Tag Archives: Fluentd

Demo Fluentd using Ubuntu with optional inclusion of OpenSearch and OCI Log Analytics

17 Wednesday Aug 2022

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One of the areas I present publicly is the use of Fluentd. including the use of distributed and multiple nodes. As many events have been virtual it has been easy to demo everything from my desktop – everything is set up so I can demo things very easily. While doing this all on one machine does point to how compact and efficient Fluentd is as I can run multiple instances concurrently it does undermine distributed capabilities somewhat.

Add to that I now work for Oracle it makes sense to use OCI resources. With that, I have been developing the scripts to configure Ubuntu VMs to set up the demo environments installing Ruby, Fluentd, and various gems needed and pulling the relevant configurations in. All the assets can be found in the GitHub repository https://github.com/mp3monster/logging-demos. The repository readme includes plenty of information as well.

While I’ve been putting this together using OCI, the fact that everything is based on Ubuntu should mean it can be run locally on VMs, WSL2, and adaptable for MacOS as well. The environment has been configured means you can still run on Ubuntu with a single node if desired.

Additional Log Destinations

As the demo will typically be run on OCI we can not only run the demo with a multinode setup, we have extended the setup with several inclusion files so we can utilize OCI services OpenSearch and OCI Log Analytics. If you don’t want to use these services simply replace the contents of several inclusion files including files with the contents of the dummy_inclusion.conf file provided.

Representation of the Demo setup

The configuration works by each destination having one or two inclusion files. The files with the postfix of label-inclusion.conf contains the configuration to direct traffic to the respective service with a configuration that will push log events at a very high frequency to the destination. The second inclusion file injects the duplication of log events to each service. The inclusion declarations in the main node Fluentd config file references an environment variable that should provide the path to the inclusion file to use. As a result, by changing the environment variable to point to a dummy file it becomes possible o configure out the use of one of the services. The two inclusions mean we can keep the store declarations compact and show multiple labels being used. With the OpenSearch setup, we have a variant of the inclusion file model where the route inclusion can reference the logic that we would use in the label directly within the sore declaration.

The best way to see the use of the inclusions is to experiment with setting the different environment variables to reference the different files and then using the Fluentd dry-run feature (more on this in the book).

Setup script

The setup script performs a number of tasks including:

  • Pulling from Git all the resources needed in terms of configuration files and folders
  • Retrieving the necessary plugins against the possibility of their use.
  • Setting up the various environment variables for:
    • Slack token
    • environment variables to reference inclusion files
    • shortcut environment variables and aliases
    • network (IP) address for external services such as OpenSearch
  • Setting up a folder for OCI tokens needed.
  • Setting up temp folders to be used by OCI Plugins as a file-based cache.

Using OpenSearch

OpenSearch setup is documented in a tutorial here, and a Reference Architecture at the time of writing there isn’t a one-click deploy Terraform available in the Oracle Reference Architecture library on GitHub.

Currently, the setup for OpenSearch means manually adding the node1 index into the configuration.

Useful Links:

Log Analytics

Feeding the log analytics service is a more complex process to set up as the feeds need to have metadata about the events being ingested. The downside is the configuration effort is greater, but the payback is that it becomes easier to extract meaningful information quickly because the service has a greater understanding of the content. For example, attributing the logs to a type of source means the predefined or default log formats are immediately understood, and maximum meaning can be retrieved from the log event.

Going to OCI Log Analytics does cut out the need for the Connections hub, which would allow rules and routing to be defined to different OCI services which functionally can help such as directing log events to PagerDuty.

Useful Links

Demo Enhancements to come

There are a few things we’re planning to do with the demo:

  • Create a terraform script to perform all the environment setup
  • Integrate the configuration script into the terraform
  • Provide some simple dashboard insights for OpenSearch – currently, this is all manual
  • Basic setup for OCI Log Analytics

Securing credentials in Fluentd configurations

07 Tuesday Jun 2022

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When configuring Fluentd we often need to provide credentials to access event sources, targets, and associated services such as notification tools like Slack and PagerDuty. The challenge is that we don’t want the credentials to be in clear text in the Fluentd configuration.

Using Env Vars

In the Logging In Action with Fluentd book, we illustrated how we can take the sensitive values from environment variables so the values don’t show up in the configuration file. But, we’ve seen regularly the question of how secure is this, can’t the environment variable be seen by everyone on that machine?

The answer to this question comes down to having a deeper understanding of how environment variables work. There is a really good explanation here. The long and short of it is that environment variables can only be seen by the process that creates the variable and any child process will receive a copy of the parent’s variables.

This means that if we create the variable in a shell, only that shell and any processes launched by that shell can see the environment variable. So as long as we don’t set variables up as part of a system-level configuration then we already have a level of security. So we could wrap the start of Fluentd with a script that sets the environment variables needed. Then everything launches that script.

An even better way?

Continue reading →

Handling multi-line log entries with Fluentd

19 Tuesday Apr 2022

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One aspect of logging I didn’t directly address with my Fluentd book was consuming multiline logs, such as those you’ll often see when a stack trace is included in the log output. Implementing the feature with Fluentd isn’t hugely complex as it leverages the use of regular expressions (addressed in the book in more depth) to recognize the 1st line in a multiline log entry and for subsequent lines.

I didn’t address it for a couple of reasons:

  • Using parsers is fairly inefficient, particularly when you’re using a parser to just decide how to then transform a line (this is why I’m not a huge fan of some of the 12 Factor App‘s recommendations when it comes to logging).
  • Incorporating into your Fluentd parser configurations for specific app log setups is arguably increasing the level of coupling.
  • Many logging frameworks can talk directly to Fluentd as we saw in the book. This is can be more efficient, which means that the log event is more likely to be passed over in a structured format (therefore less work to do).
  • Alternatively, frameworks like Log4J2 have the means to strip line feeds, etc at source – https://logging.apache.org/log4j/2.x/manual/layouts.html (see replace)

But let’s also be realistic, many applications will be configured to simply log to a file and aren’t likely to be changed. At which point we do need to process such situations, so is it done? The process remains largely the same as the tail plugin we illustrated. Except we introduce a different parser called multiline. The documentation provided by Fluentd includes several examples of multiline configurations that will work for default log formats (such as Log4J and Rails). If we took our most basic source setup:

<source>
  @type tail
  path ./Chapter3/basic-file.*
  read_lines_limit 5
  tag simpleFile
  <parse>
    @type none
  </parse>
</source>

Then assuming our log Simulator played back multiline logs (the provided configuration doesn’t do that) extended to consume standard Log4J2 logs we would have a configuration as follows:

<source>
  @type tail
  path ./Chapter3/basic-file.*
  read_lines_limit 5
  tag simpleFile
  <parse>
     @type multiline
     format_firstline /\d{4}-\d{1,2}-\d{1,2}/
     format1 /^(?<time>\d{4}-\d{1,2}-\d{1,2} \d{1,2}:\d{1,2}:\d{1,2}) \[(?<thread>.*)\] (?<level>[^\s]+)(?<message>.*)/
  </parse>
</source>

As you can see we’ve set the parser type to multiline. Then there are two regular expressions, format_firstline is used to help recognize the start of a log event. Every line of the log is tested with this expression as we now assume unless this produces a valid result that the line will be part of a multiline event. If you look at the expression you’ll realize it is looking for a DateTime stamp in the form YYYY-MM-DD. This does mean if you generate a log that starts with the date even if it is part of a multiline output then you’ll trip up the parser. You could extend the expression – but the longer it is the slower the processing.

Following format_firstline we have in our example format1 which describes how to process the first line. This can be extended to define how to handle subsequent lines but this could be multiple format definitions. They do need to be presented in numerical order eg. format1, format2, format, and so on.

LogSimulator – Playing back multi-line logs

The Log simulator uses a very similar mechanism to Fluentd to understand how to playback multiple line logs. When it is reading the log lines in for replay it uses a regular expression to recognize the start of a new log entry (FIRSTOFMULTILINEREGEX) defined in the properties file. The simulator will concatenate lines together until it either hits the end of the file or has a new line that complies with the REGEX. It stores the line with an encoded /n (newline character). It will then print the log using the format specified and will allow the /n to create a newline (or not) based on another config parameter (ALLOWNL).

Avoid creating an event storm when using social outputs with Fluentd

14 Thursday Apr 2022

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Fluentd has an incredible catalogue of plugins including notification and collaboration channels from good old-fashioned email through to slack, teams, and others.

The thing to remember if you use these channels is that if you’re sending errors, from application logs it isn’t unusual for there to be multiple error events as a root event can cause a cascade of related issues. For example, if your code is writing transactions to a database and the database goes down with no failover mechanism, then your code will most likely experience an error, roll back the transaction perhaps to some sort of queue, and then try to process the next event. Which will again fail. This is the classic situation where multiple errors will get reported for the same issue. This problem is often referred to as a mail storm given that there was a time when we didn’t have social collaboration tools and everyone used email.

There are several ways to overcome this problem. But the most simple and elegant of these is using the suppress plugin in its filter mode.

<filter **>
  @type suppress
  interval 60       # period in seconds when the condition to supress is triggered
  num 2             # number of occurences of a value before suppressing
  attr_keys source  # the element of the event to consider.
</filter>

In this example if we encounter an event with an attribute called source containing the same value twice then the suppression will kick in for 60 seconds. If you want the key to the valuebeing checked to be the tag then simply omit the attr_keys parameter.

Of course, we don’t want the suppression to kick in if the same value in the attribute keys occured once every few hours. To address this the occurence count is applied over not a time period, but a number of events received by the configuration of max_slot_num which defaults to 10k, but resets

In the filter mode, this plugin is best positionbed immediately before the match block. This means we don’t accidentally suppress messages before they are routed anywhere else.

For the purposes of a demo this is less of an issue. But for a realworld use case would probably benefit from some tuning. All the documentation for this plugin is at https://github.com/fujiwara/fluent-plugin-suppress

Logging In Action – almost there

08 Thursday Jul 2021

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We’ve got the peer review comments back on the completed 1st draft back of the book. So I’d like to take this opportunity to thanks those who have been involved as peer reviewers, particularly those involved in the previous review cycles. I hope the reviewers found it satisfying to see between iterations that their suggestions and feedback have been taken on board and where we can.

The feed back is really exciting to read. Some tweaks and refinements to do to address the suggestions made.

The work on the Kubernetes and Docker elements and the chapter which has become available on MEAP has helped round that aspect off. But importantly, the final chapters help address the wider challenges of logging, and some of the feedback positively reflects this.

To paraphrase the comments, we’ve addressed the issues of logging which don’t get the attention that they deserve. Which for me is a success.

New and coming to a screen near you soon

31 Monday May 2021

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Last night saw the final chapter of Logging in Action with Fluentd go back to my editor. The next step is that Chapter (and others I hope) will go to MEAP, so early readers not only get the final chapter, but also the raft of improvements we’ve made. Along with that, the manuscript goes for a full peers review. Once that’s back, its time for a round of edits as I address the feedback then into copy editing and Manning sign off review.

As you might have guessed, we’ve kept busy with an article in the 25th edition of OraWorld. This follows Part 1 talking about GraphQL with a look at considerations for API Security.

In addition to that we’re working on a piece around automation of OCI management activities such as setting up developers, allowing them a level of freedom to experiment without accidentally burning through all your credits by spinning up Exadata servers or 500 node Kubernetes clusters.

We might even have some time to write more about APIs and integration.

Blog Post on Oracle.com and more

19 Wednesday May 2021

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We recently received an invite to write a guest blog post for Oracle. We’re please to say it has gone live, and can be found at https://blogs.oracle.com/cloud-infrastructure/oracle-cloud-infrastructure-logging-and-alert-rapid-smoke-testing-of-config-and-alerts. A little different to my typical posts. Hope you find it interesting.

Opening of the blog post on blogs.oracle.com
my Author Profile on blogs.oracle.com

World Festival Conference

We’ve also scored another success, this time we’ve been invited to speak at WorldFestival in August, this is an online conference organized by the same team behind DeveloperWeek. This is the first time outside of an Oracle linked event where I’ve been amongst the first few named speakers, so proud of that. The conference looks really interesting as it looks beyond just core developer themes with conference tracks on Space & Transportation, Smart Cities, Robotics, Digital Health to name a few of the 12 streams. Worth checking out.

WorldFestival Conference
World Festival Conference Themes

Unified Logging with Fluentd becomes Logging in Action using Fluentd, Kubernetes and more

08 Monday Feb 2021

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The book has had a title change as Manning found that links the book was clashing with other solutions using the term ‘Unified Logging’. With the name change it helps bring the book inline with the Manning naming with their In action series. This means the book website is now https://www.manning.com/books/logging-in-action.

With the name change we’ve agreed that there should an additional chapter added. As I’d written the book with a view that everything we cover applies to both modern solutions such as Microservices coming from the CNCF camp but equally relevant to more traditional IT landscapes. Within the book we have explianed how things are positioned and can be used in Kubernetes, but it was agreed with our editorial team that not tackling the configuration of Fluentd with Kubernetes and Docker was to an extent ignoring a key community that will be using Fluentd. So the new chapter will be introduced to address this aspect.

In terms of progress we’re into the 1’s – 1 Chapter to start (the new one), 1 Chapter back from the Technical Editor (Logging Best Practises) – some edits to be done, 1 Chapter now with the editor (How To Create Custom Plugins), 1 Chapter being finished (Logging Frameworks) and finally 1 peer review cycle to go.

Given the lovely review comments that have been quoted on the book’s page. I can only recommend if you have an interest in logging and monitoring then check it out through Manning Early Access Programme (MEAP).

Latest on book and APIs

15 Tuesday Dec 2020

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My blogging is way down compared with only a post about OKit – OCI Design (on Windows). It largely comes down to lots of work on our Fluentd book. Chapter 6 is now available in the MEAP. As the promo info says …

What’s new?

Chapter 6, “Filtering and Extrapolation”

Gain control and insight!

Last chapter, we touched on the use of the Filter directive. But that was just the tip of the iceberg! In Chapter 6, we’ll plunge below the surface, exploring the when, why, and how of applying filters to give us more insight and precise control over events.

Promo Email from Manning

Earlier chapters have been tweaked, with some additional improvements which will make the live reading experience better.

Another chapter and an appendix should be finding their way to MEAP very soon as it was handed over by our project editor. That will make it seven chapters available, and all the appendices.

Whilst the peer review is taking place the chapter covering plugin development is progressing. The development work has got the basics of the output plugin with log events being stored in Redis and the input being worked on as well. If you want a peak, keep an eye on my GitHub repository (here).

But is isn’t all writing…

I presented on Twitch – you can catch that at https://m.twitch.tv/videos/809295979 I’ve been offered the opportunity to present again, so keep an eye out for something next year.

We recorded a podcast with the excellent guys over at Adventures In DevOps. We don’t have the exact date for the podcast to be released, but I imagine it will sometime during Jan 2021. I’d recommend checking out the podcasts. I’ve been dipping into their back catalogue of recordings and the team ask some really thought provoking questions.

If that wasn’t enough, we’ve been fortunate enough to have some time to talk with leading members of the Fluentd and Fluent Bit projects which was a real pleasure. Hopefully, as we leave this horrendous year behind we’ll get to talk and possibly collaborate some more.

Fluentd Book Update

02 Monday Nov 2020

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Things have been very hectic, so much so we’ve not really had much time to write a blog. Most of which has been related to my Fluentd book, so what has been happening (and keep an eye on my Twitter account for a promo code 🙂 ) …

  • Several virtual conferences (Open Source Summit, SPOUG and Oracle APAC Groundbreakers to name just a few)
  • Perhaps the biggest bit has been the book:
    • First 4 chapters went through a rigorous peer review, as a result a number of improvements have been made,
    • with Chapter 5 having been reviewed by our technical editor, and little bit of refinement applied it should be reaching MEAP very very soon along with updated appendices,
    • Chapter 6 has been reviewed by our development editor, so some revisions to apply and then onto the technical editor,
    • Chapter 7 writing in progress, with about 1/3rd complete including examples of applying scaling configuration that can be run on a desktop

So what is to follow:

  • We’re on Manning’s Twitch channel to do a session, which will cover Fluentd, some examples, the book and what it will cover,
  • Once Chapter 7 is done, then we go through a comprehensive review with external input. Depending on the feedback from this, we make another sweep through the existing chapters to make further improvements,
  • Chapter 8 I suspect will be the hardest to write, as we actually get into creating our own Plugin. So I it maybe a little while before this gets completed. The subsequent chapters will come more easily as we’ve got them part written in a rough draft already,
  • We have another round of external peer reviewing to come which will cover everything, so I’m sure we’ll be doing some refinements
  • A podcast recording is scheduled in December.

Talking of Manning on Twitch, this looks like a bit of a hidden Gem – worth looking at not only because of the live stream, but all the previous recordings with other Manning authors are available to watch.

If that isn’t enough with a day job, we have had some major work done on our house. Now we’re moved back in, there are lots of DIY jobs to do, get all the furniture back from storage. Every room apart from the kitchen needs to be painted. But that is my sob story.

I’m hoping to find time to experiment with Oracle’s new cloud native Log Management as this is built on Fluentd foundations and a little bit with API tech – but this is likely to be the Christmas break.