n6VVExSxsJq8gBJ7Z2AmfoXpmZC1L1ZwULB2KKpFXDCzgBELPLrfyIf8mNnk2nuuLT-aaMsqy2uB-ea3du4lyWo9MLk6x-L5g-n1oADKFKBY9aP2QQwruCG92XSd7jA9yLtbgr9OGVCYezxIxFp4vW6KcmPwJQjozWtwkZjeo4hv-zhRac73WDox2hDkif7WPTuEvC21fRy3GvyPIUPKPJA8pJjb2TXT7DXknR97CTnOWicuh3HMoRlVIwUzM5SVLGSXex0VjHZKgLYwQYukg5O2rab_4NxpD6LqLHx1bbPssC7BedCIfWX1Vcae40tlfvJAM09MiwQPZjWRahW_fK_9X5F5_rtUhCznm32M"}
}
]
}
Then created a kubernetes secret and mounted volumes in deployment to appear in the pod as file
kubectl create secret generic signature-public-secret --from-file=./deploy/secrets/signature-public-jwks.conf
// deployment yaml
spec:
containers:
- name: employee
image: "codingkapoor/employee-impl:latest"
volumeMounts:
- name: signature-public-secret-conf
mountPath: /opt/conf/signature-public-jwks.conf
subPath: signature-public-jwks.conf
readOnly: true
volumes:
- name: signature-public-secret-conf
secret:
secretName: signature-public-secret
Use this mounted file location in the application.conf to include the same
include file("/opt/conf/signature-public-jwks.conf")
Notice that the mountPath and the file location in the application.conf are same.
Advantages of this approach:
The solution is consistent with both the development and test, production environments as we could return json instead of string to the lib, as explained above
Secrets shouldn't be passed as environment variables anyway! You can read more about it here.