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Listen only on the unix socket during init #440

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merged 1 commit into from May 4, 2018

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@sdwolfz
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sdwolfz commented May 3, 2018

Healthchecks that used pg_isready -p 5432 were incorrectly flagging
the container as being healthy during initialization phase since
healthchecks are being run inside the container itself, so
listen_addresses='localhost' was not enough. The port 65432 was
chosen at random.

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yosifkit May 3, 2018

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If we do change this, I'd rather just switch it to -c listen_addresses='' so that it only listens on the socket and will be less likely to break users. Then users can implement their healthchecks to connect via ip or 127.0.0.1 as we have in the example postgres healthcheck.

If the list is empty, the server does not listen on any IP interface at all, in which case only Unix-domain sockets can be used to connect to it.

https://www.postgresql.org/docs/current/static/runtime-config-connection.html

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yosifkit commented May 3, 2018

If we do change this, I'd rather just switch it to -c listen_addresses='' so that it only listens on the socket and will be less likely to break users. Then users can implement their healthchecks to connect via ip or 127.0.0.1 as we have in the example postgres healthcheck.

If the list is empty, the server does not listen on any IP interface at all, in which case only Unix-domain sockets can be used to connect to it.

https://www.postgresql.org/docs/current/static/runtime-config-connection.html

@yosifkit yosifkit requested a review from tianon May 3, 2018

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tianon commented May 3, 2018

@sdwolfz sdwolfz changed the title from Use nonstandard port for the initialization phase to Listen only on the unix socket during init May 3, 2018

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I've removed localhost from the listen_addresses as you suggested. I'm happy with this approach since it seems to have the same behaviour.

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sdwolfz commented May 3, 2018

I've removed localhost from the listen_addresses as you suggested. I'm happy with this approach since it seems to have the same behaviour.

Listen only on the unix socket during init
Healthchecks that used `pg_isready -p 5432` were incorrectly flagging
the container as being healthy during initialization phase since
healthchecks are being run inside the container itself, so
`listen_addresses='localhost'` was not enough. Setting
`listen_addresses=''` forces the server to only listen on the unix
socket so no ports are open that might incorrectly interfeer with the
healthchecks.
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I see the CI fails randomly due to keyservers so I'll push a commit that implements the approach detailed here.

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sdwolfz commented May 4, 2018

I see the CI fails randomly due to keyservers so I'll push a commit that implements the approach detailed here.

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Let's not complicate this PR with unrelated gpg changes please. docker-library/official-images#4252 (comment)

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yosifkit commented May 4, 2018

Let's not complicate this PR with unrelated gpg changes please. docker-library/official-images#4252 (comment)

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OK, I removed the keyserver commit. You probably need to rerun the failing jobs manually.

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sdwolfz commented May 4, 2018

OK, I removed the keyserver commit. You probably need to rerun the failing jobs manually.

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(Builds in progress are duplicates -- the functionality has been tested sufficiently by other builds. 👍)

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tianon commented May 4, 2018

(Builds in progress are duplicates -- the functionality has been tested sufficiently by other builds. 👍)

@tianon tianon merged commit 01cf838 into docker-library:master May 4, 2018

1 check was pending

continuous-integration/travis-ci/pr The Travis CI build is in progress
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@sdwolfz sdwolfz deleted the sdwolfz:fix/postgres-healthcheck branch May 4, 2018

tianon added a commit to infosiftr/stackbrew that referenced this pull request May 8, 2018

Update docker-library images
- `docker`: docker-library/docker#110 (updated `dind` wrapper)
- `ghost`: 1.22.6
- `mariadb`: docker-library/mariadb#161 (remove unnecessary `FLUSH PRIVILEGES`)
- `openjdk`: `debian 11~12-1`, `debian 10.0.1+10-4`
- `postgres`: docker-library/postgres#440 (listen only on the unix socket during initdb)
- `tomcat`: 8.5.31, 9.0.8
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red-defender May 10, 2018

Pretty good, you've broken our initialization scripts used TCP connection. And we were forced to find the reason why our builds become failed in registry for about two hours...

Yes, we have taken unix socket as a workaround, BUT, there's no "local trust" entries in default pg_hba file, and we use other roles besides postgres, so the only fix is to add missing lines manually:

{
    echo
    echo 'local all all trust'
} >> "$PGDATA/pg_hba.conf"
pg_ctl -D "$PGDATA" reload

red-defender commented May 10, 2018

Pretty good, you've broken our initialization scripts used TCP connection. And we were forced to find the reason why our builds become failed in registry for about two hours...

Yes, we have taken unix socket as a workaround, BUT, there's no "local trust" entries in default pg_hba file, and we use other roles besides postgres, so the only fix is to add missing lines manually:

{
    echo
    echo 'local all all trust'
} >> "$PGDATA/pg_hba.conf"
pg_ctl -D "$PGDATA" reload
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@red-defender, there is local trust by default. Here is the contents of the default pg_hba.conf:

# PostgreSQL Client Authentication Configuration File
# ===================================================
#
# Refer to the "Client Authentication" section in the PostgreSQL
# documentation for a complete description of this file.  A short
# synopsis follows.
#
# This file controls: which hosts are allowed to connect, how clients
# are authenticated, which PostgreSQL user names they can use, which
# databases they can access.  Records take one of these forms:
#
# local      DATABASE  USER  METHOD  [OPTIONS]
# host       DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
# hostssl    DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
# hostnossl  DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
#
# (The uppercase items must be replaced by actual values.)
#
# The first field is the connection type: "local" is a Unix-domain
# socket, "host" is either a plain or SSL-encrypted TCP/IP socket,
# "hostssl" is an SSL-encrypted TCP/IP socket, and "hostnossl" is a
# plain TCP/IP socket.
#
# DATABASE can be "all", "sameuser", "samerole", "replication", a
# database name, or a comma-separated list thereof. The "all"
# keyword does not match "replication". Access to replication
# must be enabled in a separate record (see example below).
#
# USER can be "all", a user name, a group name prefixed with "+", or a
# comma-separated list thereof.  In both the DATABASE and USER fields
# you can also write a file name prefixed with "@" to include names
# from a separate file.
#
# ADDRESS specifies the set of hosts the record matches.  It can be a
# host name, or it is made up of an IP address and a CIDR mask that is
# an integer (between 0 and 32 (IPv4) or 128 (IPv6) inclusive) that
# specifies the number of significant bits in the mask.  A host name
# that starts with a dot (.) matches a suffix of the actual host name.
# Alternatively, you can write an IP address and netmask in separate
# columns to specify the set of hosts.  Instead of a CIDR-address, you
# can write "samehost" to match any of the server's own IP addresses,
# or "samenet" to match any address in any subnet that the server is
# directly connected to.
#
# METHOD can be "trust", "reject", "md5", "password", "scram-sha-256",
# "gss", "sspi", "ident", "peer", "pam", "ldap", "radius" or "cert".
# Note that "password" sends passwords in clear text; "md5" or
# "scram-sha-256" are preferred since they send encrypted passwords.
#
# OPTIONS are a set of options for the authentication in the format
# NAME=VALUE.  The available options depend on the different
# authentication methods -- refer to the "Client Authentication"
# section in the documentation for a list of which options are
# available for which authentication methods.
#
# Database and user names containing spaces, commas, quotes and other
# special characters must be quoted.  Quoting one of the keywords
# "all", "sameuser", "samerole" or "replication" makes the name lose
# its special character, and just match a database or username with
# that name.
#
# This file is read on server startup and when the server receives a
# SIGHUP signal.  If you edit the file on a running system, you have to
# SIGHUP the server for the changes to take effect, run "pg_ctl reload",
# or execute "SELECT pg_reload_conf()".
#
# Put your actual configuration here
# ----------------------------------
#
# If you want to allow non-local connections, you need to add more
# "host" records.  In that case you will also need to make PostgreSQL
# listen on a non-local interface via the listen_addresses
# configuration parameter, or via the -i or -h command line switches.

# CAUTION: Configuring the system for local "trust" authentication
# allows any local user to connect as any PostgreSQL user, including
# the database superuser.  If you do not trust all your local users,
# use another authentication method.


# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     trust
host    replication     all             127.0.0.1/32            trust
host    replication     all             ::1/128                 trust

host all all all md5

(The last two lines being added by the entrypoint when a password is supplied via POSTGRES_PASSWORD.)

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yosifkit commented May 10, 2018

@red-defender, there is local trust by default. Here is the contents of the default pg_hba.conf:

# PostgreSQL Client Authentication Configuration File
# ===================================================
#
# Refer to the "Client Authentication" section in the PostgreSQL
# documentation for a complete description of this file.  A short
# synopsis follows.
#
# This file controls: which hosts are allowed to connect, how clients
# are authenticated, which PostgreSQL user names they can use, which
# databases they can access.  Records take one of these forms:
#
# local      DATABASE  USER  METHOD  [OPTIONS]
# host       DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
# hostssl    DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
# hostnossl  DATABASE  USER  ADDRESS  METHOD  [OPTIONS]
#
# (The uppercase items must be replaced by actual values.)
#
# The first field is the connection type: "local" is a Unix-domain
# socket, "host" is either a plain or SSL-encrypted TCP/IP socket,
# "hostssl" is an SSL-encrypted TCP/IP socket, and "hostnossl" is a
# plain TCP/IP socket.
#
# DATABASE can be "all", "sameuser", "samerole", "replication", a
# database name, or a comma-separated list thereof. The "all"
# keyword does not match "replication". Access to replication
# must be enabled in a separate record (see example below).
#
# USER can be "all", a user name, a group name prefixed with "+", or a
# comma-separated list thereof.  In both the DATABASE and USER fields
# you can also write a file name prefixed with "@" to include names
# from a separate file.
#
# ADDRESS specifies the set of hosts the record matches.  It can be a
# host name, or it is made up of an IP address and a CIDR mask that is
# an integer (between 0 and 32 (IPv4) or 128 (IPv6) inclusive) that
# specifies the number of significant bits in the mask.  A host name
# that starts with a dot (.) matches a suffix of the actual host name.
# Alternatively, you can write an IP address and netmask in separate
# columns to specify the set of hosts.  Instead of a CIDR-address, you
# can write "samehost" to match any of the server's own IP addresses,
# or "samenet" to match any address in any subnet that the server is
# directly connected to.
#
# METHOD can be "trust", "reject", "md5", "password", "scram-sha-256",
# "gss", "sspi", "ident", "peer", "pam", "ldap", "radius" or "cert".
# Note that "password" sends passwords in clear text; "md5" or
# "scram-sha-256" are preferred since they send encrypted passwords.
#
# OPTIONS are a set of options for the authentication in the format
# NAME=VALUE.  The available options depend on the different
# authentication methods -- refer to the "Client Authentication"
# section in the documentation for a list of which options are
# available for which authentication methods.
#
# Database and user names containing spaces, commas, quotes and other
# special characters must be quoted.  Quoting one of the keywords
# "all", "sameuser", "samerole" or "replication" makes the name lose
# its special character, and just match a database or username with
# that name.
#
# This file is read on server startup and when the server receives a
# SIGHUP signal.  If you edit the file on a running system, you have to
# SIGHUP the server for the changes to take effect, run "pg_ctl reload",
# or execute "SELECT pg_reload_conf()".
#
# Put your actual configuration here
# ----------------------------------
#
# If you want to allow non-local connections, you need to add more
# "host" records.  In that case you will also need to make PostgreSQL
# listen on a non-local interface via the listen_addresses
# configuration parameter, or via the -i or -h command line switches.

# CAUTION: Configuring the system for local "trust" authentication
# allows any local user to connect as any PostgreSQL user, including
# the database superuser.  If you do not trust all your local users,
# use another authentication method.


# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     trust
host    replication     all             127.0.0.1/32            trust
host    replication     all             ::1/128                 trust

host all all all md5

(The last two lines being added by the entrypoint when a password is supplied via POSTGRES_PASSWORD.)

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red-defender May 10, 2018

@yosifkit Really, you are right, I'm used to production installations. 😇

red-defender commented May 10, 2018

@yosifkit Really, you are right, I'm used to production installations. 😇

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nmpacheco May 12, 2018

Hi @sdwolfz,
Correct me if I am wrong but I believe that this change has disabled the psql execution a couple of lines bellow. Changing "psql=( psql -v ON_ERROR_STOP=1 )" to "psql=( psql -h /var/run/postgresql -v ON_ERROR_STOP=1 )" should do the trick. This way psql also uses unix domain socket. I also believe this explains some people complaints about POSTGRES_USER and POSTGRES_DB stopped working.

nmpacheco commented on 6fe8c15 May 12, 2018

Hi @sdwolfz,
Correct me if I am wrong but I believe that this change has disabled the psql execution a couple of lines bellow. Changing "psql=( psql -v ON_ERROR_STOP=1 )" to "psql=( psql -h /var/run/postgresql -v ON_ERROR_STOP=1 )" should do the trick. This way psql also uses unix domain socket. I also believe this explains some people complaints about POSTGRES_USER and POSTGRES_DB stopped working.

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Nope, should be working fine since the local socket is the default.

$ docker run -it --rm postgres psql -? | grep 'host'
  -h, --host=HOSTNAME      database server host or socket directory (default: "local socket")
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yosifkit replied May 14, 2018

Nope, should be working fine since the local socket is the default.

$ docker run -it --rm postgres psql -? | grep 'host'
  -h, --host=HOSTNAME      database server host or socket directory (default: "local socket")

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To confirm:

$ docker pull postgres:10
10: Pulling from library/postgres
Digest: sha256:23c92d48934b254c007c08812638acfd849fe1c179a34b63c752a62100c6524d
Status: Image is up to date for postgres:10

$ docker run -dit --name test -e POSTGRES_USER=example -e POSTGRES_PASSWORD=foobar postgres:10
75b44d718fb55ccbfd1b3ac75dcd09b11f76ef431ecdeca0f0b1a31c236c18a2

$ docker logs --tail=2 test
2018-05-14 22:05:02.404 UTC [67] LOG:  database system was shut down at 2018-05-14 22:05:02 UTC
2018-05-14 22:05:02.408 UTC [1] LOG:  database system is ready to accept connections

$ docker run -it --rm --link test postgres:10 psql -h test -U example
Password for user example: 
psql (10.3 (Debian 10.3-1.pgdg90+1))
Type "help" for help.

example=# SELECT 1;
 ?column? 
----------
        1
(1 row)

example=# 
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tianon replied May 14, 2018

To confirm:

$ docker pull postgres:10
10: Pulling from library/postgres
Digest: sha256:23c92d48934b254c007c08812638acfd849fe1c179a34b63c752a62100c6524d
Status: Image is up to date for postgres:10

$ docker run -dit --name test -e POSTGRES_USER=example -e POSTGRES_PASSWORD=foobar postgres:10
75b44d718fb55ccbfd1b3ac75dcd09b11f76ef431ecdeca0f0b1a31c236c18a2

$ docker logs --tail=2 test
2018-05-14 22:05:02.404 UTC [67] LOG:  database system was shut down at 2018-05-14 22:05:02 UTC
2018-05-14 22:05:02.408 UTC [1] LOG:  database system is ready to accept connections

$ docker run -it --rm --link test postgres:10 psql -h test -U example
Password for user example: 
psql (10.3 (Debian 10.3-1.pgdg90+1))
Type "help" for help.

example=# SELECT 1;
 ?column? 
----------
        1
(1 row)

example=# 

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new-guy May 24, 2018

Oof, these changes caused us huge amounts of trouble. All of our init scripts were built around the previous ability to connect to the db at localhost:5432 during initialization. These changes led to all of them breaking with no error message other than the scripts not being able to reach the DB. I totally appreciate the value of being able to support healthchecks in the way that they are intended to be implemented, but in the process of implementing these changes, I was given multiple days of headache and difficulty to try to figure out why things were breaking.

We've forked this repo now & build our own postgres image so that we don't have to deal with any other potential breaking changes, which is probably something we should've done in the first place, but I'm sure that others would find it incredibly helpful if these sorts of changes were communicated more clearly in the future.

new-guy replied May 24, 2018

Oof, these changes caused us huge amounts of trouble. All of our init scripts were built around the previous ability to connect to the db at localhost:5432 during initialization. These changes led to all of them breaking with no error message other than the scripts not being able to reach the DB. I totally appreciate the value of being able to support healthchecks in the way that they are intended to be implemented, but in the process of implementing these changes, I was given multiple days of headache and difficulty to try to figure out why things were breaking.

We've forked this repo now & build our own postgres image so that we don't have to deal with any other potential breaking changes, which is probably something we should've done in the first place, but I'm sure that others would find it incredibly helpful if these sorts of changes were communicated more clearly in the future.

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tianon May 24, 2018

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@new-guy what do you suggest? It was already communicated in the only two places we ever communicate changes (and even have the ability to communicate changes), namely a PR in this repo, and a PR over in the https://github.com/docker-library/official-images repo 😞

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tianon replied May 24, 2018

@new-guy what do you suggest? It was already communicated in the only two places we ever communicate changes (and even have the ability to communicate changes), namely a PR in this repo, and a PR over in the https://github.com/docker-library/official-images repo 😞

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new-guy May 24, 2018

It's a tough problem for sure. Maybe some sort of changelog that gets printed when the container boots up? It could be enabled by default, and people that don't want it to be printed could pass in an env var to disable it?

new-guy replied May 24, 2018

It's a tough problem for sure. Maybe some sort of changelog that gets printed when the container boots up? It could be enabled by default, and people that don't want it to be printed could pass in an env var to disable it?

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ol2ka Jun 6, 2018

Hi guys,
In our init scripts we use bash script that is using flyway to create an initial db. This uses localhost:5432 in order to connect.
Currently I can't find a way to make it work with sockets. Any idea how this can be solved?
Thanks

ol2ka replied Jun 6, 2018

Hi guys,
In our init scripts we use bash script that is using flyway to create an initial db. This uses localhost:5432 in order to connect.
Currently I can't find a way to make it work with sockets. Any idea how this can be solved?
Thanks

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szydra Jun 12, 2018

Hi, while running an image I am trying to call a script which connects to the database as a non-default user, but I am not able to run it, because Postgres refuses connection. As a workaround I found that the command
pg_ctl -o "-c listen_addresses='localhost'" -w restart
worked. Is there a better solution?

szydra replied Jun 12, 2018

Hi, while running an image I am trying to call a script which connects to the database as a non-default user, but I am not able to run it, because Postgres refuses connection. As a workaround I found that the command
pg_ctl -o "-c listen_addresses='localhost'" -w restart
worked. Is there a better solution?

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yosifkit Jun 18, 2018

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@szydra most likely your script needs adjusting to connect to the unix socket, rather than the localhost network port. Is something setting PGHOST like #440 (comment)?. Otherwise your solution is fine; It may cause issues if you start using health checks that also use the network port.

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yosifkit replied Jun 18, 2018

@szydra most likely your script needs adjusting to connect to the unix socket, rather than the localhost network port. Is something setting PGHOST like #440 (comment)?. Otherwise your solution is fine; It may cause issues if you start using health checks that also use the network port.

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@nmpacheco I just tried this locally with the latest postgres:

docker run --rm -it -e POSTGRES_USER=newuser POSTGRES_DB=newdb postgres

Then inside the container I executed:

psql -U newuser -d newdb

And inside psql I listed the databases:

newdb=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
-----------+----------+----------+------------+------------+-----------------------
 newdb     | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(4 rows)

Are you doing some other initlaizations in your image? Maybe this helps you:
#441 (comment)

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sdwolfz commented May 13, 2018

@nmpacheco I just tried this locally with the latest postgres:

docker run --rm -it -e POSTGRES_USER=newuser POSTGRES_DB=newdb postgres

Then inside the container I executed:

psql -U newuser -d newdb

And inside psql I listed the databases:

newdb=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
-----------+----------+----------+------------+------------+-----------------------
 newdb     | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(4 rows)

Are you doing some other initlaizations in your image? Maybe this helps you:
#441 (comment)

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nmpacheco May 13, 2018

@sdwolfz you're right! I was using a swarm stack compose file that also sets PGHOST to 127.0.0.1 as part of the environment for the postgres service. I'll have to check why I need that.
Thanks!

nmpacheco commented May 13, 2018

@sdwolfz you're right! I was using a swarm stack compose file that also sets PGHOST to 127.0.0.1 as part of the environment for the postgres service. I'll have to check why I need that.
Thanks!

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