Can't create Secret in Kubernetes: illegal base64 data at input

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I want to create a secret for my kubernetes cluster. So I composed following dummy-secret.yaml file:
apiVersion: v1
kind: Secret
metadata:
  name: dummy-secret
type: Opaque
data:
  API_KEY: bWVnYV9zZWNyZXRfa2V5
  API_SECRET: cmVhbGx5X3NlY3JldF92YWx1ZTE=
When I run kubectl create -f dummy-secret.yaml I receive back following message:
Error from server (BadRequest): error when creating "dummy-secret.yaml": Secret in version "v1" cannot be handled as a Secret: v1.Secret: Data: decode base64: illegal base64 data at input byte 8, error found in #10 byte of ...|Q89_Hj1Aq","API_SECR|..., bigger context ...|sion":"v1","data":{"API_KEY":"af76fsdK_cQ89_Hj1Aq","API_SECRET":"bsdfmkwegwegwe"},"kind":"Secret","m|...
Not sure why it happens. 
As I understood, I need to encode all values under the data key in the yaml file. So I did base64 encoding, but kubernetes still doesn't handle the yaml secret file as I expect.
UPDATE:
I used this command to encode data values on my mac:
echo -n 'mega_secret_key' | openssl base64
I got the decoded values "mega_secret_key" and "really_secret_value1" from from your encoded data. Seems they are not encoded in right way. So, encode your data in right way:
$ echo "mega_secret_key" | base64
bWVnYV9zZWNyZXRfa2V5Cg==
$ echo "really_secret_value1" | base64
cmVhbGx5X3NlY3JldF92YWx1ZTEK
Then check whether they are encoded properly:
$ echo "bWVnYV9zZWNyZXRfa2V5Cg==" | base64 -d
mega_secret_key
$ echo "cmVhbGx5X3NlY3JldF92YWx1ZTEK" | base64 -d
really_secret_value1
So they are ok. Now use them in your dummy-secret.yaml:
apiVersion: v1
kind: Secret
metadata:
  name: dummy-secret
type: Opaque
data:
  API_KEY: bWVnYV9zZWNyZXRfa2V5Cg==
  API_SECRET: cmVhbGx5X3NlY3JldF92YWx1ZTEK
And run $ kubectl create -f dummy-secret.yaml.
UPDATE on 11-02-2022:
The newer versions of Kubernetes support the optional stringData property where one can provide the value against any key without decoding.
All key-value pairs in the stringData field are internally merged into the data field. If a key appears in both the data and the stringData field, the value specified in the stringData field takes precedence.
apiVersion: v1
kind: Secret
metadata:
  name: dummy-secret
type: Opaque
stringData:
  API_KEY: mega_secret_key
  API_SECRET: really_secret_value1
UPDATE:
If you use -n flag while running $ echo "some_text", it will trim the trailing \n (newline) from the string you are printing.
$ echo "some_text"
some_text
$ echo -n "some_text"
some_text⏎
Just try it,
# first encode
$ echo -n "mega_secret_key" | base64
bWVnYV9zZWNyZXRfa2V5
$ echo -n "really_secret_value1" | base64
cmVhbGx5X3NlY3JldF92YWx1ZTE=
# then decode and check whether newline is stripped
$ echo "bWVnYV9zZWNyZXRfa2V5" | base64 -d
mega_secret_key⏎
$ echo "cmVhbGx5X3NlY3JldF92YWx1ZTE=" | base64 -d
really_secret_value1⏎
You can use these newly (without newline) decoded data in your secret instead. That also should fine.
$ cat - <<-EOF | kubectl apply -f -
apiVersion: v1
kind: Secret
metadata:
  name: dummy-secret
type: Opaque
data:
  API_KEY: bWVnYV9zZWNyZXRfa2V5
  API_SECRET: cmVhbGx5X3NlY3JldF92YWx1ZTE=
secret/dummy-secret created
At the time of update, my kubernetes version is,
Minor:"17", GitVersion:"v1.17.3",
GitCommit:"06ad960bfd03b39c8310aaf92d1e7c1 2ce618213",
GitTreeState:"clean", BuildDate:"2020-02-11T18:14:22Z",
GoVersion:"go1.13.6", Compiler:"gc", Platform:"l inux/amd64"} Server
Version: version.Info{Major:"1", Minor:"17", GitVersion:"v1.17.3",
GitCommit:"06ad960bfd03b39c8310aaf92d1e7c1 2ce618213",
GitTreeState:"clean", BuildDate:"2020-02-11T18:07:13Z",
GoVersion:"go1.13.6", Compiler:"gc", Platform:"l inux/amd64"} ```
                Still receive back: Error from server (BadRequest): error when creating "dummy-secret.yaml": Secret in version "v1" cannot be handled as a Secret: v1.Secret: Data: decode base64: illegal base64 data at input byte 8, error found in #10 byte of ...|Q89_Hj1Aq","API_SECR|..., bigger context ...|sion":"v1","data":{"API_KEY":"af76fsdK_cQ89_Hj1Aq","API_SECRET":"bsdfmkwegwegwe"},"kind":"Secret","m|...
– Alex Fruzenshtein
                Nov 20, 2018 at 15:30
                apiVersion: v1 kind: Secret metadata:   name: dummy-secret type: Opaque data:   API_KEY: bWVnYV9zZWNyZXRfa2V5Cg==   API_SECRET: cmVhbGx5X3NlY3JldF92YWx1ZTEK
– Alex Fruzenshtein
                Nov 20, 2018 at 15:43
                Your commands here will include a newline in the values, which is usually not what you want.
– matte
                Jun 11, 2019 at 16:18
This was already answered but for future reference, there is no need to encode the strings by using stringData instead of data field as shown below:
#secrets.yaml
apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
stringData:
  API_KEY: "STRING_IN_CLEAR_TEXT"
  API_SECRET: "STRING_IN_CLEAR_TEXT"
                When using python kubernetes API client, how to change data to stringData cause it defaults to k v1.ObjectMeta.TypeMeta: Kind: Data not Kind: stringData
– Arsen
                May 15, 2020 at 16:50
After a while I want to return back to this question and leave an answer with a reference to official kubernetes docs:
echo -n 'admin' | base64
YWRtaW4=
echo -n '1f2d1e2e67df' | base64
MWYyZDFlMmU2N2Rm
Pay extra attention to -n, because it guaranties that after decoding your secret key will not contain 'new line symbol'.
$ kubectl create -f s.yaml
Error from server (BadRequest): error when creating "dummy-secret.yaml": Secret in version "v1" cannot be handled as a Secret: v1.Secret.Data: decode base64: illegal base64 data at input byte 8, error found in #10 byte of ...|Q89_Hj1Aq","API_SECR|..., bigger context ...|sion":"v1","data":{"API_KEY":"af76fsdK_cQ89_Hj1Aq","API_SECRET":"bsdfmkwegwegwe"},"kind":"Secret","m|...
If I use your original it works fine:
apiVersion: v1
kind: Secret
metadata:
  name: dummy-secret
type: Opaque
data:
  API_KEY: bWVnYV9zZWNyZXRfa2V5
  API_SECRET: cmVhbGx5X3NlY3JldF92YWx1ZTE=
Then:
$ kubectl create -f dummy-secret.yaml
secret/dummy-secret created
I'm using the following version:
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.2", GitCommit:"17c77c7898218073f14c8d573582e8d2313dc740", GitTreeState:"clean", BuildDate:"2018-10-30T21:39:38Z", GoVersion:"go1.11.1", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.1", GitCommit:"4ed3216f3ec431b140b1d899130a69fc671678f4", GitTreeState:"clean", BuildDate:"2018-10-05T16:36:14Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
This may also happen when trying to remove the new line characters in a wrong way (the correct way is to remove the suffix "Cg==").
I used base64 from cli although there are workarounds to avoid the NL, like
https://superuser.com/questions/1225134/why-does-the-base64-of-a-string-contain-n/1225334
they don't work in MacOS, I found it simpler to use python like this
import base64
data = "abc123!?$*&()'-=@~"
# Standard Base64 Encoding
encodedBytes = base64.b64encode(data.encode("utf-8"))
encodedStr = str(encodedBytes, "utf-8")
Or still using a pure bash-based solution:
echo 'secret_to_encode' | tr -d \\n | base64
    sudo mkdir backup 
    sudo cp -R /etc/kubernetes backup/
    sudo tar -cvzf backup/pki_backup_`hostname`-`date +%Y%m%d`.tar.gz backup/kubernetes/
look to dir /etc/kubernetes/
ls -l
total 80
-rw------- 1 root root 5440 Mar  3 13:21 admin.conf
drwxr-xr-x 2 root root 4096 Aug 17  2020 audit-policy
-rw-r--r-- 1 root root  368 Mar  4  2020 calico-config.yml
-rw-r--r-- 1 root root  270 Mar  4  2020 calico-crb.yml
-rw-r--r-- 1 root root  341 Mar  4  2020 calico-cr.yml
-rw-r--r-- 1 root root  147 Mar  4  2020 calico-node-sa.yml
-rw-r--r-- 1 root root 6363 Mar  4  2020 calico-node.yml
-rw------- 1 root root 5472 Mar  3 13:21 controller-manager.conf
-rw-r--r-- 1 root root 3041 Aug 14  2020 kubeadm-config.v1alpha3.yaml
-rw------- 1 root root 5548 Mar  3 13:21 kubelet.conf
-rw-r--r-- 1 root root 1751 Mar  4  2020 kubelet.env
drwxr-xr-x 2 kube root 4096 Aug 14  2020 manifests
lrwxrwxrwx 1 root root   28 Mar  4  2020 node-kubeconfig.yaml -> /etc/kubernetes/kubelet.conf
-rw------- 1 root root 5420 Mar  3 13:21 scheduler.conf
drwxr-xr-x 3 kube root 4096 Mar  3 10:20 ssl
try to find k8s cluster config, in my case this is
kubeadm-config.v1alpha3.yaml
if same file absent you can generate
kubectl get cm kubeadm-config -n kube-system -o yaml > /etc/kubernetes/kubeadm-config.yaml
also in my case absent folder /etc/kubernetes/pki and exist ~/ssl
I create symlink /etc/kubernetes/pki from /etc/kubernetes/ssl
ln -s /etc/kubernetes/ssl /etc/kubernetes/pki
let regenerate certs
kubeadm alpha phase certs apiserver  --config /etc/kubernetes/kubeadm-config.v1alpha3.yaml
[certificates] Using the existing apiserver certificate and key.
kubeadm alpha phase certs apiserver-kubelet-client
I0303 13:12:24.543254   40613 version.go:236] remote version is much newer: v1.20.4; falling back to: stable-1.12
[certificates] Using the existing apiserver-kubelet-client certificate and key.
kubeadm alpha phase certs front-proxy-client
I0303 13:12:35.660672   40989 version.go:236] remote version is much newer: v1.20.4; falling back to: stable-1.12
[certificates] Using the existing front-proxy-client certificate and key.
kubeadm alpha phase certs  etcd-server --config /etc/kubernetes/kubeadm-config.v1alpha3.yaml
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [prod-uct1-mvp-k8s-0001 localhost] and IPs [127.0.0.1 ::1]
kubeadm alpha phase certs  etcd-server --config /etc/kubernetes/kubeadm-config.v1alpha3.yaml
[certificates] Using the existing etcd/server certificate and key.
kubeadm alpha phase certs  etcd-healthcheck-client --config /etc/kubernetes/kubeadm-config.v1alpha3.yaml
[certificates] Generated etcd/healthcheck-client certificate and key.
kubeadm alpha phase certs  etcd-peer --config /etc/kubernetes/kubeadm-config.v1alpha3.yaml
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [product1-mvp-k8s-0001 localhost] and IPs [192.168.4.201 127.0.0.1 ::1]
check actuality certs
find /etc/kubernetes/pki/ -name '*.crt' -exec openssl x509 -text -noout -in {} \; | grep -A2 Validity
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  2 10:29:44 2030 GMT
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  3 10:07:29 2022 GMT
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  3 10:07:52 2022 GMT
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  3 10:06:48 2022 GMT
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  2 10:29:44 2030 GMT
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  2 19:39:56 2022 GMT
        Validity
            Not Before: Mar  4 10:29:43 2020 GMT
            Not After : Mar  2 10:29:43 2030 GMT
        Validity
            Not Before: Mar  4 10:29:43 2020 GMT
            Not After : Mar  2 19:40:13 2022 GMT
        Validity
            Not Before: Mar  4 10:29:44 2020 GMT
            Not After : Mar  2 19:36:38 2022 GMT
next step to generate new config files: admin.conf, controller-manager.conf, kubelet.conf, scheduler.conf, in first step move old files to /tmp
cd /etc/kubernetes/
mv {admin.conf,controller-manager.conf,kubelet.conf,scheduler.conf} /tmp/
kubeadm alpha phase kubeconfig all  --config /etc/kubernetes/kubeadm-config.v1alpha3.yaml 
[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/admin.conf"
[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/scheduler.conf"
after restart master kubelet and check status after restart
sudo systemctl stop kubelet; sudo docker stop $(docker ps -aq); sudo docker rm $(docker ps -aq); sudo systemctl start kubelet
systemctl status kubelet -l
● kubelet.service - Kubernetes Kubelet Server
   Loaded: loaded (/etc/systemd/system/kubelet.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2021-03-03 14:00:22 MSK; 10s ago
     Docs: https://github.com/GoogleCloudPlatform/kubernetes
  Process: 52998 ExecStartPre=/bin/mkdir -p /var/lib/kubelet/volume-plugins (code=exited, status=0/SUCCESS)
 Main PID: 53001 (kubelet)
   Memory: 51.2M
   CGroup: /system.slice/kubelet.service
check access master node
kubectl get nodes
kubectl get ns
NAME                  STATUS   AGE
default               Active   464d
product1-mvp          Active   318d
infra-logging         Active   315d
infra-nginx-ingress   Active   386d
kube-public           Active   464d
kube-system           Active   464d
pg                    Active   318d
check cert
notAfter=Mar  3 07:40:43 2022 GMT
repeat procedure for all master nodes.
Now we ready to renew certs for work nodes.
In first step we must delete or move kubelet.conf
cd /etc/kubernetes/
mv kubelet.conf kubelet.conf_old
after change bootstrap-kubelet.conf
**apiVersion: v1
clusters:
cluster:
certificate-authority-data:  | LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUN5RENDQWJDZ0F3SUJBZ0lCQURBTkJna3Foa2lHOXcwQkFRc0ZBREFWTVJNd0VRWURWUVFERXdwcmRXSmwKY201bGRHVnpNQjRYRFRJd01ETX
server: https://192.168.4.201:6443
name: product1
contexts:
context:
cluster: product1
user: tls-bootstrap-token-user
name: tls-bootstrap-token-user@product1
current-context: tls-bootstrap-token-user@product1
kind: Config
preferences: {}
users:
name: tls-bootstrap-token-user
user:
token: fgz9qz.lujw0bwsdfhdsfjhgds**
where:
certificate-authority-data – root certificate PKI CA master, may take from /etc/kubernetes/kubelet.conf on master nodes
server: https://192.168.4.201:6443 - ip api server master node virtual balance ip
token: fgz9qz.lujw0bwsdfhdsfjhgds - token, generate on master node
kubeadm token create
after restart and check kubelet work node and work node come back to cluster:
systemctl restart kubelet
systemctl status kubelet -l
● kubelet.service - Kubernetes Kubelet Server
   Loaded: loaded (/etc/systemd/system/kubelet.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2021-03-03 14:06:33 MSK; 11s ago
     Docs: https://github.com/GoogleCloudPlatform/kubernetes
  Process: 54615 ExecStartPre=/bin/mkdir -p /var/lib/kubelet/volume-plugins (code=exited, status=0/SUCCESS)
 Main PID: 54621 (kubelet)
   Memory: 52.1M
   CGroup: /system.slice/kubelet.service
check update certs may be ls in dir
ls -las /var/lib/kubelet/pki/
total 24
4 -rw-------. 1 root root 1135 Mar  3 14:06 kubelet-client-2021-03-03-14-06-34.pem
0 lrwxrwxrwx. 1 root root   59 Mar  3 14:06 kubelet-client-current.pem -> /var/lib/kubelet/pki/kubelet-client-2021-03-03-14-06-34.pem
4 -rw-r--r--. 1 root root 2267 Mar  2 10:40 kubelet.crt
4 -rw-------. 1 root root 1679 Mar  2 10:40 kubelet.key
after repeat this procedure by all work nodes.
I encountered the same issue.

In my case the encoding was fine - I just copied the output without the last character of "=".
Additional scenarios that might lead to the same error:
Misplaced whitespaces or broken lines in the base64 copied output.
Not specifying the type field in the secret.
                This gave me the right hint. I used Notepad++ to encode a string as Base64 and the resulting string had no padding characters. After adding two padding characters ("=") the API request got accepted.
– turbolocust
                Jun 20, 2022 at 11:09
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