I have a file in AWS S3 that is updating every second (actually collecting new data). I want to move the collected file to my local server periodically. Here are a few things that I am considering.
The transportation needs to be done in a zipped somehow to reduce the network burden since the cost the S3 is based on the network load.
After moving the data out of AWS S3, the data on S3 need to be deleted. In another way, the sum of the data on my server and the data on AWS should be the complete dataset and there should be intersection between these two datasets. Otherwise, next time, when we move the data, there will be duplicates for the dataset on my server.
The dataset on S3 is collecting all the time, and the new data is appended to the file using standard in. There is something running on the cron job to collect the data.
Here is a pseudo code that shows the idea of how the file has been built on S3.
* * * * * nohup python collectData.py >> data.txt
Which requires that the data transportation cannot break the pipeline, otherwise, the new data will be lost.
One of the option is to mount S3 bucket as local directory (for example, using RioFS project) and use standard shell tools (like rm, cp, mv ..) to remove an old file and upload a new file to Amazon S3.
Related
I'm currently building an application with Apache Spark (pyspark), and I have the following use case:
Run pyspark with local mode (using spark-submit local[*]).
Write the results of my spark job to S3 in the form of partitioned Parquet files.
Ensure that each job overwrite the particular partition it is writing to, in order to ensure idempotent jobs.
Ensure that spark-staging files are written to local disk before being committed to S3, as staging in S3, and then committing via a rename operation, is very expensive.
For various internal reasons, all four of the above bullet points are non-negotiable.
I have everything but the last bullet point working. I'm running a pyspark application, and writing to S3 (actually an on-prem Ceph instance), ensuring that spark.sql.sources.partitionOverwriteMode is set to dynamic.
However, this means that my spark-staging files are being staged in S3, and then committed by using a delete-and-rename operation, which is very expensive.
I've tried using the Spark Directory Committer in order to stage files on my local disk. This works great unless spark.sql.sources.partitionOverwriteMode.
After digging through the source code, it looks like the PathOutputCommitter does not support Dynamic Partition Overwriting.
At this point, I'm stuck. I want to be able to write my staging files to local disk, and then commit the results to S3. However, I also need to be able to dynamically overwrite a single partition without overwriting the entire Parquet table.
For reference, I'm running pyspark=3.1.2, and using the following spark-submit command:
spark-submit --repositories https://repository.cloudera.com/artifactory/cloudera-repos/ --packages com.amazonaws:aws-java-sdk:1.11.375,org.apache.hadoop:hadoop-aws:3.2.0,org.apache.spark:spark-hadoop-cloud_2.12:3.1.1.3.1.7270.0-253
I get the following error when spark.sql.sources.partitionOverwriteMode is set to dynamic:
java.io.IOException: PathOutputCommitProtocol does not support dynamicPartitionOverwrite
My spark config is as follows:
self.spark.conf.set("spark.sql.files.ignoreCorruptFiles", "true")
self.spark.conf.set("spark.sql.execution.arrow.pyspark.enabled", "true")
self.spark.conf.set("spark.hadoop.fs.s3a.committer.name", "magic")
self.spark.conf.set("spark.sql.sources.commitProtocolClass",
"org.apache.spark.internal.io.cloud.PathOutputCommitProtocol")
self.spark.conf.set("spark.sql.parquet.output.committer.class",
"org.apache.spark.internal.io.cloud.BindingParquetOutputCommitter")
self.spark.conf.set(
"spark.sql.sources.partitionOverwriteMode", "dynamic"
)
afraid the s3a committers don't support the dynamic partition overwrite feature. That actually works by doing lots of renaming, so misses the entire point of zero rename committers.
the "partioned" committer was written by netflix for their use case of updating/overwriting single partitions in an active table. it should work for you as it is the same use case.
consult the documentation
I have ~200.000 s3 files that I need to partition, and have made an Athena query to produce a target s3 key for each of the original s3 keys. I can clearly create a script out of this, but how to make the process robust/reliable?
I need to partition csv files using info inside each csv so that each file is moved to a new prefix in the same bucket. The files are mapped 1-to-1, but the new prefix depends on the data inside the file
The copy command for each would be something like:
aws s3 cp s3://bucket/top_prefix/file.csv s3://bucket/top_prefix/var1=X/var2=Y/file.csv
And I can make a single big script to copy all through Athena and bit of SQL, but I am concerned about doing this reliably so that I can be sure that all are copied across, and not have the script fail, timeout etc. Should I "just run the script"? From my machine or better to put it in an ec2 1st? These kinds of questions
This is a one-off, as the application code producing the files in s3 will start outputting directly to partitions.
If each file contains data for only one partition, then you can simply move the files as you have shown. This is quite efficient because the content of the files do not need to be processed.
If, however, lines within the files each belong to different partitions, then you can use Amazon Athena to 'select' lines from an input table and output the lines to a destination table that resides in a different path, with partitioning configured. However, Athena does not "move" the files -- it simply reads them and then stores the output. If you were to do this for new data each time, you would need to use an INSERT statement to copy the new data into an existing output table, then delete the input files from S3.
Since it is one-off, and each file belongs in only one partition, I would recommend you simply "run the script". It will go slightly faster from an EC2 instance, but the data is not uploaded/downloaded -- it all stays within S3.
I often create an Excel spreadsheet with a list of input locations and output locations. I create a formula to build the aws s3 cp <input> <output_path> commands, copy them to a text file and execute it as a batch. Works fine!
You mention that the destination depends on the data inside the object, so it would probably work well as a Python script that would loop through each object, 'peek' inside the object to see where it belongs, then issue a copy_object() command to send it to the right destination. (smart-open · PyPI is a great library for reading from an S3 object without having to download it first.)
Would there be any issues reading a spark dataframe and say persisting it via a Jupyter notebook and another process writing to the s3 bucket concurrently?
Say,
I read a dataframe like:
s3 = spark.read.parquet('s3://path/to/table')
And work on this in a notebook.
Concurrently I write out to the same s3 bucket at some point via a different process, e.g.
system('s3-dist-cp --src --dest s3://path/to/table)
Would this ever prove to be an issue? I am ok with messing up the read / dataframe but I would not want to block writing out to the bucket.
This will cause FNF exception on any action on the first DF that you read.
s3 = spark.read.parquet('s3://path/to/table')
The first spark job that is involved in the above is listing leaf files and directories. As there was another process that was writing/ rewriting data, the paths would be stale.
Furthermore, the eventual consistency behavior of the S3 should also be considered.
I have a large amount of files (~500k hdf5) inside a s3 bucket which I need to process and reupload to another s3 bucket.
I am pretty new to such tasks, so I am not quite sure if my approach is correct here. I do the following:
I use boto to get the list of keys inside the bucket and parallelize it with spark:
s3keys = bucket.list()
data = sc.parallelize(s3keys)
data = data.map(lambda x: download_process_upload(x))
result = data.collect()
where download_process_upload is a function which downloads the file specified by the key, does some processing on it and re-uploads it to another bucket (returning 1 if everything was successful, and 0 if there was an error)
So in the end I could do
success_rate = sum(result) / float(len(s3keys))
I have read that spark map statements should be stateless, while my custom map function definitely is not stateless. It downloads the file to disk and then loads it into memory etc.
So is this the proper way to do such a task?
I've successfully used your methodology to download and process data from S3. I have not tried to upload the data from within a map statement. But, I see no reason why you wouldn't be able to read the file from s3, process it, and then upload it to a new location.
Also, you can save a few keystrokes and take the explicit lambda out of the map statement like this data = data.map(download_process_upload)
We need to move our video file storage to AWS S3. The old location is a cdn, so I only have url for each file (1000+ files, > 1TB total file size). Running an upload tool directly on the storage server is not an option.
I already created a tool that downloads the file, uploads file to S3 bucket and updates the DB records with new HTTP url and works perfectly except it takes forever.
Downloading the file takes some time (considering each file close to a gigabyte) and uploading it takes longer.
Is it possible to upload the video file directly from cdn to S3, so I could reduce processing time into half? Something like reading chunk of file and then putting it to S3 while reading next chunk.
Currently I use System.Net.WebClient to download the file and AWSSDK to upload.
PS: I have no problem with internet speed, I run the app on a server with 1GBit network connection.
No, there isn't a way to direct S3 to fetch a resource, on your behalf, from a non-S3 URL and save it in a bucket.
The only "fetch"-like operation S3 supports is the PUT/COPY operation, where S3 supports fetching an object from one bucket and storing it in another bucket (or the same bucket), even across regions, even across accounts, as long as you have a user with sufficient permission for the necessary operations on both ends of the transaction. In that one case, S3 handles all the data transfer, internally.
Otherwise, the only way to take a remote object and store it in S3 is to download the resource and then upload it to S3 -- however, there's nothing preventing you from doing both things at the same time.
To do that, you'll need to write some code, using presumably either asynchronous I/O or threads, so that you can simultaneously be receiving a stream of downloaded data and uploading it, probably in symmetric chunks, using S3's Multipart Upload capability, which allows you to write individual chunks (minimum 5MB each) which, with a final request, S3 will validate and consolidate into a single object of up to 5TB. Multipart upload supports parallel upload of chunks, and allows your code to retry any failed chunks without restarting the whole job, since the individual chunks don't have to be uploaded or received by S3 in linear order.
If the origin supports HTTP range requests, you wouldn't necessarily even need to receive a "stream," you could discover the size of the object and then GET chunks by range and multipart-upload them. Do this operation with threads or asynch I/O handling multiple ranges in parallel, and you will likely be able to copy an entire object faster than you can download it in a single monolithic download, depending on the factors limiting your download speed.
I've achieved aggregate speeds in the range of 45 to 75 Mbits/sec while uploading multi-gigabyte files into S3 from outside of AWS using this technique.
This has been answered by me in this question, here's the gist:
object = Aws::S3::Object.new(bucket_name: 'target-bucket', key: 'target-key')
object.upload_stream do |write_stream|
IO.copy_stream(URI.open('http://example.com/file.ext'), write_stream)
end
This is no 'direct' pull-from-S3, though. At least this doesn't download each file and then uploads in serial, but streams 'through' the client. If you run the above on an EC2 instance in the same region as your bucket, I believe this is as 'direct' as it gets, and as fast as a direct pull would ever be.
if a proxy ( node express ) is suitable for you then the portions of code at these 2 routes could be combined to do a GET POST fetch chain, retreiving then re-posting the response body to your dest. S3 bucket.
step one creates response.body
step two
set the stream in 2nd link to response from the GET op in link 1 and you will upload to dest.bucket the stream ( arrayBuffer ) from the first fetch