I have multiple Environment Variables defined on my Postgres container, such as POSTGRES_USER. The container is running and I want to connect to Postgres from the command line using exec.
I'm unable to connect with the following:
docker exec -it <CONTAINER-ID> psql -U $POSTGRES_USER -d <DB NAME>
I understand that the variable is defined on the container and the following does work:
docker exec -it <CONTAINER-ID> bash -c 'psql -U $POSTGRES_USER -d <DB NAME>'
Is there a way for me to execute the psql command directly from docker exec and call the environment variable on the container?
docker exec -it <CONTAINER-ID> psql -U ????? -d <DB NAME>
Depending on your use case, what you could do, instead of passing a user to the psql command is to define the environment variable PGUSER to the container at boot time.
This way, it will be the default user for PostgreSQL, if you do not specify any, so you won't even have to specify it in order to connect:
$ docker run --name postgres -e POSTGRES_PASSWORD=bar -e POSTGRES_USER=foo -e PGUSER=foo -d postgres
e250f0821613a5e2021e94772a732f299874fc7a16b340ada4233afe73744423
$ docker exec -ti postgres psql -d postgres
psql (12.4 (Debian 12.4-1.pgdg100+1))
Type "help" for help.
postgres=#
The reason this isn't working for you is because when you run the command
docker exec -it <CONTAINER-ID> psql -U $POSTGRES_USER -d <DB NAME>
You're running it on your host. So, $POSTGRES_USER refers to the environment variable on your host, not your container. That variable isn't set on your host.
The second command
docker exec -it <CONTAINER-ID> bash -c 'psql -U $POSTGRES_USER -d <DB NAME>'
works because you're passing the command in the quotes to the shell in the container, where that variable actually exists.
The method in the second command is the way to do what you're trying to do, unless you set the variable on your host somehow and make sure it has the same value as it does in your container.
The easiest way to do this would be to reference your host variable at image build time.
So, in your Dockerfile, if you write ENV POSTGRES_USER=${POSTGRES_USER} it will look in the host environment for that value, and use it.
If you set the variables this way, then your command will work.
Related
I am running postgreSQL on docker.
In order to access the container I run
winpty docker exec -it postgres_db bash
Now that I am inside the docker container, I run this to access as user 'postgres' in postgres server
psql -U postgres
Then what I want to do is create a database
create database test;
I can I do this sequentially in a script?
I want something like this:
#!/bin/bash
winpty docker run -p 8005:5432 --name postgres_db -e POSTGRES_PASSWORD=password -d postgres
sleep 5
winpty docker exec -it postgres_db bash -c "psql -U postgres" [-c "create database test;"]
create database cannot be executed if im not inside "psql -U postgres". Obviously the last line -c "create database test;" is wrong, just to make you understand what I want to do.
winpty docker exec -it postgres_db bash -c "psql -U postgres -c 'CREATE DATABASE test;'"
Both bash -c and psql -c take one shell word as input. A single or double quoted string is one word. You need to nest the quotes, just like the -c commands are nested.
Alternative:
winpty docker exec -it postgres_db bash -c "psql -U postgres -c \"CREATE DATABASE test;\""
I have access to two postgres database servers on different hosts. On server A I access the client using:
psql -h localhost -U user -W db_name
db_name=>
And on the second host B I access the client using (docker image):
docker run -it --rm --network fiware_default jbergknoff/postgresql-client\
postgresql://postgres:password#postgres-db:5432/postgres
postgres=#
Now I need to dump database file copied from A (now on B) using:
psql -U postgres -d targetdb -f sourcedb.sql
However, the command psql isn´t recognised second host B. I mean I cannot run commands using psql B
what is then the difference between psqland postgres-clienthere please?
The docker image postgresql-client has psql defined as an entrypoint. See https://github.com/jbergknoff/Dockerfile/blob/master/postgresql-client/Dockerfile#L3 .
So you basically ran psql psql and psql does not understand that. Just leave psql out and start straight with the args.
You can read up on CMD vs ENTRYPOINT here What is the difference between CMD and ENTRYPOINT in a Dockerfile? or here http://goinbigdata.com/docker-run-vs-cmd-vs-entrypoint/ .
I create backups like this: docker exec DOCKER pg_dump -U USER -F t DB | gzip > ./FILE.tar.gz
What's the best way to restore the database given that the database runs within a container?
For your case:
docker exec -it <CONTAINER> gunzip < backup.tar.gz | pg_restore -U <USER> -F t -d <DB>
Remote restore is also available if your container is public facing and remote connections are allowed in pg_hba.conf for postresql:
gunzip < backup.tar.gz | pg_restore -U <USER> -F t -d <DB> -h <HOST_IP> -p 5432
As a rule of thumb, it is good idea to document your backup and restore commands specific to the project.
How take backup of the data which is existing in the running PostgreSQL container
Create some folder in your root
mkdir -p '/myfolder/bdbackup'
download the postgres image which you are using and execute the following command
docker run --name demo1 -e POSTGRES_PASSWORD=passowrd -v /myfolder/bdbackup:/var/lib/postgresql/data -d postgres
docker exec -it demo1 psql -U postgres
Back up will be stored in the following folder /myfolder/bdbackup
you can kill the container and stop the container any time but data will be stored in the host.
and once again re-run the postgres the container with same command
docker run --name demo2 -e POSTGRES_PASSWORD=passowrd -v /myfolder/bdbackup:/var/lib/postgresql/data -d postgres
docker exec -it demo1 psql -U postgres
and execute following query select * from emp;
you can see the data has restored...
I tried:
$ alias psql="docker exec -ti pg-hello-phoenix sh -c 'exec psql -h localhost -p 5432 -U postgres'"
$ mix ecto.create
but got:
** (RuntimeError) could not find executable psql in path, please guarantee it is available before running ecto commands
lib/ecto/adapters/postgres.ex:106: Ecto.Adapters.Postgres.run_with_psql/2
lib/ecto/adapters/postgres.ex:83: Ecto.Adapters.Postgres.storage_up/1
lib/mix/tasks/ecto.create.ex:34: anonymous fn/2 in Mix.Tasks.Ecto.Create.run/1
(elixir) lib/enum.ex:604: Enum."-each/2-lists^foreach/1-0-"/2
(elixir) lib/enum.ex:604: Enum.each/2
(mix) lib/mix/cli.ex:58: Mix.CLI.run_task/2
(elixir) lib/code.ex:363: Code.require_file/2
Also I tried to create symlink /usr/local/bin/psql:
#!/usr/bin/env bash
docker exec -ti pg-hello-phoenix sh -c "exec psql -h localhost -p 5432 -U postgres $#"
and then:
$ sudo chmod +x /usr/local/bin/psql
check:
$ which psql
/usr/local/bin/psql
$ psql --version
psql (PostgreSQL) 9.5.1
run again:
$ mix ecto.create
** (Mix) The database for HelloPhoenix.Repo couldn't be created, reason given: cannot enable tty mode on non tty input
.
Container with PostgreSQL is launched:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
013464d7227e postgres "/docker-entrypoint.s" 47 minutes ago Up 47 minutes 5432/tcp pg-hello-phoenix
I was able to do this by going into /config/.exs In my case it was development, so /config/dev.exs and left the hostname as localhost but added another setting for port: 32768 because that's the port that docker exposed.
Make sure to put a space between the port: and the number (not string). Otherwise it won't work.
Worked as usual after that. The natural assumption is that the username / password matches on the container as well.
To me I did the following:
sudo docker exec -it postgres-db bash
After I got the interactive shell
psql -h localhost -p 5432 -U postgres
Then I create my db manually:
CREATE DATABASE cars_dev;
Then finally:
mix ecto.migrate
Everything worked fine after that :) hope it helps.
I would like to have a way to enter into the Postgresql container and get a data dump from it.
Use the following command from a UNIX or a Windows terminal:
docker exec <container_name> pg_dump <schema_name> > backup
The following command will dump only inserts from all tables:
docker exec <container_name> pg_dump --column-inserts --data-only <schema_name> > inserts.sql
I have container named postgres with mounted volume -v /backups:/backups
To backup gziped DB my_db I use:
docker exec postgres pg_dump -U postgres -F t my_db | gzip >/backups/my_db-$(date +%Y-%m-%d).tar.gz
Now I have
user#my-server:/backups$ ls
my_db-2016-11-30.tar.gz
Although the mountpoint solution above looked promising, the following is the only solution that worked for me after multiple iterations:
docker run -it -e PGPASSWORD=my_password postgres:alpine pg_dump -h hostname -U my_user my_db > backup.sql
What was unique in my case: I have a password on the database that needs to be passed in; needed to pass in the tag (alpine); and finally the hosts version of the psql tools were different to the docker versions.
This one, using container_name instead of database_scheme's one, works for me:
docker exec {container_name} pg_dump -U {user_name} > {backup_file_name}
In instance, for me, database name, user and password are supposed declared in docker-compose.yaml
I wish it could help someone
for those who suffered with permissions, I used this following command with success to perform my dump:
docker exec -i MY_CONTAINER_NAME /bin/bash -c "PGPASSWORD=MY_PASSWORD pg_dump -Fc -h localhost -U postgres MY_DB_NAME" > /home/MY_USER/db-$(date +%d-%m-%y).backup
This will mount the pwd and include your environment variables
docker run -it --rm \
--env-file <(env) \
-w /working \
--volume $(pwd):/working \
postgres:latest /usr/bin/pg_dump -Fc -h localhost -U postgres MY_DB_NAME" > /working/db-$(date +%d-%m-%y).backup
Another workaround method is to start postgre sql with a mountpoint to the location of the dump in docker.
like docker run -v <location of the files>.
Then perform a docker inspect on the docker running container
docker inspect <image_id>
you can find "Volumes" tag inside and a corresponding location.Go to the location and you can find all the postgresql/mysql files.It worked for me.Let us know if that worked for you also.
Good luck
To run the container that has the Postgres user and password, you need to have preconfigured variables as container environment variable.
For example:
docker run -it --rm --link <container_name>:<data_container_name> -e POSTGRES_PASSWORD=<password> postgres /usr/bin/pg_dump -h <data_container_name> -d <database_name> -U <postgres_username> > dump.sql