add max length configuration for service_name and instance_name (#609)

Author: elmerzeng

CHANGES.md

@@ -9,6 +9,8 @@ Release Notes.
 * Fix the issue of createSpan failure caused by invalid request URL in HttpClient 4.x/5.x plugin
 * Optimize ElasticSearch 6.x 7.x plugin compatibility
 * Fix an issue with the httpasyncclient component where the isError state is incorrect.
+* Support customization for the length limitation of string configurations
+* Add max length configurations in `agent.config` file for service_name and instance_name
 
 #### Documentation
 

apm-commons/apm-util/src/main/java/org/apache/skywalking/apm/util/ConfigInitializer.java

@@ -85,9 +85,20 @@ private static void initNextLevel(Properties properties, Class<?> recentConfigTy
                     } else {
                         // Convert the value into real type
                         final Length lengthDefine = field.getAnnotation(Length.class);
-                        if (lengthDefine != null && propertyValue.length() > lengthDefine.value()) {
-                            StringUtil.cut(propertyValue, lengthDefine.value());
-                            System.err.printf("The config value will be truncated , because the length max than %d : %s -> %s%n", lengthDefine.value(), configKey, propertyValue);
+                        if (lengthDefine != null) {
+                            int lengthLimited = lengthDefine.value();
+                            String lengthKey = String.format("%s#length", configKey);
+                            if (properties.containsKey(lengthKey)) {
+                                try {
+                                    lengthLimited = Integer.valueOf(properties.getProperty(lengthKey));
+                                } catch (NumberFormatException ex) {
+                                    System.err.printf("The length config (%s=%s) is invalid. The value can not be cast to number.", lengthKey, properties.getProperty(lengthKey));
+                                }
+                            }
+                            if (propertyValue.length() > lengthLimited) {
+                                StringUtil.cut(propertyValue, lengthLimited);
+                                System.err.printf("The config value will be truncated , because the length max than %d : %s -> %s%n", lengthDefine.value(), configKey, propertyValue);
+                            }
                         }
                         Object convertedValue = convertToTypicalType(type, propertyValue);
                         if (convertedValue != null) {

apm-sniffer/config/agent.config

@@ -18,6 +18,7 @@
 # ${service name} = [${group name}::]${logic name}
 # The group name is optional only.
 agent.service_name=${SW_AGENT_NAME:Your_ApplicationName}
+agent.service_name#length=${SW_AGENT_NAME_MAX_LENGTH:50}
 
 # The agent namespace
 agent.namespace=${SW_AGENT_NAMESPACE:}
@@ -49,6 +50,7 @@ agent.is_open_debugging_class=${SW_AGENT_OPEN_DEBUG:false}
 # Instance name is the identity of an instance, should be unique in the service. If empty, SkyWalking agent will
 # generate an 32-bit uuid. BY Default, SkyWalking uses UUID@hostname as the instance name. Max length is 50(UTF-8 char)
 agent.instance_name=${SW_AGENT_INSTANCE_NAME:}
+agent.instance_name#length=${SW_AGENT_INSTANCE_NAME_MAX_LENGTH:50}
 
 # service instance properties in json format. e.g. agent.instance_properties_json = {"org": "apache-skywalking"}
 agent.instance_properties_json=${SW_INSTANCE_PROPERTIES_JSON:}
@@ -307,4 +309,4 @@ plugin.redisson.redis_parameter_max_length=${SW_PLUGIN_REDISSON_REDIS_PARAMETER_
 # Specify which command should be converted to write operation
 plugin.redisson.operation_mapping_write=${SW_PLUGIN_REDISSON_OPERATION_MAPPING_WRITE:getset,set,setbit,setex,setnx,setrange,strlen,mset,msetnx,psetex,incr,incrby,incrbyfloat,decr,decrby,append,hmset,hset,hsetnx,hincrby,hincrbyfloat,hdel,rpoplpush,rpush,rpushx,lpush,lpushx,lrem,ltrim,lset,brpoplpush,linsert,sadd,sdiff,sdiffstore,sinterstore,sismember,srem,sunion,sunionstore,sinter,zadd,zincrby,zinterstore,zrange,zrangebylex,zrangebyscore,zrank,zrem,zremrangebylex,zremrangebyrank,zremrangebyscore,zrevrange,zrevrangebyscore,zrevrank,zunionstore,xadd,xdel,del,xtrim}
 # Specify which command should be converted to read operation
-plugin.redisson.operation_mapping_read=${SW_PLUGIN_REDISSON_OPERATION_MAPPING_READ:getrange,getbit,mget,hvals,hkeys,hlen,hexists,hget,hgetall,hmget,blpop,brpop,lindex,llen,lpop,lrange,rpop,scard,srandmember,spop,sscan,smove,zlexcount,zscore,zscan,zcard,zcount,xget,get,xread,xlen,xrange,xrevrange}
+plugin.redisson.operation_mapping_read=${SW_PLUGIN_REDISSON_OPERATION_MAPPING_READ:getrange,getbit,mget,hvals,hkeys,hlen,hexists,hget,hgetall,hmget,blpop,brpop,lindex,llen,lpop,lrange,rpop,scard,srandmember,spop,sscan,smove,zlexcount,zscore,zscan,zcard,zcount,xget,get,xread,xlen,xrange,xrevrange}