attaché

is a younger brother of envoy and it makes a bridge between Consul and application data structures a little more beautiful.

• How to play
• Map to Consul
• Consul to Map
  • Keys with Offset
• Options
• License

How to play

In order to follow all the docs below, bring attaché in:

go get github.com/tolitius/attache

Map to Consul

attache.MapToConsul(consulapi.DefaultConfig(), configMap)

takes a consul config and a configMap, which is a map[string]string, and inserts all the {key, value} pairs into Consul.

For exampe let's say we have a configMap Go map:

{"hubble/store": "spacecraft://tape"
 "hubble/camera/mode": "color"
 "hubble/mission/target": "Horsehead Nebula"}

attaché could write all these entries into Consul respecting / hierarchy:

attache.MapToConsul(consulapi.DefaultConfig(), configMap)

will bring Hubble "online" preserving config's hierarchy:

and you can see the Consul log confirming it:

2017/10/18 15:21:53 [DEBUG] http: Request PUT /v1/kv/hubble/store (367.261µs) from=127.0.0.1:59376
2017/10/18 15:21:53 [DEBUG] http: Request PUT /v1/kv/hubble/camera/mode (278.666µs) from=127.0.0.1:59376
2017/10/18 15:21:53 [DEBUG] http: Request PUT /v1/kv/hubble/mission/target (361.468µs) from=127.0.0.1:59376

Consul to Map

attache.ConsulToMap(consulapi.DefaultConfig(), pathOffset)

returns a map[string]string of all the k/v under the pathOffset.

For exampe let's say we have this structure in Consul at localhost:8500:

{"hubble":
    {"store": "spacecraft://tape",
     "camera":
        {"mode": "color"},
     "mission":
        {"target": "Horsehead Nebula"}}}

attaché could read it all into a Go map by:

config := consulapi.DefaultConfig()
config.Address = "localhost:8500"

attache.ConsulToMap(config, "/hubble")

which would produce a Go map:

{"hubble/store": "spacecraft://tape"
 "hubble/camera/mode": "color"
 "hubble/mission/target": "Horsehead Nebula"}

where keys and values are strings

It will do that by calling Consul once (i.e. one GET), starting from the path offset we provided ("/hubble"):

2017/10/18 15:21:53 [DEBUG] http: Request GET /v1/kv/hubble?recurse= (214.843µs) from=127.0.0.1:59378

Keys with Offset

When working with several environments, application configs could live under different env specisfic offsets, for example /dev or /qa, etc.

By default attaché returns a map with keys that include a full path starting from the root. Frequently applications should not care about this difference in env specific offsets, hence we can ask attaché to exclude offset from key names:

attache.ConsulToMap(consulapi.DefaultConfig(), pathOffset, keysWithOffset)

the last optional argument is a boolean keysWithOffset which we could pass as false

config := consulapi.DefaultConfig()
config.Address = "localhost:8500"

attache.ConsulToMap(config, "/hubble", false)

which would produce a Go map:

{"/store": "spacecraft://tape"
 "/camera/mode": "color"
 "/mission/target": "Horsehead Nebula"}

notice no "hubble" offset in key names.

Options

attaché relies on the official Consul API and all attaché functions take consul/api.Config, hence any of its options can be set either by overriding the config:

consulConfig := consulapi.DefaultconsulConfig()
consulConfig.Address = "localhost:8500"
consulConfig.Datacenter = "fn42-datacenter"
consulConfig.Token = "7a0f3b39-8871-e16e-2101-c1b30a911883"

appConfig := attache.ConsulToMap(consulConfig, "/hubble")

Or by using "official" ENV variables from Consul API.

License

Copyright © 2017 tolitius

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.