Libpq functions & string to obtain connection parameters

arnaud gaboury <arnaud.gaboury@gmail.com> wrote:

I start an app which use a libpq function to read connection params in a URI.
Until now, the app was using a tcp connection to connect to postgresql with
this URI:

postgres://mmuser:mmuser_password@10.10.10.1:5432/mattermost?sslmode=disable&
connect_timeout=10

I want to switch and make the app connect to the unix socket instead. I am
trying to figure out what would then be the correct URI, with no luck until
now.

The general form for a connection URI is:

postgresql://[user[:password]@][netloc][:port][/dbname][?param1=value1&...]

The URI scheme designator can be either postgresql:// or postgres://.
Each of the URI parts is optional. The following examples illustrate
valid URI syntax uses:

postgresql:// postgresql://localhost postgresql://localhost:5433
postgresql://localhost/mydb postgresql://user@localhost
postgresql://user:secret@localhost
postgresql://other@localhost/otherdb?connect_timeout=10&application_name=myapp

Components of the hierarchical part of the URI can also be given as
parameters. For example:

postgresql:///mydb?host=localhost&port=5433

Percent-encoding may be used to include symbols with special meaning in
any of the URI parts.

Any connection parameters not corresponding to key words listed in
Section 31.1.2 are ignored and a warning message about them is sent to
stderr.

For improved compatibility with JDBC connection URIs, instances of
parameter ssl=true are translated into sslmode=require.

The host part may be either host name or an IP address. To specify an
IPv6 host address, enclose it in square brackets:

postgresql://[2001:db8::1234]/database

The host component is interpreted as described for the parameter host.
In particular, a Unix-domain socket connection is chosen if the host
part is either empty or starts with a slash, otherwise a TCP/IP
connection is initiated. Note, however, that the slash is a reserved
character in the hierarchical part of the URI. So, to specify a
non-standard Unix-domain socket directory, either omit the host
specification in the URI and specify the host as a parameter, or
percent-encode the path in the host component of the URI:

postgresql:///dbname?host=/var/lib/postgresql

postgresql://%2Fvar%2Flib%2Fpostgresql/dbname

does that help?

(Copy&Paste from
http://stackoverflow.com/questions/27037990/connecting-to-postgres-via-database-url-and-unix-socket-in-rails)

Regards, Andreas Kretschmer
--
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http://www.2ndQuadrant.com/
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On Fri, Oct 7, 2016 at 3:15 PM Andreas Kretschmer <akretschmer@spamfence.net>
wrote:

arnaud gaboury <arnaud.gaboury@gmail.com> wrote:

I start an app which use a libpq function to read connection params in a

URI.

Until now, the app was using a tcp connection to connect to postgresql

with

this URI:

postgres://

mmuser:mmuser_password@10.10.10.1:5432/mattermost?sslmode=disable&

connect_timeout=10

I want to switch and make the app connect to the unix socket instead. I

am

trying to figure out what would then be the correct URI, with no luck

until

now.

The general form for a connection URI is:

postgresql://[user[:password]@][netloc][:port][/dbname][?param1=value1&...]

The URI scheme designator can be either postgresql:// or postgres://.
Each of the URI parts is optional. The following examples illustrate
valid URI syntax uses:

postgresql:// postgresql://localhost postgresql://localhost:5433
postgresql://localhost/mydb postgresql://user@localhost
postgresql://user:secret@localhost
postgresql://other@localhost
/otherdb?connect_timeout=10&application_name=myapp

Components of the hierarchical part of the URI can also be given as
parameters. For example:

postgresql:///mydb?host=localhost&port=5433

Percent-encoding may be used to include symbols with special meaning in
any of the URI parts.

Any connection parameters not corresponding to key words listed in
Section 31.1.2 are ignored and a warning message about them is sent to
stderr.

For improved compatibility with JDBC connection URIs, instances of
parameter ssl=true are translated into sslmode=require.

The host part may be either host name or an IP address. To specify an
IPv6 host address, enclose it in square brackets:

postgresql://[2001:db8::1234]/database

The host component is interpreted as described for the parameter host.
In particular, a Unix-domain socket connection is chosen if the host
part is either empty or starts with a slash, otherwise a TCP/IP
connection is initiated. Note, however, that the slash is a reserved
character in the hierarchical part of the URI. So, to specify a
non-standard Unix-domain socket directory, either omit the host
specification in the URI and specify the host as a parameter, or
percent-encode the path in the host component of the URI:

postgresql:///dbname?host=/var/lib/postgresql

postgresql://%2Fvar%2Flib%2Fpostgresql/dbname

does that help?

Honestly not so much, as it is a nearly perfect Copy/past of postgresql
official doc[0]https://www.postgresql.org/docs/9.5/static/libpq-connect.html.
My postgresql socket is in the usual place:
/run/postgresql/.s.PGSQL.5432=
So no need to specify it. But for the rest, I am still not sure of my URI

[0]: https://www.postgresql.org/docs/9.5/static/libpq-connect.html

On 10/07/2016 06:42 AM, arnaud gaboury wrote:

does that help?

Honestly not so much, as it is a nearly perfect Copy/past of postgresql
official doc[0].
My postgresql socket is in the usual place:
/run/postgresql/.s.PGSQL.5432=
So no need to specify it. But for the rest, I am still not sure of my URI

Something like:

psql postgresql:///test?connect_timeout=10

From ps:

4228 pts/1 S+ 0:00 psql postgresql:///test?connect_timeout=10
4229 ? Ss 0:00 postgres: aklaver test [local] idle

[0]https://www.postgresql.org/docs/9.5/static/libpq-connect.html

(Copy&Paste from
http://stackoverflow.com/questions/27037990/connecting-to-postgres-via-database-url-and-unix-socket-in-rails)

Regards, Andreas Kretschmer
--
Andreas Kretschmer
http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

--
Adrian Klaver
adrian.klaver@aklaver.com

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On 10/07/2016 06:42 AM, arnaud gaboury wrote:

Honestly not so much, as it is a nearly perfect Copy/past of postgresql
official doc[0].
My postgresql socket is in the usual place:
/run/postgresql/.s.PGSQL.5432=
So no need to specify it. But for the rest, I am still not sure of my URI

[0]https://www.postgresql.org/docs/9.5/static/libpq-connect.html

Aah, just remembered you wanted username and password, so:

psql postgresql://aklaver:pwd@/test?connect_timeout=10

4408 pts/1 S+ 0:00 psql postgresql://aklaver:pwd@/test?connect_timeout=10
4409 ? Ss 0:00 postgres: aklaver test [local] idle

--
Adrian Klaver
adrian.klaver@aklaver.com

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On Fri, Oct 7, 2016 at 3:56 PM Adrian Klaver <adrian.klaver@aklaver.com>
wrote:

On 10/07/2016 06:42 AM, arnaud gaboury wrote:

Honestly not so much, as it is a nearly perfect Copy/past of postgresql
official doc[0].
My postgresql socket is in the usual place:
/run/postgresql/.s.PGSQL.5432=
So no need to specify it. But for the rest, I am still not sure of my URI

[0]https://www.postgresql.org/docs/9.5/static/libpq-connect.html

Aah, just remembered you wanted username and password, so:

psql postgresql://aklaver:pwd@/test?connect_timeout=10

It helps, but I must have something else misconfigured then:

-------------------------------------
# su postgres
postgres@thetradinghall ➤➤ mattermost/bin % bash
bash-4.3$ psql postgresql:///mattermost?connect_timeout=10
psql (9.5.4)
Type "help" for help.

mattermost=# \q
=====> OK
-----------------------------------------
Now with the Unix user I want to use:

--------------------------------------------------------
% su mattermost
bash-4.3$ psql postgresql:///mattermost?connect_timeout=10
psql: FATAL: no pg_hba.conf entry for host "[local]", user "mattermost",
database "mattermost", SSL off
--------------------------------------------

As a reminder, I made an entry in pg_ident.conf this way:
mattermap mattermost mmuser

and add this line in pg_hba.conf
local mattermost mmuser peer
map=mattermap

What is wromg in my UNIX/postgresql user mapping?

On 10/07/2016 07:28 AM, arnaud gaboury wrote:

On Fri, Oct 7, 2016 at 3:56 PM Adrian Klaver <adrian.klaver@aklaver.com
<mailto:adrian.klaver@aklaver.com>> wrote:

On 10/07/2016 06:42 AM, arnaud gaboury wrote:

Honestly not so much, as it is a nearly perfect Copy/past of

postgresql

official doc[0].
My postgresql socket is in the usual place:
/run/postgresql/.s.PGSQL.5432=
So no need to specify it. But for the rest, I am still not sure of

my URI

[0]https://www.postgresql.org/docs/9.5/static/libpq-connect.html

Aah, just remembered you wanted username and password, so:

psql postgresql://aklaver:pwd@/test?connect_timeout=10

It helps, but I must have something else misconfigured then:

-------------------------------------
# su postgres
postgres@thetradinghall ➤➤ mattermost/bin % bash
bash-4.3$ psql postgresql:///mattermost?connect_timeout=10
psql (9.5.4)
Type "help" for help.

mattermost=# \q
=====> OK
-----------------------------------------
Now with the Unix user I want to use:

--------------------------------------------------------
% su mattermost
bash-4.3$ psql postgresql:///mattermost?connect_timeout=10
psql: FATAL: no pg_hba.conf entry for host "[local]", user
"mattermost", database "mattermost", SSL off
--------------------------------------------

As a reminder, I made an entry in pg_ident.conf this way:
mattermap mattermost mmuser

and add this line in pg_hba.conf
local mattermost mmuser peer
map=mattermap

What is wromg in my UNIX/postgresql user mapping?

Did you reload the server after making the changes?:

https://www.postgresql.org/docs/9.6/static/auth-pg-hba-conf.html

The pg_hba.conf file is read on start-up and when the main server
process receives a SIGHUP signal. If you edit the file on an active
system, you will need to signal the postmaster (using pg_ctl reload or
kill -HUP) to make it re-read the file.

https://www.postgresql.org/docs/9.6/static/auth-username-maps.html

The pg_ident.conf file is read on start-up and when the main server
process receives a SIGHUP signal. If you edit the file on an active
system, you will need to signal the postmaster (using pg_ctl reload or
kill -HUP) to make it re-read the file.

--
Adrian Klaver
adrian.klaver@aklaver.com

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On Fri, Oct 7, 2016 at 4:42 PM Adrian Klaver <adrian.klaver@aklaver.com>
wrote:

On 10/07/2016 07:28 AM, arnaud gaboury wrote:

On Fri, Oct 7, 2016 at 3:56 PM Adrian Klaver <adrian.klaver@aklaver.com
<mailto:adrian.klaver@aklaver.com>> wrote:

On 10/07/2016 06:42 AM, arnaud gaboury wrote:

Honestly not so much, as it is a nearly perfect Copy/past of

postgresql

official doc[0].
My postgresql socket is in the usual place:
/run/postgresql/.s.PGSQL.5432=
So no need to specify it. But for the rest, I am still not sure of

my URI

[0]https://www.postgresql.org/docs/9.5/static/libpq-connect.html

Aah, just remembered you wanted username and password, so:

psql postgresql://aklaver:pwd@/test?connect_timeout=10

It helps, but I must have something else misconfigured then:

-------------------------------------
# su postgres
postgres@thetradinghall ➤➤ mattermost/bin % bash
bash-4.3$ psql postgresql:///mattermost?connect_timeout=10
psql (9.5.4)
Type "help" for help.

mattermost=# \q
=====> OK
-----------------------------------------
Now with the Unix user I want to use:

--------------------------------------------------------
% su mattermost
bash-4.3$ psql postgresql:///mattermost?connect_timeout=10
psql: FATAL: no pg_hba.conf entry for host "[local]", user
"mattermost", database "mattermost", SSL off
--------------------------------------------

As a reminder, I made an entry in pg_ident.conf this way:
mattermap mattermost mmuser

and add this line in pg_hba.conf
local mattermost mmuser peer
map=mattermap

What is wromg in my UNIX/postgresql user mapping?

Did you reload the server after making the changes?:

GGGrrrhhhhh

-------------------------------
# systemctl restart postgresql
# su mattermost
bash-4.3$ psql postgresql://mmuser:XXXYYYY@/mattermost?
psql (9.5.4)
Type "help" for help.

mattermost=> \q
-----------------------------------------

OK. Now I know unix user mattermost can connect to mattermost Db via unix
socket. BUT when trying to write this in my URI:

postgresql://mmuser:MyPwd@/mattermost?connect_timeout=10

I get this from my app :
Failed to ping db err:pq: SSL is not enabled on the server

Is it normal to still have this error ? Adding sslmode param will not
change anything as it is ignored for Unix domain socket communication.

https://www.postgresql.org/docs/9.6/static/auth-pg-hba-conf.html

The pg_hba.conf file is read on start-up and when the main server
process receives a SIGHUP signal. If you edit the file on an active
system, you will need to signal the postmaster (using pg_ctl reload or
kill -HUP) to make it re-read the file.

https://www.postgresql.org/docs/9.6/static/auth-username-maps.html

The pg_ident.conf file is read on start-up and when the main server
process receives a SIGHUP signal. If you edit the file on an active
system, you will need to signal the postmaster (using pg_ctl reload or
kill -HUP) to make it re-read the file.

--
Adrian Klaver
adrian.klaver@aklaver.com

On 10/07/2016 07:58 AM, arnaud gaboury wrote:

GGGrrrhhhhh

-------------------------------
# systemctl restart postgresql
# su mattermost
bash-4.3$ psql postgresql://mmuser:XXXYYYY@/mattermost?
psql (9.5.4)
Type "help" for help.

mattermost=> \q
-----------------------------------------

OK. Now I know unix user mattermost can connect to mattermost Db via
unix socket. BUT when trying to write this in my URI:

postgresql://mmuser:MyPwd@/mattermost?connect_timeout=10

So what app/framework/code is processing the above?

I get this from my app :
Failed to ping db err:pq: SSL is not enabled on the server

That does not look like something coming from Postgres, but from
whatever is initiating the connection.

Is it normal to still have this error ? Adding sslmode param will not
change anything as it is ignored for Unix domain socket communication.

--
Adrian Klaver
adrian.klaver@aklaver.com

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arnaud gaboury <arnaud.gaboury@gmail.com> writes:

OK. Now I know unix user mattermost can connect to mattermost Db via unix
socket. BUT when trying to write this in my URI:

postgresql://mmuser:MyPwd@/mattermost?connect_timeout=10

I get this from my app :
Failed to ping db err:pq: SSL is not enabled on the server

Is it normal to still have this error ? Adding sslmode param will not
change anything as it is ignored for Unix domain socket communication.

That message isn't coming out of libpq; I can't find any such string
in the community git repo.

regards, tom lane

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On Fri, Oct 7, 2016 at 5:01 PM Adrian Klaver <adrian.klaver@aklaver.com>
wrote:

On 10/07/2016 07:58 AM, arnaud gaboury wrote:

GGGrrrhhhhh

-------------------------------
# systemctl restart postgresql
# su mattermost
bash-4.3$ psql postgresql://mmuser:XXXYYYY@/mattermost?
psql (9.5.4)
Type "help" for help.

mattermost=> \q
-----------------------------------------

OK. Now I know unix user mattermost can connect to mattermost Db via
unix socket. BUT when trying to write this in my URI:

postgresql://mmuser:MyPwd@/mattermost?connect_timeout=10

So what app/framework/code is processing the above?

I get this from my app :
Failed to ping db err:pq: SSL is not enabled on the server

That does not look like something coming from Postgres, but from
whatever is initiating the connection.

Yes. I will contact the app maintener and see how we can deal with this
issue.

Thank you for your time and help. Have a good weekend.