Fix nasty 500 error on POST to /_config

[wenli200133]

Overview

When the ini config file is read only, ini file shouldn't be updated when the endpoint of _node/_local/_config/ is invoked.

For example:

curl -X PUT localhost:15984/_node/_local/_config/admins/joan -d '"500"'

when you check the local.ini file, you shouldn't find out the joan key and hash value of 500

and it also should not return this error like below:

{"error":"badmatch","reason":"{badrpc,{'EXIT',{{{badmatch,{error,eacces}},\n  

expected returned error should like this:

{"error":"bad_request","reason":"eacces"}

Testing recommendations

wenwl@wenwl_mbp:~/cloudant/couchdb$ chmod a-w ./dev/lib/node1/etc/local.ini
wenwl@wenwl_mbp:~/cloudant/couchdb$ curl -X PUT localhost:15984/_node/_local/_config/admins/joan1 -d '"500"' -u adm:pass
{"error":"bad_request","reason":"eacces"}
wenwl@wenwl_mbp:~/cloudant/couchdb$ curl -X DELETE localhost:15984/_node/_local/_config/admins/joan1 -u adm:pass
{"error":"bad_request","reason":"eacces"}

Related Issues or Pull Requests

#1380
apache/couchdb-config#21

Checklist

• Code is written and works correctly;
• Changes are covered by tests;
• Documentation reflects the changes;

[wohali]

Your tests are failing.

Does this impact what happens if I do something like:

curl -X PUT localhost:15984/_node/_local/_config/admins/joan -d '500'

i.e., an invalid body?

[wenli200133]

Hi @wohali , now checks have passed.
I think '500' is invalid body, "500" is valid body.
I have another PR for fixing this issue, #1717 and apache/couchdb-config#21, #1717 is dependent on apache/couchdb-config#21.

[wenli200133]

PR apache/couchdb-config#21 need first enter into the master, then #1717 can pick the updated config codes up.

[wenli200133]

Hi @wohali can you help review this PR again if you have free time? @jiangphcn can you also help with it?
Thanks.

[wohali]

@wenli200133 sorry, I'm busy with release activities and this sort of technical review isn't what I normally engage in - please work with @jiangphcn @eiri or other Erlang developers on CouchDB. 👍

[jiangphcn]

+1