|
|
@@ -0,0 +1,159 @@
|
|
|
+<!---
|
|
|
+ Licensed under the Apache License, Version 2.0 (the "License");
|
|
|
+ you may not use this file except in compliance with the License.
|
|
|
+ You may obtain a copy of the License at
|
|
|
+
|
|
|
+ http://www.apache.org/licenses/LICENSE-2.0
|
|
|
+
|
|
|
+ Unless required by applicable law or agreed to in writing, software
|
|
|
+ distributed under the License is distributed on an "AS IS" BASIS,
|
|
|
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
|
+ See the License for the specific language governing permissions and
|
|
|
+ limitations under the License. See accompanying LICENSE file.
|
|
|
+-->
|
|
|
+
|
|
|
+# YARN Service Examples
|
|
|
+
|
|
|
+This document describes some example service definitions (`Yarnfile`).
|
|
|
+
|
|
|
+<!-- MACRO{toc|fromDepth=0|toDepth=3} -->
|
|
|
+
|
|
|
+## Apache web server - httpd (with registry DNS)
|
|
|
+Below is the `Yarnfile` for a service called `httpd-service` with two `httpd` instances.
|
|
|
+There is also an httpd proxy instance (httpd-proxy-0) that proxies between the other two httpd instances (httpd-0 and httpd-1).
|
|
|
+
|
|
|
+Note this example requires registry DNS.
|
|
|
+```
|
|
|
+{
|
|
|
+ "name": "httpd-service",
|
|
|
+ "lifetime": "3600",
|
|
|
+ "components": [
|
|
|
+ {
|
|
|
+ "name": "httpd",
|
|
|
+ "number_of_containers": 2,
|
|
|
+ "artifact": {
|
|
|
+ "id": "centos/httpd-24-centos7:latest",
|
|
|
+ "type": "DOCKER"
|
|
|
+ },
|
|
|
+ "launch_command": "/usr/bin/run-httpd",
|
|
|
+ "resource": {
|
|
|
+ "cpus": 1,
|
|
|
+ "memory": "1024"
|
|
|
+ },
|
|
|
+ "configuration": {
|
|
|
+ "files": [
|
|
|
+ {
|
|
|
+ "type": "ENV",
|
|
|
+ "dest_file": "/var/www/html/index.html",
|
|
|
+ "props": {
|
|
|
+ "content": "<html><header><title>Title</title></header><body>Hello from ${COMPONENT_INSTANCE_NAME}!</body></html>"
|
|
|
+ }
|
|
|
+ }
|
|
|
+ ]
|
|
|
+ }
|
|
|
+ },
|
|
|
+ {
|
|
|
+ "name": "httpd-proxy",
|
|
|
+ "number_of_containers": 1,
|
|
|
+ "artifact": {
|
|
|
+ "id": "centos/httpd-24-centos7:latest",
|
|
|
+ "type": "DOCKER"
|
|
|
+ },
|
|
|
+ "launch_command": "/usr/bin/run-httpd",
|
|
|
+ "resource": {
|
|
|
+ "cpus": 1,
|
|
|
+ "memory": "1024"
|
|
|
+ },
|
|
|
+ "configuration": {
|
|
|
+ "files": [
|
|
|
+ {
|
|
|
+ "type": "TEMPLATE",
|
|
|
+ "dest_file": "/etc/httpd/conf.d/httpd-proxy.conf",
|
|
|
+ "src_file": "httpd-proxy.conf"
|
|
|
+ }
|
|
|
+ ]
|
|
|
+ }
|
|
|
+ }
|
|
|
+ ],
|
|
|
+ "quicklinks": {
|
|
|
+ "Apache HTTP Server": "http://httpd-proxy-0.${SERVICE_NAME}.${USER}.${DOMAIN}:8080"
|
|
|
+ }
|
|
|
+}
|
|
|
+```
|
|
|
+This `Yarnfile` is already included in the Hadoop distribution, along with the required configuration template `httpd-proxy.conf`.
|
|
|
+First upload the configuration template file to HDFS:
|
|
|
+```
|
|
|
+hdfs dfs -copyFromLocal ${HADOOP_YARN_HOME}/share/hadoop/yarn/yarn-service-examples/httpd/httpd-proxy.conf .
|
|
|
+```
|
|
|
+
|
|
|
+The proxy configuration template looks like the following and will configure the httpd-proxy-0 container to balance between the httpd-0 and httpd-1 containers evenly:
|
|
|
+```
|
|
|
+<Proxy balancer://test>
|
|
|
+ BalancerMember http://httpd-0.${SERVICE_NAME}.${USER}.${DOMAIN}:8080
|
|
|
+ BalancerMember http://httpd-1.${SERVICE_NAME}.${USER}.${DOMAIN}:8080
|
|
|
+ ProxySet lbmethod=bytraffic
|
|
|
+</Proxy>
|
|
|
+
|
|
|
+ProxyPass "/" "balancer://test/"
|
|
|
+ProxyPassReverse "/" "balancer://test/"
|
|
|
+```
|
|
|
+
|
|
|
+Then run the service with the command:
|
|
|
+```
|
|
|
+yarn service create [service-name] --example httpd
|
|
|
+```
|
|
|
+where `service-name` is optional. If omitted, it uses the name defined in the `Yarnfile`.
|
|
|
+
|
|
|
+Once the service is running, navigate to `http://httpd-proxy-0.${SERVICE_NAME}.${USER}.${DOMAIN}:8080` to see the root page.
|
|
|
+The pages should alternately show "Hello from httpd-0!" or "Hello from httpd-1!"
|
|
|
+
|
|
|
+The individual httpd URLs can also be visited, `http://httpd-0.${SERVICE_NAME}.${USER}.${DOMAIN}:8080` and `http://httpd-1.${SERVICE_NAME}.${USER}.${DOMAIN}:8080`.
|
|
|
+
|
|
|
+If unsure of your hostnames, visit the apiserver REST endpoint `http://<apiserver host>:9191/ws/v1/services/httpd-service`.
|
|
|
+
|
|
|
+## Apache web server - httpd (without registry DNS)
|
|
|
+
|
|
|
+A similar IP-based example is provided for environments that do not have registry DNS set up.
|
|
|
+The service name for this example is `httpd-service-no-dns`.
|
|
|
+There are a couple of additions to the `Yarnfile` for the `httpd-service` described above.
|
|
|
+A readiness check is added for the `httpd` component:
|
|
|
+```
|
|
|
+ "readiness_check": {
|
|
|
+ "type": "HTTP",
|
|
|
+ "props": {
|
|
|
+ "url": "http://${THIS_HOST}:8080"
|
|
|
+ }
|
|
|
+ },
|
|
|
+```
|
|
|
+and `httpd` is added as a dependency for the `httpd-proxy` component:
|
|
|
+```
|
|
|
+ "dependencies": [ "httpd" ],
|
|
|
+```
|
|
|
+
|
|
|
+This means that the httpd-proxy-0 instance will not be started until after an HTTP probe has succeeded for the httpd-0 and httpd-1 containers.
|
|
|
+This is necessary so that the IPs of the containers can be used in the configuration of httpd-proxy-0.
|
|
|
+The proxy configuration is similar to that of the previous example, with the BalancerMember lines changed as follows:
|
|
|
+```
|
|
|
+ BalancerMember http://${HTTPD-0_IP}:8080
|
|
|
+ BalancerMember http://${HTTPD-1_IP}:8080
|
|
|
+```
|
|
|
+
|
|
|
+Note that IP and HOST variables such as `${HTTPD-0_IP}` and `${HTTPD-0_HOST}` should only be used by a component that has a dependency on the named component (`httpd` in this case) AND should only be used when the named component specifies a readiness check.
|
|
|
+Here, `httpd-proxy` has a dependency on `httpd` and `httpd` has an HTTP readiness check.
|
|
|
+Without the dependency and readiness check, the httpd-proxy-0 container would be started in parallel with the httpd-0 and http-1 containers, and the IPs and hosts would not be assigned yet for httpd-0 and httpd-1.
|
|
|
+
|
|
|
+Other variables can be used by any component.
|
|
|
+
|
|
|
+Before creating the service, upload the proxy configuration to HDFS:
|
|
|
+```
|
|
|
+hdfs dfs -copyFromLocal ${HADOOP_YARN_HOME}/share/hadoop/yarn/yarn-service-examples/httpd-no-dns/httpd-proxy-no-dns.conf .
|
|
|
+```
|
|
|
+
|
|
|
+Then run the service with the command:
|
|
|
+```
|
|
|
+yarn service create [service-name] --example httpd-no-dns
|
|
|
+```
|
|
|
+where `service-name` is optional. If omitted, it uses the name defined in the `Yarnfile`.
|
|
|
+
|
|
|
+Look up your IPs at the apiserver REST endpoint `http://<apiserver host>:9191/ws/v1/services/httpd-service`.
|
|
|
+Then visit port 8080 for each IP to view the pages.
|
Jian He