ngx-cache-inspector

Inspect headers and bodies of nginx's cache files. Currently cache files marked as version 3 and 5 are supported.

Example output of inspecting a cache file:

Version:             3
Valid until:         Wed Mar  1 19:09:18 UTC 2017
Last modified:       Wed Dec 31 23:59:59 UTC 1969
Created:             Wed Mar  1 18:39:18 UTC 2017
CRC32:               2863228699
Valid msec:          0
Header start offset: 195
Body start offset:   476
ETag length:         0
ETag:
Vary len:            15
Vary:                Accept-Encoding
Variant:             some variant
Cache key:           your cache key

The code itself is a thin CLI wrapper around parsing facilities included in ngx-cache-purge.

Installation

Grab yourself a binary from the releases page or build your own from source - see below.

Building from source

The easiest way to build the project is using haskell stack tool:

$ git clone https://github.com/pbogdan/ngx-cache-inspector.git
$ cd ngx-cache-inspector
$ stack build

the executable can then be run with:

$ stack exec -- nci

To find the location of nci you can use:

$ stack exec -- which nci

Usage

Inspecting a single file

$ nci inspect file [--dump-body]

Inspect the header of a single cache file.

Flags

• --dump-body - an optional flag that can be used to dump the cached response body stored in the file. nci will attempt to decompress the body, if that fails it will dump the raw result.

Searching for cache files mathching a predicate.

$ nci find path (--key needle | --valid-until [+-]date | --created [+-]date | --etag needle | --vary needle) ([--and] | [--or]) [--inspect]

Find cache files matching the flags.

path specifies the location of the cache directory.

Flags.

At least one of --key, --valid-until, --created, --etag, --vary flags needs to be specified. When more than one flag is specified they will be combined with "and" semantics. For example:

$ nci find /srv/nginx/cache --key example.com --valid-until 2017-03-06

will search for cache files with the key containing example.com string that are due to expire on 2017-03-06. This can be overridden with the --or flag, this will search for files matching any of the conditions.

The arguments passed to valid-until and created flags accept an optional + or - prefix. If not specified an exact match will performed. + allows searching for values that are greater than the argument, with - searching for values that are lower than the argument. For example:

$ nci find /srv/nginx/cache --valid-until 2017-03-06 00:00:00

will find cache files that are due to expire exactly on 2017-03-06 00:00:00.

$ nci find /srv/nginx/cache --valid-until "+2017-03-06 00:00:00"

will find cache files that are due to expire after 2017-03-06 00:00:00. And

$ nci find /srv/nginx/cache --valid-until "-2017-03-06 00:00:00"

will find cache files that are due to expire before 2017-03-06 00:00:00.

nci supports the same date formats as git.

• --key needle- search for needle within the cache key.
• --valid-until [+-]date - compare valid until date against the argument.
• --created [+-]date - compare created date against the argument.
• --etag needle - search for needle within the etag.
• --vary needle - search for needle within vary.
• --and - combine the flags with "and".
• --or - combine the flags with "or".
• --inspect - optionally dump the header of each matched cache file

License

BSD3