What is the best Monitoring and Alerting Tool for applications hosted in cloud?

http://ruxit.com checks all of your boxes. It also does a lot more and does not require you to configure alerts. It uses AI to do the first layer of issue sleuthing for you. Try it out.

Both Nagios, Zabbix as well as all the top performing System Monitoring Solutions have been evaluated by real users on IT Central Station: https://www.itcentralstation.com/categories/system-monitoring?tid=c38-st-qu2.Users who looked at Nagios and Zabbix also considered CA UIM as its a more fully featured monitoring solution. This user wrote, "We tried several Open Source tools like Nagios and Zenoss, but as the environment grew we found that those tools wouldn’t scale the way we wanted. CA UIM is really the best of breed if you need monitoring for all Operating Systems and a large list of diverse applications". To read the full review: https://www.itcentralstation.com/product_reviews/ca-unified-infrastructure-management-review-31889-by-jason-downey?tid=c38-st-qu2Best of luck.

These are lots of different use cases that you're describing here, and many tools to choose from in each of these categories. It's hard to come up with a single tool that could address all this, and give the best answers, so most companies use a toolkit they assemble from a set of tools that each addresses other questions. You can read more about it on this blog post that covers some of the more popular choices for production monitoring and alerting tools: http://blog.takipi.com/15-tools-to-use-when-deploying-code-to-production/

Did you try Stackify? I've been using it for quite sometime and I believe it covers all your list. And it's very reasonably priced. If you don't find all the features you should talk to their support, they've been extremely helpful and they've some features I was looking for to upcoming releases.

As others have said, Nagios and Zabbix are definitely viable options for much of what you’ve listed. You might also find https://bigpanda.io/monitoringscape/ helpful in researching the various tools available. It offers a rather comprehensive directory of systems monitoring tools.

Based on these requirements, CoScale’s http://www.coscale.com/devops-engineer solution could be a good option for you. I work for them and we look at resource metrics, application metrics from logs and APIs, also database metrics (such as slow queries), etc. We also look at the impact on the end user (such as page load times) and business metrics.As mentioned, what is important in cloud environments is easy config mgmt via config files and integration with config mgmt tools. CoScale allows this and we integrate with tools as Chef, Puppet, Saltstack, etc.What is also important in large and dynamic environments is some form of automation in looking over the many metrics that you want to monitor. At CoScale we use specialized anomaly detection techniques for this, automatically detecting abnormal behavior without having to set up manual alerts.If you are interested, just give us a try…

I would echo Tim Macchi’s recommendation. Deployments today have gotten so large, so complex, so dynamic that monitoring and managing applications manually in a traditional APM solution has become prohibitively time-consuming.Dynatrace (nee Dynatrace Ruxit) was built from the ground up with universal monitoring of cloud-native applications in mind. As noted, the full-stack performance management is powered by artificial intelligence, which applies algorithms and context-rich diagnostic to auto-discover all components of your full technology stack end to end—from the customers’ web browsers all the way down to the host infrastructure map out the entire IT environment in an interactive visual display identify the millions of dependencies among websites, applications, services, processes, hosts, networks, and cloud infrastructure learn how it all works together and what constitutes normal behavior automatically detect, analyze, and prioritize anomalies and performance problems actually recommend solutions to the root cause of those problems And AI does all this at a speed, scale, and precision that no human could ever match.Don’t take my word for it (I work for Dynatrace after all) — see for yourself how Dynatrace stacks up against other solutions you’re looking at.Dynatrace offers a http://www.dynatrace.com/en/ruxit/—the complete full-blown version, not a stripped-down demo—all you have to do is install the single agent to be up and running within minutes.

I almost sure that Anturis can suit you (http://www.anturis.com), as it seems to be able to do everything you want, except the point where you are able to change the code. This tool is not an open source unfortunately, but in all other respects it is quite OK.

Zabbix is by far the most efficient open source platform - compared to others free ones. Easiest way to try  Zabbix is by using the one click deploy on  vpsie its free for a month - one click. https://vpsie.com/how-to-deploy-zabbix-on-vpsie/ ..That should give you a running instance in less than a minute - you can configure VPN to your gears internally or monitor your devices visible on the Internet, You will have the option to select the retention period for your data. hope that helps