Decoding Kubernetes secret

Question

I inherited a Kubernetes/Docker setup, and I accidentally crashed the pod by changing something relating to the DB password.

I am trying to troubleshoot this.

I don't have much Kubernetes or Docker experience, so I'm still learning how to do things.

The value is contained inside the db-user-pass credential I believe, which is an Opaque type secret.

I'm describing it:

kubectl describe secrets/db-user-pass
Name:         db-user-pass
Namespace:    default
Labels:       <none>
Annotations:  <none>

Type:  Opaque

Data
====
password:  16 bytes
username:  13 bytes

but I have no clue how to get any data from this secret. The example on the Kubernetes site seems to assume I'll have a base64 encoded string, but I can't even seem to get that. How do I get the value for this?

Answer 1

You can use kubectl get secrets/db-user-pass -o yaml or -o json where you'll see the base64-encoded username and password. You can then copy the value and decode it with something like echo <ENCODED_VALUE> | base64 -D (Mac OS X).

A more compact one-liner for this:

kubectl get secrets/db-user-pass --template={{.data.password}} | base64 -D

and likewise for the username:

kubectl get secrets/db-user-pass --template={{.data.username}} | base64 -D

Note: on GNU/Linux, the base64 flag is -d, not -D.

Answer 2

I would suggest using this handy command. It utilizes a power of go-templates. It iterates over all values, decodes them, and prints them along with the key. It also handles not set values.

kubectl get secret name-of-secret -o go-template='
{{range $k,$v := .data}}{{printf "%s: " $k}}{{if not $v}}{{$v}}{{else}}{{$v | base64decode}}{{end}}{{"\n"}}{{end}}'

## In your case it would output
# password: decoded_password
# username: doceded_username

If you don't like go-templates you can use different output formats e.g. yaml or json, but that will output secrets encoded by base64.

Answer 3

If you have jq (json query) this works:

kubectl get secret db-user-pass -o json | jq '.data | map_values(@base64d)'

NOTE:

• db-user-pass is the name of the k8s secret
• .data is the variable within that contains the secret value

Answer 4

If your secret keys contain dash (-) or dot (.):

kubectl get secret db-user-pass -o=go-template='{{index .data "password"}}' | base64 -d

Answer 5

This is the link you might be looking for.

Kubernetes secrets need the secrets to be given in base64 encoded format, which can be created using base64 binary in case of linux distributions.

Example:

echo "hello" | base64
aGVsbG8K

Kubernetes decodes the base64 encoding when we pass the secret key as environment variable or mounted as volume.

Answer 6

First, get the secret from the etcd by querying the api server using kubectl.

kubectl get secret db-user-pass -o yaml 

This will give you the base64 encoded secret in yaml format.

Once you have the yaml file decode them using

"base64 --decode"

Final command will look like this: Don't forget the -n flag in echo command

echo -n "jdddjdkkdkdmdl" | base64 --decode

Answer 7

on ubuntu 18+

kubectl get secrets/db-user-pass --template={{.data.password}} | base64 -d

Answer 8

For easier decoding you can use a tool like ksd that will do the base64 decoding for you

kubectl get secrets/db-user-pass -o yaml | ksd

or using https://github.com/elsesiy/kubectl-view-secret

kubectl view-secret secrets/db-user-pass

Answer 9

Kubernetes 1.11+

kubectl get secrets/db-user-pass --template='{{.data.password | base64decode }}'

Answer 10

This one liner is used to get an encoded kubeconfig file from a secret, and generate a file from it to be used dynamically on a ci job for example:

kubectl get secret YOUR_SECRET -o json | grep -oP '(?<=\"YOUR_SECRET_KEY\": \")[^\"]*' | base64 --decode > ./YOUR_KUBECONFIG_FILE_NAME

Answer 11

Extending @Břetislav Hájek solution (thank you very much for that). If you need to get it by a label, then you'll need to add an extra range command to iterate over the returned items.

$ LABEL_FILTER="app.kubernetes.io/name=mysql-chart"

$ kubectl get secret  -l "$LABEL_FILTER"  -o go-template='
{{range $i := .items}}{{range $k,$v := $i.data}}{{printf "%s: " $k}}{{if not $v}}{{$v}}{{else}}{{$v | base64decode}}{{end}}{{"\n"}}{{end}}{{end}}'

mysql_password: ...
mysql_root_password: ...
mysql_user: ...

Answer 12

With bash. This is running ubuntu 18.04, and Kubernetes 1.18.5

kubectl -n metallb-system get secrets memberlist -o json | grep secretkey | grep -v f:s | awk -F '"' '{print$4}' |base64 --decode; echo