docs: Add dev doc for component upgrade

Signed-off-by: Suraj Deshmukh <suraj@kinvolk.io>

docs/development/updating-components.md

@@ -0,0 +1,90 @@
+# How to update components?
+
+## Introduction
+
+This is a developer document (not for end users) which explains how to upgrade a particular component in lokoctl. This includes steps to pull config from upstream.
+
+## Find updates
+
+To figure out which component is out dated run the following command in the root of this repository:
+
+```bash
+./scripts/find-updates.sh
+```
+
+## Etcd
+
+Find the old version and newer version from the `./scripts/find-updates.sh` script and export it accordingly.
+
+```bash
+export OLD_VERSION="<old version>"
+export NEW_VERSION="<new version>"
+```
+
+Now run the following commands in the root of this repository:
+
+```bash
+sed -i "s|$OLD_VERSION|$NEW_VERSION|g" assets/lokomotive-kubernetes/*/flatcar-linux/kubernetes/cl/controller.yaml.tmpl
+make update-assets
+```
+
+- Releases: https://github.com/etcd-io/etcd/releases.
+
+## Calico
+
+To update Calico update the image tags in following files:
+
+- `assets/lokomotive-kubernetes/bootkube/resources/charts/calico/values.yaml`
+- `assets/lokomotive-kubernetes/bootkube/variables.tf`
+
+If there are changes necessary in the helm chart, make them in `assets/lokomotive-kubernetes/bootkube/resources/charts/calico`.
+
+- Releases: https://github.com/projectcalico/calico/releases.
+
+## Cert Manager
+
+Run the following commands in the root of this repository:
+
+```bash
+cd assets/components/cert-manager
+helm repo add jetstack https://charts.jetstack.io
+helm repo update
+
+rm -rf manifests
+helm fetch --untar --untardir ./ jetstack/cert-manager
+mv cert-manager manifests
+
+git checkout ./manifests/templates/letsencrypt-clusterissuer-prod.yaml
+git checkout ./manifests/templates/letsencrypt-clusterissuer-staging.yaml
+git checkout ./manifests/templates/namespace.yaml
+```
+
+- Releases: https://github.com/jetstack/cert-manager/releases.
+
+## Metrics Server
+
+Run the following commands in the root of this repository:
+
+```bash
+cd assets/components
+rm -rf metrics-server
+helm fetch --untar --untardir ./ stable/metrics-server
+```
+
+- More information about the chart can be found here: https://github.com/helm/charts/tree/master/stable/metrics-server.
+- Code repository: https://github.com/kubernetes-sigs/metrics-server.
+
+## OpenEBS
+
+Run the following commands in the root of this repository:
+
+```bash
+cd assets/components
+rm -rf openebs
+helm fetch --untar --untardir ./ stable/openebs
+git checkout openebs/crds/storagepoolclaims.yaml
+```
+
+- Installation instructions: https://docs.openebs.io/docs/next/installation.html.
+- More information about the chart: https://github.com/helm/charts/tree/master/stable/openebs.
+- Code repository: https://github.com/openebs/openebs.