Tag: aws

microk8s, nginx ingress and X-Forwarded-For

Sometimes when you run microk8s in AWS, you may want to have an application load balancer in front. Such configurations mess around with the value of the header X-Forwarded-For regardless of whether the append attribute is present on the load balancer. By reading the nginx ingress documentation, you need to edit the ConfigMap resource and add proxy-real-ip-cidr and use-forwarded-headers. You may also set compute-full-forwarded-for.

It only remains to figure out the name of the ConfigMap when ingress is installed with microk8s enable ingress. It is named nginx-load-balancer-microk8s-conf :

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-load-balancer-microk8s-conf
  namespace: ingress
data:
  proxy-real-ip-cidr: 172.31.0.0/16
  use-forwarded-headers: "true"

aws ssm describe-instance-information for quick ansible dynamic inventory

The aws ssm agent is very useful when working both with EC2 instances and with machinery outside AWS. Once you add an outside instance by installing and configuring the SSM agent, be it on-premises or a VM at another provider, you can tag it for further granularity with aws ssm add-tags-to-resource --resource-type ManagedInstance --resource-id mi-WXYZWXYZ --tags Key=onpremise,Value=true --region eu-west-1 where mi-WXYZWXYZ is the instance ID you see at the SSM’s managed instances list (alternatively you can get this list with aws ssm describe-instance-information along with lots of other information).

It may the case that sometimes you want to apply with ansible a certain change to those machines that live outside AWS. Yes you can run ansible workbooks via the SSM directly, but this requires ansible installed on said machines. If you need the simplest of dynamic inventories, to $ ansible -u user -i ./lala all -m ping here is the crudest version of ./lala, one that happily ignores the --list argument:

#!/bin/bash
printf "%s%s%s" \
'{ "all": { "hosts": [' \
$(aws ssm describe-instance-information --region eu-west-1 --filter Key=tag:onpremise,Values=true --query "InstanceInformationList[].IPAddress" --output text | tr '[:blank:]' ',') \
'] } }'

You can go all the way scripting something like this for a proper solution though.

Why printf instead of echo above? Because jpmens suggested so.