Web 服务

服务型组件是以容器为核心支撑对外访问服务的组件，其功能涵盖了主流微服务场景的需要，即在后端长时间运行、可水平扩展、且对外暴露服务端口的服务。

如何使用

为了便于你快速学习，请直接复制下面的 Shell 执行，应用会部署到集群中：

cat <<EOF | kubectl apply -f -
# YAML 文件开始
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  name: website
spec:
  components:
    - name: frontend
      type: webservice
      properties:
        image: oamdev/testapp:v1
        cmd: ["node", "server.js"]
        port: 8080
        cpu: "0.1"
        env:
          - name: FOO
            value: bar
# YAML 文件结束
EOF

你也可以自行将 YAML 文件保存为 website.yaml，使用 kubectl apply -f website.yaml 命令进行部署。

接下来，通过 kubectl get application <应用 name> -o yaml 查看应用的部署状态：

$ kubectl get application website -o yaml
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  name: website
  ... #  省略非关键信息
spec:
  components:
  - name: frontend
    properties:
      ... #  省略非关键信息
    type: webservice
status:
  conditions:
  - lastTransitionTime: "2021-08-28T10:26:47Z"
    reason: Available
    status: "True"
    ... #  省略非关键信息
    type: HealthCheck
  observedGeneration: 1
  ... #  省略非关键信息
  services:
  - healthy: true
    name: frontend
    workloadDefinition:
      apiVersion: apps/v1
      kind: Deployment
  status: running

当我们看到 status-services-healthy 的字段为 true，并且 status 为 running 时，即表示整个应用交付成功。

如果 status 显示为 rendering，或者 healthy 为 false，则表示应用要么部署失败，要么还在部署中。请根据 kubectl get application <应用 name> -o yaml 中返回的信息对应地进行处理。

你也可以通过 vela 的 CLI 查看，使用如下命令：

$ vela ls
APP     COMPONENT   TYPE        TRAITS  PHASE   HEALTHY STATUS  CREATED-TIME                 
website frontend    webservice          running healthy         2021-08-28 18:26:47 +0800 CST

我们也看到 website APP 的 PHASE 为 running，同时 STATUS 为 healthy。

属性说明

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
cmd	Commands to run in the container	[]string	false
env	Define arguments by using environment variables	[]env	false
image	Which image would you like to use for your service	string	true
port	Which port do you want customer traffic sent to	int	true	80
imagePullPolicy	Specify image pull policy for your service	string	false
cpu	Number of CPU units for the service, like 0.5 (0.5 CPU core), 1 (1 CPU core)	string	false
memory	Specifies the attributes of the memory resource required for the container.	string	false
volumes	Declare volumes and volumeMounts	[]volumes	false
livenessProbe	Instructions for assessing whether the container is alive.	livenessProbe	false
readinessProbe	Instructions for assessing whether the container is in a suitable state to serve traffic.	readinessProbe	false
imagePullSecrets	Specify image pull secrets for your service	[]string	false

readinessProbe

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
exec	Instructions for assessing container health by executing a command. Either this attribute or the	exec	false
	httpGet attribute or the tcpSocket attribute MUST be specified. This attribute is mutually exclusive
	with both the httpGet attribute and the tcpSocket attribute.
httpGet	Instructions for assessing container health by executing an HTTP GET request. Either this attribute	httpGet	false
	or the exec attribute or the tcpSocket attribute MUST be specified. This attribute is mutually
	exclusive with both the exec attribute and the tcpSocket attribute.
tcpSocket	Instructions for assessing container health by probing a TCP socket. Either this attribute or the	tcpSocket	false
	exec attribute or the httpGet attribute MUST be specified. This attribute is mutually exclusive with
	both the exec attribute and the httpGet attribute.
initialDelaySeconds	Number of seconds after the container is started before the first probe is initiated.	int	true	0
periodSeconds	How often, in seconds, to execute the probe.	int	true	10
timeoutSeconds	Number of seconds after which the probe times out.	int	true	1
successThreshold	Minimum consecutive successes for the probe to be considered successful after having failed.	int	true	1
failureThreshold	Number of consecutive failures required to determine the container is not alive (liveness probe) or	int	true	3
	not ready (readiness probe).

tcpSocket

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
port	The TCP socket within the container that should be probed to assess container health.	int	true

httpGet

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
path	The endpoint, relative to the port, to which the HTTP GET request should be directed.	string	true
port	The TCP socket within the container to which the HTTP GET request should be directed.	int	true
httpHeaders		[]httpHeaders	false

httpHeaders

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
name		string	true
value		string	true

exec

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
command	A command to be executed inside the container to assess its health. Each space delimited token of	[]string	true
	the command is a separate array element. Commands exiting 0 are considered to be successful probes,
	whilst all other exit codes are considered failures.

livenessProbe

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
exec	Instructions for assessing container health by executing a command. Either this attribute or the	exec	false
	httpGet attribute or the tcpSocket attribute MUST be specified. This attribute is mutually exclusive
	with both the httpGet attribute and the tcpSocket attribute.
httpGet	Instructions for assessing container health by executing an HTTP GET request. Either this attribute	httpGet	false
	or the exec attribute or the tcpSocket attribute MUST be specified. This attribute is mutually
	exclusive with both the exec attribute and the tcpSocket attribute.
tcpSocket	Instructions for assessing container health by probing a TCP socket. Either this attribute or the	tcpSocket	false
	exec attribute or the httpGet attribute MUST be specified. This attribute is mutually exclusive with
	both the exec attribute and the httpGet attribute.
initialDelaySeconds	Number of seconds after the container is started before the first probe is initiated.	int	true	0
periodSeconds	How often, in seconds, to execute the probe.	int	true	10
timeoutSeconds	Number of seconds after which the probe times out.	int	true	1
successThreshold	Minimum consecutive successes for the probe to be considered successful after having failed.	int	true	1
failureThreshold	Number of consecutive failures required to determine the container is not alive (liveness probe) or	int	true	3
	not ready (readiness probe).

tcpSocket

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
port	The TCP socket within the container that should be probed to assess container health.	int	true

httpGet

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
path	The endpoint, relative to the port, to which the HTTP GET request should be directed.	string	true
port	The TCP socket within the container to which the HTTP GET request should be directed.	int	true
httpHeaders		[]httpHeaders	false

httpHeaders

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
name		string	true
value		string	true

exec

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
command	A command to be executed inside the container to assess its health. Each space delimited token of	[]string	true
	the command is a separate array element. Commands exiting 0 are considered to be successful probes,
	whilst all other exit codes are considered failures.

volumes

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
name		string	true
mountPath		string	true
type	Specify volume type, options: "pvc","configMap","secret","emptyDir"	string	true

env

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
name	Environment variable name	string	true
value	The value of the environment variable	string	false
valueFrom	Specifies a source the value of this var should come from	valueFrom	false

valueFrom

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
secretKeyRef	Selects a key of a secret in the pod's namespace	secretKeyRef	true

secretKeyRef

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
name	The name of the secret in the pod's namespace to select from	string	true
key	The key of the secret to select from. Must be a valid secret key	string	true