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ConfigMap 简介
ConfigMap 是 k8s 中的一种 API 对象，用于镜像和配置文件解耦（对标非 k8s 环境，咱们常常用配置管理核心解耦代码和配置，其实是一个意思），这样镜像就具备了可移植性和可复用性。Pods 能够将其用作环境变量、命令行参数或者存储卷中的配置文件。在生产环境中，它作为环境变量配置的应用十分常见。
跟它相似的，还有另一个 API 对象 Secret。
二者的区别是，前者用于存储不敏感和非保密性数据。例如 ip 和端口。后者用于存储敏感和保密性数据，例如用户名和明码，秘钥，等等，应用 base64 编码贮存。
对于 configmap 的更多内容能够看看官网：
https://kubernetes.io/zh-cn/d…
应用 ConfigMap 的限度条件
- ConfigMap 要在 Pod 启动前创立好。因为它是要被 Pod 应用的嘛。
- 只有当 ConfigMap 和 Pod 处于同一个 NameSpace 时 Pod 才能够援用它。
- 当 Pod 对 ConfigMap 进行挂载（VolumeMount）操作时，在容器外部只能挂载为目录，不能挂载为文件。
- 当挂载曾经存在的目录时，且目录内含有其它文件，ConfigMap 会将其笼罩掉。
实操
本次操作，最后的 yaml 配置如下，总共蕴含三个局部：
- ConfigMap
- Deployment
- Service
也能够将这三个局部拆分到 3 个 yaml 文件中别离执行。
apiVersion: v1
kind: ConfigMap
metadata:
name: nginx-conf
data:
nginx.conf: |
user nginx;
worker_processes 2;
error_log /var/log/nginx/error.log;
events {worker_connections 1024;}
http {
include mime.types;
#sendfile on;
keepalive_timeout 1800;
log_format main
'remote_addr:$remote_addr'
'time_local:$time_local'
'method:$request_method'
'uri:$request_uri'
'host:$host'
'status:$status'
'bytes_sent:$body_bytes_sent'
'referer:$http_referer'
'useragent:$http_user_agent'
'forwardedfor:$http_x_forwarded_for'
'request_time:$request_time';
access_log /var/log/nginx/access.log main;
server {
listen 80;
server_name localhost;
location / {
root html;
index index.html index.htm;
}
error_page 500 502 503 504 /50x.html;
}
include /etc/nginx/conf.d/*.conf;
}
virtualhost.conf: |
upstream app {
server localhost:8080;
keepalive 1024;
}
server {
listen 80 default_server;
root /usr/local/app;
access_log /var/log/nginx/app.access_log main;
error_log /var/log/nginx/app.error_log;
location / {
proxy_pass http://app/;
proxy_http_version 1.1;
}
}
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-demo-nginx
spec:
replicas: 1
selector:
matchLabels:
app: my-demo-nginx
template:
metadata:
labels:
app: my-demo-nginx
spec:
containers:
- name: my-demo-nginx
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
volumeMounts:
- mountPath: /etc/nginx/nginx.conf # mount nginx-conf volumn to /etc/nginx
#readOnly: true
#name: nginx-conf
#name: my-demo-nginx
name: nginx
subPath: nginx.conf
- mountPath: /var/log/nginx
name: log
volumes:
- name: nginx
configMap:
name: nginx-conf # place ConfigMap `nginx-conf` on /etc/nginx
items:
- key: nginx.conf
path: nginx.conf
- key: virtualhost.conf
path: conf.d/virtualhost.conf # dig directory
- name: log
emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
name: nginx-service #定义 service 名称为 nginx-service
labels:
app: nginx-service #为 service 打上 app 标签
spec:
type: NodePort #应用 NodePort 形式开明，在每个 Node 上调配一个端口作为内部拜访入口
#type: LoadBalancer #工作在特定的 Cloud Provider 上，例如 Google Cloud，AWS，OpenStack
#type: ClusterIP #默认，调配一个集群外部能够拜访的虚构 IP（VIP）ports:
- port: 8000 #port 是 k8s 集群外部拜访 service 的端口，即通过 clusterIP: port 能够拜访到某个 service
targetPort: 80 #targetPort 是 pod 的端口，从 port 和 nodePort 来的流量通过 kube-proxy 流入到后端 pod 的 targetPort 上，最初进入容器
nodePort: 32500 #nodePort 是内部拜访 k8s 集群中 service 的端口，通过 nodeIP: nodePort 能够从内部拜访到某个 service
selector:
app: my-nginx 执行该 yaml 文件，遇到了问题：
本模板 & 此实操中 Deployment 的配置，它的 spec.template.spec.containers.volumeMounts.name 的值应用 nginx 能力胜利，如果是 my-demo-nginx 则报错如下：
[root@k8s-master k8s-install]# kubectl create -f configmap-nginx.yaml
configmap/nginx-conf created
service/nginx-service created
The Deployment "my-demo-nginx" is invalid: spec.template.spec.containers[0].volumeMounts[0].name: Not found: "my-demo-nginx"如果是 nginx-conf 则报错如下：
[root@k8s-master k8s-install]# kubectl apply -f configmap-nginx.yaml
Warning: resource configmaps/nginx-conf is missing the kubectl.kubernetes.io/last-applied-configuration annotation which is required by kubectl apply. kubectl apply should only be used on resources created declaratively by either kubectl create --save-config or kubectl apply. The missing annotation will be patched automatically.
configmap/nginx-conf configured
Warning: resource services/nginx-service is missing the kubectl.kubernetes.io/last-applied-configuration annotation which is required by kubectl apply. kubectl apply should only be used on resources created declaratively by either kubectl create --save-config or kubectl apply. The missing annotation will be patched automatically.
service/nginx-service configured
The Deployment "my-demo-nginx" is invalid: spec.template.spec.containers[0].volumeMounts[0].name: Not found: "nginx-conf"当改为 nginx 后才失常：
[root@k8s-master k8s-install]# kubectl apply -f configmap-nginx.yaml
configmap/nginx-conf unchanged
deployment.apps/my-demo-nginx created
service/nginx-service unchanged 该报错的起因是 spec.template.spec.volumes.name 的值为 nginx，二者需保持一致（ 编辑和应用 yaml 比拟蛋疼的中央也在于此：字段越多，坑越多。官网没有具体的阐明文档间接通知你每个字段的意义，以及哪里跟哪里应该保持一致，哪里须要留神什么，等等。很多货色须要你通过实际本人发现。所以 yaml 的最佳实际也不是很容易总结 ）。
查看 ConfigMap、Deployment、Service、Pod 是否创立胜利：
[root@k8s-master k8s-install]# kubectl get cm nginx-conf
NAME DATA AGE
nginx-conf 2 12m
[root@k8s-master k8s-install]# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
my-demo-nginx 0/2 2 0 7m29s
[root@k8s-master k8s-install]# kubectl get svc nginx-service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx-service NodePort 10.103.221.135 <none> 8000:32500/TCP 10m
[root@k8s-master k8s-install]# kubectl get po -A | grep nginx
default my-demo-nginx-7bff4cd4dd-hs4bx 0/1 CrashLoopBackOff 6 (4m18s ago) 10m
default my-demo-nginx-7bff4cd4dd-tdjqd 0/1 CrashLoopBackOff 6 (4m11s ago) 10m 此时遇到了第二个问题：
查看 pod 状态发现始终是 CrashLoopBackOff 状态，阐明 pod 没有失常运行。
查看 pod 和容器的日志，均为空。
应用 describe 查看 pod 事件，只有一条无价值的信息：Back-off restarting failed container。删除方才部署的所有重复从新创立也不行。
[root@k8s-master k8s-install]# kubectl describe po my-demo-nginx-9c5b6cc8c-5bws7
Name: my-demo-nginx-9c5b6cc8c-5bws7
Namespace: default
Priority: 0
Node: k8s-slave2/192.168.100.22
Start Time: Tue, 14 Jun 2022 00:13:44 +0800
Labels: app=my-demo-nginx
pod-template-hash=9c5b6cc8c
Annotations: <none>
Status: Running
IP: 10.244.1.25
IPs:
IP: 10.244.1.25
Controlled By: ReplicaSet/my-demo-nginx-9c5b6cc8c
Containers:
my-demo-nginx:
Container ID: docker://cd6c27ee399cce85adf64465dce43e7b361c92f5f85b46944a2749068a111a5e
Image: 192.168.100.20:8888/my-demo/nginx
Image ID: docker-pullable://192.168.100.20:5000/mynginx@sha256:a12ca72a7db4dfdd981003da98491c8019d2de1da53c1bff4f1b378da5b1ca32
Port: 80/TCP
Host Port: 0/TCP
State: Terminated
Reason: Completed
Exit Code: 0
Started: Tue, 14 Jun 2022 00:14:22 +0800
Finished: Tue, 14 Jun 2022 00:14:22 +0800
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Tue, 14 Jun 2022 00:13:59 +0800
Finished: Tue, 14 Jun 2022 00:13:59 +0800
Ready: False
Restart Count: 3
Environment: <none>
Mounts:
/etc/nginx/nginx.conf from nginx (rw,path="nginx.conf")
/var/log/nginx from log (rw)
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-nxbxk (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
nginx:
Type: ConfigMap (a volume populated by a ConfigMap)
Name: nginx-conf
Optional: false
log:
Type: EmptyDir (a temporary directory that shares a pod's lifetime)
Medium:
SizeLimit: <unset>
kube-api-access-nxbxk:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 39s default-scheduler Successfully assigned default/my-demo-nginx-9c5b6cc8c-5bws7 to k8s-slave2
Normal Pulled 38s kubelet Successfully pulled image "192.168.100.20:8888/my-demo/nginx" in 135.495946ms
Normal Pulled 37s kubelet Successfully pulled image "192.168.100.20:8888/my-demo/nginx" in 68.384569ms
Normal Pulled 24s kubelet Successfully pulled image "192.168.100.20:8888/my-demo/nginx" in 81.06582ms
Normal Created 1s (x4 over 38s) kubelet Created container my-demo-nginx
Normal Started 1s (x4 over 38s) kubelet Started container my-demo-nginx
Normal Pulling 1s (x4 over 38s) kubelet Pulling image "192.168.100.20:8888/my-demo/nginx"
Normal Pulled 1s kubelet Successfully pulled image "192.168.100.20:8888/my-demo/nginx" in 178.317289ms
Warning BackOff 0s (x5 over 36s) kubelet Back-off restarting failed container 解决办法：
在 spec.template.spec.containers.image 这一行上面减少如下 3 行配置：别离是 command、args、imagePullPolicy 这个 3 个参数：
spec:
containers:
- name: my-demo-nginx
image: 192.168.100.20:8888/my-demo/nginx
command: ["/bin/bash", "-c", "--"]
args: ["while true; do sleep 30; done;"]
imagePullPolicy: IfNotPresent重新部署，pod 终于失常运行：
[root@k8s-master k8s-install]# kubectl create -f configmap-nginx.yaml
configmap/nginx-conf created
deployment.apps/my-demo-nginx created
service/nginx-service created
[root@k8s-master k8s-install]#
[root@k8s-master k8s-install]# kubectl get po
NAME READY STATUS RESTARTS AGE
my-demo-nginx-6849476467-7bml4 1/1 Running 0 10s 起因：
本次导致 pod 始终没能失常运行的起因是援用的 nginx 镜像本身存在问题，容器中的 nginx 过程没能失常启动，所以容器和 pod 都无奈失常运行。所以减少以上参数后，应用 /bin/bash 代替 nginx 作为根过程，容器就能失常运行了。这是容器运行的设定决定的。不懂的同学再温习一下容器的内容。
晓得了问题的起因，就能晓得本次实操中起初追加的三个参数，其实外围参数只有一个，就是 command，另外两个参数可有可无。所以也能够只减少一个参数即可，例如：command: [“/bin/bash”, “-ce”, “tail -f /dev/null”]
如果是援用的 nginx 镜像没问题的话，就不会遇到第二个问题。所以这里要顺便分享下本次的解决思路： 当 pod 状态为 CrashLoopBackOff，并且 pod 和容器的日志都为空，能够思考是援用的容器镜像出了问题 。以本例来说，镜像启动容器后，本来应该运行的 nginx 过程没有启动。加个 command 参数很容易就能验进去这个问题。
如下所示，当 pod 和容器失常启动后（通过减少 command 参数），登录容器后发现，根过程是 /bin/bash，而不是 nginx，从而验证了后面的判断：
[root@k8s-master ~]# kubectl exec my-demo-nginx-6849476467-7bml4 -c my-demo-nginx -it -- /bin/bash
[root@my-demo-nginx-6849476467-7bml4 /]#
[root@my-demo-nginx-6849476467-7bml4 /]# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 11904 1512 ? Ss Jun14 0:00 /bin/bash -c -- while true; do sleep 30; done;
root 1463 0.0 0.1 12036 2096 pts/0 Ss 03:34 0:00 /bin/bash
root 1479 0.0 0.0 23032 932 ? S 03:34 0:00 /usr/bin/coreutils --coreutils-prog-shebang=sleep /usr/bin/sleep 30
root 1480 0.0 0.0 44652 1772 pts/0 R+ 03:34 0:00 ps aux
最终残缺的配置如下：
apiVersion: v1
kind: ConfigMap
metadata:
name: nginx-conf
data:
nginx.conf: |
user nginx;
worker_processes 2;
error_log /var/log/nginx/error.log;
events {worker_connections 1024;}
http {
include mime.types;
#sendfile on;
keepalive_timeout 1800;
log_format main
'remote_addr:$remote_addr'
'time_local:$time_local'
'method:$request_method'
'uri:$request_uri'
'host:$host'
'status:$status'
'bytes_sent:$body_bytes_sent'
'referer:$http_referer'
'useragent:$http_user_agent'
'forwardedfor:$http_x_forwarded_for'
'request_time:$request_time';
access_log /var/log/nginx/access.log main;
server {
listen 80;
server_name localhost;
location / {
root html;
index index.html index.htm;
}
error_page 500 502 503 504 /50x.html;
}
include /etc/nginx/conf.d/*.conf;
}
virtualhost.conf: |
upstream app {
server localhost:8080;
keepalive 1024;
}
server {
listen 80 default_server;
root /usr/local/app;
access_log /var/log/nginx/app.access_log main;
error_log /var/log/nginx/app.error_log;
location / {
proxy_pass http://app/;
proxy_http_version 1.1;
}
}
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-demo-nginx
spec:
replicas: 1
selector:
matchLabels:
app: my-demo-nginx
template:
metadata:
labels:
app: my-demo-nginx
spec:
containers:
- name: my-demo-nginx
image: 192.168.100.20:8888/my-demo/nginx
command: ["/bin/bash", "-c", "--"]
args: ["while true; do sleep 30; done;"]
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80
volumeMounts:
- mountPath: /etc/nginx/nginx.conf # mount nginx-conf volumn to /etc/nginx
#readOnly: true
#name: nginx-conf
#name: my-demo-nginx
name: nginx
subPath: nginx.conf
- mountPath: /var/log/nginx
name: log
volumes:
- name: nginx
configMap:
name: nginx-conf # place ConfigMap `nginx-conf` on /etc/nginx
items:
- key: nginx.conf
path: nginx.conf
- key: virtualhost.conf
path: conf.d/virtualhost.conf # dig directory
- name: log
emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
name: nginx-service #定义 service 名称为 nginx-service
labels:
app: nginx-service #为 service 打上 app 标签
spec:
type: NodePort #应用 NodePort 形式开明，在每个 Node 上调配一个端口作为内部拜访入口
#type: LoadBalancer #工作在特定的 Cloud Provider 上，例如 Google Cloud，AWS，OpenStack
#type: ClusterIP #默认，调配一个集群外部能够拜访的虚构 IP（VIP）ports:
- port: 8000 #port 是 k8s 集群外部拜访 service 的端口，即通过 clusterIP: port 能够拜访到某个 service
targetPort: 80 #targetPort 是 pod 的端口，从 port 和 nodePort 来的流量通过 kube-proxy 流入到后端 pod 的 targetPort 上，最初进入容器
nodePort: 32500 #nodePort 是内部拜访 k8s 集群中 service 的端口，通过 nodeIP: nodePort 能够从内部拜访到某个 service
selector:
app: my-nginx正文完