This document describes how to configure the services to be deployed on YARN.
There are mainly three types of configurations:
Service#configuration
) or component level(Component#configuration
).Configuration#properties
).
yarn.service.am-restart.max-attempts
which controls how many times the framework AM can be retried if it fails. These configs are mainly to control the behavior of the framework AM , rather than the custom services launched by the framework.SERVICE_NAME
for referring some system properties.
Below describes the details for each type of configurations.
Below is how a configuration object typically looks like:
"configuration" : { "properties" : { "yarn.service.am-restart.max-attempts" : 10 // config for the service AM }, "env" : { // The environment variables to be exported when container gets launched "env1" : "val1" }, "files" : [ // The list of configuration files to be mounted for the container { "type": "HADOOP_XML", // The format of the config file into which the "properties" are dumped "dest_file": "/etc/hadoop/conf/core-site.xml", // The location where the config file is mounted inside the container "properties" : { // The list of key/value pairs to be dumped into the config file "fs.defaultFS" : "hdfs://myhdfs" // This property will be written into core-site.xml } }, { "type": "HADOOP_XML", // The format of the config file. "src_file" : ""hdfs://mycluster/tmp/conf/yarn-site.xml"" // The location of the source config file to be downloaded "dest_file": "/etc/hadoop/conf/yarn-site.xml", // The location where the config file will be mounted inside the container/ "properties" : { "yarn.resourcemanager.webapp.address" : "${COMPONENT_INSTANCE_NAME}.${SERVICE_NAME}.${USER}.${DOMAIN}" // Merge into (or override existing property in) yarn-site.xml } } ] }
dest_file
) to be mounted inside the container. If src_file
is specified, it is also the format for both src_file
and dest_file
.src_file
is specified, the file content will be read as parsed in hadoop xml format.src_file
is specified, the content of the src_file
will be written into dest_file
post constant substitution. If src_file
is not specified, use content
as the key in properties
field, and the value will be the actual content to be written in the dest_file
post constant substitution. E.g
{ "type": "TEMPLATE" "dest_file": "/etc/conf/hello" "properties" : { "content" : "Hello world" } }
The string Hello world
will be written into a file located at /etc/conf/hello
inside the container.
src_file
and dest_file
are defined by type
.HADOOP_XML
and TEMPLATE
type.src_file
will be downloaded by YARN NodeManager and be mounted inside the container as in the location specified by dest_file
.properties
field, they are added into (or overwriting existing properties in) the src_file
.src_file
is not specified, only the properties in the properties
field will be written into the dest_file
file.type
. dest_file can be an absolute path or a relative path. If it’s a relative path, the file will be located in the $PWD/conf
directory (where $PWD
is the container local directory which is mounted to all docker containers launched by YARN)dest_file
in the format as defined in type
. If src_file
is specified, these properties will be added into (or overwriting existing properties in) the src_file
.This section describes the configurations for configuring the YARN service AM.
System-wide service AM properties can only be configured in the cluster yarn-site.xml
file.
System-Level Config Name | Description |
---|---|
yarn.service.framework.path | HDFS path of the service AM dependency tarball. When no file exists at this location, AM dependencies will be uploaded by the RM the first time a service is started or launched. If the RM user does not have permission to upload the file to this location or the location is not world readable, the AM dependency jars will be uploaded each time a service is started or launched. If unspecified, value will be assumed to be /yarn-services/${hadoop.version}/service-dep.tar.gz. |
yarn.service.base.path | HDFS parent directory where service artifacts will be stored (default ${user_home_dir}/.yarn/). |
yarn.service.client-am.retry.max-wait-ms | Max retry time in milliseconds for the service client to talk to the service AM (default 900000, i.e. 15 minutes). |
yarn.service.client-am.retry-interval-ms | Retry interval in milliseconds for the service client to talk to the service AM (default 2000, i.e. 2 seconds). |
yarn.service.queue | Default queue to which the service will be submitted (default submits to the default queue). Note that queue can be specified per-service through the queue field, rather than through the service-level configuration properties. |
Service-level service AM configuration properties can be specified either in the cluster yarn-site.xml
at the global level (effectively overriding the default values system-wide) or specified per service in the properties
field of the Configuration
object as in the example below:
{ "configuration" : { "properties" : { "yarn.service.am-restart.max-attempts" : 10 } } }
The above config allows the service AM to be retried a maximum of 10 times.
Service-Level Config Name | Description |
---|---|
yarn.service.am-restart.max-attempts | Max number of times to start the service AM, after which the service will be killed (default 20). |
yarn.service.am-resource.memory | Memory size in MB for the service AM (default 1024). |
yarn.service.am.java.opts | Additional JVM options for the service AM (default " -Xmx768m" will be appended to any JVM opts that do not specify -Xmx). |
yarn.service.container-recovery.timeout.ms | Timeout in milliseconds after which a newly started service AM releases all the containers of previous AM attempts which are not yet recovered from the RM (default 120000, i.e. 2 minutes). |
yarn.service.failure-count-reset.window | Interval in seconds after which the container failure counts that will be evaluated for the per-component yarn.service.container-failure-per-component.threshold and yarn.service.node-blacklist.threshold are reset (default 21600, i.e. 6 hours). |
yarn.service.readiness-check-interval.seconds | Interval in seconds between readiness checks (default 30 seconds). |
yarn.service.log.include-pattern | Regex expression for including log files by name when aggregating the logs after the application completes (default includes all files). |
yarn.service.log.exclude-pattern | Regex expression for excluding log files by name when aggregating the logs after the application completes. If the log file name matches both include and exclude pattern, this file will be excluded (default does not exclude any files). |
yarn.service.rolling-log.include-pattern | Regex expression for including log files by name when aggregating the logs while app is running. |
yarn.service.rolling-log.exclude-pattern | Regex expression for excluding log files by name when aggregating the logs while app is running. If the log file name matches both include and exclude pattern, this file will be excluded. |
yarn.service.classpath | Comma separated extra class path parameters for yarn services AM. These path elements will be appended to the end of the YARN service AM classpath. |
yarn.service.am.client.port-range | Range of ports that the Yarn Service AM can use when binding. Leave blank if you want all possible ports. For example 50000-50050,50100-50200. |
Component-level service AM configuration properties can be specified either in the cluster yarn-site.xml
at the global level (effectively overriding the default values system-wide), specified per service in the properties
field of the Configuration
object, or specified per component in the properties
field of the component’s Configuration
object.
Component-Level Config Name | Description |
---|---|
yarn.service.container-failure.retry.max | Max number of retries for the container to be auto restarted if it fails (default -1, which means forever). |
yarn.service.container-failure.retry-interval-ms | Retry interval in milliseconds for the container to be restarted (default 30000, i.e. 30 seconds). |
yarn.service.container-failure.validity-interval-ms | Failure validity interval in milliseconds. When set to a value greater than 0, the container retry policy will not take the failures that happened outside of this interval into the failure count (default -1, which means that all the failures so far will be included in the failure count). |
yarn.service.container-failure-per-component.threshold | Max absolute number of container failures (not including retries) for a given component before the AM stops the service (default 10). |
yarn.service.node-blacklist.threshold | Maximum number of container failures on a node (not including retries) before the node is blacklisted by the AM (default 3). |
yarn.service.default-readiness-check.enabled | Whether or not the default readiness check is enabled (default true). |
yarn.service.container-health-threshold.percent | The container health threshold percent when explicitly set for a specific component or globally for all components, will schedule a health check monitor to periodically check for the percentage of healthy containers. A container is healthy if it is in READY state. It runs the check at a specified/default poll frequency. It allows a component to be below the health threshold for a specified/default window after which it considers the service to be unhealthy and triggers a service stop. When health threshold percent is enabled, yarn.service.container-failure-per-component.threshold is ignored. |
yarn.service.container-health-threshold.poll-frequency-secs | Health check monitor poll frequency. It is an advanced setting and does not need to be set unless the service owner understands the implication and does not want the default. The default is 10 secs. |
yarn.service.container-health-threshold.window-secs | The amount of time the health check monitor allows a specific component to be below the health threshold after which it considers the service to be unhealthy. The default is 600 secs (10 mins). |
yarn.service.container-health-threshold.init-delay-secs | The amount of initial time the health check monitor waits before the first check kicks in. It gives a lead time for the service containers to come up for the first time. The default is 600 secs (10 mins). |
yarn.service.container-state-report-as-service-state | The boolean flag indicates that if this component is finished, the service is also terminated. The default is false. |
There is one component-level configuration property that is set differently in the yarn-site.xml
file than it is in the service specification. To select the docker network type that will be used for docker containers, docker.network
may be set in the service Configuration
properties
or the component Configuration
properties
. The system-wide default for the docker network type (for both YARN service containers and all other application containers) is set via the yarn.nodemanager.runtime.linux.docker.default-container-network
property in the yarn-site.xml
file.
The AM can be configured to perform readiness checks for containers through the Component
field readiness_check
. A container will not reach the READY
state until its readiness check succeeds. If no readiness check is specified, the default readiness check is performed unless it is disabled through the yarn.service.default-readiness-check.enabled
component-level configuration property.
The default readiness check succeeds when an IP becomes available for a container. There are also optional properties that configure a DNS check in addition to the IP check. DNS checking ensures that a DNS lookup succeeds for the container hostname before the container is considered ready. For example, DNS checking can be enabled for the default readiness check as follows:
"readiness_check": { "type": "DEFAULT", "properties": { "dns.check.enabled": "true" } },
Here is a full list of configurable properties for readiness checks that can be performed by the AM.
Readiness Check | Configurable Property | Description |
---|---|---|
DEFAULT, HTTP, PORT | dns.check.enabled | true if DNS check should be performed (default false) |
DEFAULT, HTTP, PORT | dns.address | optional IP:port address of DNS server to use for DNS check |
HTTP | url | required URL for HTTP response check, e.g. http://${THIS_HOST}:8080 |
HTTP | timeout | connection timeout (default 1000) |
HTTP | min.success | minimum response code considered successful (default 200) |
HTTP | max.success | maximum response code considered successful (default 299) |
PORT | port | required port for socket connection |
PORT | timeout | socket connection timeout (default 1000) |
HTTP readiness check example:
"readiness_check": { "type": "HTTP", "properties": { "url": "http://${THIS_HOST}:8080" } },
PORT readiness check example:
"readiness_check": { "type": "PORT", "properties": { "port": "8080" } },
host
network for docker containersWhen the host
docker network is configured for a component that has more than one container and the containers are binding to a specific port, there will be a port collision if the containers happen to be allocated on the same host. HTTP and PORT readiness checks will not be valid in this situation. In particular, both containers (the one that successfully binds to the port and the one that does not) may have their HTTP or PORT readiness check succeed since the checks are being performed against the same IP (the host’s IP). A valid configuration for such a service could use the anti-affinity placement policy, ensuring that containers will be assigned on different hosts so that port collisions will not occur.
The service framework provides some constant variables for user to configure their services. These variables are either dynamically generated by the system or are static ones such as service name defined by the user. User can use these constants in their configurations to be dynamically substituted by the service AM. E.g.
{ "type" : "HADOOP_XML", "dest_file" : "/etc/hadoop/hbase-site.xml", "properties" : { "hbase.regionserver.hostname": "${COMPONENT_INSTANCE_NAME}.${SERVICE_NAME}.${USER}.${DOMAIN}" } }
Here, COMPONENT_INSTANCE_NAME
and SERVICE_NAME
are the constants to be substituted by the system.
Suppose the COMPONENT_INSTANCE_NAME
is regionserver-0
and SERVICE_NAME
is defined by user as hbase
, user name is devuser
and domain name is dev.test
. Then, the config will be substituted by the service AM and written in the config file /etc/hadoop/hbase-site.xml
inside the container as below:
<property> <name>hbase.regionserver.hostname</name> <value>regionserver-0.hbase.devuser.dev.test</value> </property>
where regionserver-0
is the actual component instance name assigned by the system for this container.
Name | Description |
---|---|
SERVICE_NAME | name of the service defined by the user |
USER | user who submits the service. Note that user name which has “_” will be converted to use “-”, to conform with DNS hostname RFC format which doesn’t allow “_”, and all characters will be lowercased E.g. “Bob_dev” will be converted to “bob-dev” |
DOMAIN | the domain name for the cluster |
COMPONENT_NAME | the name for a given component |
COMPONENT_INSTANCE_NAME | the name for a given component instance (i.e. container) |
COMPONENT_ID | the monotonically increasing integer for a given component |
CONTAINER_ID | the YARN container Id for a given container |
${COMPONENT_INSTANCE_NAME}_HOST | the hostname for a component instance (i.e. container), e.g. REGIONSERVER-0_HOST will be substituted by the actual hostname of the component instance. Note all characters must be uppercase. |
${COMPONENT_INSTANCE_NAME}_IP | the ip for a component instance (i.e. container), e.g. REGIONSERVER-0_IP will be substituted by the actual IP address of the component instance. Note all characters must be uppercase. |
CLUSTER_FS_URI | the URI of the cluster hdfs |