Add DNS provider for Variomedia

[ldez]

• have a homogeneous design with the other providers
• pass the linter
• do go mod tidy
• add tests (units)
• add tests ("live")
• add a provider descriptor
• generate CLI help, documentation, and readme.
• be able to do: (and put the output of this command to a comment)

rm -rf .lego/

VARIOMEDIA_API_TOKEN=xxx ./lego -m [email protected] --dns variomedia -d *.example.com -d example.com -s https://acme-staging-v02.api.letsencrypt.org/directory run

Note the wildcard domain is important.

@SIMULATAN could you test by running the previous command (you have to use a real domain and email)?

Closes #1637

[SIMULATAN]

I'll do that real quick!

One quick question: I found some of my placeholder values in the code, is that on purpose?
For example here: https://github.com/go-acme/lego/pull/1654/files#diff-964f1c0847ff2e18a14c04de7e463833ef723fff9e5dd8d6dd399b15cbe4db60R100-R101
EDIT: just read through the code and it seems like it indeed was on purpose, sorry!

[SIMULATAN]

It ran through and the last log line includes Server responded with a certificate, so it seems good!
I uploaded the full log here: https://gist.github.com/SIMULATAN/c753f8a225d61d2cbd963c3596609417
The certificates directory contains _.example.com with the extensions .crt, .issuer.crt, .json, .key
Also interesting is that the .json file with the metadata (presumably) contains the following json:

{                                                                                                                                                                                                                  
        "domain": "*.example.com",                                                                                                                                                                             
        "certUrl": "https://acme-staging-v02.api.letsencrypt.org/acme/cert/mycert",                                                                                                  
        "certStableUrl": "https://acme-staging-v02.api.letsencrypt.org/acme/cert/mycert"                                                                                             
}

is it a problem that only the wildcard domain is in there? I couldn't find an entry for the root domain alone somewhere.

2022/06/06 18:52:38 No key found for account [email protected]. Generating a P256 key.
2022/06/06 18:52:38 Saved key to /my/path/.lego/accounts/acme-staging-v02.api.letsencrypt.org/[email protected]/keys/[email protected]
2022/06/06 18:52:39 Please review the TOS at https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf
Do you accept the TOS? Y/n
y
2022/06/06 18:52:41 [INFO] acme: Registering account for [email protected]
!!!! HEADS UP !!!!

Your account credentials have been saved in your Let's Encrypt
configuration directory at "/my/path/.lego/accounts".

You should make a secure backup of this folder now. This
configuration directory will also contain certificates and
private keys obtained from Let's Encrypt so making regular
backups of this folder is ideal.
2022/06/06 18:52:41 [INFO] [*.example.com, example.com] acme: Obtaining bundled SAN certificate
2022/06/06 18:52:42 [INFO] [*.example.com] AuthURL: https://acme-staging-v02.api.letsencrypt.org/acme/authz-v3/080808
2022/06/06 18:52:42 [INFO] [example.com] AuthURL: https://acme-staging-v02.api.letsencrypt.org/acme/authz-v3/090909
2022/06/06 18:52:42 [INFO] [*.example.com] acme: use dns-01 solver
2022/06/06 18:52:42 [INFO] [example.com] acme: Could not find solver for: tls-alpn-01
2022/06/06 18:52:42 [INFO] [example.com] acme: Could not find solver for: http-01
2022/06/06 18:52:42 [INFO] [example.com] acme: use dns-01 solver
2022/06/06 18:52:42 [INFO] [*.example.com] acme: Preparing to solve DNS-01
2022/06/06 18:52:43 [INFO] Wait for variomedia: apply change on example.com [timeout: 1m0s, interval: 2s]
2022/06/06 18:52:43 [INFO] variomedia: [example.com] 101010: dns-record%!(EXTRA string=pending)
2022/06/06 18:52:45 [INFO] variomedia: [example.com] 101010: dns-record%!(EXTRA string=done)
2022/06/06 18:52:45 [INFO] [*.example.com] acme: Trying to solve DNS-01
2022/06/06 18:52:45 [INFO] [*.example.com] acme: Checking DNS record propagation using [my-dns:53]
2022/06/06 18:52:47 [INFO] Wait for propagation [timeout: 1m0s, interval: 2s]
2022/06/06 18:52:47 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:52:49 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:52:51 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:52:53 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:52:55 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:52:57 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:52:59 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:53:01 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:53:04 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:53:06 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:53:08 [INFO] [*.example.com] acme: Waiting for DNS record propagation.
2022/06/06 18:53:23 [INFO] [*.example.com] The server validated our request
2022/06/06 18:53:23 [INFO] [*.example.com] acme: Cleaning DNS-01 challenge
2022/06/06 18:53:23 [INFO] Wait for variomedia: apply change on example.com [timeout: 1m0s, interval: 2s]
2022/06/06 18:53:23 [INFO] variomedia: [example.com] 111111: dns-record%!(EXTRA string=pending)
2022/06/06 18:53:25 [INFO] variomedia: [example.com] 111111: dns-record%!(EXTRA string=done)
2022/06/06 18:53:25 [INFO] sequence: wait for 1m0s
2022/06/06 18:54:25 [INFO] [example.com] acme: Preparing to solve DNS-01
2022/06/06 18:54:26 [INFO] Wait for variomedia: apply change on example.com [timeout: 1m0s, interval: 2s]
2022/06/06 18:54:26 [INFO] variomedia: [example.com] 121212: dns-record%!(EXTRA string=pending)
2022/06/06 18:54:28 [INFO] variomedia: [example.com] 121212: dns-record%!(EXTRA string=done)
2022/06/06 18:54:28 [INFO] [example.com] acme: Trying to solve DNS-01
2022/06/06 18:54:28 [INFO] [example.com] acme: Checking DNS record propagation using [my-dns:53]
2022/06/06 18:54:30 [INFO] Wait for propagation [timeout: 1m0s, interval: 2s]
2022/06/06 18:54:51 [INFO] [example.com] The server validated our request
2022/06/06 18:54:51 [INFO] [example.com] acme: Cleaning DNS-01 challenge
2022/06/06 18:54:52 [INFO] Wait for variomedia: apply change on example.com [timeout: 1m0s, interval: 2s]
2022/06/06 18:54:52 [INFO] variomedia: [example.com] 131313: dns-record%!(EXTRA string=pending)
2022/06/06 18:54:54 [INFO] variomedia: [example.com] 131313: dns-record%!(EXTRA string=done)
2022/06/06 18:54:54 [INFO] [*.example.com, example.com] acme: Validations succeeded; requesting certificates
2022/06/06 18:54:54 [INFO] [*.example.com] Server responded with a certificate.

[ldez]

I fixed the log problem variomedia: [example.com] 131313: dns-record%!(EXTRA string=done).

The log seems right: I see 2 creates and 2 deletes.

[SIMULATAN]

I just checked the certificate and it seems like it covers both domains, even though the json only states one.
It seems like the full cert gets stored in a file with the name of the first domain passed via the -d flag. This makes sense, but it just confused me.

[dmke]

LGTM