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I have an existing service running using docker containers:

  • nginx (nginx:1.13.5)
  • node-api (node container)
  • node-website (node container)

I wanted to add SSL certificates for both api and website. So I've used certbot/certbot docker container to do so, without any problem.

I've generate the certificates using dns challenge, running the following command (from my local machine):

docker run --rm -it \
  --name certbot \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/certbot \
    certonly --manual -d api.mydomain.com --preferred-challenges dns --renew-by-default --email xxx@xxxx --agree-tos --manual-public-ip-logging-ok

I was asked to enter TXT dns record for _acme-challenge.api.mydomain.com which I did, and got the certificates generated without any issues.

I then updated my Nginx configuration (/etc/nginx/nginx.conf/api.conf):

upstream api {
  server node-api:5000 max_fails=3;
}

map $http_upgrade $connection_upgrade {
  default       "upgrade";
  ""            "";
}

# Force HTTPS
server {
  listen 80;
  server_name api.domain.com;
  return 301 https://$host$request_uri;
}

server {
  listen 443 ssl http2;
  server_name       api.domain.com;

  ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
  ssl_certificate   /etc/nginx/certificates/api.domain.com/fullchain.pem;
  ssl_certificate_key /etc/nginx/certificates/api.domain.com/privkey.pem;
  ssl_trusted_certificate /etc/nginx/certificates/api.domain.com/chain.pem;

  access_log /var/log/nginx/api-domain.access.log main;
  error_log  /var/log/nginx/api-domain.error.log error;

  location / {
    proxy_pass         http://api;
    proxy_redirect     off;

    proxy_set_header   Connection $connection_upgrade;
    proxy_set_header   Upgrade $http_upgrade;
    proxy_set_header   Host $host;
    proxy_set_header   X-Real-IP $remote_addr;
    proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
  }
}

And all good, restarted my server and now running perfectly with letsencrypt certificates! Awesome!


The problem

Now come the test of renewing the certificates... And here comes the troubles. First I just tried to run the renew --dry-run command without much of a success.

Attempting to renew cert (api.mydomain.com) from /etc/letsencrypt/renewal/api.mydomain.com.conf produced an unexpected error: The manual plugin is not working; there may be problems with your existing configuration. The error was: PluginError('An authentication script must be provided with --manual-auth-hook when using the manual plugin non-interactively.',). Skipping.

So I've tried using the standalone option:

docker run --rm -it \
  --name certbot \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/certbot \
    renew --dry-run --standalone --preferred-challenges dns

and got this error:

Attempting to renew cert (api.mydomain.com) from /etc/letsencrypt/renewal/api.mydomain.com.conf produced an unexpected error: None of the preferred challenges are supported by the selected plugin. Skipping.

So I'm deducting that I cannot use dns challenges for the renewal of the certificate, fair enough.

Let's try with tls-sni that Nginx is supporting (I verified, it is enabled)

docker run --rm -it \
  --name certbot \
  -v $(pwd)/letsencrypt:/etc/letsencrypt \
  certbot/certbot \
    renew --dry-run --standalone --preferred-challenges tls-sni

And now I have this error:

Attempting to renew cert (api.mydomain.com) from /etc/letsencrypt/renewal/api.mydomain.com.conf produced an unexpected error: Failed authorization procedure. api.mydomain.com (tls-sni-01): urn:acme:error:unauthorized :: The client lacks sufficient authorization :: Incorrect validation certificate for tls-sni-01 challenge. Requested e0fd03ddade6d902d5947028985253ba.63b177f317335bf9297f0bb963135fee.acme.invalid from 13.210.106.2:443. Received 2 certificate(s), first certificate had names "api.mydomain.com". Skipping.

I'm wondering if I need to enable something specific on Nginx side such as OCSP, ssl_stapling or ssl_dhparam

I've also noticed that if I'm trying to re-run the certonly on a different server than I got the certificates from, the dns challenge value is not the same.


So I have 2 questions:

  • Can I easily fix the tls-sni verification challenge tuning the nginx configuration?

  • If I re-run certonly with dns challenge on the actual server (where nginx container is running), updating the TXT record with the new ones generated. Can I renew certificates later on, using certonly command? Will the TXT record values change over time?

Thanks a lot in advance

1

Not much activity on ServerFault, so here is the answer:

https://github.com/certbot/certbot/issues/5252#issuecomment-346500852

1

Thanks maxwell2022! Here's what my final solution looks like, based on your answer. Tested on CentOS 7. I manually created the directory /etc/letsencrypt/acme-challenge.

NGINX Server Block

server {
    listen 80;
    server_name MY_DOMAIN;

    location /.well-known/acme-challenge/ {
        root /etc/letsencrypt/acme-challenge;
    }
}

Create the Cert

docker run -it --rm --name certbot -v /etc/letsencrypt:/etc/letsencrypt -v /var/lib/letsencrypt:/var/lib/letsencrypt certbot/certbot certonly --webroot -w /etc/letsencrypt/acme-challenge/ --domain MY_DOMAIN --agree-tos --email MY_EMAIL

Renew the Cert

docker run -it --rm --name certbot -v /etc/letsencrypt:/etc/letsencrypt -v /var/lib/letsencrypt:/var/lib/letsencrypt certbot/certbot renew --webroot -w /etc/letsencrypt/acme-challenge/
docker kill --signal=HUP proxy
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This wasn't your problem when the issue first occurred, but it'd cause problems now so I'll mention it:

The TLS-SNI challenges are being phased out, as they are insecure under many common hosting platforms. If you are currently relying on having certificates issued this way, you will need to transition to HTTP- or DNS-based challenges.

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