There are various tools and frameworks available in Hadoop Ecosystem, using which you can import and export data to HDFS & from HDFS respectively.
let me tell you few of them and their use cases:
- hdfs dfs -put - simple way to insert files from local file system to HDFS
- HDFS Java API
- Sqoop - for bringing data to/from databases
- Flume - streaming files, logs
- Kafka - distributed queue, mostly for near-real time stream processing
- Nifi - incubating project at Apache for moving data into HDFS without making lots of changes
So for your purpose, the best solution for bringing web application logs to HDFS is through Flume.