SonarQube not reachable on 127.0.0.1:9000 under Ubuntu 18.04 - nginx

Question

I want to run SonarQube on my Ubuntu 18.04 server along with nginx (a Droplet at DigitalOcean).
Mostly I've followed these instructions. I've used Postgres instead of MySQL.
Nginx should accept the request and pass it to the localhost-address used by SonarQube (127.0.0.1:9000).
Nginx is running and working. SSL is active and working. Here my codequality.example.com.conf:
server {
listen 443 ssl http2;
listen [::]:443 ssl http2;
server_name codequality.example.com www.codequality.example.com;
root /var/www/html;
index index.html index.htm;
access_log /var/log/nginx/codequality.example.com.access.log;
error_log /var/log/nginx/codequality.example.com.error.log;
ssl_certificate /etc/letsencrypt/live/codequality.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/codequality.example.com/privkey.pem;
include /etc/letsencrypt/options-ssl-nginx.conf;
ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
location / {
proxy_pass http://127.0.0.1:9000;
proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto http;
}
}
The command systemctl status sonarqube gives me the following response:
● sonarqube.service - SonarQube service
Loaded: loaded (/etc/systemd/system/sonarqube.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2020-03-17 22:16:50 UTC; 5s ago
Process: 21796 ExecStop=/opt/sonarqube/bin/linux-x86-64/sonar.sh stop (code=exited, status=0/SUCCESS)
Process: 21855 ExecStart=/opt/sonarqube/bin/linux-x86-64/sonar.sh start (code=exited, status=0/SUCCESS)
Main PID: 21918 (wrapper)
Tasks: 43 (limit: 2361)
CGroup: /system.slice/sonarqube.service
├─21918 /opt/sonarqube/bin/linux-x86-64/./wrapper /opt/sonarqube/bin/linux-x86-64/../../conf/wrapper.co
├─21922 java -Dsonar.wrapped=true -Djava.awt.headless=true -Xms8m -Xmx32m -Djava.library.path=./lib -cl
└─21954 /usr/lib/jvm/java-11-openjdk-amd64/bin/java -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyF
lines 1-11/11 (END)
So I can assume that SonarQube-Server is running correctly. Trying to access SonarQube via https://codequality.example.com results in a 502 Error. The log-file says:
2020/03/17 22:19:44 [error] 19598#19598: *233 connect() failed (111: Connection refused) while connecting to upstream, client: 79.254.63.100, server: codequality.example.com, request: "GET / HTTP/2.0", upstream: "http://127.0.0.1:9000/", host: "codequality.example.com"
Trying to access the localhost (127.0.0.1:9000) during a ssh-session via curl http://127.0.0.1:9000 I get the error:
curl: (7) Failed to connect to 127.0.0.1 port 9000: Connection refused
This is the log from SonarQube:
2020.03.17 22:38:53 INFO app[][o.s.a.AppFileSystem] Cleaning or creating temp directory /opt/sonarqube/temp
2020.03.17 22:38:53 INFO app[][o.s.a.es.EsSettings] Elasticsearch listening on /127.0.0.1:9001
2020.03.17 22:38:54 INFO app[][o.s.a.ProcessLauncherImpl] Launch process[[key='es', ipcIndex=1, logFilenamePrefix=es]] from [/opt/sonarqube/elasticsearch]: /opt/sonarqube/elasticsearch/bin/elasticsearch
2020.03.17 22:38:54 INFO app[][o.s.a.SchedulerImpl] Waiting for Elasticsearch to be up and running
2020.03.17 22:38:55 INFO app[][o.e.p.PluginsService] no modules loaded
2020.03.17 22:38:55 INFO app[][o.e.p.PluginsService] loaded plugin [org.elasticsearch.transport.Netty4Plugin]
OpenJDK 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
ERROR: [2] bootstrap checks failed
1: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65535]
[2]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
2020.03.17 22:39:11 WARN app[][o.s.a.p.AbstractManagedProcess] Process exited with exit value [es]: 78
2020.03.17 22:39:11 INFO app[][o.s.a.SchedulerImpl] Process[es] is stopped
2020.03.17 22:39:11 INFO app[][o.s.a.SchedulerImpl] SonarQube is stopped
<-- Wrapper Stopped
--> Wrapper Started as Daemon
Launching a JVM...
Wrapper (Version 3.2.3) http://wrapper.tanukisoftware.org
Copyright 1999-2006 Tanuki Software, Inc. All Rights Reserved.
What am I doing wrong?

Answer 1

the problem is not the NGINX Proxy. The logfile you shared gives some insides
max file descriptors [4096] for elasticsearch process is too low, increase to at least [65535] [2]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144] 2020.03.17 22:39:11 WARN app[][o.s.a.p.AbstractManagedProcess] Process exited with exit value [es]: 78 2020.03.17 22:39:11 INFO app[][o.s.a.SchedulerImpl] Process[es] is stopped
Your SonarQube isn't running correctly because of some misconfiguration of elastic sarch.
Check this links to find out how to adjust the limit:
general information
https://www.elastic.co/guide/en/elasticsearch/reference/current/file-descriptors.html
how to chnage the settings
https://www.elastic.co/guide/en/elasticsearch/reference/master/setting-system-settings.html
Make sure SonarQube is running correctly on localhost:9000 before move on to the proxy configuration.