feat!: remove node exporter from monitoring stack (#9)

## What ❔
Remove node exporter from monitoring

## Why ❔
Redundant for this context 

## Checklist

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- [x] PR title corresponds to the body of PR (we generate changelog
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- [x] Documentation comments have been added / updated.

README.md

@@ -1,6 +1,6 @@
 # ansible-en-role
 
-Ansible role to deploy and configure zkSync Era External Node, including DB instance setup on the same machine, Traefik as reverse proxy, and Prometheus monitoring (PostgreSQL exporter, Node exporter, cAdvisor, Traefik, External Node native metrics, and VictoriaMetrics vmagent to scrape all of them).
+Ansible role to deploy and configure zkSync Era External Node, including DB instance setup on the same machine, Traefik as reverse proxy, and Prometheus monitoring (PostgreSQL exporter, cAdvisor, Traefik, External Node native metrics, and VictoriaMetrics vmagent to scrape all of them).
 
 Make sure to configure Prometheus remote write endpoint to send metrics to centralized metrics storage.
 
@@ -26,6 +26,8 @@ l1_chain_id: ""
 l2_chain_id: ""
 ```
 
+Please refer to [External Node docs](https://github.com/matter-labs/zksync-era/tree/main/docs/guides/external-node/prepared_configs) to find values for different zkSync Era chains.
+
 If you want to use monitoring (which we highly recommend), you have to change these variables:
 
 ```yaml
@@ -54,7 +56,7 @@ iptables_packages:
 loadbalancer_ip: "1.2.3.4"
 ```
 
-In most cases, you'd want to change PostgreSQL parameters (we recommend to use <https://pgtune.leopard.in.ua/> with "Online transaction processing system" preset as sane defaults), so you can do it using `postgres_arguments` variable, eg:
+In most cases, you'd want to change PostgreSQL parameters, so you can do it using `postgres_arguments` variable, eg:
 
 ```yaml
 postgres_arguments:
@@ -66,14 +68,16 @@ postgres_arguments:
   - -c
 ```
 
-We recommend using pgtune [online]<https://pgtune.leopard.in.ua/> or [self-hosted](https://github.com/le0pard/pgtune) version with "Online transaction processing system" preset as a good starting point for generating optimal config for your hardware.
+We recommend using pgtune [online](https://pgtune.leopard.in.ua/) or [self-hosted](https://github.com/le0pard/pgtune) version with "Online transaction processing system" preset as a good starting point for generating optimal config for your hardware.
 
 If you want to use basic auth for inbound requests, you have to change next variables:
+
 ```yaml
 # Enable basic auth for external node
 enable_basic_auth: true
 basic_auth_secret: "htpasswd-generated-secret"
 ```
+
 Basic auth secret can be generated by `htpasswd` and `sed` for interpolation:
 ```echo $(htpasswd -nb <username> <password>) | sed -e s/\\$/\\$\\$/g```
 
@@ -82,12 +86,17 @@ Basic auth secret can be generated by `htpasswd` and `sed` for interpolation:
 1. Install the ansible collection on your machine from where you will run ansible:
 `ansible-galaxy collection install community.general`
 
-2. Prepare the latest database backup on your host. you can download it from our [public GCS bucket](https://storage.googleapis.com/zksync-era-mainnet-external-node-backups/external_node_latest.pgdump).
-you should place it to `{{ storage_directory }}/pg_backups` directory. By default, `{{ storage_directory }}` is `/usr/src/en`
+2. Prepare the latest database backup on your host. you can download it from our public GCS buckets:
 
-3. **OPTIONAL**: If you already have external-node, you can copy tree directory to new host. Copy external-node database tree to `{{ storage_directory }}/db`.
+* [Era Mainnet latest dump](https://storage.googleapis.com/zksync-era-mainnet-external-node-backups/external_node_latest.pgdump)
+* [Era Sepolia Testnet latest dump](https://storage.googleapis.com/zksync-era-boojnet-external-node-snapshots/external_node_latest.pgdump)
+* [Era Goerli Testnet latest dump](https://storage.googleapis.com/zksync-era-testnet-external-node-backups/external_node_latest.pgdump)
 
-**Keep in mind, external-node tree should be older than PostgreSQL database backup.**
+Downloaded dump file should be placed into `{{ storage_directory }}/pg_backups` directory (`/usr/src/en/pg_backups` by default)
+
+3. **OPTIONAL**: If you already have running node, you can copy its tree and state directory to a new host's `{{ storage_directory }}/db`. (`/usr/src/en/db` by default)
+
+**Keep in mind that tree and state should be older than PostgreSQL database backup.**
 
 4. Run ansible-playbook using this role. We recommend encrypting next variables with ansible-vault or some another way:
 

defaults/main.yml

@@ -13,7 +13,6 @@ traefik_version: 2.11
 postgres_version: 14
 external_node_version: 21.0.2
 vmagent_version: 1.95.1
-node_exporter_version: 1.7.0
 cadvisor_version: 0.47.2
 postgres_exporter_version: 0.15.0
 

templates/monitoring.yaml.j2

@@ -21,18 +21,6 @@ services:
       - "--remoteWrite.vmProtoCompressLevel=2"
     restart: always
 
-  node-exporter:
-    image: "prom/node-exporter:v{{ node_exporter_version }}"
-    volumes:
-      - /proc:/host/proc:ro
-      - /sys:/host/sys:ro
-      - /:/rootfs:ro
-    restart: unless-stopped
-    command:
-      - '--path.procfs=/host/proc'
-      - '--path.sysfs=/host/sys'
-      - '--collector.filesystem.ignored-mount-points=^/(sys|proc|dev|host|etc)($$|/)'
-
   cadvisor:
     image: "gcr.io/cadvisor/cadvisor:v{{ cadvisor_version }}"
     volumes:

templates/vmagent-config.yml.j2

@@ -14,14 +14,6 @@ scrape_configs:
       - source_labels: [instance]
         target_label: instance
         replacement: '{{ node_name | mandatory }}'
-  - job_name: node-exporter
-    static_configs:
-      - targets:
-          - "node-exporter:9100"
-    relabel_configs:
-      - source_labels: [instance]
-        target_label: instance
-        replacement: '{{ node_name | mandatory }}'
   - job_name: cadvisor
     static_configs:
       - targets: