HOST: http://ngxcbm.apiary.io/
--- Couchbase NGINX Module ---
---
This document describes the REST API exposed to access Couchbase
resources
There are several terms we are using while describing this API.
Term |
Definition |
document |
Arbitrary JSON or BLOB value. It could be referenced by its ID |
mount point |
The part of URI which where couchbase nginx module connected |
---
--
Configuration and URIs
The Couchbase API could be mount to any endpoint in your application, and during configuration the bucket name and credentials should be specified like this:
server {
location /wonderland/ {
couchbase_pass example.com:8091,example.org bucket=wonderland;
}
...
}
The config section above tell nginx to use `/wonderland/` mount point to expose Couchbase API.
By default only Document API will be mounted, i.e. only CRUD operations can be executed there. Because in Couchbase itself both Document and Views APIs lives in completely different namespaces, the nginx module also keeps them separate. The example below will mount views and the documents into the common root.
server {
location /wonderland/docs/ {
couchbase_pass example.com:8091,example.org bucket=wonderland;
}
location /wonderland/views/ {
couchbase_pass example.com:8091,example.org bucket=wonderland views=true;
}
...
}
The connection configuration could be shared amound the locations using upstream
upstream couchbase {
couchbase_server example.com:8091;
couchbase_server example.org;
couchbase_bucket wonderland;
}
server {
location /wonderland/docs/ {
couchbase_pass couchbase;
}
location /wonderland/views/ {
couchbase_pass views=true;
}
...
}
--
--
Document CRUD
The module maps basic data operations to HTTP methods. The table below assumes that the bucket mount to `/storage` location:
Couchbase operation |
HTTP method |
Comments |
get "foo" |
GET /storage/foo |
|
add "foo" "bar" |
POST /storage/foo |
document goes in request's body, fails if ID exists already |
|
POST /storage |
the same as above, but will generate ID |
set "foo" "bar" |
PUT /storage/foo |
document goes in request's body |
delete "foo" |
DELETE /storage/foo |
|
Apart from HTTP methods, it is possible to use arguments in query string, to specify the command. To do so, the name of the parameter must be specified in the config:
server {
location /wonderland/ {
couchbase_pass example.com:8091,example.org bucket=wonderland;
set $couchbase_cmd $arg_cmd
set $couchbase_exptime $arg_exptime;
}
...
}
The snippet above will translate this URI `/storage/foo?cmd=replace&exptime=40` to the `replace "foo" ...` command with expiration of 40 seconds. In the same way can be controller ID, value, flags and expiration time.
The rest of the section demonstrates various example of usage the API, including optimistic locking with CAS. It assumes the following config:
server {
location /wonderland/ {
couchbase_pass example.com:8091,example.org bucket=wonderland;
add_header ETag $couchbase_cas;
}
...
}
--
Create document in the bucket
POST /wonderland
> Content-Type: application/json
{"name":"Alice","species":"human"}
< 201
< ETag: 10952782243130507264
< Location: http://ngxcbm.apiary.io/wonderland/0a4683e4b4b161f505d0c2ae0c3a1abf
You can also specify ID with POST request if you need to `create` the
document with given ID.
POST /wonderland/alice
> Content-Type: application/json
{"name":"Alice","species":"human"}
< 201
< ETag: 10952782243130507265
< Location: http://ngxcbm.apiary.io/wonderland/alice
Note that when you are using POST request, the server is always
supposed to create the new document. This means that you will get an
error if the document already exists.
POST /wonderland/foobar
> Content-Type: application/json
{"foo":"bar"}
< 409
< Content-Type: application/json
< Content-Length: 74
{"error":"key_eexists","reason":"Key exists (with a different ETag value)"}
Update the document
PUT /wonderland/white-rabbit
> Content-Type: application/json
{"name":"Write Rabbit","species":"rabbit"}
< 204
< ETag: 10952782243130507266
< Location: http://ngxcbm.apiary.io/wonderland/white-rabbit
You can also specify `If-Match` header and the server will perform
optimistic lock before updating. This operation might fail `412
Precondition Failed`
PUT /wonderland/duchess
> Content-Type: application/json
> If-Match: "wrong_etag"
{"name":"Duchess","species":"human"}
< 412
< Content-Type: application/json
< Content-Length: 74
{"error":"key_eexists","reason":"Key exists (with a different ETag value)"}
If the document being updated doesn't exist, you will get `404 Not
Found` error
PUT /wonderland/sheep
{"name":"Sheep","species":"sheep"}
< 404
< Content-Type: application/json
< Content-Length: 45
{"error":"key_enoent","reason":"No such key"}
Removing document from the bucket
DELETE /wonderland/caterpillar
< 204
< ETag: 10952782243130507267
You can also specify `If-Match` header if you need to ensure you are removing
know version of the document.
DELETE /wonderland/bill-the-lizard
> If-Match: "wrong_etag"
< 412
< Content-Type: application/json
< Content-Length: 74
{"error":"key_eexists","reason":"Key exists (with a different ETag value)"}
If the document being removed doesn't exist, you will get `404 Not
Found` error
DELETE /wonderland/jabberwock
< 404
< Content-Type: application/json
< Content-Length: 45
{"error":"key_enoent","reason":"No such key"}
Getting the document by ID.
GET /wonderland/hatter
< 200
< Content-Type: application/json
< Content-Length: 36
< ETag: 10952782243130507268
{"name":"Hatter","species":"human"}
In case when the given document ID isn't exist in the bucket you will
get `404 Not Found`
GET /wonderland/red-queen
< 404
< Content-Type: application/json
< Content-Length: 45
{"error":"key_enoent","reason":"No such key"}
Use `HEAD` request to skip the document body
HEAD /wonderland/gryphon
< 200
< Content-Type: application/json
< ETag: 10952782243130507269
Each operation is carry ETag, which internally is CAS value. The ETag
value can be used in the conditional requests with `If-Match`,
`If-None-Match`. See examples of `If-Match` above.
Check if the key has been modified (in this case the server responds
that it wasn't modified):
HEAD /wonderland/dormouse
> If-None-Match: 10952782243130507269
< 304
--
Couchbase Views
This section shows more advanced server feature: View indexes
One of the features of the Couchbase is ability to build efficient indexes leveraging Map/Reduce. They are called Views and you can define them on Admin Console UI.
The module allows you to query your views proxying them to Couchbase. All arguments will be transparently passed to Couchbase and the result will be streamed back.
As mentioned above, the view endpoint should be mount separately
server {
location /wonderland/views/ {
couchbase_pass example.com:8091,example.org bucket=wonderland views=true;
}
...
}
For example we have a view *all* defined in the design document *characters*. It is simple map which will just emit all known characters (without any reduce function):
function (doc, meta) {
emit(meta.id);
}
--
Query view with default settings
GET /wonderland/views/_design/characters/_view/all
< 200
< Transfer-Encoding: chunked
< Content-Type: application/json
{"total_rows":20,"rows":[
{"id":"alice","key":"alice","value":null},
{"id":"bill-the-lizard","key":"bill-the-lizard","value":null},
{"id":"caterpillar","key":"caterpillar","value":null},
{"id":"cheshire-cat","key":"cheshire-cat","value":null},
{"id":"dodo","key":"dodo","value":null},
{"id":"dormouse","key":"dormouse","value":null},
{"id":"duchess","key":"duchess","value":null},
{"id":"duck","key":"duck","value":null},
{"id":"eaglet","key":"eaglet","value":null},
{"id":"gryphon","key":"gryphon","value":null},
{"id":"hatter","key":"hatter","value":null},
{"id":"king-of-hearts","key":"king-of-hearts","value":null},
{"id":"knave-of-hearts","key":"knave-of-hearts","value":null},
{"id":"lory","key":"lory","value":null},
{"id":"march-hare","key":"march-hare","value":null},
{"id":"mock-turtle","key":"mock-turtle","value":null},
{"id":"mouse","key":"mouse","value":null},
{"id":"pat","key":"pat","value":null},
{"id":"queen-of-hearts","key":"queen-of-hearts","value":null},
{"id":"white-rabbit","key":"white-rabbit","value":null}
]
}
You can pass the any of supported query parameters, like *include_docs=true* for example (note that {{rev}} field replaced with {{etag}}:
GET /wonderland/views/_design/characters/_view/all?include_docs=true
< 200
< Transfer-Encoding: chunked
< Content-Type: application/json
{"total_rows":20,"rows":[
{"id":"alice","key":"alice","value":null,"doc":{"meta":{"id":"alice","expiration":0,"flags":0,"etag":88499348547108864},"json":{"name":"Alice","species":"human"}}},
{"id":"bill-the-lizard","key":"bill-the-lizard","value":null,"doc":{"meta":{"id":"bill-the-lizard","expiration":0,"flags":0,"etag":12227673967682453504},"json":{"name":"BilltheLizard","species":"lizard"}}},
{"id":"caterpillar","key":"caterpillar","value":null,"doc":{"meta":{"id":"caterpillar","expiration":0,"flags":0,"etag":7907600423173816320},"json":{"name":"Caterpillar","species":"caterpillar"}}},
{"id":"cheshire-cat","key":"cheshire-cat","value":null,"doc":{"meta":{"id":"cheshire-cat","expiration":0,"flags":0,"etag":15887700786432507904},"json":{"name":"CheshireCat","species":"cat"}}},
{"id":"dodo","key":"dodo","value":null,"doc":{"meta":{"id":"dodo","expiration":0,"flags":0,"etag":14764617828380246016},"json":{"name":"Dodo","species":"bird"}}},
{"id":"dormouse","key":"dormouse","value":null,"doc":{"meta":{"id":"dormouse","expiration":0,"flags":0,"etag":4027757040775528448},"json":{"name":"Dormouse","species":"dormouse"}}},
{"id":"duchess","key":"duchess","value":null,"doc":{"meta":{"id":"duchess","expiration":0,"flags":0,"etag":17543907245979402240},"json":{"name":"Duchess","species":"human"}}},
{"id":"duck","key":"duck","value":null,"doc":{"meta":{"id":"duck","expiration":0,"flags":0,"etag":13461959332744724480},"json":{"name":"Duck","species":"bird"}}},
{"id":"eaglet","key":"eaglet","value":null,"doc":{"meta":{"id":"eaglet","expiration":0,"flags":0,"etag":8572459711327174656},"json":{"name":"Eaglet","species":"bird"}}},
{"id":"gryphon","key":"gryphon","value":null,"doc":{"meta":{"id":"gryphon","expiration":0,"flags":0,"etag":14715372901595414528},"json":{"name":"Gryphon","species":"gryphon"}}},
{"id":"hatter","key":"hatter","value":null,"doc":{"meta":{"id":"hatter","expiration":0,"flags":0,"etag":3615690869010661376},"json":{"name":"Hatter","species":"human"}}},
{"id":"king-of-hearts","key":"king-of-hearts","value":null,"doc":{"meta":{"id":"king-of-hearts","expiration":0,"flags":0,"etag":6164167507172196352},"json":{"name":"KingofHearts","species":"card"}}},
{"id":"knave-of-hearts","key":"knave-of-hearts","value":null,"doc":{"meta":{"id":"knave-of-hearts","expiration":0,"flags":0,"etag":205344449230864384},"json":{"name":"KnaveofHearts","species":"card"}}},
{"id":"lory","key":"lory","value":null,"doc":{"meta":{"id":"lory","expiration":0,"flags":0,"etag":13830705845886844928},"json":{"name":"Lory","species":"bird"}}},
{"id":"march-hare","key":"march-hare","value":null,"doc":{"meta":{"id":"march-hare","expiration":0,"flags":0,"etag":14847959710254039040},"json":{"name":"MarchHare","species":"hare"}}},
{"id":"mock-turtle","key":"mock-turtle","value":null,"doc":{"meta":{"id":"mock-turtle","expiration":0,"flags":0,"etag":211262020811554816},"json":{"name":"MockTurtle","species":"turtle"}}},
{"id":"mouse","key":"mouse","value":null,"doc":{"meta":{"id":"mouse","expiration":0,"flags":0,"etag":7144275470706606080},"json":{"name":"Mouse","species":"mouse"}}},
{"id":"pat","key":"pat","value":null,"doc":{"meta":{"id":"pat","expiration":0,"flags":0,"etag":89110677012152320},"json":{"name":"Pat","species":"pig"}}},
{"id":"queen-of-hearts","key":"queen-of-hearts","value":null,"doc":{"meta":{"id":"queen-of-hearts","expiration":0,"flags":0,"etag":8409231712625688576},"json":{"name":"QueenofHearts","species":"card"}}},
{"id":"white-rabbit","key":"white-rabbit","value":null,"doc":{"meta":{"id":"white-rabbit","expiration":0,"flags":0,"etag":14777043409285742592},"json":{"name":"WhiteRabbit","species":"rabbit"}}}
]
}