Skip to main content
Redhat Developers  Logo
  • Products

    Featured

    • Red Hat Enterprise Linux
      Red Hat Enterprise Linux Icon
    • Red Hat OpenShift AI
      Red Hat OpenShift AI
    • Red Hat Enterprise Linux AI
      Linux icon inside of a brain
    • Image mode for Red Hat Enterprise Linux
      RHEL image mode
    • Red Hat OpenShift
      Openshift icon
    • Red Hat Ansible Automation Platform
      Ansible icon
    • Red Hat Developer Hub
      Developer Hub
    • View All Red Hat Products
    • Linux

      • Red Hat Enterprise Linux
      • Image mode for Red Hat Enterprise Linux
      • Red Hat Universal Base Images (UBI)
    • Java runtimes & frameworks

      • JBoss Enterprise Application Platform
      • Red Hat build of OpenJDK
    • Kubernetes

      • Red Hat OpenShift
      • Microsoft Azure Red Hat OpenShift
      • Red Hat OpenShift Virtualization
      • Red Hat OpenShift Lightspeed
    • Integration & App Connectivity

      • Red Hat Build of Apache Camel
      • Red Hat Service Interconnect
      • Red Hat Connectivity Link
    • AI/ML

      • Red Hat OpenShift AI
      • Red Hat Enterprise Linux AI
    • Automation

      • Red Hat Ansible Automation Platform
      • Red Hat Ansible Lightspeed
    • Developer tools

      • Red Hat Trusted Software Supply Chain
      • Podman Desktop
      • Red Hat OpenShift Dev Spaces
    • Developer Sandbox

      Developer Sandbox
      Try Red Hat products and technologies without setup or configuration fees for 30 days with this shared Openshift and Kubernetes cluster.
    • Try at no cost
  • Technologies

    Featured

    • AI/ML
      AI/ML Icon
    • Linux
      Linux Icon
    • Kubernetes
      Cloud icon
    • Automation
      Automation Icon showing arrows moving in a circle around a gear
    • View All Technologies
    • Programming Languages & Frameworks

      • Java
      • Python
      • JavaScript
    • System Design & Architecture

      • Red Hat architecture and design patterns
      • Microservices
      • Event-Driven Architecture
      • Databases
    • Developer Productivity

      • Developer productivity
      • Developer Tools
      • GitOps
    • Secure Development & Architectures

      • Security
      • Secure coding
    • Platform Engineering

      • DevOps
      • DevSecOps
      • Ansible automation for applications and services
    • Automated Data Processing

      • AI/ML
      • Data Science
      • Apache Kafka on Kubernetes
      • View All Technologies
    • Start exploring in the Developer Sandbox for free

      sandbox graphic
      Try Red Hat's products and technologies without setup or configuration.
    • Try at no cost
  • Learn

    Featured

    • Kubernetes & Cloud Native
      Openshift icon
    • Linux
      Rhel icon
    • Automation
      Ansible cloud icon
    • Java
      Java icon
    • AI/ML
      AI/ML Icon
    • View All Learning Resources

    E-Books

    • GitOps Cookbook
    • Podman in Action
    • Kubernetes Operators
    • The Path to GitOps
    • View All E-books

    Cheat Sheets

    • Linux Commands
    • Bash Commands
    • Git
    • systemd Commands
    • View All Cheat Sheets

    Documentation

    • API Catalog
    • Product Documentation
    • Legacy Documentation
    • Red Hat Learning

      Learning image
      Boost your technical skills to expert-level with the help of interactive lessons offered by various Red Hat Learning programs.
    • Explore Red Hat Learning
  • Developer Sandbox

    Developer Sandbox

    • Access Red Hat’s products and technologies without setup or configuration, and start developing quicker than ever before with our new, no-cost sandbox environments.
    • Explore Developer Sandbox

    Featured Developer Sandbox activities

    • Get started with your Developer Sandbox
    • OpenShift virtualization and application modernization using the Developer Sandbox
    • Explore all Developer Sandbox activities

    Ready to start developing apps?

    • Try at no cost
  • Blog
  • Events
  • Videos

Istio Egress: Exit Through the Gift Shop

May 1, 2018
Don Schenck
Related topics:
JavaService MeshKubernetes

Share:

    Using Istio with Red Hat OpenShift and Kubernetes makes life with microservices easier. Tucked away inside of Kubernetes pods, using the Istio service mesh, your code can run (mostly) in isolation. Performance, ease-of-changes, tracing, and so on are made available by simply using the Istio sidecar container model. But what if you want your microservice to talk to another service that is outside of your OpenShift/Kubernetes/pods environment?

    Enter Istio Egress.

    [This is part nine of my ten-part Introduction to Istio Service Mesh series. My previous article was Part 8: Istio Smart Canary Launch: Easing into Production.]

    Bin There, Done That

    Istio Egress, put simply, allows you to access resources (read: services) outside of your Kubernetes pods. In an out-of-the-box Istio-enabled environment, traffic is routed within and between the clusters of pods based on internal IP tables. This walled-off approach is fine...until you need to access a service elsewhere.

    Egress gives you the power to bypass those IP tables, either based on Egress rules or for a range of IP addresses.

    As an example, we'll use a Java program that makes a GET request to httpbin.org/headers.

    (If you're not familiar with httpbin.org, it's a great resource for testing outgoing service requests.)

    If I simply run curl http://httpbin.org/headers from the command line, I'll see the following:

    If I point my browser to the URL, I see this:

    Clearly, the test is doing its job and returning the headers passed into it.

    Thinking Inside the Box

    Next, I'll take some Java code that uses this URL and run that code inside of Istio. (You can do this yourself by visiting our Istio tutorial.) After building the image and running it in OpenShift, I can invoke it using curl egresshttpbin-istioegress.$(minishift ip).nip.io, which gives me this:

    Wait. What just happened? It was working a few minutes ago. What do you mean "Not Found"?? It's right there! I just curl-ed it.

    Bring the Web to the (IP) Tables

    Blame (or thank) Istio. Remember: Istio is a sidecar container that is handling your discovery and routing (and a bunch of other stuff, as the past eight weeks' blog posts have pointed out). Because of this, the IP tables are limited to your internal services. Since httpbin.org is outside of our cluster, it's not available. That's where Istio Egress comes to the rescue.

    Again.

    Without changing your source code.

    Again.

    By implementing the following Egress rule, we can direct Istio to look out (across the vast world wide web, if you will) to find a service—in this case, httpbin.org. As you can see from this file (egress_httpbin.yml), the functionality is rather obvious:

    Implementing this rule is as simple as a one-liner:

    istioctl create -f egress_httpbin.yml -n istioegress

    I can then see the Egress rule by using the command istioctl get egressrules:

    Finally, I can run the curl command again and see the correct results:

    Thinking Outside the Box

    As you can see, Istio works well with others. While you can create OpenShift services, managed by Kubernetes, and keep everything in pods and scale up and down as necessary, you still have the ability to reach outside of your environment to use services—without changing your source code...have I ever mentioned that?


    All articles in the “Introduction to Istio” series:

    • Part 1: Introduction to Istio Service Mesh
    • Part 2: Istio Route Rules: Telling Service Requests Where to Go
    • Part 3: Istio Circuit Breaker: How to Handle (Pool) Ejection
    • Part 4: Istio Circuit Breaker: When Failure Is an Option
    • Part 5: Istio Tracing & Monitoring: Where Are You and How Fast Are You Going?
    • Part 6: Istio Chaos Engineering: I Meant to Do That
    • Part 7: Istio Dark Launch: Secret Services
    • Part 8: Istio Smart Canary Launch: Easing into Production
    • Part 9: Istio Egress: Exit Through the Gift Shop
    • Part 10: Istio Service Mesh Blog Series Recap
    Last updated: September 3, 2019

    Recent Posts

    • Unleashing multimodal magic with RamaLama

    • Integrate Red Hat AI Inference Server & LangChain in agentic workflows

    • Streamline multi-cloud operations with Ansible and ServiceNow

    • Automate dynamic application security testing with RapiDAST

    • Assessing AI for OpenShift operations: Advanced configurations

    Red Hat Developers logo LinkedIn YouTube Twitter Facebook

    Products

    • Red Hat Enterprise Linux
    • Red Hat OpenShift
    • Red Hat Ansible Automation Platform

    Build

    • Developer Sandbox
    • Developer Tools
    • Interactive Tutorials
    • API Catalog

    Quicklinks

    • Learning Resources
    • E-books
    • Cheat Sheets
    • Blog
    • Events
    • Newsletter

    Communicate

    • About us
    • Contact sales
    • Find a partner
    • Report a website issue
    • Site Status Dashboard
    • Report a security problem

    RED HAT DEVELOPER

    Build here. Go anywhere.

    We serve the builders. The problem solvers who create careers with code.

    Join us if you’re a developer, software engineer, web designer, front-end designer, UX designer, computer scientist, architect, tester, product manager, project manager or team lead.

    Sign me up

    Red Hat legal and privacy links

    • About Red Hat
    • Jobs
    • Events
    • Locations
    • Contact Red Hat
    • Red Hat Blog
    • Inclusion at Red Hat
    • Cool Stuff Store
    • Red Hat Summit

    Red Hat legal and privacy links

    • Privacy statement
    • Terms of use
    • All policies and guidelines
    • Digital accessibility

    Report a website issue