Caddy JSON support

[fyr77]

Hi!

This project looks really cool! Is there any chance of compatibility with Caddy's flavour of JSON logs in the future?

Thanks in any case!

[K0lin]

Thank you for raising this
discussion.

We are currently resolving some issues, but one of our goals will be to include Caddy. I will keep you updated on developments.

[K0lin]

Can I ask you for some more information about the standard format of Caddy logs? Is there automatic file rotation, does each endpoint have its own "personal" file, or is everything stored in one file, as with Traefik?

[fyr77]

Sure!

The annoying part: it depends.
To good part: You can configure it quite freely. Docs are here: https://caddyserver.com/docs/caddyfile/directives/log

• The path can be freely specified in the config. I don't believe there to be a default path.
• By default, Caddy rolls the logs automatically into gzip compressed archives:
  • After 100MiB
  • Keeps last 10 log files before deleting the oldest one
  • Keeps log files for maximum 2160h (90 days)
  • Users can modify all these settings
• Caddy has two format options by default, console and json, where the former is for better human readability.
• Separate vs. one single log file depends on what the user configures. If all vhosts have the same log file specified, they will all log to one file.

Example Caddy JSON log

{"level":"info","ts":1767690562.5659065,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/","headers":{"Te":["trailers"],"Cache-Control":["no-cache"],"Sec-Fetch-Mode":["navigate"],"Sec-Gpc":["1"],"Sec-Fetch-User":["?1"],"Priority":["u=0, i"],"Pragma":["no-cache"],"Sec-Fetch-Dest":["document"],"Upgrade-Insecure-Requests":["1"],"Sec-Fetch-Site":["none"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Cookie":["REDACTED"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Accept":["text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.00226026,"size":1546,"status":200,"resp_headers":{"Etag":["\"1844-602ce41663600-gzip\""],"Accept-Ranges":["bytes"],"Via":["1.1 Caddy"],"Strict-Transport-Security":["max-age=15552000"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Vary":["Accept-Encoding"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Content-Encoding":["gzip"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Server":["Apache/2.4.57 (Debian)"],"Content-Length":["1546"],"Content-Type":["text/html"]}}
{"level":"info","ts":1767690562.5878196,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/lib/leaflet/1.6.0/leaflet.css","headers":{"Pragma":["no-cache"],"Sec-Gpc":["1"],"Referer":["https://test.example.org/"],"Te":["trailers"],"Accept":["text/css,*/*;q=0.1"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Cookie":["REDACTED"],"Sec-Fetch-Dest":["style"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Sec-Fetch-Mode":["no-cors"],"Cache-Control":["no-cache"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Sec-Fetch-Site":["same-origin"],"Priority":["u=2"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.00201323,"size":3265,"status":200,"resp_headers":{"Etag":["\"353c-602ce41663600-gzip\""],"Vary":["Accept-Encoding"],"Content-Encoding":["gzip"],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Server":["Apache/2.4.57 (Debian)"],"Accept-Ranges":["bytes"],"Strict-Transport-Security":["max-age=15552000"],"Content-Length":["3265"],"Content-Type":["text/css"]}}
{"level":"info","ts":1767690562.5879638,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/style.css","headers":{"Pragma":["no-cache"],"Cache-Control":["no-cache"],"Accept":["text/css,*/*;q=0.1"],"Sec-Gpc":["1"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Sec-Fetch-Mode":["no-cors"],"Sec-Fetch-Site":["same-origin"],"Te":["trailers"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Referer":["https://test.example.org/"],"Cookie":["REDACTED"],"Sec-Fetch-Dest":["style"],"Priority":["u=2"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.002132982,"size":2109,"status":200,"resp_headers":{"Accept-Ranges":["bytes"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Vary":["Accept-Encoding"],"Content-Length":["2109"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Etag":["\"1bac-602ce41663600-gzip\""],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Strict-Transport-Security":["max-age=15552000"],"Content-Encoding":["gzip"],"Content-Type":["text/css"],"Server":["Apache/2.4.57 (Debian)"]}}
{"level":"info","ts":1767690562.5888326,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/main.js","headers":{"Sec-Fetch-Site":["same-origin"],"Cache-Control":["no-cache"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Referer":["https://test.example.org/"],"Sec-Fetch-Dest":["script"],"Pragma":["no-cache"],"Te":["trailers"],"Accept":["*/*"],"Cookie":["REDACTED"],"Sec-Fetch-Mode":["no-cors"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Sec-Gpc":["1"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.002807112,"size":9546,"status":200,"resp_headers":{"Alt-Svc":["h3=\":443\"; ma=2592000"],"Etag":["\"9446-602ce41663600-gzip\""],"Vary":["Accept-Encoding"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Strict-Transport-Security":["max-age=15552000"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Accept-Ranges":["bytes"],"Content-Encoding":["gzip"],"Content-Type":["text/javascript"],"Server":["Apache/2.4.57 (Debian)"],"Content-Length":["9546"],"Via":["1.1 Caddy"]}}
{"level":"info","ts":1767690562.5893676,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/assets/location-pending.svg","headers":{"Referer":["https://test.example.org/"],"Cookie":["REDACTED"],"Sec-Fetch-Site":["same-origin"],"Priority":["u=5, i"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Sec-Fetch-Mode":["no-cors"],"Accept":["image/avif,image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5"],"Pragma":["no-cache"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Sec-Fetch-Dest":["image"],"Cache-Control":["no-cache"],"Te":["trailers"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Sec-Gpc":["1"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.001072904,"size":781,"status":200,"resp_headers":{"Content-Length":["781"],"Content-Type":["image/svg+xml"],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Strict-Transport-Security":["max-age=15552000"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Server":["Apache/2.4.57 (Debian)"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Etag":["\"30d-602ce41663600\""],"Accept-Ranges":["bytes"]}}
{"level":"info","ts":1767690562.5894578,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/dynamic.js.php","headers":{"Sec-Fetch-Dest":["script"],"Sec-Fetch-Mode":["no-cors"],"Cache-Control":["no-cache"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Cookie":["REDACTED"],"Sec-Fetch-Site":["same-origin"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Accept":["*/*"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Referer":["https://test.example.org/"],"Priority":["u=2"],"Sec-Gpc":["1"],"Pragma":["no-cache"],"Te":["trailers"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.003646689,"size":347,"status":200,"resp_headers":{"Strict-Transport-Security":["max-age=15552000"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"X-Powered-By":["PHP/8.2.8"],"Vary":["Accept-Encoding"],"Content-Encoding":["gzip"],"Content-Length":["347"],"Content-Type":["text/javascript; charset=utf-8"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Server":["Apache/2.4.57 (Debian)"],"Via":["1.1 Caddy"]}}
{"level":"info","ts":1767690562.5894833,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/assets/logo.svg","headers":{"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Sec-Gpc":["1"],"Cookie":["REDACTED"],"Priority":["u=5, i"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Sec-Fetch-Dest":["image"],"Te":["trailers"],"Sec-Fetch-Site":["same-origin"],"Cache-Control":["no-cache"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Referer":["https://test.example.org/"],"Sec-Fetch-Mode":["no-cors"],"Pragma":["no-cache"],"Accept":["image/avif,image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.001144928,"size":10354,"status":200,"resp_headers":{"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Server":["Apache/2.4.57 (Debian)"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Accept-Ranges":["bytes"],"Etag":["\"2872-602ce41663600\""],"Content-Length":["10354"],"Content-Type":["image/svg+xml"],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Strict-Transport-Security":["max-age=15552000"]}}
{"level":"info","ts":1767690562.5909753,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/lib/leaflet/1.6.0/leaflet.js","headers":{"Sec-Gpc":["1"],"Referer":["https://test.example.org/"],"Cookie":["REDACTED"],"Te":["trailers"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Sec-Fetch-Mode":["no-cors"],"Sec-Fetch-Site":["same-origin"],"Priority":["u=2"],"Cache-Control":["no-cache"],"Pragma":["no-cache"],"Accept":["*/*"],"Sec-Fetch-Dest":["script"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Accept-Encoding":["gzip, deflate, br, zstd"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.005223634,"size":41046,"status":200,"resp_headers":{"Strict-Transport-Security":["max-age=15552000"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Server":["Apache/2.4.57 (Debian)"],"Vary":["Accept-Encoding"],"Content-Type":["text/javascript"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Content-Encoding":["gzip"],"Content-Length":["41046"],"Etag":["\"22d51-602ce41663600-gzip\""],"Accept-Ranges":["bytes"],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"]}}
{"level":"info","ts":1767690562.6122444,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/assets/lang/en.json","headers":{"Sec-Fetch-Dest":["empty"],"Pragma":["no-cache"],"Cache-Control":["no-cache"],"Te":["trailers"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Sec-Fetch-Site":["same-origin"],"Accept":["*/*"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Sec-Fetch-Mode":["cors"],"Sec-Gpc":["1"],"Referer":["https://test.example.org/"],"Cookie":["REDACTED"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.001782519,"size":2173,"status":200,"resp_headers":{"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Etag":["\"87d-602ce41663600\""],"Content-Length":["2173"],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Strict-Transport-Security":["max-age=15552000"],"Content-Type":["application/json"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Server":["Apache/2.4.57 (Debian)"],"Accept-Ranges":["bytes"]}}
{"level":"info","ts":1767690562.7300415,"logger":"http.log.access.log9","msg":"handled request","request":{"remote_ip":"100.200.300.172","remote_port":"49476","client_ip":"100.200.300.172","proto":"HTTP/2.0","method":"GET","host":"test.example.org","uri":"/assets/favicon.svg","headers":{"Te":["trailers"],"Accept-Encoding":["gzip, deflate, br, zstd"],"Sec-Fetch-Mode":["no-cors"],"User-Agent":["Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0"],"Sec-Gpc":["1"],"Referer":["https://test.example.org/"],"Cookie":["REDACTED"],"Priority":["u=6"],"Pragma":["no-cache"],"Accept":["image/avif,image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5"],"Accept-Language":["en-GB,en-US;q=0.7,en;q=0.3"],"Sec-Fetch-Dest":["image"],"Sec-Fetch-Site":["same-origin"],"Cache-Control":["no-cache"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","server_name":"test.example.org"}},"bytes_read":0,"user_id":"","duration":0.001927809,"size":8687,"status":200,"resp_headers":{"Content-Type":["image/svg+xml"],"Date":["Tue, 06 Jan 2026 09:09:22 GMT"],"Last-Modified":["Sun, 13 Aug 2023 13:52:24 GMT"],"Via":["1.1 Caddy"],"Alt-Svc":["h3=\":443\"; ma=2592000"],"Etag":["\"21ef-602ce41663600\""],"Accept-Ranges":["bytes"],"Server":["Apache/2.4.57 (Debian)"],"Strict-Transport-Security":["max-age=15552000"],"Content-Length":["8687"]}}

This is from accessing an instance of Hauk in its official container that uses Apache behind Caddy, that's why there are mentions of that in there.

I have redacted the IP addresses and domains, I have also accessed this in the same network. If you need different logs, let me know.

I am guessing one could use the Caddy transform-encoder plugin to make the log look like traefik logs, but I have not gotten around to doing that yet.

[K0lin]

Thank you @fyr77,

development for caddy support is underway. If you don't mind, I'd like to ask you if you have a caddy instance, could you try running the code from the k0lin/loglynx:dev-k image, which has caddy support.

You can see the changes in the caddy-support branch.

To enable caddy parsing, you should configure the environment variable:

CADDY_LOG_PATH = #your_log_path

If you can't, it's no problem, but if you try it, let me know how it goes by opening an issue if there are any problems or here if everything goes well. Thanks in advance.

P.S. In this PR #45 you can see the changes made.

[Stylee32]

@K0lin - in the wiki for Caddy setup, it says "Configure separate log files per site and add multiple sources in LogLynx". How do you add multiple sources to Loglynx when using Docker? I thought doing CADDY_LOG_PATH=/var/log/caddy/test1_test_ovh_access.log,/var/log/caddy/test2_test_ovh_access.log would parse them (with the comma) but no luck.

[K0lin]

@Stylee32 Thank you for writing. Currently, support for multiple Caddy log files is not yet available, so for now Loglynx supports the parsing and management of a single log file. You can set up the unified log via Caddy.