Welcome!

@DevOpsSummit Authors: Pat Romanski, Elizabeth White, Yeshim Deniz, Aruna Ravichandran, Liz McMillan

Blog Feed Post

10 Things We Forgot to Monitor

10 Things We Forgot to Monitor

After publishing Ben’s blog post about “Memory Monitoring with LXC” we realized there is a lot of interest in articles about Monitoring. I got in touch with Jehiah Czebotar, Head of Engineering at bitly, and asked him if we could republish his blog post about things bitly forgot to monitor.

Jehiah originally published his blog post on the bitly engeneering blog. You can find Jehiah on twitter and on his personal page. Definitely check out his “Personal Annual Reports“.


There is always a set of standard metrics that are universally monitored (Disk Usage, Memory Usage, Load, Pings, etc). Beyond that, there are a lot of lessons that we’ve learned from operating our production systems that have helped shape the breadth of monitoring that we perform at bitly.

One of my favorite all-time tweets is from @DevOps_Borat

What follows is a small list of things we monitor at bitly that have grown out of those (sometimes painful!) experiences, and where possible little snippets of the stories behind those instances.

1 – Fork Rate

We once had a problem where IPv6 was intentionally disabled on a box via options ipv6 disable=1 and alias ipv6 off in /etc/modprobe.conf. This caused a large issue for us: each time a new curl object was created, modprobe would spawn, checking net-pf-10 to evaluate IPv6 status. This fork bombed the box, and we eventually tracked it down by noticing that the process counter in /proc/stat was increasing by several hundred a second. Normally you would only expect a fork rate of 1-10/sec on a production box with steady traffic.

2 – flow control packets

TL;DR; If your network configuration honors flow control packets and isn’t configured to disable them, they can temporarily cause dropped traffic. (If this doesn’t sound like an outage, you need your head checked.)

$ /usr/sbin/ethtool -S eth0 | grep flow_control
rx_flow_control_xon: 0
rx_flow_control_xoff: 0
tx_flow_control_xon: 0
tx_flow_control_xoff: 0

Note: Read this to understand how these flow control frames can cascade to switch-wide loss of connectivity if you use certain Broadcom NIC’s. You should also trend these metrics on your switch gear. While at it, watch your dropped frames.

3 – Swap In/Out Rate

It’s common to check for swap usage above a threshold, but even if you have a small quantity of memory swapped, it’s actually the rate it’s swapped in/out that can impact performance, not the quantity. This is a much more direct check for that state.

4 – Server Boot Notification

Unexpected reboots are part of life. Do you know when they happen on your hosts? Most people don’t. We use a simple init script that triggers an ops email on system boot. This is valuable to communicate provisioning of new servers, and helps capture state change even if services handle the failure gracefully without alerting.

5 – NTP Clock Offset

If not monitored, yes, one of your servers is probably off. If you’ve never thought about clock skew you might not even be running ntpd on your servers. Generally there are 3 things to check for. 1) That ntpd is running, 2) Clock skew inside your datacenter, 3) Clock skew from your master time servers to an external source.

We use check_ntp_time for this check.

6 – DNS Resolutions

Internal DNS – It’s a hidden part of your infrastructure that you rely on more than you realize. The things to check for are 1) Local resolutions from each server, 2) If you have local DNS servers in your datacenter, you want to check resolution, and quantity of queries, 3) Check availability of each upstream DNS resolver you use.

External DNS – It’s good to verify your external domains resolve correctly against each of your published external nameservers. At bitly we also rely on several CC TLD’s and we monitor those authoritative servers directly as well (yes, it’s happened that all authoritative nameservers for a TLD have been offline).

7 – SSL Expiration

It’s the thing everyone forgets about because it happens so infrequently. The fix is easy, just check it and get alerted with enough timeframe to renew your SSL certificates.

define command{
    command_name    check_ssl_expire
    command_line    $USER1$/check_http --ssl -C 14 -H $ARG1$
}
define service{
    host_name               virtual
    service_description     bitly_com_ssl_expiration
    use                     generic-service
    check_command           check_ssl_expire!bitly.com
    contact_groups          email_only
    normal_check_interval   720
    retry_check_interval    10
    notification_interval   720
}

8 – DELL OpenManage Server Administrator (OMSA)

We run bitly split across two data centers, one is a managed environment with DELL hardware, and the second is Amazon EC2. For our DELL hardware it’s important for us to monitor the outputs from OMSA. This alerts us to RAID status, failed disks (predictive or hard failures), RAM Issues, Power Supply states and more.

9 – Connection Limits

You probably run things like memcached and mysql with connection limits, but do you monitor how close you are to those limits as you scale out application tiers?

Related to this is addressing the issue of processes running into file descriptor limits. We make a regular practice of running services with ulimit -n 65535 in our run scripts to minimize this. We also set Nginx worker_rlimit_nofile.

10 – Load Balancer Status.

We configure our Load Balancers with a health check which we can easily force to fail in order to have any given server removed from rotation.We’ve found it important to have visibility into the health check state, so we monitor and alert based on the same health check. (If you use EC2 Load Balancers you can monitor the ELB state from Amazon API’s).

Various Other things to watch

New entries written to Nginx Error Logs, service restarts (assuming you have something in place to auto-restart them on failure), numa stats, new process core dumps (great if you run any C code).


We want to thank Jehiah for making his original article available to our readers. Is there something missing on this list in your opportunity? Let us know in the comments!

Codeship – A hosted Continuous Deployment platform for web applications

Read the original blog entry...

More Stories By Manuel Weiss

I am the cofounder of Codeship – a hosted Continuous Integration and Deployment platform for web applications. On the Codeship blog we love to write about Software Testing, Continuos Integration and Deployment. Also check out our weekly screencast series 'Testing Tuesday'!

@DevOpsSummit Stories
Most technology leaders, contemporary and from the hardware era, are reshaping their businesses to do software. They hope to capture value from emerging technologies such as IoT, SDN, and AI. Ultimately, irrespective of the vertical, it is about deriving value from independent software applications participating in an ecosystem as one comprehensive solution. In his session at @ThingsExpo, Kausik Sridhar, founder and CTO of Pulzze Systems, will discuss how given the magnitude of today's application ecosystem, tweaking existing software to stitch various components together leads to sub-optimal solutions. This definitely deserves a re-think, and paves the way for a new breed of lightweight application servers that are micro-services and DevOps ready!
SYS-CON Events announced today that NetApp has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. NetApp is the data authority for hybrid cloud. NetApp provides a full range of hybrid cloud data services that simplify management of applications and data across cloud and on-premises environments to accelerate digital transformation. Together with their partners, NetApp empowers global organizations to unleash the full potential of their data to expand customer touchpoints, foster greater innovation and optimize their operations.
The dynamic nature of the cloud means that change is a constant when it comes to modern cloud-based infrastructure. Delivering modern applications to end users, therefore, is a constantly shifting challenge. Delivery automation helps IT Ops teams ensure that apps are providing an optimal end user experience over hybrid-cloud and multi-cloud environments, no matter what the current state of the infrastructure is. To employ a delivery automation strategy that reflects your business rules, making real-time decisions based on a combination of real user monitoring, synthetic testing, APM, NGINX / local load balancers, and other data sources, is critical.
We all know that end users experience the Internet primarily with mobile devices. From an app development perspective, we know that successfully responding to the needs of mobile customers depends on rapid DevOps – failing fast, in short, until the right solution evolves in your customers' relationship to your business. Whether you’re decomposing an SOA monolith, or developing a new application cloud natively, it’s not a question of using microservices – not doing so will be a path to eventual business failure.
SYS-CON Events announced today that Avere Systems, a leading provider of enterprise storage for the hybrid cloud, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere delivers a more modern architectural approach to storage that doesn't require the overprovisioning of storage capacity to achieve performance, overspending on expensive storage media for inactive data or the overbuilding of data centers to house increasing amounts of storage infrastructure.
Enterprises are adopting Kubernetes to accelerate the development and the delivery of cloud-native applications. However, sharing a Kubernetes cluster between members of the same team can be challenging. And, sharing clusters across multiple teams is even harder. Kubernetes offers several constructs to help implement segmentation and isolation. However, these primitives can be complex to understand and apply. As a result, it’s becoming common for enterprises to end up with several clusters. This leads to a waste of cloud resources and increased operational overhead.
Microsoft Azure Container Services can be used for container deployment in a variety of ways including support for Orchestrators like Kubernetes, Docker Swarm and Mesos. However, the abstraction for app development that support application self-healing, scaling and so on may not be at the right level. Helm and Draft makes this a lot easier. In this primarily demo-driven session at @DevOpsSummit at 21st Cloud Expo, Raghavan "Rags" Srinivas, a Cloud Solutions Architect/Evangelist at Microsoft, will cover Docker Swarm and Kubernetes deployments on Azure with some simple examples. He will look at Helm and Draft and how they can simplify app development significantly, like app scaling, rollback, etc. Helm is a tool that streamlines installing and managing Kubernetes applications, like the apt/yum/homebrew for Kubernetes. Draft works with pre-provided charts to deploy the apps via Helm.
Containers are rapidly finding their way into enterprise data centers, but change is difficult. How do enterprises transform their architecture with technologies like containers without losing the reliable components of their current solutions? In his session at @DevOpsSummit at 21st Cloud Expo, Tony Campbell, Director, Educational Services at CoreOS, will explore the challenges organizations are facing today as they move to containers and go over how Kubernetes applications can deploy with legacy components, and also go over automated capabilities provided by operators to auto-update Kubernetes with zero downtime for current and secure deployments.
SYS-CON Events announced today that Avere Systems, a leading provider of hybrid cloud enablement solutions, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere Systems was created by file systems experts determined to reinvent storage by changing the way enterprises thought about and bought storage resources. With decades of experience behind the company’s founders, Avere got its start in 2008 with a mission to use fast, flash-based storage in the most efficient, effective manner possible. What the team had discovered was a technology that optimized storage resources and reduced dependencies on sprawling storage installations. Launched as the Avere OS, this advanced file system not only boosted performance within standard, on-premises, network-attached storage systems but ...
Today most companies are adopting or evaluating container technology - Docker in particular - to speed up application deployment, drive down cost, ease management and make application delivery more flexible overall. As with most new architectures, this dream takes significant work to become a reality. Even when you do get your application componentized enough and packaged properly, there are still challenges for DevOps teams to making the shift to continuous delivery and achieving that reduction in cost and increase in speed. Sometimes in order to reduce complexity teams compromise features or change requirements
As you move to the cloud, your network should be efficient, secure, and easy to manage. An enterprise adopting a hybrid or public cloud needs systems and tools that provide: Agility: ability to deliver applications and services faster, even in complex hybrid environments Easier manageability: enable reliable connectivity with complete oversight as the data center network evolves Greater efficiency: eliminate wasted effort while reducing errors and optimize asset utilization Security: implement always-vigilant DNS security
High-velocity engineering teams are applying not only continuous delivery processes, but also lessons in experimentation from established leaders like Amazon, Netflix, and Facebook. These companies have made experimentation a foundation for their release processes, allowing them to try out major feature releases and redesigns within smaller groups before making them broadly available. In his session at 21st Cloud Expo, Brian Lucas, Senior Staff Engineer at Optimizely, will discuss how by using new techniques such as feature flagging, rollouts, and traffic splitting, experimentation is no longer just the future for marketing teams, it’s quickly becoming an essential practice for high-performing development teams as well.
SYS-CON Events announced today that CAST Software will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CAST was founded more than 25 years ago to make the invisible visible. Built around the idea that even the best analytics on the market still leave blind spots for technical teams looking to deliver better software and prevent outages, CAST provides the software intelligence that matter most.
SYS-CON Events announced today that Daiya Industry will exhibit at the Japanese Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Ruby Development Inc. builds new services in short period of time and provides a continuous support of those services based on Ruby on Rails. For more information, please visit https://github.com/RubyDevInc.
The next XaaS is CICDaaS. Why? Because CICD saves developers a huge amount of time. CD is an especially great option for projects that require multiple and frequent contributions to be integrated. But… securing CICD best practices is an emerging, essential, yet little understood practice for DevOps teams and their Cloud Service Providers. The only way to get CICD to work in a highly secure environment takes collaboration, patience and persistence. Building CICD in the cloud requires rigorous architectural and coordination work to minimize the volatility of the cloud environment and leverage the security features of the cloud to the benefit of the CICD pipeline.
When it comes to cloud computing, the ability to turn massive amounts of compute cores on and off on demand sounds attractive to IT staff, who need to manage peaks and valleys in user activity. With cloud bursting, the majority of the data can stay on premises while tapping into compute from public cloud providers, reducing risk and minimizing need to move large files. In his session at 18th Cloud Expo, Scott Jeschonek, Director of Product Management at Avere Systems, discussed the IT and business benefits that cloud bursting provides, including increased compute capacity, lower IT investment, financial agility, and, ultimately, faster time-to-market.
SYS-CON Events announced today that Yuasa System will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Yuasa System is introducing a multi-purpose endurance testing system for flexible displays, OLED devices, flexible substrates, flat cables, and films in smartphones, wearables, automobiles, and healthcare.
Is advanced scheduling in Kubernetes achievable? Yes, however, how do you properly accommodate every real-life scenario that a Kubernetes user might encounter? How do you leverage advanced scheduling techniques to shape and describe each scenario in easy-to-use rules and configurations? In his session at @DevOpsSummit at 21st Cloud Expo, Oleg Chunikhin, CTO at Kublr, will answer these questions and demonstrate techniques for implementing advanced scheduling. For example, using spot instances and cost-effective resources on AWS, coupled with the ability to deliver a minimum set of functionalities that cover the majority of needs – without configuration complexity.
DevOps is under attack because developers don’t want to mess with infrastructure. They will happily own their code into production, but want to use platforms instead of raw automation. That’s changing the landscape that we understand as DevOps with both architecture concepts (CloudNative) and process redefinition (SRE). Rob Hirschfeld’s recent work in Kubernetes operations has led to the conclusion that containers and related platforms have changed the way we should be thinking about DevOps and controlling infrastructure. The rise of Site Reliability Engineering (SRE) is part of that redefinition of operations vs development roles in organizations.
SYS-CON Events announced today that Taica will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Taica manufacturers Alpha-GEL brand silicone components and materials, which maintain outstanding performance over a wide temperature range -40C to +200C. For more information, visit http://www.taica.co.jp/english/.
SYS-CON Events announced today that SourceForge has been named “Media Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. SourceForge is the largest, most trusted destination for Open Source Software development, collaboration, discovery and download on the web serving over 32 million viewers, 150 million downloads and over 460,000 active development projects each and every month.
SYS-CON Events announced today that Dasher Technologies will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Dasher Technologies, Inc. ® is a premier IT solution provider that delivers expert technical resources along with trusted account executives to architect and deliver complete IT solutions and services to help our clients execute their goals, plans and objectives. Since 1999, we've helped public, private and nonprofit organizations implement technology solutions that speed and simplify their operations. As one of the fastest growing IT solution providers in the country, we have gained a reputation for effortless implementations with relentless follow-through and enduring support.
SYS-CON Events announced today that MIRAI Inc. will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MIRAI Inc. are IT consultants from the public sector whose mission is to solve social issues by technology and innovation and to create a meaningful future for people.
SYS-CON Events announced today that Massive Networks, that helps your business operate seamlessly with fast, reliable, and secure internet and network solutions, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. As a premier telecommunications provider, Massive Networks is headquartered out of Louisville, Colorado. With years of experience under their belt, their team of engineers can navigate the Carrier Ecosystem for your IT team acting as an extension of your business, producing a hassle-free experience.
SYS-CON Events announced today that TidalScale, a leading provider of systems and services, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. TidalScale has been involved in shaping the computing landscape. They've designed, developed and deployed some of the most important and successful systems and services in the history of the computing industry - internet, Ethernet, operating systems, programming languages and microprocessors. Their elite team has collectively earned dozens of patents, three film credits and grown record setting businesses. And collectively, they've shipped more than 2 billion licensed products. They are difference makers who have a reputation for delivering innovative products and accomplishing what many others don't believe is even possible. They are ...