pg_isready features

On Wed, Jun 15, 2016 at 12:09 PM, Jimmy <jimmyjack@gmail.com> wrote:

Not sure if this was discussed in the past and decided it does not belong
to pg_isready utility....

I am using pg_isready in dockerized development environment as part of
docker-compose. Simply say I have POSTGRES container and APP container. I
use pg_isready inside app container and wait till postgres is ready
to accept connections before app starts.

There are two features which would make this a bit smoother and better.

*1. enforce login*
This could be optional and turned off by default. Basically if user
supplies username/database as part of pg_isready call and the login fails
(for whatever reason), pg_isready should fail.

Why I need it? There is tiny window between postgres being ready to
accept connections and final scripts which create initial user/database.
Ideally having option to say "postgres is ready after specific user can
login to specific database" would be ideal. Again, this can be optional and
turned off by default.

​It shouldn't have to enforce login if there is a way for the server to
communicate ready or not ready for login without requiring credentials to
actually be supplied. I guess it would be more effort and invasive. Are
you trying to avoid psql here?​

*2. retry*
This is something I can do via unix script, but ideally it would be nice
if there would be retry mechanism. For example if I say retry=30 then
pg_isready would try 30x with x seconds pause in between and fail only
after 30 retries. This could use default retry=0 (current behavior)

And the value of this instead of setting a timeout 30x higher is?
​

Not sure if this was discussed in the past and decided it does not belong
to pg_isready utility....

I am using pg_isready in dockerized development environment as part of
docker-compose. Simply say I have POSTGRES container and APP container. I
use pg_isready inside app container and wait till postgres is ready
to accept connections before app starts.

There are two features which would make this a bit smoother and better.

*1. enforce login*
This could be optional and turned off by default. Basically if user
supplies username/database as part of pg_isready call and the login fails
(for whatever reason), pg_isready should fail.

Why I need it? There is tiny window between postgres being ready to accept
connections and final scripts which create initial user/database. Ideally
having option to say "postgres is ready after specific user can login to
specific database" would be ideal. Again, this can be optional and turned
off by default.

*2. retry*
This is something I can do via unix script, but ideally it would be nice
if there would be retry mechanism. For example if I say retry=30 then
pg_isready would try 30x with x seconds pause in between and fail only
after 30 retries. This could use default retry=0 (current behavior)

thanks a lot!

Why I need it? There is tiny window between postgres being ready to

accept connections

and final scripts which create initial user/database.
Ideally having option to say "postgres is ready after specific user can

login to specific database" would be ideal.

temporary - the official docker-postgres solution is not OK?
see :
https://github.com/docker-library/postgres/blob/master/9.5/docker-entrypoint.sh#L50

*# internal start of server in order to allow set-up using psql-client *
*# does not listen on external TCP/IP and waits until start finishes*
*gosu postgres pg_ctl -D "$PGDATA" -o "-c listen_addresses='localhost'" *

*.....*

more info: https://github.com/docker-library/postgres/issues/146

2016-06-15 18:09 GMT+02:00 Jimmy <jimmyjack@gmail.com>:

Not sure if this was discussed in the past and decided it does not belong
to pg_isready utility....

I am using pg_isready in dockerized development environment as part of
docker-compose. Simply say I have POSTGRES container and APP container. I
use pg_isready inside app container and wait till postgres is ready
to accept connections before app starts.

There are two features which would make this a bit smoother and better.

*1. enforce login*
This could be optional and turned off by default. Basically if user
supplies username/database as part of pg_isready call and the login fails
(for whatever reason), pg_isready should fail.

Why I need it? There is tiny window between postgres being ready to
accept connections and final scripts which create initial user/database.
Ideally having option to say "postgres is ready after specific user can
login to specific database" would be ideal. Again, this can be optional and
turned off by default.

*2. retry*
This is something I can do via unix script, but ideally it would be nice
if there would be retry mechanism. For example if I say retry=30 then
pg_isready would try 30x with x seconds pause in between and fail only
after 30 retries. This could use default retry=0 (current behavior)

thanks a lot!