How to build an old version of NGINX Ingress Controller and patch it

In this HOWTO, we will fix a bug in the ancient version of nginx ingress controller v0.20.0 and learn how to work with Go dependencies of older versions through dep + vendor.

The original article was taken with the consent of the author from the site vitya.top.

Problem

ingress-nginx version v0.20.0 adds extra slashes when rewrite. This prevents seamless migration to the latest version (v0.32.0), so developers in some cases had to do this design:

path: /service/api/v1/tokens
rewrite-target: /api/v1/tokens

If add / to the end a YAML object of type Ingressthen ingress-nginx 0.20.0 starts doing rewrite in / api / v1 / tokens //. It is impossible to refuse such a construction, because someone accesses the service with a slash at the end, and someone without.

We decided to patch the old NGINX Ingress to get rid of the annoying bug. And then move according to plan:

• Change the paths and rewrites in ingresses to human ones first (with a slash at the end).
• Migrate to a new Ingress Controller running on a different port.

But first, you need to fix the problem in the source code of the controller of the old version.

Decision

AT these lines variable location.Rewrite.Target change to strings.TrimSuffix (location.Rewrite.Target, “/”).

Download source:

go get k8s.io/ingress-nginx
cd ~/go/src/k8.io/ingress-inginx

Switch to the branch you want to fix:

git checkout v0.20.0

We rule architecture in Makefile. so as not to collect an extra 40 minutes:

vim Makefile

(or sed -i -e 's/^ALL_ARCH.*/ALL_ARCH = amd64/g')

We introduce their edits:

vim internal/ingress/controller/template/template.go +539

(here we change the variable – see “Purpose”)

Fixim Docker image to build Go:

vim build/go-in-docker.sh

Namely:

• change E2E_IMAGE on the docker.myregistry.com/ops/golang:1.10.7-alpine3.8-v7;
• delete in the same file –entrypoint $ {FLAGS}.

Save edits:

git add -A
git commit -m "Fix trailing slash bug"

Install the dependencies for the assembly:

dep ensure =v  # ключевой момент, без этого будет ругаться на internal инклуды

We start the assembly and wait (5 minutes):

make

tagged quay.io/kubernetes-ingress-controller/nginx-ingress-controller-amd64:0.20.0

We hang tag and push:

docker tag quay.io/kubernetes-ingress-controller/nginx-ingress-controller-amd64:0.20.0 docker.myregistry.com/ops/nginx-ingress-controller:0.20.0-patched-2

docker push docker.myregistry.com/ops/nginx-ingress-controller:0.20.0-patched-2

Done!

By the way, we are looking for a cool Kubernetes admin.